Antibacterial resistance

In vitro influence of PEG functionalized ZnO-CuO nanocomposites on bacterial growth

Polyethyleneglycol-coated biocompatible CuO-ZnO nanocomposites were fabricated hydrothermally varying Zn:Cu ratios as 1:1, 2:1, and 1:2, and their antibacterial activity was determined through the well diffusion method against the Gram-negative Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and the Gram-positive Staphylococcus aureus. The minimum inhibitory concentration and the minimum bactericidal concentration values of the synthesized samples were determined. Subsequently, the time synergy kill assay was performed to elucidate the nature of the overall inhibitory effect against the aforementioned bacterial species. The mean zone of inhibition values for all four samples are presented. The inhibitory effect increased with increasing concentration of the nanocomposite (20, 40 and 60 mg/ml) on all the bacterial species except for S. aureus. According to the MBC/MIC ratio, ZnO was found to be bacteriostatic for E. coli and P. aeruginosa, and bactericidal for S. aureus and K. pneumoniae. Zn:Cu 2:1 was bactericidal on all bacterial species. A bacteriostatic effect was observed on E. coli and P. aeruginosa in the presence of Zn:Cu 1:1 whereas, it showed a bactericidal effect on S. aureus and K. pneumoniae. Zn:Cu 1:2 exhibited a bacteriostatic effect on E. coli while a bactericidal effect was observed for E. coli, P. aeruginosa, and K. pneumoniae. The metal oxide nanocomposites were found to be more sensitive towards the Gram-positive strain than the Gram-negative strains. Further, all the nanocomposites possess anti-oxidant activity as shown by the DPPH assay.

Statistical optimization of a podoviral anti-MRSA phage CCASU-L10 generated from an under sampled repository: Chicken rinse

Introduction

The insurgence of antimicrobial resistance is an imminent health danger globally. A wide range of challenging diseases are attributed to methicillin-resistant Staphylococcus aureus (MRSA) as it is weaponized with a unique array of virulence factors, and most importantly, the resistance it develops to most of the antibiotics used clinically. On that account, the present study targeted the optimization of the production of a bacteriophage active against MRSA, and evaluating some of its characters.

Methods and results

The bacteriophage originated from a quite peculiar environmental source, raw chicken rinse and was suggested to belong to Podoviridae, order Caudovirales. It withstood a variety of extreme conditions and yield optimization was accomplished via the D-optimal design by response surface methodology (RSM). A reduced quadratic model was generated, and the ideal production conditions recommended were pH 8, glycerol 0.9% v/v, peptone 0.08% w/v, and 107 CFU/ml as the host inoculum size. These conditions led to a two-log fold increase in the phage titer (1.17x10¹² PFU/ml), as compared to the regular conditions.

Discussion

To conclude, statistical optimization successfully enhanced the output of the podoviral phage titer by two-log fold and therefore, can be regarded as a potential scale-up strategy. The produced phage was able to tolerate extreme environmental condition making it suitable for topical pharmaceutical preparations. Further preclinical and clinical studies are required to ensure its suitability for use in human.

Recent Development of Polyhydroxyalkanoates (PHA)-Based Materials for Antibacterial Applications: A Review

The diseases caused by microorganisms are innumerable existing on this planet. Nevertheless, increasing antimicrobial resistance has become an urgent global challenge. Thus, in recent decades, bactericidal materials have been considered promising candidates to combat bacterial pathogens. Recently, polyhydroxyalkanoates (PHAs) have been used as green and biodegradable materials in various promising alternative applications, especially in healthcare for antiviral or antiviral purposes. However, it lacks a systematic review of the recent application of this emerging material for antibacterial applications. Therefore, the ultimate goal of this review is to provide a critical review of the state of the art recent development of PHA biopolymers in terms of cutting-edge production technologies as well as promising application fields. In addition, special attention was given to collecting scientific information on antibacterial agents that can potentially be incorporated into PHA materials for biological and durable antimicrobial protection. Furthermore, the current research gaps are declared, and future research perspectives are proposed to better understand the properties of these biopolymers as well as their possible applications.

Prevalence of extended spectrum beta lactamase and molecular detection of blaTEM, blaSHV and blaCTX-M genotypes among Gram negative bacilli isolates from pediatric patient population in Gaza strip

BACKGROUND

Extended-spectrum β lactamases (ESBLs), have the ability to hydrolyze and cause resistance to various types of the β-lactam antibiotics, including the extended-spectrum (or third-generation) cephalosporins (e.g., cefotaxime, ceftriaxone, ceftazidime) and monobactams (e.g., aztreonam). ESBL-producing Gram negative bacteria is still posing significant therapeutic challenges.

OBJECTIVES

To assess the prevalence and molecular characteristics of ESBL producing Gram negative bacilli, isolated from a cohort of pediatric patients in Gaza hospitals.

METHODS

A total of 322 isolates of Gram-negative bacilli were collected from four referral pediatric hospitals in Gaza, namely: Al-Nasr, Al-Rantisi, Al-Durra and Beit Hanoun hospitals. These isolates were tested for ESBL production using the double disk synergy and CHROMagar phenotypic methods. Molecular characterization of the ESBL producing strains was performed using PCR targeting the CTX-M, TEM and SHV genes. Antibiotic profile was done using Kirby Bauer method according to Clinical and Laboratory Standard Institute.

