[Fungal Keratitis Associated with Curvularia lunata: First Case Report from Türkiye]

Fungal keratitis is a medical emergency that is among the most common causes of blindness in developing countries. The type of the agent may vary depending on the geographical conditions under which the patient lives, trauma exposure, the use of contact lenses and profession. Curvularia spp. is a saprophytic genus that rarely causes systemic disease in humans and has 250 species identified to date. They proliferate in soil and plants and spread to the environment with their spores and the formation of blackish and fluffy colonies is its most well-known morphological feature. There may be difficulties in cultivating brown (dematiaceous) fungi. Due to the similarity between the genera, conventional methods remain inadequate for diagnosis. In this report, a case of fungal keratitis associated with C.lunata was presented. Seventy-five years-old female patient admitted to the hospital with the symptoms of stinging pain, blurred vision, and swelling in the right eye. Her symptoms had begun four days ago after her eye was hit by a plant. The patient who had a history of peripheral neuropathy due to diabetes mellitus (DM) was hospitalized with a preliminary diagnosis of keratitis, and in the cultures of the patient's corneal scraping samples, the filamentous, black pigment-forming colonies of the pathogen growing on 5% sheep blood agar and potato dextrose agar showing an aerial hyphal structure, were stained with lactophenol cotton blue and examined under the microscope. The microscopic examination revealed geniculate conidiophores with brown pigmentation. On top of these structures were tetralocular macroconidia, one of which appeared to be larger than the main axis. The fungus was subjected to molecular identification with the prediagnosis of Curvularia/Bipolaris. DNA extraction of the ITS region polymerase chain reaction amplification and Sanger sequencing were performed for molecular identification. Sanger sequencing identified the agent to be Curvularia lunata with a similarity rate of 99.79% (NCBI-GenBank Nucleotide ID: OR365075). In vitro antifungal susceptibility of C.lunata was evaluated by microdilution method. Itraconazole and amphotericin B showed higher activity against C.lunata compared to other antifungals while fluconazole was the least active antifungal. Intrastromal and subconjunctival voriconazole injection was applied to the patient who was unresponsive to empirically initiated oral moxifloxacin and different topical treatments (vancomycin, ceftazidime, flucanozole, ganciclovir, cyclopentolate hydrochloride, hyaluronic acid and trehalose). After injection, right penetrating keratoplasty was applied due to increased thinning of the ulcerated area. No pathogen was detected in cultures taken after keratoplasty. Rare fungi should be considered in cases of keratitis that are difficult to treat. Fungal keratitis caused by brown fungi are clinically similar to each other and effective treatment protocols cannot be implemented without a species identification. Identification of the pathogen will enable genus-specific treatment. This will also help prevent complications that may occur. This article aims to present a case of fungal keratitis associated with C.lunata.

Corynebacterium lipophilum sp. nov., a lipophilic bacterium isolated from clinical breast specimens and emended description of the species Corynebacterium pilbarense

Two isolates (MC-18T and MC-17D), representing the Gram-stain-positive, facultatively anaerobic, irregular rod-shaped, non-motile, and non-spore-forming actinobacteria, were isolated from clinical breast specimens in Guangzhou, China. The growth of the isolates is enhanced by supplementing 1% Tween-80 on Luria Bertani agar. Optimal growth of the isolates was observed at 37 °C, pH 7-8, and with 1% (w/v) NaCl on Columbia blood agar. Pairwise comparison of the 16S rRNA gene sequences revealed that isolates MC-18T and MC-17D shared the highest sequence similarities with Corynebacterium liangguodongii 2184T (96.9%), which were lower than the threshold value for species delineation (98.65%). Phylogenetic dendrograms based on the 16S rRNA gene, rpoB gene, and core genomes indicated that two isolates formed a distinct lineage within the genus Corynebacterium. The estimated dDDH, ANIb, ANIm, and AAI values between strain MC-18T and its closely related strains were below the threshold values generally considered for recognizing a new species. The genome DNA G + C contents of both the isolates MC-18T and MC-17D are 60.6%. The two isolates have virulence-related genes of the VF classes of adhesion and antiphagocytosis, and also contain the antimicrobial resistance genes ErmX, mtrA, rpoB2, and RbpA. The major fatty acids (> 10%) of isolates MC-18T and MC-17D were C16:0, C18:1 ω9c, C18:0 and summed feature 5 (anteiso-C18:0 and/or C18:2 ω6,9c). The main respiratory quinone of strain MC-18T was MK-8(H2), and the polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, three unidentified glycolipids, an unidentified aminolipid, and four unidentified phosphoglycolipids. The two isolates lack mycolic acids in the cell envelope. Based on the above findings, the two isolates are considered to represent a novel species of the genus Corynebacterium, for which the name Corynebacterium lipophilum sp. nov. is proposed, with isolate MC-18T (= NBRC 115144T = CCTCC AB 2020201T) as the type strain. An emended description of the Corynebacterium pilbarense is also provided.

Prevalence and characterization of ESBL-producing Escherichia coli in healthy pregnant women and hospital environments in Benin: an approach based on Tricycle

Introduction

Extended-Spectrum Beta-Lactamase (ESBL)-producing Enterobacterales are recognized as significant pathogens due to their resistance to multiple antibiotics. This study aimed to determine the prevalence of ESBL-producing Escherichia coli (E. coli) in different settings, including healthy pregnant women, the food chain, and the environment of tertiary hospitals in Benin.

Methods

Samples were collected from various sources, including fecal samples from healthy pregnant women, food samples from hospital canteens, and hospital effluents from four tertiary hospitals in southern Benin. Fecal samples were plated on MacConkey agar supplemented with cefotaxime (4 μg/mL), while food and water samples were plated on Tryptone Bile X agar supplemented with cefotaxime (4 μg/mL). Urea indole tests were used for preliminary identification of E. coli colonies, followed by confirmation of ESBL production using the double disk synergy technique. Antibiotic susceptibility testing of ESBL-producing E. coli strains was conducted using the disk diffusion method on MH agar. Polymerase Chain Reaction (PCR) was used to investigate the presence of ESBL-encoding genes.

Results

Among the 296 fecal samples collected from four tertiary hospitals, ESBL-producing E. coli was isolated from 22.30% (66) of the samples. All E. coli isolates from hospital effluents exhibited ESBL production, while ESBL-producing E. coli was not detected in food and drinking water samples. The analysis of variable associations showed no significant associations (p > 0.05) for the studied factors. Antibiotic susceptibility testing revealed high resistance rates among the ESBL-Ec isolates against several tested antibiotics, including amoxicillin, aztreonam, ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole. However, most isolates remained susceptible to ertapenem, amoxicillin-clavulanate, and imipenem. The most prevalent ESBL-encoding genes were blaTEM (37.50%), blaOXA-1 (19.44%), and blaSHV (11.11%), while a smaller proportion of isolates carried blaCTXM-1/blaCTXM-15 (5.55%) and blaCTXM-9.

Discussion

This study provides insights into the prevalence of ESBL-producing E. coli carriage in the feces of healthy pregnant women in southern Benin. Additionally, it highlights hospital wastewater as a potential reservoir of ESBL-producing bacteria in the environment. The detection of ESBL-producing E. coli in hospital effluents raises concerns about the dissemination of antibiotic resistance genes into the environment. The high resistance rates observed among ESBL-Ec isolates against commonly used antibiotics emphasize the urgent need for antimicrobial stewardship and infection control measures. The identification of prevalent ESBL-encoding genes contributes to understanding the genetic basis of ESBL resistance in the studied population. Further research is warranted to explore the mechanisms of transmission and potential interventions to mitigate the spread of ESBL-producing Enterobacterales.

Comparative Analysis of Sampling Methods for Assessing Bacterial Contamination on Hospital Partition Curtains: Moistened Swabs versus RODAC Agar Plates

BACKGROUND Partition curtains are one of the main sources of nosocomial infection in the hospital environment. However, there are no unified standards for monitoring medical textiles across different countries or regions. This study aimed to investigate the accuracy of 2 different sampling methods - swabbing vs RODAC (replicate organism detection and counting) agar plate - in terms of detection of bacterial contamination, and their suitability as monitoring methods for partition curtains and other medical textiles. MATERIAL AND METHODS A total of 24 partition curtains were selected by stratified random sampling. The swabbing technique and RODAC agar plates were the chosen sampling methods. The number of colony-forming units was calculated and colony morphologies and strains on the plates were observed and identified after culturing. RESULTS A total of 192 samples were collected. Of them, 161 pathogenic strains were isolated via the swabbing technique and 309 pathogenic strains were isolated using the RODAC agar plates. The swabbing technique had a higher proportion for gram-positive bacteria (P=0.0004), while RODAC agar plates had a higher proportion for gram-negative bacteria (P=0.72). The detection of bacterial contamination rates using the swabbing technique was superior to that of the RODAC agar plate method (P<0.001). CONCLUSIONS The swabbing technique offers more advantages in terms of detection of bacterial contamination rates and gram-positive bacteria, while the RODAC agar plate is more sensitive for detection of gram-negative bacteria.

Effect of poly (lactic-co-glycolic acid) polymer nanoparticles loaded with vancomycin against Staphylococcus aureus biofilm

Staphylococcus aureus is a unique challenge for the healthcare system because it can form biofilms, is resistant to the host's immune system, and is resistant to numerous antimicrobial therapies. The aim of this study was to investigate the effect of poly (lactic-co-glycolic acid) (PLGA) polymer nanoparticles loaded with vancomycin and conjugated with lysostaphin (PLGA-VAN-LYS) on inhibiting S. aureus biofilm formation. Nano drug carriers were produced using the double emulsion evaporation process. we examined the physicochemical characteristics of the nanoparticles, including particle size, polydispersity index (PDI), zeta potential, drug loading (DL), entrapment efficiency (EE), Lysostaphin conjugation efficiency (LCE), and shape. The effect of the nano drug carriers on S. aureus strains was evaluated by determining the minimum inhibitory concentration (MIC), conducting biofilm formation inhibition studies, and performing agar well diffusion tests. The average size, PDI, zeta potential, DL, EE, and LCE of PLGA-VAN-LYS were 320.5 ± 35 nm, 0.270 ± 0.012, -19.5 ± 1.3 mV, 16.75 ± 2.5%, 94.62 ± 2.6%, and 37% respectively. Both the agar well diffusion and MIC tests did not show a distinction between vancomycin and the nano drug carriers after 72 h. However, the results of the biofilm analysis demonstrated that the nano drug carrier had a stronger inhibitory effect on biofilm formation compared to the free drug. The use of this technology for treating hospital infections caused by the Staphylococcus bacteria may have favorable effects on staphylococcal infections, considering the efficacy of the nano medicine carrier developed in this study.

