Characterization of Virulence Potential of Pseudomonas Aeruginosa Isolated from Bovine Meat, Fresh Fish, and Smoked Fish

Antimicrobial resistance, virulence gene profiling, and genetic diversity of multidrug-resistant Pseudomonas aeruginosa isolates in Mazandaran, Iran

BACKGROUND

Pseudomonas aeruginosa is a major cause of healthcare-associated infections (HAIs), particularly in immunocompromised patients, leading to high morbidity and mortality rates. This study aimed to investigate the antimicrobial resistance patterns, virulence gene profiles, and genetic diversity among P. aeruginosa isolates from hospitalized patients in Mazandaran, Iran.

METHODS

From September 2021 to April 2022, 82 non-duplicate P. aeruginosa isolates were collected from diverse clinical sources. Identification was confirmed using API 20 NE (bioMérieux, Marcy l'Etoile, France). Antimicrobial susceptibility testing was conducted using the Kirby-Bauer disk diffusion method according to CLSI guidelines to assess resistance to a range of antibiotics. The virulence profile (exoT, exoY, exoU, toxA, plcH, plcN, algD, aprA, lasB and exoS) of each P. aeruginosa isolate was determined by PCR. The genetic diversity among the strains was evaluated using the random amplification of polymorphic DNA (RAPD) technique. Clustering was based on a Dice similarity coefficient of ≥ 85%.

RESULTS

Of the 82 total strains, P. aeruginosa exhibited the highest and lowest resistance toward ticarcillin-clavulanate (98.78%) and colistin (0%), respectively. Moreover, 100% of the P. aeruginosa isolates were MDR. The following prevalence of virulence factor genes was observed: aprA, lasB, algD, toxA, plcH, exoY, and exoT in 100% of isolates. The plcN, exoS, and exoU were identified 98.78%, 67.07%, and 45.12%, respectively. The RAPD patterns obtained with primers 272 and 208 had respectively 2-19 and 6-17 bands. According to the Dice similarity coefficient of higher than 85%, 56 and 39 clusters were recognized.

CONCLUSION

The high rate of multidrug resistance combined with the widespread presence of virulence genes in P. aeruginosa isolates highlights the potential for increased infection severity, morbidity, and mortality in hospitalized patients. The substantial genetic diversity observed among isolates suggests that P. aeruginosa in this region may rapidly evolve, necessitating ongoing surveillance and more targeted antimicrobial strategies.

CLINICAL TRIAL NUMBER

Not applicable.

Molecular Typing of Pseudomonas aeruginosa Isolates Collected in Abidjan Hospitals (Côte d'Ivoire) Using the Multiple-Locus Variable Number of Tandem Repeats Method

Background/objectives:Pseudomonas aeruginosa can cause community-acquired infections affecting various body sites. The present retrospective study investigated the genetic diversity of 173 isolates (166 clinical, 7 environmental) of P. aeruginosa collected from clinical pathology laboratories in Abidjan, Côte d'Ivoire (2001-2011). Methods: Multiple-Locus Variable Number of Tandem Repeats (VNTR) Analysis (MLVA) using 13 loci was applied to all isolates and compared to published MLVA data. The antibiotics status of the isolates was compiled when available and compared to published profiles. Results: Among 95 isolates analyzed for their antibiotics status, 14 displayed concerning resistance profiles: five multidrug-resistant (MDR) and nine extensively drug-resistant (XDR). MLVA typing revealed a high genetic diversity (>130 genotypes), with many genotypes represented by a single strain. Notably, thirteen clusters (≥4 related isolates) were observed. Some clusters displayed close genetic relatedness to isolates from France, Korea, and well-studied strains (ST560, LES and PA14). Comparative analysis suggested the presence of international high-risk MDR clones (CC233, CC111) in Côte d'Ivoire. Importantly, MLVA clustering revealed a close relationship of CC235-MDR strains with a locally identified cluster (group 9). Conclusions: These findings support MLVA as a reliable and cost-effective tool for low-resource settings, allowing the selection of relevant strains for future whole genome sequence analyses. This approach can improve outbreak investigations and public health interventions aimed at curbing MDR P. aeruginosa transmission within hospitals and at the national level.