RESULTS

Out of 322 isolates tested by phenotypic methods, 166 (51.6%) were ESBL positive. The prevalence of ESBL production in Al-Nasr, Al-Rantisi, Al-Durra and Beit Hanoun hospitals was 54%, 52.5%, 45.5% and 52.8% respectively. The prevalence of ESBL production among Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter spp., Proteus mirabilis, Enterobacter spp., Citrobacter spp., and Serratia marcescens is 55.3%, 63.4%, 17.8%, 57.1%, 33.3%, 28.5%, 38.4%, and 4% respectively. ESBL production among urine, pus, blood, CSF and sputum was 53.3%, 55.2%, 47.4%, 33.3%, and 25% respectively. Out of the 322 isolates, 144 were screened for CTX-M, TEM and SHV production. Using PCR, 85 (59%) had at least one gene. The prevalence rate of CTX-M, TEM and SHV genes was 60%, 57.6%, and 38.3% respectively. Meropenem and amikacin were highest rates of susceptibility antibiotics against ESBLs producers (83.1% and 82.5% respectively), while the least effective antibiotics were amoxicillin (3.1%) and cephalexin (13.9%). Moreover, ESBLs producers showed high resistance rate to cefotaxime, ceftriaxone and ceftazidime (79.5%, 78.9% and 79.5% respectively).

CONCLUSION

Our results show high prevalence of ESBL production among Gram negative bacilli isolated from children in different pediatric hospitals in Gaza strip. A substantial level of resistance to first and second generation cephalosporins was also observed. This ascertains the need for a rational antibiotic prescription and consumption policy.

Rapid separation of bacteria from primary nasal samples using inertial microfluidics

Microbial populations play a crucial role in human health and the development of many diseases. These diseases often arise from the explosive proliferation of opportunistic bacteria, such as those in the nasal cavity. Recently, there have been increases in the prevalence of these opportunistic pathogens displaying antibiotic resistance. Thus, the study of the nasal microbiota and its bacterial diversity is critical in understanding pathogenesis and developing microbial-based therapies for well-known and emerging diseases. However, the isolation and analysis of these populations for clinical study complicates the already challenging task of identifying and profiling potentially harmful bacteria. Existing methods are limited by low sample throughput, expensive labeling, and low recovery of bacteria with ineffective removal of cells and debris. In this study, we propose a novel microfluidic channel with a zigzag configuration for enhanced isolation and detection of bacteria from human clinical nasal swabs. This microfluidic zigzag channel separates the bacteria from epithelial cells and debris by size differential focusing. As such, pure bacterial cell fractions devoid of large contaminating debris or epithelial cells are obtained. DNA sequencing performed on the separated bacteria defines the diversity and species present. This novel method of bacterial separation is simple, robust, rapid, and cost-effective and has the potential to be used for the rapid identification of bacterial cell populations from clinical samples.

Dietary supplementation with Clostridium butyricum improves growth performance of broilers by regulating intestinal microbiota and mucosal epithelial cells

Clostridium butyricum has been widely considered an antibiotic substitute in recent years. It can promote growth performance, improve the immune response and enhance the intestinal barrier function of the host. In the present study, 1-d-old Arbor Acres (AA) broilers were fed C. butyricum (1 × 10⁹ cfu/kg) for 28 d. The transcriptomic characteristics of epithelial cells of the cecal mucosa were determined by RNA-sequence, and the cecal microbiota composition was explored by 16S ribosomal RNA gene sequencing. The changes in the intestinal mucosa of broilers were then analyzed by tissue staining. Gene Ontology (GO) annotations identified substance transport and processes and pathways that might participate in intestinal development and cell viability. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the differentially expressed genes are involved in numerous pathways related to amino acid and vitamin metabolism and antioxidant and defensive functions, among others. The relative expression of some genes associated with intestinal barrier function (claudins 2, 15, 19, and 23, tight junction proteins 1, 2, and 3 and mucin 1) was significantly increased in the treatment group (P < 0.05 or P < 0.01). Moreover, the proportion of Firmicutes was higher in the C. butyricum-treated group, whereas the proportion of Proteobacteria was higher in the control group. At the genus level, the relative abundances of Butyricicoccus and Lactobacillus, among other bacteria, were increased after C. butyricum supplementation. The tissue staining analysis showed that the cecal mucosa of broilers was significantly ameliorated after the addition of C. butyricum (P < 0.05 or P < 0.01). These results showed that dietary supplementation with C. butyricum can enhance the antioxidant capacity, mucosal barrier function, and stabilize the cecal microbiota, resulting in improving the growth performance.

Bacterial Etiology of Neonatal Sepsis, Antibiotic Susceptibility Profile, and Associated Factors at Burdwan Medical College, Burdwan, West Bengal, India

Objective Neonatal sepsis remains to be a major cause of neonatal mortality and morbidity in developing countries like India. This study was aimed to identify the bacterial isolates and study antimicrobial profile among admitted babies with neonatal sepsis.