Microbiological evaluation of homemade mayonnaise and self-serve acai sold in Araguaína, Tocantins

Foodborne diseases are common illnesses caused by the consumption of food contaminated with microorganisms, such as viruses, fungi, bacteria, and protozoa. Every year, 600 million people become ill and 420,000 people die as a result of consuming contaminated food. Therefore, food safety is an important issue. In this study, samples of homemade spiced mayonnaise and self-serve acai sold in the city of Araguaína, Tocantins, Brazil were analyzed for microbiological contaminants. Acai was collected from 10 stores, one sample from each store, and tested for mold, yeast, and coliforms, as well as coliform identification and total and thermotolerant coliform counts. Mayonnaise was collected from 20 snack bars, one sample from each. These samples were inoculated on MacConkey and Salmonella Shigella agar plates, and the plates were analyzed for growth. Salmonella spp. were detected in some Mayonnaise samples, and coliforms were detected in all acai samples; 60% of samples had thermotolerant coliforms, and only 40% were within the limits established by ANVISA. The collected samples of mayonnaise and acai were contaminated with molds and yeasts above the established limit of 103 CFU/g. Thus, the analyzed mayonnaise and acai samples were contaminated and unfit for consumption, demonstrating the importance of hygienic-sanitary measures in food handling.

Inoculation of Arabidopsis seedlings with Ralstonia solanacearum in sterile agar plates

Ralstonia solanacearum invades plants through their roots and causes devastating bacterial diseases in multiple crops. Here, we present a versatile inoculation assay in Arabidopsis thaliana seedlings grown in sterile agar plates. We describe steps for plant preparation, bacterial inoculation, tissue sampling, and bacterial quantification. This protocol can be used for accurate assessment of bacterial colonization and observation of plant response to infection. For complete details on the use and execution of this protocol, please refer to Dindas et al. (2022).1.

First evidence of sex-specific responses to chemical cues in tardigrade mate searching behaviour

Chemical cues are widely used in intraspecific and interspecific communication, either as substances deposited in the substrate or as molecules diffused in water or air. In tardigrades, an emerging microscopic study system, chemical communication and its role in reproduction are poorly known. Here, we assessed sex differences in the detection of (a) short-range diffusing signals and (b) deposited cue trails during the mate-searching behaviour of freely moving virgin male and female Macrobiotus polonicus. We tracked individual behaviour (a) in simultaneous double-choice chambers, where live conspecifics of each sex were presented in water and (b) of freely moving pairs on agar without water. We found that males, but not females, preferentially associated with opposite-sex individuals in trials conducted in water. In contrast, neither sex detected nor followed cues deposited on agar. In conclusion, our study suggests that mate discrimination and approach are male-specific traits and are limited to waterborne chemical cues. These results support the existence of Darwinian sex roles in pre-mating behaviour in an animal group with virtually non-existing sex differences in morphology or ecology.

Soft agar colony formation assay to quantify mouse embryonic fibroblast transformation after Salmonella infection

Links between bacterial infections and cancer are actively investigated. Cost-effective assays to quantify bacterial oncogenic potential can shed new light on these links. Here, we present a soft agar colony formation assay to quantify mouse embryonic fibroblast transformation after Salmonella Typhimurium infection. We describe how to infect and seed cells in soft agar for anchorage-independent growth, a hallmark of cell transformation. We further detail automated cell colony enumeration. This protocol is adaptable to other bacteria or host cells. For complete details on the use and execution of this protocol, please refer to Van Elsland et al.1.

Two new species of Trichocomaceae (Eurotiales), accommodated in Rasamsonia and Talaromyces section Bacillispori, from the Czech Republic

During a previous study on microfungi associated with clematis roots, Penicillium-like fungi were isolated and identified based on morphology. In this study, we subjected those strains to a detailed examination which led to the proposal of two taxonomic novelties, named Rasamsonia chlamydospora and Talaromyces clematidis. The first taxon is characterized by rough-walled mycelium, acerose to flask shaped phialides, cylindrical conidia and by production of chlamydospore-like structures. The four-loci-based phylogeny analysis delineated the taxon as a taxonomic novelty in Rasamsonia. Talaromyces clematidis is characterized by restricted growth on Czapek yeast extract agar, dichloran 18% glycerol agar and yeast extract sucrose agar, and production of yellow ascomata on oatmeal agar. Phylogenetic analyses placed this taxon as a taxonomic novelty in Talaromyces sect. Bacillispori. Both taxa are introduced here with detailed descriptions, photoplates and information on their phylogenetic relationship with related species.

Investigation of virulence factors in Pseudomonas aeruginosa isolates by phenotypic and genotypic methods

INTRODUCTION

Pseudomonas aeruginosa possesses a variety of virulence factors that may contribute to its pathogenicity, and relationship has been determined between antibiotic resistance and biofilm. The aim of this study was to investigate the virulence factors of Pseudomonas aeruginosa isolates by genotypic and phenotypic methods, as well as whether there is a relationship between other virulence factors and antibiotic resistance.

METHODS

A total of 80 Pseudomonas aeruginosa strains were sent from various clinics included in the study. Identification and antibiotic resistance profile of isolates were determined by Vitek 2 (Biomerioux, France) automated system. Pseudomonas P agar, Pseudomonas F agar, and motility test medium were used for phenotyping tests. Tox A, Exo S, Plc N, and Las B were evaluated with Real-time PCR (Anatolia, Geneworks, Turkey).

RESULTS

The highest rates of antibiotic resistance were observed against imipenem (42.5%) and meropenem (40%). Among the isolates, 81.3% tested positive for Tox A, 30% for Exo S, 32.5% for Plc N, and 42.5% for Las B. Additionally, 70.4% of the isolates tested positive for pyocyanin, 41.3% for pyoverdine, 1.8% for pyorubin, and 8.9% tested negative for pyorubin. No statistically significant difference was found between antibiotic resistance and the presence of virulence factors (p > 0.005).

CONCLUSIONS

The relationship between antibiotic resistance and virulence factors is controversial. There are studies demonstrating the relationship between virulence factors and antibiotic resistance, as well as studies that indicate the absence of such a relationship. Investigating virulence and antibiotic resistance rates may be important for identifying potential drug targets for subsequent research.

Establishment of a modified opsonophagocytic killing assay for anti-pneumococcal surface protein A antibody

Streptococcus pneumoniae (pneumococcus) is a pathogenic gram-positive bacterium that causes pneumonia, meningitis, and sepsis. Pneumococcal surface protein A (PspA) induces antibodies that protect against lethal infections by pneumococci. PspA is a choline-binding protein present on the cell surface of almost all pneumococcal strains and is a non-capsular polysaccharide vaccine candidate. For research and development of PspA-based vaccines, an in-vitro test system to measure the activity of functional antibodies capable of killing pneumococci is essential. The opsonophagocytic killing (OPK) assay is used to evaluate the opsonic activity of functional antibodies induced by capsular polysaccharide (CPS)-based vaccines (standard OPK assay). Despite the potential of anti-PspA antibodies to protect against lethal infections in mice, the standard OPK assay fails to evaluate anti-PspA antibodies. Using a pneumococcal surface protein C-deficient strain and extending the incubation time of opsonized bacteria, complement, and HL-60 cells reportedly results in enhanced bactericidal activity (modified OPK assay). We aimed to measure the bactericidal activity of anti-PspA antibodies in intact pneumococcal strains. We optimized the pneumococcal culture method used in the OPK assay to increase the efficiency of anti-PspA antibody-mediated phagocytosis of HL-60 cells. As thick capsules hinder phagocytosis, we attempted to obtain pneumococci with thin capsules through an improved culture method. As pneumococci attached to cells exhibit thin capsules, pneumococci cultured in Todd Hewitt yeast extract (THY) broth were spread on blood agar plates and incubated for 4 h. cpsA mRNA transcript levels in pneumococci cultured on blood agar were lower than those in pneumococci cultured in THY broth. OPK activity against pneumococci expressing PspA of clades 1-5 was reasonably well detected using pneumococci cultured on blood agar in the modified OPK assay. The modified OPK assay for anti-PspA antibody using pneumococci cultured on blood agar represents a useful assay to determine the killing activity of functional anti-PspA antibodies against pneumococci.

Elucidating the physiological and molecular characteristics of bacterial blight incitant Xanthomonas auxonopodis pv. punicae; a life threatening phytopathogen of pomegranate (Punica granatum. L) and assessment of H2O2 accumulation during host-pathogen interaction

Bacterial blight of pomegranate caused by Xanthomonas auxonopodis pv.punicae (Xap) threaten the existence of a group of farmers for the past few decades who rely on pomegranate cultivation for their livelihood since it will cause huge yield loss. The primary focus of this study was to conduct a thorough analysis of the characterization of this blight incitant Xap. Physiological, biochemical, and molecular characteristics of six phytopathogenic strains of Xap, designated as PBF1 (PBF: Pomegranate Blight Fruit), PBF2, PBF3, PBF4, PBF5, and PBF6, isolated from the infected fruits were examined. Bacterial colonies were featured as gram-negative, yellow-pigmented circular with a glistening appearance. An attempt to determine the best culture medium, favouring bacterial proliferation was successfully done with four distinct medium, Nutrient Glucose Agar (NGA), Nutrient sucrose Agar (NSA), Yeast Dextrose Calcium Carbonate Agar (YDCA) and Yeast Glucose Calcium Carbonate Agar (YGCA) and comparatively, significant growth was found in NGA (66.66%) followed by YDCA (33%). According to the antibiotic susceptibility results, both ampicillin and streptomycin were determined as potentially effective drugs in preventing the proliferation of Xap (P 0.05). The reactive oxygen species-mediated plant immune response during host-pathogen interaction was confirmed by accessing the presence of H2O2 accumulation in infected leaves via 3,3 - diaminobenzidine (DAB) -staining technique. Bacterial isolates from this study were confirmed by two universal constitutive genes such as gyrB and 16S rRNA. From the BLAST analysis, the isolates were identified as Xap with base pair lengths of 1408bp, 1180bp, and 1159bp, which correspond to PBF1, PBF2, and PBF3, respectively. A neighbor-joining phylogenetic tree study explaining a strong phylogenetic relationship between the query sequence and closely related bacterial species.

Detection and genetic characterization of blaESBL-carrying plasmids of cloacal Escherichia coli isolates from white stork nestlings (Ciconia ciconia) in Spain

OBJECTIVES

This study aimed to characterize Escherichia coli isolates from cloacal samples of white stork nestlings, with a special focus on extended-spectrum β-lactamases (ESBLs)-producing E. coli isolates and their plasmid content.