Resistance patterns, virulence determinants, and biofilm genes of multidrug-resistant Pseudomonas aeruginosa isolated from fish and fish handlers

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic bacterium that is widely distributed in aquatic environments and causes major economic losses in fish and public health hazards.This study aimed to identify the occurrence of P. aeruginosa in samples collected from fish and fish handlers, and to investigate the antimicrobial susceptibility, virulence determinants, and biofilm genes of P. aeruginosa isolates. A total of 276 samples were cross-sectionally collected from Nile tilapia (53), Golden grey mullet (52), Mediterranean horse mackerel (50), Striped red mullet (71), and fish handlers (50) at five different retail fish markets in Damietta Governorate, Egypt. Pseudomonas species (spp.) were biochemically identified in 57.9% of the total examined samples. Peudomonas aeruginosa were the most prevalent species isolated from the fish and human samples via PCR technique. Peudomonas aeruginosa isolates exhibited full resistance (100%) to tobramycin (TOB), gentamicin (CN), and colistin (CL), with a high level of susceptibility (88.5%) to imipenem (IPM) using the disk diffusion method. Most P. aeruginosa isolates (84.6%) exhibited drug resistance, with 61.5% were multidrug resistance (MDR) and 23.1% were extensive drug resistance (XDR). Most isolates had at least four virulence-associated genes (lasB, toxA, exoU, and oprL) and three biofilm genes (psIA, peIA, and lasR) by using uniplex PCR. The lasI, and rhlR Quorum Sensing (QS) genes were identified in 84.6% and 61.5% in the examined P. aeruginosa isolates, respectively. The highest mortality rate in Nile tilapia experimentally infected with P. aeruginosa isolate encoding most of virulent genes. Multivariate analyses revealed high heterogeneity among the examined isolates. This study revealed the emergence of virulent and drug resistant P. aeruginosa isolates in fish, poses high risks to consumers and food. Thus, strict hygienic measures should be considered when catching, handling, and storing fish, in addition to the routine application of antimicrobial susceptibility testing.

The effect of Dunaliella salina extracts on the adhesion of Pseudomonas aeruginosa to 3D printed polyethylene terephthalate and polylactic acid

Polyethylene terephthalate (PET) and polylactic acid (PLA) are among the polymers used in the food industry. In this study, crude extracts of Dunaliella salina were used to treat the surface of 3D printed materials studied, aiming to provide them with an anti-adhesive property against Pseudomonas aeruginosa. The hydrophobicity of treated and untreated surfaces was characterized using the contact angle method. Furthermore, the adhesive behavior of P. aeruginosa toward the substrata surfaces was also studied theoretically and experimentally. The results showed that the untreated PLA was hydrophobic, while the untreated PET was hydrophilic. It was also found that the treated materials became hydrophilic and electron-donating. The total energy of adhesion revealed that P. aeruginosa adhesion was theoretically favorable on untreated materials, while it was unfavorable on treated ones. Moreover, the experimental data proved that the adhesion to untreated substrata was obtained, while there was complete inhibition of adhesion to treated surfaces.

Transforming microbial pigment into therapeutic revelation: extraction and characterization of pyocyanin from Pseudomonas aeruginosa and its therapeutic potential as an antibacterial and anticancer agent

BACKGROUND

The objectives of the current study were to extract pyocyanin from Pseudomonas aeruginosa clinical isolates, characterize its chemical nature, and assess its biological activity against different bacteria and cancer cells. Due to its diverse bioactive properties, pyocyanin, being one of the virulence factors of P. aeruginosa, holds a promising, safe, and available therapeutic potential.

METHODS

30 clinical P. aeruginosa isolates were collected from different sources of infections and identified by routine methods, the VITEK 2 compact system, and 16 S rRNA. The phenazine-modifying genes (phzM, phzS) were identified using polymerase chain reaction (PCR). Pyocyanin chemical characterization included UV-Vis spectrophotometry, Fourier Transform Infra-Red spectroscopy (FTIR), Gas Chromatography-Mass Spectrometry (GC-MS), and Liquid Chromatography-Mass Spectrometry (LC-MS). The biological activity of pyocyanin was explored by determining the MIC values against different clinical bacterial strains and assessing its anticancer activity against A549, MDA-MB-231, and Caco-2 cancer cell lines using cytotoxicity, wound healing and colony forming assays.