Methods A cross-sectional retrospective study was conducted in the sick neonatal wards and neonatal intensive care unit of Burdwan Medical College from March 2017 to February 2018. A total of 299 neonates suspected of neonatal sepsis was evaluated. Diagnosis of neonatal sepsis was made through positive blood culture. Positive samples were subcultured on specific media like blood, chocolate agar, nutrient, Muller–Hinton agar, and MacConkey plates, and the organisms were identified by gram staining and biochemical reactions. Antibiotic susceptibility was tested by Kirby–Bauer disc diffusion method.

Results Overall, 118 blood cultures out of 299 patients (39.46%) were bacteria-positive. Of these, 31.3% cases had early-onset septicemia (EOS), while 68.6% had late-onset septicemia (LOS). The prevalence of sepsis was higher in males (55.9%), preterm babies (58.47%), and low birth weight neonates (37.29%). The highest bacterial strains isolated were Klebsiella spp. (33.8%) followed by Staphylococcus aureus (25.8%), Escherichia coli (22.8%), coagulase-negative Staphylococcus (12.5%), Pseudomonas spp. (2.5%), Enterococcus spp. (1.6%), Acinetobacter spp. (0.8%), and Burkholderia spp. (0.8%). Resistance is high among the gram-negative bacteria, like Enterobacter and Pseudomonas, for piperacillin–tazobactam and cephalosporins but they are mostly sensitive to meropenem, colistin, and levofloxacin. Gram-positive bacteria, like S. aureus, are mostly resistant to amoxicillin–clavulanic acid but highly sensitive to linezolid, vancomycin, azithromycin, and teicoplanin.

Conclusion K. spp. and S. aureus are the most common isolates in our study. The level of resistance among the organisms toward conventional antibiotics like amoxicillin, cephalosporins, and piperacillin–tazobactum is alarmingly high. This warrants formulation of a hospital-specific guideline for antibiotic use and periodic review of the same.

Preliminary Biocompatibility Tests of Poly-ε-Caprolactone/Silver Nanofibers in Wistar Rats

Currently, nanotechnology is perceived as a promising science that produces materials with diverse unique properties at a nanometric scale. Biocompatibility tests of poly-ε-caprolactone nanofibers, embedded with silver nanoparticles manufactured by means of the electrospinning technique, were carried out in Wistar rats to be used as oral dressings for the eradication of bacteria. Solutions of 12.5, 25, 50 and 100 mM of silver nitrate were made using N-dimethylformamide (DMF) and tetrahydrofuran (THF) as reducing solvents with 8% of poly-ε-caprolactone (PCL) polymer. The solutions were electrospun, and the nanofibers obtained in the process were characterized by infrared spectroscopy, Raman spectroscopy, dark field optical microscopy, scanning electron microscopy and X-ray scattering spectroscopy. The nanofibers had an average diameter of 400 ± 100 nm. Once the characterization of the material was done, three implants of each concentration of the nanofibers were formed and placed in the subcutaneous tissue of the rats. Three experimental subjects were used, leaving the material in them for a length of two, four and six weeks, respectively. The rats showed good healing, with the lesions completely healed at four weeks after implantation. After that time, biopsies were taken, and histopathological sections were made to evaluate the inflammatory infiltrate. The tissues of the rats presented chronic inflammatory infiltrate composed mainly of lymphocytes and giant multinucleated cells. The material was rejected by the rats when a layer of collagen and fibroblasts was produced, coating the material, a process characteristic of a foreign body reaction.

Antibacterial properties of snake venom components

An increasing problem in the field of health protection is the emergence of drug-resistant and multi-drug-resistant bacterial strains. They cause a number of infections, including hospital infections, which currently available antibiotics are unable to fight. Therefore, many studies are devoted to the search for new therapeutic agents with bactericidal and bacteriostatic properties. One of the latest concepts is to search for this type of substances among toxins produced by venomous animals. In this approach, however, special attention is paid to snake venom because it contains molecules with antibacterial properties. Thorough investigations have shown that the phospholipases A2 (PLA2) and l-amino acids oxidases (LAAO), as well as fragments of these enzymes, are mainly responsible for the bactericidal properties of snake venoms. Some preliminary research studies also suggest that fragments of three-finger toxins (3FTx) are bactericidal. It has also been proven that some snakes produce antibacterial peptides (AMP) homologous to human defensins and cathelicidins. The presence of these proteins and peptides means that snake venoms continue to be an interesting material for researchers and can be perceived as a promising source of antibacterial agents.

Antimicrobial misuse in pediatric urinary tract infections: recurrences and renal scarring

Background

In children, urinary tract infection (UTI) is one of a common bacterial infection. This study was conducted to detect the uropathogen, antimicrobial susceptibility, pathogen associated with recurrences and renal scarring in children initially taken care from general practitioners and later presented to tertiary care.

Methods

Every inward UTI episode, culture and antimicrobial susceptibility was done while on past 6-month, history of infections and use of antimicrobials was collected using clinical records and demonstration of antimicrobials. Children with recurrent pyelonephritis was followed and in vitro bio film formation was assessed.