METHODS

Cloacal samples of 88 animals were seeded on MacConkey-agar and chromogenic-ESBL plates to recover E. coli and ESBL-producing E. coli. Antimicrobial susceptibility was screened using the disc diffusion method, and the genotypic characterization was performed by polymerase chain reaction (PCR) and subsequent sequencing. S1 nuclease Pulsed-Field-Gel-Electrophoresis (PFGE), Southern blotting, and conjugation essays were performed on ESBL-producing E. coli, as well as whole-genome sequencing by short- and long-reads. The four blaESBL-carrying plasmids were completely sequenced.

RESULTS

A total of 113 non-ESBL-producing E. coli isolates were collected on antibiotic-free MacConkey-agar, of which 27 (23.9%) showed a multidrug-resistance (MDR) phenotype, mainly associated with β-lactam-phenicol-sulfonamide resistance (blaTEM/cmlA/floR/sul1/sul2/sul3). Moreover, four white stork nestlings carried ESBL-producing E. coli (4.5%) with the following characteristics: blaSHV-12/ST38-D, blaSHV-12/ST58-B1, blaCTX-M-1/ST162-B1, and blaCTX-M-32/ST155-B1. Whole-genome sequencing followed by Southern blot hybridizations on S1-PFGE gels in ESBL-positive isolates proved that the blaCTX-M-1 gene and one of the blaSHV-12 genes were carried by IncI1/pST3 plasmids, while the second blaSHV-12 gene and the blaCTX-M-32 gene were located on IncF plasmids. The two blaSHV-12 genes and the two blaCTX-M genes had similar but non-identical close genetic environments, as all four genes were flanked by a variety of insertion sequences.

CONCLUSION

The role played by several genetic platforms in the mobility of ESBL genes allows for interchangeability on a remarkably small scale (gene-plasmid-clones), which may support the spread of ESBL genes.

The occurrence of fungi from burn wound patients and antifungal susceptibility patterns: a cross-sectional study in Lusaka, Zambia

Background

Fungal opportunistic infections in burn wound patients are among the leading cause of morbidity and mortality. Attention remains focused on preventing bacterial infection at the expense of increasing fungal infection in burn wound patients.

Objective

To determine the occurrence of common fungi in admitted burn wound patients and their environment: and their antifungal susceptibility patterns at the University Teaching Hospitals, Lusaka, Zambia.

Methods

This laboratory-based cross-sectional study enrolled a total 101 participants whose pus swab specimens were collected from their burn wounds as well as 50 environmental swabs collected from strategic points. Wet mount, gram stain, culture on Sabouraud dextrose agar, Corn meal agar and Germ tube were used to identify possible fungal isolates. Agar based disc susceptibility test was carried out using fluconazole. Data was analysed using Excel and STAT version 14.

Results

Median age was 3 years and median burn % of TBSA was 18 in participants' who had burn wound fungal infection and consisted of 3 males and 6 females. Organisms isolated included Candida albicans from 8(7.9%) participants and 2(4%) from 50 environmental swabs. 1(1%) Candida spp was isolated from pus swabs. Out of the total 11 Candida isolates, 4 (36.4%) were susceptible to fluconazole and 7 (63.6%) were resistant.

Conclusion

The isolation of Candida albicans and Candida spp from burn wound patients and the hospital ward environment suggests presence of fungi in burn wound patients and hospital ward environments. Candida isolated showed varying susceptibility patterns to fluconazole.

Formation of silver halos by Sphingomonas paucimobilis MX8 and its bioleaching of silver from computer keyboard printed circuit boards

Silver (Ag) is currently obtained from primary and secondary sources through hydrometallurgical and pyrometallurgical processes. However, these processes consume high amounts of energy and are environmentally unfriendly. The search for bacteria tolerant with a high leaching capacity for to Ag is therefore a necessary requirement as part of the development of bioleaching technologies with reduced impact on the environment and lower energy expenditure. In this sense, the objective of this research was to evaluate the tolerance of Sphingomonas paucimobilis MX8 to Ag added to nutrient agar, and to determine whether this tolerance could favor the bioleaching of Ag present on the printed circuit boards (PCBs) of computer keyboards. The bacteria Sphingomonas paucimobilis MX8 was cultured in Petri dishes with nutrient agar and four different concentrations of AgNO3 (200, 400, 600, and 800 mg L-1) at 28 °C for 10 days. For the bioleaching experiment, the bacteria were grown in a mineral medium with computer keyboard PCBs for 30 days at room temperature (17 to 22 °C) and centrifugation at 150 rpm. The results indicate that Sphingomonas paucimobilis MX8 is tolerant to Ag and forms a silvery halo around its growth in the presence of this metal. Furthermore, Sphingomonas paucimobilis MX8 was able to bioleach 12% of the Ag found in computer keyboard PCBs. The results obtained could help generate more environmentally friendly silver bioleaching processes in which the silver bioleaching capacity of this bacterium is increased.

Antimicrobial efficacy of chlorine agents against selected oral pathogens

OBJECTIVES

Method-dependent comparison of antimicrobial agents' efficacy against oral pathogens.

MATERIALS AND METHODS

Several sodium hypochlorite solutions (NaOCl)-Perisolv®, Carisolv® and Dakin's solution-were equated with chlorhexidine (CHX) and hydrogen peroxide (H2O2) against ten oral micro-organisms related to caries and periodontitis using different minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) techniques. Agents were adjusted to the final 70 mmol/L concentration of active chlorine molecule.

RESULTS

Apart from H2O2 and the amino acids of Perisolv®, all the agents revealed an antimicrobial effect. Agar diffusion test ranked CHX (p < 0.05) as the most effective against all ten specimens, followed by the NaOCl of Perisolv® and Dakin's solution. Correspondingly, in broth microdilution on agar, CHX was the most effective in eradicating micro-organisms at 0.03 mmol/L compared with 2.2 mmol/L of Dakin's solution. In contrast, the bactericidal concentration of Dakin's solution was the most effective at 0.2 mmol/L, (p < 0.001), followed by Perisolv® (2.14 mmol/L), CHX (2.38 mmol/L) and Carisolv® (3.33 mmol/L) after 5 and 10 min in broth dilution test. In live/dead analysis, 60-min exposure to a 2-fold concentration of agents resulted in two-log Aggregatibacter actinomycetemcomitans inhibition by CHX (35 mmol/L) whilst Streptococcus mutans was more susceptible, in 0.8 and 8.8 mmol/L, after 10 min to CHX and Dakin's respectively.

CONCLUSION

Replacement of CHX with tested hypochlorite agents showed evident potential and promoted rapid antimicrobial effect.

CLINICAL RELEVANCE

Effective antimicrobial agents are crucial in controlling pathogen-induced oral infections increasing clinical possibilities to combat oral biofilms. Additionally, CHX substitution with hypochlorite agents could eliminate CHX's adverse effects.

Comparative antimicrobial activity of four different endodontic sealers

Dental cements are widely used in the clinical routine, specifically for root canal sealing. Within this context, it is expected that these materials present antimicrobial activity, since it would help in the prevention of apical and periapical infections. The present study aimed to comparatively verify the antimicrobial activity of four dental cements against microorganisms that are routinely isolated from endodontic infections. Reference strains of Enterococcus faecalis, Candida albicans and Escherichia coli were submitted to the agar diffusion test and to modified direct contact test using four different sealers: an eugenol zinc oxide compound, an epoxy resin associated to calcium hydroxide and bismuth, a mineral trioxide aggregate (MTA) and a bioceramics. Different E. coli, C. albicans and E. faecalis growth inhibition profiles were observed in the agar diffusion assay. In the direct contact test, the bioceramics presented a higher microbicide activity on all microorganisms tested herein. Dental cements have different antimicrobial activities, being that the bioceramics present the most consistent antimicrobial activity, and that the direct contact test presented more uniform results than the agar diffusion test. This study reveals the antimicrobial activities of different cements and allow dentists to decide which material to employ in their daily practice.

Validation of the CompactDry "Nissui" BC for Enumeration of Bacillus cereus in a Variety of Foods: AOAC Performance Tested MethodSM 092201

BACKGROUND

The CompactDry "Nissui" BC is a ready-to-use dry media sheet using a chromogenic medium with selective agents for the detection and enumeration of Bacillus cereus in products after incubation at 30 ± 1°C for 24 ± 2 h.

OBJECTIVE

The CompactDry "Nissui" BC method was validated to achieve AOAC Performance Tested MethodsSM certification.

METHOD

The performance of the CompactDry "Nissui" BC was compared to that of ISO 7932:2004 for 10 matrixes, including panna cotta, double cream, dried baby food, dried vegetable soup mix, seafood sticks, salmon pâté, sliced ham, pork liver pâté, ham and cheese sandwich, and Caesar pasta salad with chicken and bacon. Performance indicators included repeatability, difference of means (DOM), and inclusivity/exclusivity.

RESULTS

After log10 transformation of the data, the relative standard deviation of repeatability (RSDr) was ≤9.2% for 28 of the 30 materials (10 matrixes each at three contamination levels) analyzed by the CompactDry "Nissui" BC method and ≤13% for 27 of the 30 matrix/level combinations analyzed by the reference method. Method equivalence was demonstrated in 28 of the 30 matrix/level combinations based on the 90% confidence interval of the DOM being within (-0.5, 0.5). For inclusivity, 47 of 50 strains tested showed typical colonies and confirmed positive. For exclusivity, 28 of 33 strains tested resulted in no growth or were negative, and five were positive. Inclusivity and exclusivity results were similar on the reference method agar. The method was shown to be robust to changes in sample volume, incubation temperature, and incubation time, and data are presented supporting product consistency and 18-month shelf life.

CONCLUSIONS

The CompactDry "Nissui" BC method is validated for the determination of Bacillus cereus in a variety of matrixes.

HIGHLIGHTS

The CompactDry "Nissui" BC method is equivalent to the ISO 7932:2004 reference method and is suitable for Performance Tested MethodsSM certification for the matrixes tested.

Phycoremediation potential and agar yield of red macroalgae (Gracilaria corticata) against HEDP (hydroxyethylidene diphosphonic acid) and CAPB (cocoamidopropyl betaine) detergents and the heavy metal pollutants

The discharge of raw industrial, agricultural, and domestic wastes leads to an increase in heavy metal (HM) burden and detergents in aquatic environs, which can have destructive effects on aquatic organisms. Agarophyte Gracilaria corticata, a major component of seaweed flora of the southern coast of Iran (Bushehr) that contains agar and red pigments, is one of the economically valuable red marine algae. Agar is one of the important polysaccharides with high economic value, widely used in pharmaceutical, medicinal, and cosmetic product manufacturing industries. The aim of this work was to investigate the effect of 5 HMs and two common surfactants in household and industrial detergents on the agar yield, appearance color, and the red algae's phycoremediation potential against HMs. The metal ions were Zn(II), Cu(II), Ni(II), Mn(II), and Cr(VI), and the surfactants were HEDP and CAPB. The analysis results of samples cultured for 60 days in seawater and polluted environments showed that G. corticata can accumulate copper and nickel. In the presence of detergents without HMs, the amount of extracted agar significantly increased compared to the control sample with no change in algae color. But with increasing concentration of HMs, the amount of agar in seaweed samples decreased significantly, and the algae discolored from red to dark green or yellowish-green color (signs of death in the algae). These results show that increasing of HM pollution and detergents can lead to toxicological effects and reduce the species diversity of red seaweeds in the future.