RESULTS

All identified isolates harboured at least one of the phzM or phzS genes. The co-presence of both genes was demonstrated in 13 isolates. The UV-VIS absorbance peaks were maxima at 215, 265, 385, and 520 nm. FTIR could identify the characteristic pyocyanin functional groups, whereas both GC-MS and LC-MS elucidated the chemical formula C11H18N2O2, with a molecular weight 210. The quadri-technical analytical approaches confirmed the chemical nature of the extracted pyocyanin. The extract showed broad-spectrum antibacterial activity, with the greatest activity against Bacillus, Staphylococcus, and Streptococcus species (MICs 31.25-125 µg/mL), followed by E. coli isolates (MICs 250-1000 µg/mL). Regarding the anticancer activity, the pyocyanin extract showed IC50 values against A549, MDA-MB-231, and Caco-2 cancer cell lines of 130, 105, and 187.9 µg/mL, respectively. Furthermore, pyocyanin has markedly suppressed colony formation and migratory abilities in these cells.

CONCLUSIONS

The extracted pyocyanin has demonstrated to be a potentially effective candidate against various bacterial infections and cancers. Hence, the current findings could contribute to producing this natural compound easily through an affordable method. Nonetheless, future studies are required to investigate pyocyanin's effects in vivo and analyse the results of combining it with other traditional antibiotics or anticancer drugs.

Bacterial Quality and Molecular Detection of Food Poisoning Virulence Genes Isolated from Nasser Lake Fish, Aswan, Egypt

The microbial analysis of fish is critical for ensuring overall health. Uncooked fish can serve as a conduit for transmitting several types of microbes; the current investigation sought to assess the bacterial levels in various kinds of fish from Nasser Lake, Aswan, Egypt, considered the chief source of potable water in Egypt. Two hundred and fifty fish samples, including 50 of each Oreochromis niloticus, Sander lucioperca, Lates niloticus, Clarias gariepinus, and Mormyrus kannume, from Nasser Lake, Aswan, Egypt, were collected to detect the bacterial load, isolation, and identification of Aeromonas hydrophila, Pseudomonas aeruginosa, and Vibrio parahaemolyticus and their virulence genes. The findings revealed that Oreochromis niloticus and Clarias gariepinus exhibited higher bacterial loads than other fish species. Incidences of bacterial contamination among examined fishes were 28.8%, 20.4%, and 16% for Aeromonas hydrophila, Pseudomonas aeruginosa, and Vibrio parahaemolyticus, respectively. Additionally, PCR analysis detected the presence of aerA (60%) and Act (40%) genes in A. hydrophila, rpoB (70%) and LasB (30%) genes in P. aeruginosa, and ToxR (70%) and tdh (50%) genes in V. parahaemolyticus. The study suggested that the bacterial contamination levels in Oreochromis niloticus and Clarias gariepinus could be notably more significant than in other species that could potentially be harmful to the consumers, especially considering the identification of particular bacteria known to cause foodborne illnesses. Further recommendations emphasized that regular monitoring and assessments are required to preserve their quality.

Isolation, identification and characterisation of Pseudomonas koreensis CM-01 isolated from diseased Malaysian mahseer (Tor tambroides)

Pseudomonas species are one of the most threatening fish pathogens which reside a wide range of environments. In this study, the dominant bacteria were isolated from diseased Malaysian mahseer (Tor tambroides) and tentatively named CM-01. It was identified as Pseudomonas koreensis based on its biochemical, morphological, genetic and physiological information. Its pathogenicity was found to be correlated with twelve virulence genes identified including iron uptake, protease, acylhomoserine lactone synthase gacS/gacA component regulation system, type IV secretion system, hydrogen cyanide production, exolysin, alginate biosynthesis, flagella and pili. The median lethal dose (LD50) for the CM-01 isolate on Malaysian mahseer was documented at 5.01 × 107 CFU/mL. The experimental infection revealed that CM-01 led to significant histological lesions in the fish, ultimately resulting in death. These lesions comprise necrosis, tissue thickening and aggregation. Drug sensitivity tests had shown its susceptibility to beta-lactam combination agents and further suggest its drug of choice. Its growing features had shown its growth at optimal temperature and pH. To the best of our knowledge, this is the first report of P. koreensis linked to diseased T. tambroides. STATEMENT OF RELEVANCE: In this research, a novel strain of Pseudomonas koreensis, CM-01 was isolated from diseased T. tambroides for the first time. The antimicrobial susceptibility, pathogenicity, virulence genes and growth characteristics of CM-01 were studied. These findings established a scientific foundation for the recognition of P. koreensis and the management of fish infections caused by this pathogen.