Results

Frequency of UTI was significantly high among infants (p = 0.03). Last 6-month, all (220) were exposed to antimicrobials. Cefixime was the commonly prescribed antimicrobial (p = 0.02). In current UTI episode, 64.5% (142/220) of children with UTI were consulted GPs’ prior to seek treatment from tertiary care pediatric unit (p = 0.02). While on follow up child who developed UTI, found urine culture isolates were significantly shifted from E. coli and K. pneumoniae to extended spectrum of beta-lactamase (ESBL) E. coli and K. pneumoniae. Out of 208 participants, 36 of them had re-current pyelonephritis (R-PN). Renal scarring (RS) was detected in 22 out of 70 patients with pyelonephritis following dimercaptosuccinic acid scan. Following each episodes of recurrent pyelonephritis 11% of new scar formation was detected (p = 0.02). Bio film forming E. coli and K. pneumoniae was significantly associated in patients with R-PN (p = 0.04).

Discussion

Medical care providers often prescribe antimicrobials without having an etiological diagnosis. While continuing exposure of third generation cephalosporin and carbapenem leads to development of ESBL and CRE microbes in great. The empiric uses of antimicrobials need to be stream lined with local epidemiology and antimicrobial susceptibility pattern. R-PN in childhood leads to RS. In great, bio film formation act as the focus for such recurrences.

Occurrence and Characterization of Carbapenemase-Producing Enterobacteriaceae in a Tunisian Hospital

Carbapenem-resistant Enterobacteriaceae have become of particular concern, since they were quickly disseminated in various areas in the world. The aim of the study was to investigate the prevalence of carbapenemase production among clinical isolates of Enterobacteriaceae recovered from the Military Hospital of Tunisia. Bacterial isolates (n = 125) were recovered from patients in diverse services from March 2014 to February 2016 and identified by Vitek II Compact^®. The multiplex PCR for bla_VIM, bla_IMP, bla_NDM, bla_KPC, and bla_OXA-48 with subsequent amplicon detection by reverse hybridization was performed with the Hyplex SuperBug ID test system (AmplexDiagnostics GmbH, Gars-Bahnhof, Germany). The 125 strains showed resistance to carbapenems of which 102 strains (81.6%) were carbapenemase-producing Enterobacteriaceae and were identified as Klebsiella pneumoniae (85.2%), Enterobacter cloacae (9.8%), Escherichia coli (2.9%), Providencia stuartii (0.9%) and Enterobacter aerogenes (0.9%). These strains were isolated mainly from blood, anal, and urine samples. Patients were mainly hospitalized in the intensive care units, surgery, and medical services. All strains were resistant to ertapenem (100%) and 55.8% showed resistance to imipenem. Carbapenemases genes detected in our study were as follows: bla_OXA-48 (84 isolates), bla_NDM-1 (8 isolates), bla_OXA-48 + bla_VIM (5 isolates), and bla_OXA-48 + bla_NDM-1 (5 isolates). Our research provides epidemiological data showing the quick spread of carbapenem-resistant bacteria in our region, which calls for new surveillance strategies and strict hygiene rules.

Development of botanicals to combat antibiotic resistance

The discovery of antibiotics in the previous century lead to reduction in mortality and morbidity due to infectious diseases but their inappropriate and irrational use has resulted in emergence of resistant microbial populations. Alteration of target sites, active efflux of drugs and enzymatic degradations are the strategies employed by the pathogenic bacteria to develop intrinsic resistance to antibiotics. This has led to an increased interest in medicinal plants since 25-50% of current pharmaceuticals are plant derived. Crude extracts of medicinal plants could serve as an alternate source of resistance modifying agents owing to the wide variety of secondary metabolites. These metabolites (alkaloids, tannins, polyphenols etc.) could act as potentials for antimicrobials and resistance modifiers. Plant extracts have the ability to bind to protein domains leading to modification or inhibition protein-protein interactions. This enables the herbals to also present themselves as effective modulators of host related cellular processes viz immune response, mitosis, apoptosis and signal transduction. Thus they may exert their activity not only by killing the microorganism but by affecting key events in the pathogenic process, thereby, the bacteria, fungi and viruses may have a reduced ability to develop resistance to botanicals. The article is meant to stimulate research wherein the cidal activity of the extract is not the only parameter considered but other mechanism of action by which plants can combat drug resistant microbes are investigated. The present article emphasizes on mechanisms involved in countering multi drug resistance.

Antibacterial and antibiotic potentiating activity of Vangueria madagascariensis leaves and ripe fruit pericarp against human pathogenic clinical bacterial isolates