Combination of the electronic nose with microbiology as a tool for rapid detection of Salmonella

Salmonella is one of the most important foodborne pathogens and its analysis in raw and processed products is mandatory in the food industry. Although microbiological analysis is the standard practice for Salmonella determination, these assays are commonly laborious and time-consuming, thus, alternative techniques based on easy operation, few manipulation steps, low cost, and reduced time are desirable. In this paper, we demonstrate the use of an e-nose based on ionogel composites (ionic liquid + gelatine + Fe3O4 particles) as a complementary tool for the conventional microbiological detection of Salmonella. We used the proposed methodology for differentiating Salmonella from Escherichia coli, Pseudomonas fluorescens, Pseudomonas aeruginosa, and Staphylococcus aureus in nonselective medium: pre-enrichment in brain heart infusion (BHI) (incubation at 35 °C, 24 h) and enrichment in tryptone soy agar (TSA) (incubation at 35 °C, 24 h), whereas Salmonella differentiation from E. coli and P. fluorescens was also evaluated in selective media, bismuth sulfite agar (BSA), xylose lysine deoxycholate agar (XLD), and brilliant green agar (BGA) (incubation at 35 °C, 24 h). The obtained data were compared by principal component analysis (PCA) and different machine learning algorithms: multilayer perceptron (MLP), linear discriminant analysis (LDA), instance-based (IBk), and Logistic Model Trees (LMT). For the nonselective media, under optimized conditions, taking merged data of BHI + TSA (total incubation time of 48 h), an accuracy of 85% was obtained with MLP, LDA, and LMT, while five separated clusters were presented in PCA, each cluster corresponding to a bacterium. In addition, for evaluation of the e-nose for discrimination of Salmonella using selective media, considering the combination of BSA + XLD and total incubation of 72 h, the PCA showed three separated and well-defined clusters corresponding to Salmonella, E. coli, and P. fluorescens, and an accuracy of 100% was obtained for all classifiers.

Comparison between broth microdilution and agar disk diffusion methods for antimicrobial susceptibility testing of bovine mastitis pathogens

In order to counter the antibiotic resistance phenomenon, a prudent and rational use of antimicrobials should be driven by an accurate clinical diagnosis and, when possible, by the isolation of the etiological agent followed by susceptibility testing, with the aim to select the most suitable molecule for therapy. Cow mastitis is considered the main cause of antibiotic use in the cattle breeding sector. The purpose of this study was to compare the broth microdilution (BMD) method performed with Sensititre Custom Plates and the agar disk diffusion (ADD) method in determining antimicrobial susceptibility of 215 isolates from bovine mastitis, including contagious pathogens (Staphylococcus aureus, Streptococcus agalactiae) and environmental (Streptococcus uberis, Streptococcus dysgalactiae, Enterococcus spp., Escherichia coli, Serratia marcescens, Klebsiella pneumoniae). We compared results of the following antimicrobials: amoxicillin/clavulanic acid, ampicillin, cefazolin, ceftiofur, enrofloxacin, erythromycin, kanamycin, oxacillin, penicillin, pirlimycin, rifampicin and trimethoprim/sulphonamides. We applied MIC breakpoints and zone diameter breakpoints as recommended by CLSI and EUCAST. MIC and disk diffusion diameters were compared for 1839 microorganism/antimicrobial combination and discrepancies between the two methods were classified as very major discrepancy (VMD), major discrepancy (MD) and minor discrepancy (MiD). The overall agreement between the two methods was found to be 80.7% with a Cohen's kappa coefficient of 0.397, thus indicating a fair concordance. BMD method and ADD method demonstrated a satisfactory agreement (89 to 100%) for S. aureus and S. marcescens and all antimicrobial agents tested. Low agreement was observed for S. uberis and rifampicin (20%), enrofloxacin (49%), penicillin (51%) and pirlimycin (52%), E. coli and ampicillin (20%), S. dysgalactiae and enrofloxacin (44%), S. agalactiae and rifampicin (25%). A possible explanation for the discrepancies detected could be found in the breakpoints used which, sometimes, are not specific for the tissue-matrix of isolation/animal species/pathogen agent. The majority of the discrepancies found were MiD and MD, revealing a higher restrictiveness of the BMD method, while VMD represented only 0.2% of the total observations, a comforting fact since this type of error may result in treatment failure.

Biochemical typing and evaluation of pathogenicity in vulvovaginal isolates of Candida albicans complex

Introduction

Candida albicans, C. dubliniensis, and C. africana form the Candida albicans complex.

Objective

To identify the phenotypic and pathogenic characteristics of isolates of the C. albicans complex preserved in a collection.

Materials and methods

Three hundred presumptive strains of the C. albicans complex were evaluated using CHROMagarTM Candida. Germ tube production was determined by three methods, chlamydospores formation was assessed and colonies were characterized in artisanal agars (Rosmarinus officinalis and Nicotiana tabacum). MALDI-TOF was used as the gold standard identification test. To detect pathogenicity factors, we evaluated the hemolytic activity of each isolate and cocultured with Staphylococcus aureus, coagulase enzyme production, and biofilm formation.

Results

Out of the 300 isolates, 43.7% produced germ tube in the heart-brain infusion broth and 47% of the isolates produced chlamydospores. In the artisan media, 6% of the isolates produced brown colonies on rosemary agar and 5% did so on tobacco agar. None of the strains hemolyzed the blood agar alone or cocultured with S. aureus. However, 50% of the isolates hemolyzed the potato dextrose agar supplemented with blood. All strains were coagulase producers, and biofilm production was variable. For germ tube production, the human serum method showed the same positivity as the milk broth method. All isolates were identified as C. albicans by MALDI-TOF.

Conclusions

The use of proteomics, molecular tests or a combination of methods is required for species identification.

Fabrication of dual physically cross-linked polyvinyl alcohol/agar hydrogels with mechanical stability and antibacterial activity for wound healing

Bacterial infection is one of the most critical obstacles in wound healing, and severe bacterial infections can lead to inflammatory conditions and delay the healing process. Herein, a novel hydrogel based on polyvinyl alcohol (PVA), agar, and silk-AgNPs was prepared using a straightforward one-pot physical cross-linking method. The in situ synthesis of AgNPs in hydrogels exploited the reducibility of tyrosine (Tyr tyrosine) in silk fibroin, which endowed the hydrogels with outstanding antibacterial qualities. In addition, the strong hydrogen bond cross-linked networks of agar and the crystallites formed by PVA as the physical cross-linked double network of the hydrogel gave it excellent mechanical stability. The PVA/agar/SF-AgNPs (PASA) hydrogels exhibited excellent water absorption, porosity, and significant antibacterial effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Furthermore, in vivo experimental results confirmed that the PASA hydrogel significantly promoted wound repair and skin tissue reconstruction by reducing inflammation and promoting collagen deposition. Immunofluorescence staining showed that the PASA hydrogel enhanced CD31 expression to promote angiogenesis while decreasing CD68 expression to reduce inflammation. Overall, the novel PASA hydrogel showed great potential for bacterial infection wound management.

Antibacterial potential of biosynthesized silver nanoparticles using Nepeta sessilifolia Bunge and Salvia hydrangea DC. ex Benth. extracts from the natural habitats of Iran's Rangelands

BACKGROUND

Nowadays, the use of herbal extracts for the production of nanoparticles has attracted a lot of attention due to the fast reaction, economy, and compatibility with the environment. The aim of the present study is the biosynthesis of silver nanoparticles from the extracts of Nepeta sessilifolia Bunge and Salvia hydrangea DC. ex Benth. and their antibacterial activity was measured.

METHODS

For this purpose, the flowering branch of N. sessilifolia and the flower of S. hydrangea were randomly collected from three places, respectively, from the rangelands of Aqdash Mountain and Biabe in Isfahan province, Iran in May 2021. After extracting aqueous extracts by hot method, silver nanoparticles were synthesized by the biological method. Green synthesized silver nanoparticles were analyzed by UV-Vis spectroscopy, XRD, FTIR, and FESEM-EDAX. The antibacterial effect was evaluated by diffusion method in agar and determination of minimum growth inhibitory and lethal concentration (MIC and MBC) by dilution method in liquid culture medium.

RESULTS

Based on the results of UV-Vis spectroscopy, silver nanoparticles synthesized from N. sessilifolia and S. hydrangea had distinct absorption peaks at wavelengths of 407 to 424 nm and 414 to 415 nm, respectively. The crystalline nature of these synthetic silver nanoparticles was confirmed by XRD. FESEM analysis showed that the size of biosynthesized silver nanoparticles from N. sessilifolia and S. hydrangea extracts were 10-50 nm and 10-80 nm, respectively, and were cubic. The results of diffusion in agar showed that the largest diameter of the growth inhibition zone belonging to the synthetic silver nanoparticles from both extracts of N. sessilifolia (~ 26.00 mm) and S. hydrangea (~ 23.50 mm) was against Gram-positive bacteria Staphylococcus aureus. The most vigorous killing activity by synthetic silver nanoparticles from N. sessilifolia extract was against Klebsiella pneumoniae with a value of 250 μg/mL, two times stronger than rifampin.

CONCLUSION

Therefore, the studied extracts can be suitable options for fast and safe green synthesis of silver nanoparticles effective against some bacterial strains. These synthetic silver nanoparticles can be used as possible options and have strong potential for the production of natural antibiotics.

Discovery of a New Antibiotic Demethoxytetronasin Using a Dual-Sided Agar Plate Assay (DAPA)

For over a century, researchers have cultured microorganisms together on solid support─typically agar─in order to observe growth inhibition via antibiotic production. These simple bioassays have been critical to both academic researchers that study antibiotic production in microorganisms and to the pharmaceutical industry's global effort to discover drugs. Despite the utility of agar assays to researchers around the globe, several limitations have prevented their widespread adoption in advanced high-throughput compound discovery and dereplication campaigns. To address a list of specific shortcomings, we developed the dual-sided agar plate assay (DAPA), which exists in a 96-well plate format, allows microorganisms to compete through opposing sides of a solid support in individual wells, is amenable to high-throughput screening and automation, is reusable, and is low-cost. Herein, we validate the use of DAPA as a tool for drug discovery and show its utility to discover new antibiotic natural products. From the screening of 217 bacterial isolates on multiple nutrient media against 3 pathogens, 55 hits were observed, 9 known antibiotics were dereplicated directly from agar plugs, and a new antibiotic, demethoxytetronasin (1), was isolated from a Streptomyces sp. These results demonstrate that DAPA is an effective, accessible, and low-cost tool to screen, dereplicate, and prioritize bacteria directly from solid support in the front end of antibiotic discovery pipelines.

Work in nursing homes and occupational exposure to endotoxin and bacterial and fungal species

Indoor microbial exposure may cause negative health effects. Only little is known about the occupational microbial exposure in nursing homes and the factors that influence the exposure. The exposure in nursing homes may be increased due to close contact with elderly persons who may carry infectious or antimicrobial-resistant microorganisms and due to handling of laundry, such as used clothing and bed linen. We investigated the microbial exposure in 5 nursing homes in Denmark, by use of personal bioaerosol samples from different groups of staff members taken during a typical working day, stationary bioaerosol measurements taken during various work tasks, sedimented dust samples, environmental surface swabs, and swabs from staff members' hands. From the samples, we explored bacterial and fungal concentrations and species composition, endotoxin levels, and antimicrobial resistance in Aspergillus fumigatus isolates. Microbial concentrations from personal exposure samples differed among professions, and geometric means (GM) were 2,159 cfu/m3 (84 to 1.5 × 105) for bacteria incubated on nutrient agar, 1,745 cfu/m3 (82 to 2.0 × 104) for bacteria cultivated on a Staphylococcus selective agar, and 16 cfu/m3 air for potential pathogenic fungi incubated at 37 °C (below detection limit to 257). Bacterial exposures were elevated during bed making. On surfaces, the highest bacterial concentrations were found on bed railings. The majority of bacterial species found were related to the human skin microflora, such as different Staphylococcus and Corynebacterium species. Endotoxin levels ranged from 0.02 to 59.0 EU/m3, with a GM of 1.5 EU/m3. Of 40 tested A. fumigatus isolates, we found one multiresistant isolate, which was resistant towards both itraconazole and voriconazole, and one isolate resistant towards amphotericin B. In conclusion, we give an overview of the general microbial exposure in nursing homes and show that microbial exposures are higher for staff with more care and nursing tasks compared with administrative staff.

Quantification, Viability Assessment, and Visualization Strategies for Acinetobacter Biofilms

Acinetobacter causes nosocomial infections and its biofilm formation can contribute to the survival on dry surfaces such as hospital environments. Thus, biofilm quantification and visualization are important methods to assess the potential of Acinetobacter strains to cause nosocomial infections. The biofilms forming on the surface of the microplate can be quantified in terms of volume and cell numbers. Biofilm volumes can be quantified by staining using crystal violet, washing, destaining using ethanol, then measuring the solubilized dye using a microplate reader. To quantify the number of cells embedded in the biofilms, the biofilms are scrapped off using cell scrapers, harvested in the saline, vigorously agitated in the presence of glass beads, and spread on Acinetobacter agar. Then, the plates are incubated at 30 °C for 24-42 h. After incubation, the red colonies are enumerated to estimate the number of cells in biofilms. This viable count method can also be useful for counting Acinetobacter cells in mixed-species biofilms. Acinetobacter biofilms can be visualized using fluorescent dyes. A commercially available microplate designed for microscopic analysis is employed to form biofilms. Then, the bottom-surface attached biofilms are stained with SYTO9 and propidium iodide dyes, washed, then visualized with confocal laser scanning microscopy.

A membrane filtration method for the enumeration of Escherichia coli in bathing water and other waters with high levels of background bacteria

The presence and level of faecal indicator bacteria are important factors in estimating the microbiological quality of surface water and the risk of human infection upon exposure to this water. Until 2014, ISO 9308-1:2000 was available and used to enumerate faecal indicator Escherichia coli in bathing water. In 2014, this ISO was technically revised and replaced by ISO 9308-1:2014. This ISO introduced a less selective method for enumeration of E. coli that allows non-specific growth from waters containing high levels of bacteria, such as surface waters. This implies that currently there is no suitable reference membrane filtration method for the compliance monitoring of official bathing sites for E. coli according to the European Bathing Water Directive. Here, the performance characteristics of three chromogenic culture media, namely Tryptone Bile X-glucuronide (TBX) agar, Chromogenic Coliform Agar (CCA), and CHROMagar E. coli/Coliform (ECC) were investigated at 44 °C for water with varying levels of bacteria according to ISO 13843:2017. Based on performance characteristics, colony counts, and practical usage, TBX appeared the most suitable culture medium for the enumeration of E. coli in bathing water and other waters with high levels of background bacteria, such as surface water in agricultural areas and wastewater discharge points.

First report on mycetoma in Turkana County-North-western Kenya

Mycetoma is one of the six Neglected Tropical Diseases that are prevalent in Turkana County (northwest Kenya). The aim of the study was to estimate the prevalence of mycetoma in the county, as well as to describe the main causative agents involved in the disease using methods affordable locally. Based on the data collected by the team of cooperative medicine Cirugia en Turkana (Surgery in Turkana), a specific study for mycetoma was started during the 16th humanitarian medicine campaign in February 2019. Patients with suspected mycetoma were studied at the Lodwar County Referral Hospital (LCRH). After informing the patient and getting their consent, the lesions were examined and sampled (mainly by biopsy) and clinical data were recorded. Samples were washed in sterile saline solution and cut in fragments. Some of these were inoculated on Sabouraud Dextrose Agar, Malt Extract Agar, and diluted Nutrient Agar plates. One fragment of each sample was used for DNA extraction. The DNA and the rest of the fragments of samples were kept at -20°C. All cultures were incubated at room temperature at the LCRH laboratory. The DNA obtained from clinical samples was submitted to PCR amplification of the ITS-5.8S and the V4-V5 16S rRNA gene region, for the detection and identification of fungi and bacteria respectively. From February 2019 till February 2022, 60 patients were studied. Most of them were men (43, 74,1%) between 13 and 78 y.o. (mean age 37). Half of the patients were herdsmen but, among women 40% (6) were housewives and 26.7% (4) charcoal burners. Lesions were mainly located at the feet (87.9%) and most of the patients (54; 93.1%) reported discharge of grains in the exudate, being 27 (46.6%) yellow or pale colored and 19 (32.8%) of them dark grains. Culture of clinical samples yielded 35 fungal and bacterial putative causative agents. Culture and molecular methods allowed the identification of a total of 21 causative agents of mycetoma (39.6% of cases studied). Most of them (17) corresponded to fungi causing eumycetoma (80.9%) being the most prevalent the genus Madurella (7; 41.2%), with two species involved (M. mycetomatis and M. fahalii), followed by Aspergillus (2; 11.8%). Other minority genera detected were Cladosporium, Fusarium, Acremonium, Penicillium, and Trichophyton (5.9% each of them). Actinobacteria were detected in 19.1% of samples, but only Streptomyces somaliensis was identified as a known agent of mycetoma, the rest being actinobacteria not previously described as causative agents of the disease, such as Cellulosimicrobium cellulans detected in two of the patients. Although Kenya is geographically located in the mycetoma belt, to our knowledge this is the first report on mycetoma in this country from 1973, and the first one for Turkana County.

Conjunctival Microbiota and Blepharitis Symptom Scores in Patients With Ocular Rosacea

PURPOSE

Investigation of the relationship between blepharitis-related symptom scores, tear film functions, and conjunctival microbiota in patients with ocular rosacea (OR) compared with healthy controls was aimed.

METHODS

Consecutive 33 eyes of 33 patients with OR who were admitted from the dermatology clinic and age-matched and gender-matched 30 healthy controls were included in the study. Tear breakup time (TBUT), Schirmer score, and blepharitis symptom score (BLISS) were recorded for each patient. For the bacteriological examination, bacterial culture was obtained by inoculating the samples on chocolate agar, blood agar, and fluid thioglycollate medium. The growth of different colonies of bacteria was identified using matrix-assisted laser desorption or ionization time-of-flight mass spectrometry.

RESULTS

Bacterial culture positivity was observed in 13 eyes (39.4%) in the patients with OR and 10 eyes (33.3%) in the controls ( P =0.618). Patients with OR showed worse TBUT and Schirmer scores, and higher BLISSs ( P =0.005, P =0.007, and P =0.001, respectively). Patients with OR with conjunctival culture-positive results showed higher BLISSs (8.0±4.7) compared with those with negative results (4.7±2.3; P <0.001). The most frequent bacteria was Micrococcus luteus (18.2%) in patients with OR and Staphylococcus epidermidis (20.0%) in the controls.

CONCLUSION

This pilot study showed that patients with OR had similar conjunctival culture positivity compared with healthy controls. However, the observation of different dominant bacterial species in conjunctival microbiota and the observation of worse BLISSs in patients with OR with positive culture might suggest a potential role of conjunctival microbiota in the pathogenesis of OR.

Chitinophaga nivalis sp. nov., isolated from forest soil in Pyeongchang, Republic of Korea

Rod-shaped Gram-stain-negative, aerobic bacterial strains, designated PC14 and PC15T, were isolated from a forest soil sample collected in Pyeongchang county, Gangwon-do, Republic of Korea. Strains PC14 and PC15T grew at 15-37 °C (optimum, 28-30 °C in tryptone soya agar and Mueller-Hinton agar), hydrolysed chitin and casein, and tolerated pH 8.5 and 2 % (w/v) NaCl. The strains were most closely related to members of the genus Chitinophaga, namely Chitinophaga arvensicola DSM 3695T (98.4 %), Chitinophaga longshanensis Z29T (98.3 %), Chitinophaga ginsengisegetis Gsoil 040T (97.8 %), Chitinophaga polysaccharea MRP-15T (97.8 %) and Chitinophaga niastensis JS16-4T (97.7 %). The type strain grew well on conventional commercial media in the laboratory, including tryptone soya agar, Mueller-Hinton agar, Reasoner's 2A agar, nutrient agar and Luria-Bertani agar. The major polar lipid profile comprised phosphatidylethanolamine, an unidentified aminolipid and unidentified polar lipids. The major respiratory quinone was menaquinone-7. The main fatty acids were iso-C15:0, C16:1 ω5c, C16:0 3-OH, iso-C15:0 3-OH and iso-C17:0 3-OH. The DNA G+C content of the isolated strain based on the whole genome sequence was 46.6 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strains PC14 and PC15T and the reference type strains ranged from 71.0 to 76.5 %, and from 20.3 to 20.7 %, respectively. Based on phenotypic, chemotypic and genotypic evidence, strain PC15T could be differentiated phylogenetically and phenotypically from the recognized species of the genus Chitinophaga. Therefore, strain PC15T is considered to represent a novel species, for which the name Chitinophaga nivalis sp. nov. is proposed. The type strain is PC15T (=KACC 22893T=JCM 35788T).