This study aimed to assess the antibacterial and antibiotic potentiating property of Vangueria madagascariensis (VM) (fruit and leaf extracts) against 10 clinical isolates. A microdilution broth susceptibility assay for bacteria was used for the determination of the minimum inhibitory concentration (MIC) and associated with antibiotics to evaluate any synergistic effect. VM extracts were found to potentiate the activity of 3 conventional antibiotics. Chloramphenicol and Ciprofloxacin showed no activity against Acinetobacter spp. but when mixed with VM (in a ratio of 50% VM extracts: 30% antibiotic), showed potentiating effect. The methanolic fruit extract at lower concentration of Chloramphenicol (30%) gave better synergistic effect (MIC = 3.75 μg/mL) as compared to 50% (MIC = 12.5 μg/mL). With Gentamicin, no activity was detected with leaf decoction but other extracts (methanolic leaf/fruit extract and fruit decoction) showed enhancement (MIC- 0.47, 7.5 and 15 μg/mL respectively). Interestingly, Chloramphenicol showed no activity against MRSA, but when mixed with VM, produced low MICs (<0.39-0.78 μg/mL with 50% antibiotic and from <0.47 to 0.94 μg/mL with 30% antibiotic). Combining Gentamicin with VM extracts showed an enhancement in the potentiating activity against MRSA. In conclusion, the observed antimicrobial property of VM tend to suggest a promising alternative and complementary strategy to manage bacterial infections and hence can open new avenues for further research using traditional medicinal food plant.

Extended-Spectrum Beta-Lactamase Bacteria From Urine Isolates in Children

OBJECTIVES

Multidrug-resistant Gram-negative bacteria, including extended-spectrum beta-lactamase (ESBL)-producing organisms, are a growing problem. The primary objective of this study was to describe the proportion of children with ESBL-producing urinary isolates at a tertiary medical center as well as these organisms' susceptibility patterns. The secondary objective was to identify the risk factors for acquiring ESBL urinary pathogens.

METHODS

This retrospective study evaluated a cohort of children with ESBL urinary isolates, admitted to a tertiary children's hospital during a 6-year period. The proportion of patients with an ESBL-producing urinary isolate among all patients who grew a Gram-negative isolate is described together with the organism's susceptibility pattern. Patients with non-ESBL Gram-negative urinary organisms were used as a control group for identifying patient risk factors for ESBL.

RESULTS

A total of 7.8% (29 of 370) of patients in our cohort grew Gram-negative urinary isolates with an ESBL strain. Most of the ESBL organisms isolated were sensitive to carbapenems (100% of ESBL organisms susceptible to ertapenem and 93.8% susceptible to meropenem) and amikacin (92.3% of ESBL organisms susceptible). Patients with longer hospitalization, recent antibiotic use, and recent intensive care unit admission were found to be at increased risk for ESBL organisms in the urine.

CONCLUSIONS

When selecting empiric antibiotic therapy for suspected urinary tract infection in children, it may be prudent to consider the risk factors identified for acquiring an ESBL urinary pathogen.

Assessment of the Antimicrobial Activity of Few Saudi Arabian Snake Venoms

Background

Venoms of two cobras, four vipers, a standard antibiotic and an antimycotic, were evaluated comparatively, as antimicrobials.

Methods:

Six venom concentrations and three of the standard antibiotic and the antimycotic were run in micro-dilution and diffusion plates against the microorganisms.

RESULTS:

Echis pyramidum, Echis coloratus and Cerastes cerastes gasperettii highest venom concentrations gave significant growth inhibition zones (GIZ) with respect to a negative control, except Bitis arietans, whose concentrations were significant. The cobra Walterinnesia aegyptia had significant venom concentrations more than Naja haje arabica. The Staphylococcus aureus Methicillin Resistant (MRSA) bacterium was the most susceptible, with a highly (P < 0.001) significant GIZ mean difference followed by the Gram positive Staphylococcus aureus, (P < 0.001), Escherichia coli (P < 0.001), Enterococcus faecalis (P < 0.001) and Pseudomonas aeruginosa which, had the least significance (P < 0.05). The fungus Candida albicans was resistant to both viper and cobra venoms (P > 0.05). The antibiotic Vancomycin was more effective than snake venoms though, they were more efficient in inhibiting growth of the resistant Pseudomonas aeruginosa. This antibiotic was also inactive against the fungus, whilst its specific antifungal Fungizone was highly efficient with no antibacterial activity.

Conclusions:

These findings showed that snake venoms had antibacterial activity comparable to antibiotics, with a directly proportional relationship of venom concentration and GIZ, though, they were more efficient in combatting resistant types of bacteria. Both venoms and the standard antibiotic, showed no antifungal benefits.

[Role of Helicobacter pylori coccoid forms in infection and recrudescence]

Helicobacter pylori is a spiral Gram-negative bacillus, which colonizes the human stomach and plays a key role in the pathogenesis of a number of gastroduodenal diseases. However, when expose to environmental stressed conditions, such as increased oxygen tension, extended incubation and exposure to antibiotics, Helicobacter pylori is able to entering the viable but nonculturable state, in which the bacterium modifies its morphology from a spiral to coccoid form, as a manifestation of cell adaptation to these adverse conditions. In gastric tissues, viable coccoid forms may remain latent for long time and retain virulence factors, so these forms possibly contribute to the treatment failures and recurrence of Helicobacter pylori infection and gastroduodenal diseases as well. In this review, we will discuss several aspects of cellular adaptation and survival of Helicobacter pylori, antibiotic susceptibility and virulence of coccoid forms and its involvement with recrudescence.