Marinobacterium lacunae sp. nov. isolated from estuarine sediment

A novel motile bacterium was isolated from a sediment sample collected in Kochi backwaters, Kerala, India. This bacterium is Gram negative, rod shaped, 1.0-1.5 µm wide, and 2.0-3.0 µm long. It was designated as strain AK27T. Colonies were grown on marine agar displayed circular, off-white, shiny, moist, translucent, flat, margin entire, 1-2 mm in diameter. The major fatty acids identified in this strain were C18:1 ω7c, C16:0, and summed in feature 3. The composition of polar lipids in the strain AK27T included phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, one unidentified amino lipid, two unidentified aminophospholipids, two unidentified phospholipids, and six unidentified lipids. The genomic DNA of strain AK27T exhibited a G+C content of 56.4 mol%. Based on the analysis of 16S rRNA gene sequence, strain AK27T showed sequence similarity to M. ramblicola D7T and M. zhoushanense WM3T as 98.99% and 98.58%, respectively. Compared to other type strains of the Marinobacterium genus, strain AK27T exhibited sequence similarities ranging from 91.7% to 96.4%. When compared to Marinobacterium zhoushanense WM3T and Marinobacterium ramblicola D7T, strain AK27T exhibited average nucleotide identity values of 80.25% and 79.97%, and dDDH values of 22.9% and 22.6%, respectively. The genome size of the strain AK27T was 4.55 Mb, with 4,229 coding sequences. Based on the observed phenotypic and chemotaxonomic features, and the results of phylogenetic and phylogenomic analysis, this study proposes the classification of strain AK27T as a novel species within the genus Marinobacterium. The proposed name for this novel species is Marinobacterium lacunae sp. nov.

TEMPORAL EFFICACY AND STERILITY TESTING OF POVIDONE-IODINE FROM AN OPEN BOTTLE

PURPOSE

To investigate the temporal efficacy and sterility of povidone-iodine (PI) against bacteria associated with postinjection endophthalmitis in an in vitro study.

METHODS

A single PI bottle was opened and tested for sterility and antibacterial efficacy. Povidone-iodine from the open bottle was inoculated onto a blood agar plate and evaluated for growth 24 hours later to test sterility; this was repeated for five consecutive days. To test for antibacterial efficacy, PI was instilled onto the surface of plates of Staphylococcus , Streptococcus , Enterococcus , Pseudomonas , and Haemophilus species. The plates were then evaluated 24 hours later for a clear zone of inhibition (i.e., no growth) where the PI was placed. This process was repeated for five consecutive days.

RESULTS

Sterility testing showed no growth of organisms on the blood agar plates for each of the five days of testing. For antibacterial efficacy testing, zones of inhibition of growth were seen on each plate of bacterial colonies only where PI was placed, for each of the five days of testing.

CONCLUSION

In this study, PI from an open bottle maintained its sterility and antibacterial efficacy for five days. These data could help support repeated use of the same bottle, reducing waste and costs for retina practices.

Species diversity of microorganisms previously identified as nontuberculous mycobacteria by DNA hybridization

Background

Over the past 10 years, the clinical importance of opportunistic bacteria of the order Actinomycetales has increased significantly. While many problems for the Mycobacterium tuberculosis complex have been solved, for nontuberculous mycobacteria, some questions remain open. These pathogens have a number of structural features that allow them to persist in the external environment for a long time.

Methods

The main inclusion criteria were cultural characteristics in assessing the growth of microorganisms on solid egg media. If nontuberculous mycobacteria (NTM) growth was detected, identification signs were carried out using the DNA hybridization method. Subsequently, these cultures were identified using the matrix-assisted laser desorption/ionization-time-of-flight (MALDI-ToF) mass spectrometry method. In case of obtaining unacceptable results of identification from primary inoculations, re-identification to obtain pure cultures was carried out after transferring the material from primary media to agar media: 5% blood agar and universal chromogenic medium. When re-identifying isolated cultures using MALDI-ToF mass spectrometry, all isolated cultures were analyzed, regardless of whether they belonged to the NTM group or not.

Results

DNA hybridization, which accounted for 59.5% of the total number of cultures included in the study, performed species identification of 188 strains. Using MALDI-ToF mass spectrometry, 345 strains were identified.

Conclusion

The use of methods based on DNA hybridization makes it possible to identify quite accurately some of the most common NTM species. MALDI-ToF mass spectrometry is an important technique to allow species identification of most Actinomycetales. However, algorithms to standardize methods for their isolation from clinical material are needed.

[Evaluation of In vitro Efficacy of Meropenem/Colistin and Meropenem/Fosfomycin Combinations on Multidrug Resistant Gram-Negative Bacilli]

The rate of extensively drug-resistant and pan-resistant gram-negative rods isolated as infectious agents is increasing around the world and in Türkiye. One of the important options in the treatment of these infections is the combined use of antibiotics. Therefore, the aim of this study was to investigate the in vitro effect of meropenem/colistin and meropenem/fosfomycin combinations on carbapenem-resistant gram-negative bacilli isolated as infectious agents. Escherichia coli (n= 6), Klebsiella pneumoniae (n= 10), Pseudomonas aeruginosa (n= 5), and Acinetobacter baumannii (n= 6) isolates were recovered from blood and tracheal aspirate samples of patients hospitalized in our hospital's intensive care unit were included in the study. In the first stage of the combination study, minimal inhibitory concentrations (MIC) were investigated by broth microdilution for meropenem and colistin, and agar dilution methods for fosfomycin. In the second stage of the study, synergy, partial synergy, indifference, and antagonistic effects were investigated with the checkerboard method for the meropenem/colistin combination and the agar dilution method for the meropenem/fosfomycin combination. The checkerboard results were interpreted as follows: fractional inhibitory concentration index (FICI) values ≤ 0.5 synergy, < 0.5-≤ 1 partial synergy, > 1-≤ 4 indifference and FIC values of > 4 antagonism. MIC values obtained in the study were interpreted according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Of the 27 isolates studied with the broth microdilution method, 63% were found to be colistin-resistant and 37% susceptible. The MIC values of fosfomycin against Enterobacterales group bacteria were found to be in the range of 2-2048 mg/L. Two of the six E.coli isolates and nine of the 10 K.pneumoniae isolates were found to be resistant to fosfomycin (IV). The MIC values of ≥ 128 mg/L were found in all 11 non-fermentative gram-negative rods with intrinsic resistance to fosfomycin. In the combination of meropenem/ colistin, synergy and partial synergy were observed in 11 (40.7%) of 27 isolates, an indifference effect was observed in 13 (48.2%), and antagonistic effects were observed in three (11.1%) of the isolates. The synergy and partial synergy effects of this combination were 37.5% for Enterobacterales group bacteria, 50% for E.coli, and 30% for K.pneumoniae. Regarding the 11 non-fermentative gram-negative rods included in the study, 83.3% synergy and partial synergy was found in A.baumannii for the meropenem/colistin combination, while no synergy and partial synergistic effect was found in P.aeruginosa. Meropenem/fosfomycin synergy and partial synergy effects were 83.3% (5/6) for E.coli, 100% (8/8) for K.pneumoniae, 100% (6/6) for A.baumannii, and 25% (1/4) for P.aeruginosa. In all of the isolates studied, meropenem/fosfomycin combination was found to be more effective than the meropenem/colistin combination. It would be meaningful to support these data obtained in vitro with clinical efficacy results to be obtained as a result of the application of antibiotics in vivo, taking into account the pharmacokinetic and pharmacodynamic properties of the antibiotics used in this study.

Comparison of 4 agar gel immunodiffusion kits for serologic detection of equine infectious anemia virus antibodies

Using 85 sera collected from horses that had been experimentally infected with equine infectious anemia virus (EIAV) and 200 field sera collected from racehorses in Japan, we compared 4 agar gel immunodiffusion (AGID) kits for serologic detection of EIAV antibodies from Idexx, VMRD, IDvet, and the National Engineering Research Center of Veterinary Biologics, China (NECVB). The positive control lines were sufficiently clear in all kits for evaluation to be made, with slight differences in sharpness: NECVB was the sharpest, followed by VMRD, IDvet, and Idexx. The test results for all 285 samples agreed among the 4 kits, with 62 positives and 223 negatives. The sensitivities and specificities of VMRD, IDvet, and NECVB compared with the Idexx kit were 100%, and the kappa coefficient values between the kits were 1.0 for all combinations. We concluded that the testing capacity of these 4 kits was virtually identical.

Secondary metabolites produced by four Colletotrichum species in vitro and on fruits of diverse olive cultivars

This study was aimed to characterize the secondary metabolites produced by four Colletotrichum species, C. acutatum, C. gloeosporioides, C. godetiae and C. karsti, both in vitro, on potato dextrose agar (PDA) and oatmeal agar (OA), and during the infection process of fruits of four olive cultivars differing in susceptibility to anthracnose, 'Coratina' and 'Ottobratica', both susceptible, 'Frantoio' and 'Leccino', both resistant. The metabolites were extracted from axenic cultures after seven days incubation and from olives inoculated singularly with each Colletotrichum species, at three different times, 1, 3 and 7 days post inoculation (dpi). They were identified using the UHPLC-QTOF-MS analysis method. In total, as many as 45 diverse metabolites were identified. Only 10 metabolites were present in both fruits and axenic cultures while 19 were found exclusively on olives and 16 exclusively in axenic cultures. The identified metabolites comprised fatty acid, phenolics, pyrones, sterols, terpenes and miscellaneous compounds. Each Colletotrichum species produced a different spectrum of metabolites depending on the type of matrices. On artificially inoculated olives the severity of symptoms, the amount of fungal secondary metabolites and their number peaked 7 dpi irrespective of the cultivar susceptibility and the virulence of the Colletotrichum species.