Essential oils, a new horizon in combating bacterial antibiotic resistance

For many years, the battle between humans and the multitudes of infection and disease causing pathogens continues. Emerging at the battlefield as some of the most significant challenges to human health are bacterial resistance and its rapid rise. These have become a major concern in global public health invigorating the need for new antimicrobial compounds. A rational approach to deal with antibiotic resistance problems requires detailed knowledge of the different biological and non-biological factors that affect the rate and extent of resistance development. Combination therapy combining conventional antibiotics and essential oils is currently blooming and represents a potential area for future investigations. This new generation of phytopharmaceuticals may shed light on the development of new pharmacological regimes in combating antibiotic resistance. This review consolidated and described the observed synergistic outcome between essential oils and antibiotics, and highlighted the possibilities of essential oils as the potential resistance modifying agent.

Dirty hands: photodynamic killing of human pathogens like EHEC, MRSA and Candida within seconds

Hand hygiene is one of the most important interventions for reducing transmission of nosocomial life-threatening microorganisms, like methicillin resistant Staphylococcus aureus (MRSA), enterohemorrhagic Escherichia coli (EHEC) or Candida albicans. All three pathogens have become a leading cause of infections in hospitals. Especially EHEC is causing severe diarrhoea and, in a small percentage of cases, haemolytic-uremic syndrome (HUS) as reported for E. coli 104:H4 in Germany 2011. We revealed the possibility to inactivate very fast and efficiently MRSA, EHEC and C. albicans using the photodynamic approach. MRSA, EHEC and C. albicans were incubated in vitro with different concentrations of TMPyP for 10 s and illuminated with visible light (50 mW cm(-2)) for 10 and 60 s. 1 μmol l(-1) of TMPyP and an applied radiant exposure of 0.5 J cm(-2) achieved a photodynamic killing of ≥99.9% of MRSA and EHEC. Incubation with higher concentrations (up to 100 μmol l(-1)) of TMPyP caused bacteria killing of >5 log(10) (≥99.999%) after illumination. Efficient Candida killing (≥99.999%) was achieved first at a higher light dose of 12 J cm(-2). Different rise and decay times of singlet oxygen luminescence signals could be detected in Candida cell suspensions for the first time, indicating different oxygen concentrations in the surrounding for the photosensitizer and singlet oxygen, respectively. This confirms that TMPyP is not only found in the water-dominated cell surrounding, but also within the C. albicans cells. Applying a water-ethanol solution of TMPyP on ex vivo porcine skin, fluorescence microscopy of histology showed that the photosensitizer was exclusively localized in the stratum corneum regardless of the incubation time. TMPyP exhibited a fast and very effective killing rate of life-threatening pathogens within a couple of seconds that encourages further testing in an in vivo setting. Being fast and effective, antimicrobial photodynamic applications might become acceptable as a tool for hand hygiene procedures and also in other skin areas.

Bacteriological profile and antibiogram of neonatal septicemia

OBJECTIVES

To determine the incidence of neonatal septicemia, identify the bacterial isolates and study their antimicrobial susceptibility pattern in neonates visiting out-patient door (OPD) and admitted to the pediatric ward and neonatal intensive care unit (NICU) of the College of Medical Sciences, Teaching Hospital, Chitwan, Nepal.

METHODS

Blood culture of all neonates who were suspected for septicemia was performed. Isolate identification and antimicrobial susceptibility testing was done by standard microbiological method.

RESULTS

Out of the total 7,868 blood culture samples submitted to the microbiology laboratory, 1,572 (19.97 %) samples were from suspected cases of neonatal septicemia. The blood culture was positive for neonatal sepsis in 238 (15.13 %) samples. The incidence of gram positive and gram negative organisms were 44.1 % and 55.9 % respectively. Staphylococcus aureus remained the predominant isolate followed by Klebsiella spp. Most of the gram positive isolates exhibited higher resistance to penicillin and cephalosporin. Susceptibility to commonly used aminoglycosides and quinolones was found. Similarly, more than two third isolates of gram negative Enterobacteriaceae showed resistance to ampicillin. Third generation cephalosporin and aminoglycosides were found to be more satisfactory among gram negative organisms as compared to gram positive.

CONCLUSIONS

The high incidence of neonatal septicemia in the present setting reflects high magnitude of problem in central part of Nepal. Organisms isolated in the study exhibited higher resistance towards commonly used antimicrobials. High resistances to recommended drugs awares health care workers to seek for alternative antimicrobial agents. The periodic survey of etiological agents and their antibiotic susceptibility patterns is indeed necessary for the timely alarm of such type of problems.

Fast and effective: intense pulse light photodynamic inactivation of bacteria

The goal of this study was to investigate the photodynamic toxicity of TMPyP (5, 10, 15, 20-Tetrakis (1-methylpyridinium-4-yl)-porphyrin tetra p-toluenesulfonate) in combination with short pulses (ms) of an intense pulse light source within 10 s against Bacillus atrophaeus, Staphylococcus aureus, Methicillin-resistant S. aureus and Escherichia coli, major pathogens in food industry and in health care, respectively. Bacteria were incubated with a photoactive dye (TMPyP) that is subsequently irradiated with visible light flashes of 100 ms to induce oxidative damage immediately by generation of reactive oxygen species like singlet oxygen. A photodynamic killing efficacy of up to 6 log(10) (>99.9999%) was achieved within a total treatment time of 10 s using a concentration range of 1-100 μmol TMPyP and multiple light flashes of 100 ms (from 20 J cm(-2) up to 80 J cm(-2)). Both incubation of bacteria with TMPyP alone or application of light flashes only did not have any negative effect on bacteria survival. Here we could demonstrate for the first time that the combination of TMPyP as the respective photosensitizer and a light flash of 100 ms of an intense pulsed light source is enough to generate sufficient amounts of reactive oxygen species to kill these pathogens within a few seconds. Increasing antibiotic resistance requires fast and efficient new approaches to kill bacteria, therefore the photodynamic process seems to be a promising tool for disinfection of horizontal surfaces in industry and clinical purposes where savings in time is a critical point to achieve efficient inactivation of microorganisms.