Microorganism Test on Biscuits Combined With Red Algae Extract (Eucheuma denticulatum) and Tempeh (Glycine max)

<b>Background and Objective:</b> Biscuits are snacks that are widely circulated in the market but do not meet Indonesian National standards so they are harmful to consumer health. This study aims to determine the total plate count (TPC) value of bacteria and mold/yeast and determine the presence or absence of bacterial contamination of <i>Staphylococcus aureus </i>and <i>Escherichia coli</i> in biscuit products. <b>Materials and Methods:</b> This study is descriptive in nature using three different sample types. Total plate count (TPC) value testing was carried out using the pour plate method. Meanwhile, to determine the presence or absence of <i>Staphylococcus aureus</i> bacteria using MSA (mannitol salt agar) media with the spread plate technique. The <i>Escherichia coli</i> test uses EMBA (eosin methylene blue agar) media with a streak plate technique. <b>Results:</b> Three samples of biscuit formula obtained ALT of bacteria in sample A) 2.2×10⁷ colonies/g, sample B) 1.9×10⁷ colonies/g and sample C) 4.1×10⁷ colonies/g. Mold/khamir obtained in sample A) 7.7×10⁵ colonies/g, sample B) 5.1×10⁶ colonies/g and sample C) 1.1×10⁶ colonies/g. In the <i>Staphylococcus aureus</i> bacteria test, the results were not overgrown with <i>Staphylococcus aureus</i> bacteria and in the <i>Escherichia coli</i> bacteria test, the results were easily purplish red in color. <b>Conclusion:</b> It can be concluded that only formula C samples meet the requirements of the SNI quality standards. In the pathogenic microbial test, there was no growth of <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> microbes in the three biscuit formula samples.

Antimicrobial susceptibility of western Canadian Brachyspira isolates: Development and standardization of an agar dilution susceptibility test method

The re-emergence of Brachyspira-associated disease in pigs since the late 2000s has illuminated some of the diagnostic challenges associated with this genus; notably, the lack of standardized antimicrobial susceptibility testing (AST) methods and interpretive criteria. Consequently, laboratories have relied heavily on highly variable in-house developed methods. There are currently no published investigations describing the antimicrobial susceptibility of Brachyspira isolates collected from pigs in Canada. The first objective of this study was therefore to develop a standardized protocol for conducting agar dilution susceptibility testing of Brachyspira spp., including determining the optimal standardized inoculum density, a key test variable that impacts test performance. The second objective was to determine the susceptibility of a collection of western Canadian Brachyspira isolates using the standardized methodology. After assessing multiple media, an agar dilution test was standardized in terms of starting inoculum (1-2 × 108 CFU/ml), incubation temperature and time, and assessed for repeatability. The antimicrobial susceptibility of a collection of clinical porcine Brachyspira isolates (n = 87) collected between 2009-2016 was then determined. This method was highly reproducible; repeat susceptibility testing yielded identical results 92% of the time. Although most of the isolates had very low MICs to the commonly used antimicrobials to treat Brachyspira-associated infections, several isolates with elevated MICs (>32 μg/ml) for tiamulin, valnemulin, tylosin, tylvalosin, and lincomycin were identified. Overall, this study underscores the importance of establishing CLSI approved clinical breakpoints for Brachyspira to facilitate the interpretation of test results and support the evidence-based selection of antimicrobials in swine industry.

Study of bacterial respiratory infections and antimicrobial susceptibility profile among antibiotics naive outpatients visiting Meru teaching and referral hospital, Meru County, Kenya in 2018

OBJECTIVE

Respiratory tract infections cause significant morbidity and mortality globally and are the most common infectious diseases in humans. This study aims at assessing the presence of bacterial respiratory infections, number of people infected and antimicrobial susceptibility profile among antibiotic naïve outpatients presenting with respiratory tract infections in Meru Teaching and Referral Hospital.

METHODS

The study was conducted in Meru Teaching and Referral Hospital, Meru County from April 2017 to August 2018. Upper respiratory infections were characterized by acute infection of nasal cavity, pharynx and larynx while lower respiratory infections were characterized by chest pains, prolonged cough, productive sputum, difficulty in breathing, fever and weight loss. A total of 384 sputum and throat samples were collected aseptically from patients who were clinically suspected to have respiratory infections and cultured in blood agar, MacConkey agar and chocolate agar. Bacterial isolates were identified by colonial morphology, Gram stain and confirmed by biochemical tests. Antimicrobial susceptibility profile was determined using agar disc diffusion method.

RESULTS

Respiratory bacterial pathogens were isolated in 45.6% of the samples. The prevalence of the bacteria species isolated were as follows Pseudomonas species (36.6%), Klebsiella species (20.6%), Staphylococcus aureus (16.6%), Streptococcus pyogenes (13.7%), Streptococcus pneumoniae (10.3%) and mixed isolates (2.3%). Amoxicillin and ampicillin recorded the highest resistance rate. Most of the isolates displayed high level of resistance to more than two antibiotics. Although multidrug resistance is reported in the study, gentamicin, amikacin and cefuroxime are recommended as the antibiotics of choice against bacterial isolates obtained.

CONCLUSION

Bacterial respiratory infections were prevalent in the study area and the isolates obtained showed resistance to commonly used antibiotics such as amoxicillin, ampicillin, ciprofloxacin piperacillin ciprofloxacin, ceftazidime, piperacillin-tazobactam and cephalexin. Therefore need for a continuous surveillance of antimicrobial resistance in management of respiratory infections in the study area.

Constructing Marine Bacterial Metabolic Chassis for Potential Biorefinery of Red Algal Biomass and Agaropectin Wastes

Marine red algal biomass is a promising feedstock for sustainable production of value-added chemicals. However, the major constituents of red algal biomass, such as agar and carrageenan, are not easily assimilated by most industrial metabolic chassis developed to date. Synthetic biology offers a solution by utilizing nonmodel organisms as metabolic chassis for consolidated biological processes. In this study, the marine heterotrophic bacterium Pseudoalteromonas atlantica T6c was harnessed as a metabolic chassis to produce value-added chemicals from the affordable red algal galactans or agaropectin, a byproduct of industrial agarose production. To construct a heterologous gene expression device in P. atlantica T6c, promoters related to agar metabolism were screened from the differentially expressed genes using RNA-Seq analysis. The expression device was built and tested with selected promoters fused to a reporter gene and tuned by incorporation of a cognate repressor predicted from the agar-specific polysaccharide utilization locus. The feasibility of the marine bacterial metabolic chassis was examined by introducing the biosynthetic gene clusters of β-carotene and violacein. Our results demonstrate that the metabolic chassis platform enables direct conversion of low-cost red algal galactans or industrial waste agaropectin into valuable bioactive pigments without any pretreatment of biomass. The developed marine bacterial chassis could potentially be used in a biorefinery framework to produce value-added chemicals from marine algal galactans.

Detection of Atypical Salmonella Infantis Phenotypes in Broiler Environmental Samples

In numerous countries, strict and targeted measures concerning Salmonella monitoring and control are implemented and high quality of surveillance is ensured by obligatory investigation of samples from the primary production level of animals according to EN/ISO standards. Here, 2 phenotypic characteristics of Salmonella exhibited on compulsory media are crucial, namely, motility demonstrated on modified semisolid Rappaport Vassiliadis agar (MSRV), and production of hydrogen sulfide (H2S) on xylose lysine deoxycholate agar (XLD). In the present study, we describe the detection of Salmonella Infantis variants found in broiler environmental samples with major alterations in their growth characteristics on MSRV, XLD, and brilliant green-phenol red-agar (BPLS). The variants proved to be non-motile on MSRV and displayed non-confirming colony appearances on the previously mentioned selective agars. The growth spectrum comprised pinhead sized yellow colonies with small black centers, but also pinpoint sized colorless colonies, both colony types of regular shape. Our work contributes to highlight the finding of S. Infantis variants which possess more than one phenotypic deviation from the "typical" growth characteristics and by this limit the detection power of the actual obligatory used media. IMPORTANCE Salmonellosis caused by non-typhoidal Salmonella serovars is the second most frequently reported zoonotic disease in humans in the EU. The transmission of these agents is mainly via contaminated food of animal origin. In this context, poultry products are the main source of infection. Therefore, continuous and standardized surveillance of the prevalence of such Salmonella serovars at the primary production level is essential. Our findings show the phenotypic heterogeneity of the serovar Infantis and provide growth characteristics of atypical variants. Such variants pass unnoticed official screening methods, resulting in incorrect identification and being underrepresented in epidemiological surveillance programs.

Multidrug-resistant and extended-spectrum beta-lactamase-producing Enterobacteriaceae isolated from chicken droppings in poultry farms at Gondar City, Northwest Ethiopia

BACKGROUND

The poultry sector is one of the largest and fastest-growing agricultural sub-sector, especially in developing countries like Ethiopia. In poultry production, poultry farmers use sub-optimum doses of antibiotics for growth promotion and disease prevention purpose. This indiscriminate use of antibiotics in poultry farms contributes to the emergence of antibiotic-resistant bacteria, which has adverse implications for public health. Therefore, this study is aimed to assess multidrug resistance and extended-spectrum beta-lactamase-producing Enterobacteriaceae from chicken droppings in poultry farms.

METHODS

A total of 87 pooled chicken-dropping samples were collected from poultry farms from March to June 2022. Samples were transported with buffered peptone water. Selenite F broth was used for the enrichment and isolation of Salmonella spp. Isolates were cultured and identified by using MacConkey agar, Xylose lysine deoxycholate agar, and routine biochemical tests. Kirby-Bauer disk diffusion technique and combination disk test were used for antibiotic susceptibility testing and confirmation of extended-spectrum beta-lactamase production, respectively. Data were entered using Epi-data version 4.6 and then exported to SPSS version 26 for analysis.

RESULT

Out of 87 pooled chicken droppings, 143 Enterobacteriaceae isolates were identified. Of these, E. coli accounts for 87 (60.8%), followed by Salmonella spp. 23 (16.1%), P. mirabilis 18 (12.6%) and K. pneumoniae 11 (7.7%). A high resistance rate was observed for ampicillin 131 (91.6%), followed by tetracycline 130 (90.9), and trimethoprim-sulfamethoxazole 94 (65.7%). The overall multidrug resistance rate was 116/143 (81.1%; 95% CI: 74.7-87.5). A total of 12/143 (8.4%; CI: 3.9-12.9) isolates were extended-spectrum beta-lactamase producers, with 11/87 (12.6%) E. coli and 1/11 (9.1%) K. pneumoniae.

CONCLUSION AND RECOMMENDATIONS

High prevalence of multi-drug resistant isolates was observed. This study alarms poultry as a potential reservoir of extended-spectrum beta-lactamase-producing Enterobacteriaceae, which might shed and contaminate the environment through faecal matter. Prudent use of antibiotics should be implemented to manage antibiotic resistance in poultry production.

Evaluation of the Effects of Probiotics and Prebiotics on the Salmonella typhi Infections

Typhoid fever is one of the most commonly disseminated diseases and is considered to be linked to poor sanitation. It is responsible for 2-5% of all deaths, and its causative agent is Salmonella typhi. The current study aimed to investigate the antibacterial activity of prebiotics (inulin and starch) and probiotics against multidrug resistance of S. typhi bacterial isolates. Determination of the inhibitory effect of probiotics and prebiotics against S. typhi isolates was performed by agar well diffusion method and minimal inhibitory concentration. Body samples of all eligible patients were collected and cultured. Finally, 50 (25%) out of the total cultured samples were S. Typhi bacteria isolated from different samples. The bacteria were mainly found in blood, followed by stool and fluid (74%, 24%, and 2%, respectively). On differential medium, xylose lysine deoxycholate agar, the colonies appear red with black centers, while on MacConkey agar, the colonies appear smooth, pale, transparent, colorless, and raised. Regarding the inhibition zone values of bacteriocins of Lactobacillus from Yogurt against S. typhi in plate, significant differences were identified between the ones with and without prebiotic addition. Accordingly, the value of the inhibition zone for those without prebiotic addition (13.18±7.403) was significantly lower than that of cutoff values of 20 with a significant difference of -6.820 (t= -6.514, df 49, P=0.000). Moreover, the inhibition effect of prebiotics (inulin and starch) against S. typhi at 37 °C for 24 h in part dish glucose as control, only the mean of inulin was found to be significantly lower than that of the cutoff value of 18 with the mean difference of -3.900 (t=-4.115, df 49, P=0.000). Other prebiotics of glucose and starch in 24 h showed negative inhibition. Probiotics are live microorganisms that have beneficial host effects by enhancing microbial balance in the intestine, whereas prebiotics are indigestible food components having beneficial effects by enhancing the activity and growth of one or more colonic bacteria. Lactobacillus filtrates had considerable effects against the test S. typhi isolates.

Laser Capture Microdissection, Culture Analysis, and Bacterial Sequencing to Evaluate the Microbiota of Focal Duodenal Necrosis in Egg Layers

Focal duodenal necrosis (FDN) is a common intestinal disease of table egg layers. In this research we aimed to identify the bacteria commonly found in FDN lesions as seen with histopathological analysis. Fifty-nine ethanol-fixed duodenum samples were collected from egg layers on eight FDN-affected farms, and 42 samples had typical FDN lesions. Excision of bacteria-containing lesions using laser capture microdissection was performed, followed by 16S rRNA gene sequencing of extracted DNA for bacterial identification. Bacterial sequencing analysis revealed no consistent bacterial species identified from samples with FDN. However, analysis of the relative phylum abundance revealed differences in the duodenal microbiota between layers with FDN and healthy birds. There were differences in the abundance of Proteobacteria, Firmicutes, and Actinobacteria between FDN-positive and FDN-negative control samples compatible with intestinal dysbiosis. In addition, 10 duodenal samples with FDN lesions were collected for bacteriological analysis, yielding 47 colonies on tryptone soy agar, MacConkey agar, and blood agar plates. Using 16S rRNA gene PCR, 39/47 (53.8%) colonies were identified as Escherichia coli. PCR for E. coli virulence genes identified 21/39 (53.8%) E. coli isolates as avian pathogenic E. coli-like. PCR analysis for 19 E. coli virulence genes associated with intestinal disease strains including inflammatory bowel disease found 11/39 (28.2%) isolates containing more than 10 of these virulence genes. In conclusion, FDN appears to be a multifactorial inflammatory intestinal disease associated with intestinal dysbiosis, and Gram-negative bacteria including E. coli may contribute to the pathogenesis of this disease.

Development of an US, MRI, and CT imaging compatible realistic mouse phantom for thermal ablation and focused ultrasound evaluation

Tissue mimicking phantoms (TMPs) play an essential role in modern biomedical research as cost-effective quality assurance and training tools, simultaneously contributing to the reduction of animal use. Herein, we present the development and evaluation of an anatomically accurate mouse phantom intended for image-guided thermal ablation and Focused Ultrasound (FUS) applications. The proposed mouse model consists of skeletal and soft tissue mimics, whose design was based on the Computed tomography (CT) scans data of a live mouse. Advantageously, it is compatible with US, CT, and Magnetic Resonance Imaging (MRI). The compatibility assessment was focused on the radiological behavior of the phantom due to the lack of relevant literature. The X-ray linear attenuation coefficient of candidate materials was estimated to assess the one that matches best the radiological behavior of living tissues. The bone part was manufactured by Fused Deposition Modeling (FDM) printing using Acrylonitrile styrene acrylate (ASA) material. For the soft-tissue mimic, a special mold was 3D printed having a cavity with the unique shape of the mouse body and filled with an agar-based silica-doped gel. The mouse phantom accurately matched the size and reproduced the body surface of the imaged mouse. Tissue-equivalency in terms of X-ray attenuation was demonstrated for the agar-based soft-tissue mimic. The phantom demonstrated excellent MRI visibility of the skeletal and soft-tissue mimics. Good radiological contrast between the skeletal and soft-tissue models was also observed in the CT scans. The model was also able to reproduce realistic behavior during trans-skull sonication as proved by thermocouple measurements. Overall, the proposed phantom is inexpensive, ergonomic, and realistic. It could constitute a powerful tool for image-guided thermal ablation and FUS studies in terms of testing and optimizing the performance of relevant equipment and protocols. It also possess great potential for use in transcranial FUS applications, including the emerging topic of FUS-mediated blood brain barrier (BBB) disruption.

Antibacterial activity of chloroxylenol and thymol against pathogenic bacteria isolated from under long nails

OBJECTIVE

Fingernails are a perfect area for harboring bacteria such as Staphylococcus aureus, Salmonella sp., Shigella sp., and Escherichia coli. These bacteria under the long nails may cause diseases due to the contact of nails with food or while biting the nails. Our study aimed to compare the antibacterial activity of chloroxylenol and thymol, two different detergent ingredients, on microorganisms isolated from long fingernails. This study was performed to raise awareness of the dangers of long nails and the importance of good nail hygiene.

PATIENTS AND METHODS

The present study was performed on female students at the Faculty of Science, King Abdelaziz University. Bacteria were isolated from under one finger nails and cultured on both McConkey agar and mannitol salt agar. After incubation, we isolated bacteria on nutrient agar. After that, we conducted several tests to determine the isolate type. Finally, we prepared three different concentrations of chloroxylenol and thymol to compare their effect on the isolated bacteria using antibacterial activity on Mueller-Hinton agar.

RESULTS

Two types of bacteria were isolated, pathogenic bacteria called Staphylococcus aureus and non-pathogenic bacteria called Staphylococcus epidermidis. Staphylococci have more sensitivity to chloroxylenol than thymol. In addition, chloroxylenol, at high concentrations had a more powerful antibacterial effect.

CONCLUSIONS

The results emphasized that fingernails could harbor pathogenic bacteria which are difficult to remove. Perfect hand hygiene is essential to prevent the spread of diseases.

Susceptibility antibiotic screening reveals high rates of multidrug resistance of Salmonella, Shigella and Campylobacter in HIV infected and uninfected patients from Mozambique

BACKGROUND

Antibacterial resistance is a growing concern worldwide, including in Mozambique. Diarrhea is an important cause of mortality in Mozambique, yet few local studies have reported on the resistance of bacterial pathogens in this context. Therefore, this study aims to characterize antibiotic susceptibility patterns of Salmonella, Shigella and Campylobacter spp. among patients with diarrhea, including those who are HIV-infected and-uninfected.

METHODS

We conducted antibiotic susceptibility testing on 157 stool isolates recovered from 129 patients aged between 0 and 80 years with diarrhea, including HIV infected (n = 68) and-uninfected individuals (n = 61), assisted at two health centers in Maputo city. The isolates comprised of 99 Salmonella, 45 Shigella and 13 Campylobacter strains. The Kirby-Bauer disk diffusion method was used on Mueller-Hinton II agar for Salmonella and Shigella spp., while Mueller-Hinton II agar with 5% defibrinated sheep blood was used for Campylobacter spp. We tested six antibiotics listed on the national essential medicines list, including ciprofloxacin, erythromycin, azithromycin, trimethoprim-sulfamethoxazole, gentamicin, and tetracycline.

RESULTS

All isolates were resistant to at least one antibiotic. A high percentage of Salmonella spp. isolates were found to be resistant to trimethoprim-sulfamethoxazole (89.9%, n = 89), erythromycin (88.9%, n = 88) and tetracycline (76.8%, n = 76). In addition, 86.6% (n = 39) and 68.9% (n = 31) of Shigella isolates were resistant to trimethoprim-sulfamethoxazole and tetracycline, respectively. The majority of Campylobacter isolates (92.3%, n = 12) were resistant to erythromycin, azithromycin and tetracycline. Multidrug resistance (MDR) was observed in 79.8% of Salmonella spp., 76.9% of Campylobacter spp., and 57.8% of Shigella spp. Drug susceptibility profiles for Salmonella spp. and Campylobacter were similar in both HIV-1 infected and uninfected patients. However, Shigella spp. isolates obtained from patients without HIV infection were significantly more likely to be resistant to erythromycin, azithromycin or to exhibit multidrug resistance than those obtained from patients with HIV-1 infection (p < 0.05). All Shigella spp. and Campylobacter spp. isolates were susceptible to gentamicin.

CONCLUSION

Our study highlights concerning rates of antibiotic resistance and MDR among diarrheal bacterial pathogens in Mozambique. Further research is needed to understand the impact of HIV, ART therapy and immunosuppression on antibiotic resistance. Urgent interventions are essential to prevent the spread of resistant strains.

Clinical Evaluation of Nontuberculous Mycobacteria (NTM) Elite Agar, a New Medium for the Isolation of NTM: a Multicenter Study

Nontuberculous mycobacteria (NTM) are gaining interest with the increased number of infected patients. NTM Elite agar is designed specifically for the isolation of NTM without the decontamination step. We assessed the clinical performance of this medium combined with Vitek mass spectrometry (MS) matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) technology for the isolation and identification of NTM in a prospective multicenter study, including 15 laboratories (24 hospitals). A total of 2,567 samples from patients with suspected NTM infection were analyzed (1,782 sputa, 434 bronchial aspirates, 200 bronchoalveolar lavage samples, 34 bronchial lavage samples, and 117 other samples). A total of 220 samples (8.6%) were positive with existing laboratory methods against 330 with NTM Elite agar (12.8%). Using the combination of both methods, 437 isolates of NTM were detected in 400 positive samples (15.6% of samples). In total, 140 samples of the standard procedures (SP) and 98 of the NTM Elite agar were contaminated. NTM Elite agar showed a higher performance for rapidly growing mycobacteria (RGM) species than SP (7% versus 3%, P < 0.001). A trend has been noted for the Mycobacterium avium complex (4% with SP versus 3% with NTM Elite agar, P = 0.06). The time to positivity was similar (P = 0.13) between groups. However, the time to positivity was significantly shorter for the RGM in subgroup analysis (7 days with NTM and 6 days with SP, P = 0.01). NTM Elite agar has been shown to be useful for the recovery of NTM species, especially for the RGM. Using NTM Elite agar + Vitek MS system in combination with SP increases the number of NTM isolated from clinical samples.