Surveillance programmes and antibiotic resistance: worldwide and regional monitoring of antibiotic resistance trends

Since the introduction of the penicillins many decades ago, multiple species of bacteria have responded to the use of antimicrobial agents in their ability to develop and transmit antimicrobial resistance. Increased consumption of antimicrobial agents, their misappropriate use among other factors have further catalysed this resistance phenomenon. As bacterial resistance is a global healthcare issue, appropriate monitoring through governmental, institutional and industry or pharmaceutical led surveillance programmes is essential. This chapter describes the resistance issue, factors affecting this issue and examples of such ongoing resistance surveillance programmes.

Comparative analysis of viperidae venoms antibacterial profile: a short communication for proteomics

Bacterial infections involving multidrug-resistant strains are one of the ten leading causes of death and an important health problem in need for new antibacterial sources and agents. Herein, we tested and compared four snake venoms (Agkistrodon rhodostoma, Bothrops jararaca, B. atrox and Lachesis muta) against 10 Gram-positive and Gram-negative drug-resistant clinical bacteria strains to identify them as new sources of potential antibacterial molecules. Our data revealed that, as efficient as some antibiotics currently on the market (minimal inhibitory concentration (MIC) = 1–32 μg mL⁻¹), A. rhodostoma and B. atrox venoms were active against Staphylococcus epidermidis and Enterococcus faecalis (MIC = 4.5 μg mL⁻¹), while B. jararaca inhibited S. aureus growth (MIC = 13 μg ml⁻¹). As genomic and proteomic technologies are improving and developing rapidly, our results suggested that A. rhodostoma, B. atrox and B. jararaca venoms and glands are feasible sources for searching antimicrobial prototypes for future design new antibiotics against drug-resistant clinical bacteria. They also point to an additional perspective to fully identify the pharmacological potential of these venoms by using different techniques.

Enhancement of vancomycin activity by phenothiazines against vancomycin-resistant Enterococcus faecium in vitro

The antimicrobial and resistance-reversal activities of seven phenothiazine derivatives were evaluated against vancomycin-sensitive Enterococcus faecalis ATCC 29212, vancomycin resistant E. faecalis ATCC 51299 and ten vancomycin-resistant E. faecium strains originating from human infections. Minimum inhibitory concentrations (MIC) of the compounds were determined by agar dilution method, and synergy between phenothiazines and vancomycin was investigated using Checkerboard (microbroth dilution) technique. We found that all enterococci strains, regardless of their susceptibility to vancomycin, were inhibited by phenothiazines at concentrations varying from 8 to 256 microg/ml, with thiethylperazine being the most potent inhibitory agent. Besides, all the phenothiazines showed partial synergy with vancomycin and could lessen MIC of vancomycin from 512 to 8 microg/ml at their sub-inhibitory concentrations. The highest reduction in MIC was observed with chlorpromazine (32 times); however, thiethylperazine and promethazine stood next (24 times). Although resistance modification was observed at concentrations higher than those that phenothiazines reach in vivo, the potential offered by non-antibiotics justify further animal experiments as well as clinical trials to establish their clinical relevance.

Antibacterial effect of essential oils from two medicinal plants against Methicillin-resistant Staphylococcus aureus (MRSA)

Antimicrobial properties of plants essential oils (EOs) have been investigated through several observations and clinical studies which purpose them as potential tools to overcome the microbial drug resistance problem. The aim of this research is to study the antibacterial effect of two traditional plants essential oils, Thymus vulgaris and Eucalyptus globulus against clinical isolates of Methicillin resistant Staphylococcus aureus (MRSA) and other standard bacterial strains through disk diffusion and agar dilution methods. Gas Chromatography (GC) and Gas Chromatography/Mass Spectrometry (GC/MS) analysis examined the chemical composition of the oils. Results revealed both of oils to possess degrees of antibacterial activity against Gram (+) and Gram (-) bacteria. T. vulgaris EO showed better inhibitory effects than E. globulus essential oil. GC analysis of T. vulgaris resulted in thymol as the oil major compound whereas GC/MS assay exhibited eucalyptol as the most abundant constitute of E. globulus EO. These results support previous studies on these oils and suggest an additional option to treat MRSA infections. Clinical and further analytical trials of these data are necessary to confirm the obtained outcomes.

Role of contaminated aspiration tubes in nosocomial outbreak of Klebsiella pneumoniae producing SHV-2 and CTX-M-15 extended-spectrum beta-lactamases

Klebsiella pneumoniae resistant to ceftazidime was isolated from ten neonates hospitalised between February and March 2006 in two Antananarivo hospitals, Madagascar. The main environmental source, for one hospital in particular, was the liquid used to rinse aspiration tubes in the paediatric wards. The risk of contamination from aspiration tubes is very high in the hospitals of Antananarivo since tap water used to rinse the tubes is not regularly changed. Phenotypical (biotyping and antibiotyping) and genotypical (pulsed-field gel electrophoresis) analysis of all the clinical isolates indicated that nine cases were due to a single clone. This clone carried the genes encoding SHV-2 and CTX-M-15 beta-lactamases. This is the first description of an epidemic due to an ESBL-producing member of the family Enterobacteriaceae in Malagasy hospitals.

High prevalence of multidrug-resistant MRSA in a tertiary care hospital of northern India

Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial and community pathogen. The objectives of this study were to estimate the prevalence of multidrug-resistant MRSA strains in clinical specimens and to investigate the sensitivity pattern of these strains against various antibiotics used for treating hospitalized and out patients. Strains were identified using standard procedures, and their sensitivity pattern was investigated using such techniques as disc diffusion, minimum inhibitory concentration (MIC), and the mecA gene PCR. Among 783 isolates of S. aureus, 301 (38.44%) were methicillin-resistant, of which 217 (72.1%) were found to be multidrug-resistant. Almost all MRSA strains were resistant to penicillin, 95.68% were resistant to cotrimoxazole, 92.36% were resistant to chloramphenicol, 90.7% were resistant to norfloxacin, 76.1% were resistant to tetracycline, and 75.75% were resistant to ciprofloxacin. Vancomycin was the most effective drug, with only 0.33% of MRSA strains being resistant to it. It is concluded that antibiotics other than vancomycin can be used as anti-MRSA agents after a sensitivity test so as to preclude the emergence of resistance to it and that prevailing problems in chemotherapy will escalate unless indiscriminate and irrational usage of antibiotics is checked.

World Wide Web resources on antimicrobial resistance

Advances of modern technology, including the development of the Internet and the World Wide Web, have given clinicians and researches the opportunity to have immediate access to continuously updated information in various scientific fields. We compiled a list of World Wide Web resources of data from surveillance studies on antimicrobial resistance that may be useful to practitioners--especially infectious diseases specialists--as well as to scientists with a research interest in the field of antimicrobial resistance.

Antimicrobial and antiplasmid activities of essential oils

The antimicrobial and antiplasmid activities of essential oils (orange oil, eucalyptus oil, fennel oil, geranium oil, juniper oil, peppermint oil, rosemary oil, purified turpentine oil, thyme oil, Australian tea tree oil) and of menthol, the main component of peppermint oil, were investigated. The antimicrobial activities were determined on the Gram (+) Staphylococcus epidermidis and the Gram (-) Escherichia coli F'lac K12 LE140, and on two yeast Saccharomyces cerevisiae 0425 delta/1 and 0425 52C strains. The antiplasmid activities were investigated on E. coli F'lac bacterial strain. Each of the oils exhibited antimicrobial activity and three of them antiplasmid action. The interaction of peppermint oil and menthol with the antibiotics was studied on the same bacterial strain with the checkerboard method. Peppermint oil and menthol displayed additive synergy with oxytetracycline. A new mechanism of plasmid curing was established for one of the oil components.

Antibacterial activity of polygodial

Polygodial was found to possess moderate antibacterial activity against gram-positive bacteria including Bacillus subtilis, Staphylococcus aureus and gram-negative bacteria including Escherichia coli and Salmonella choleraesuis with minimum bactericidal concentrations (MBC) of 100 and 100 microg/mL (0.34 mm) and 100 and 50 microg/mL, respectively. The time kill curve study showed that polygodial was bactericidal against B. subtilis and S. choleraesuis. However, there was a difference in its bactericidal action against endospore-forming B. subtilis and food-borne S. choleraesuis.

Considerations for the Management of Gram-Positive Pathogens in the Intensive Care Unit

Surveillance data demonstrate that the majority of gram-positive bacterial isolates obtained in the intensive care unit (ICU) setting are staphylococci and enterococci. Staphylococci, mainly Staphylococcus aureus and coagulase-negative staphylococci, compose the majority of clinical isolates. Data from 25 North American ICUs reported methicillin-resistant Saureus (MRSA) in more than 50% of the Saureus organisms isolated mainly from a respiratory source. In addition to MRSA, Saureus with reduced susceptibility to vancomycin has been reported. Enterococci are typically considered opportunistic pathogens, infecting immunocompromised hosts. Resistance of enterococci to vancomycin, along with the newer gram-positive antimicrobials, is an increasing problem. Investigators have demonstrated that nearly 30% of enterococci isolated in the ICU are resistant to vancomycin. The high level of resistance and limited therapeutic options make treating resistant gram-positive organisms such as MRSA and vancomycin-resistant enterococci particularly problematic. While vancomycin has long been considered the gold standard for the treatment of resistant gram-positive infections, newer agents (eg, quinupristin-dalfopristin, linezolid, and daptomycin) offer therapeutic alternatives.