Global transcriptome analysis of Pseudomonas aeruginosa NT06 response to potassium chloride, sodium lactate, sodium citrate, and microaerophilic conditions in a fish ecosystem

Pseudomonas aeruginosa is an opportunistic pathogen that recently has been increasingly isolated from foods, especially from minimally processed fish-based products. Those are preserved by the addition of sodium chloride (NaCl) and packaging in a modified atmosphere. However, the current trends of minimizing NaCl content may result in an increased occurrence of P. aeruginosa. NaCl can be replaced with potassium chloride (KCl) or sodium salts of organic acids. Herein, we examined the antimicrobial effects of KCl, sodium lactate (NaL), sodium citrate (NaC), and sodium acetate (NaA) against P. aeruginosa NT06 isolated from fish. Transcriptome response of cells grown in medium imitating a fish product supplemented with KCl and KCl/NaL/NaC and maintained under microaerophilic conditions was analysed. Flow cytometry analysis showed that treatment with KCl and KCl/NaL/NaC resulted in changed metabolic activity of cells. In response to KCl and KCl/NaL/NaC treatment, genes related to cell maintenance, stress response, quorum sensing, virulence, efflux pump, and metabolism were differentially expressed. Collectively, our results provide an improved understanding of the response of P. aeruginosa to NaCl alternative compounds that can be implemented in fish-based products and encourage further exploration of the development of effective methods to protect foods against the P. aeruginosa, underestimate foodborne bacteria.

Potassium Chloride, Sodium Lactate and Sodium Citrate Impaired the Antimicrobial Resistance and Virulence of Pseudomonas aeruginosa NT06 Isolated from Fish

Sodium chloride (NaCl) is a commonly used additive in minimally processed fish-based products. The addition of NaCl to fish products and packaging in a modified atmosphere is usually efficient with regard to limiting the occurrence of the aquatic environmental pathogen Pseudomonas aeruginosa. Given the negative effects of excess NaCl in the diet, there is a growing demand to reduce NaCl in food products with safer substituents, but the knowledge of their impact on antibiotic resistant P. aeruginosa is limited. This study aimed to evaluate the physiological and transcriptome characteristics of P. aeruginosa NT06 isolated from fish and to determine the effect of selected concentrations of alternative NaCl compounds (KCl/NaL/NaC) on the P. aeruginosa NT06 virulence phenotype and genotype. In the study, among the isolated microorganisms, P. aeruginosa NT06 showed the highest antibiotic resistance (to ampicillin, ceftriaxone, nalidixic acid, and norfloxacin) and the ability to grow at 4 °C. The Comprehensive Antibiotic Resistance Database (CARD) and the Virulence Factor Database (VFDB) revealed the presence of 24 and 134 gene products assigned to AMR and VF in the P. aeruginosa NT06 transcriptome, respectively. KCl, KCl/NaL and KCl/NaL/NaC inhibited pyocyanin biosynthesis, elastase activity, and protease activity from 40 to 77%. The above virulence phenotypic observations were confirmed via RT-qPCR analyses, which showed that all tested AMR and VF genes were the most downregulated due to KCl/NaL/NaC treatment. In conclusion, this study provides insight into the potential AMR and VF among foodborne P. aeruginosa and the possible impairment of those features by KCl, NaL, and NaC, which exert synergistic effects and can be used in minimally processed fish-based products.

Quorum-quenching enzymes: Promising bioresources and their opportunities and challenges as alternative bacteriostatic agents in food industry

The problems of spoilage, disease, and biofilm caused by bacterial quorum-sensing (QS) systems have posed a significant challenge to the development of the food industry. Quorum-quenching (QQ) enzymes can block QS by hydrolyzing or modifying the signal molecule, making these enzymes promising new candidates for use as antimicrobials. With many recent studies of QQ enzymes and their potential to target foodborne bacteria, an updated and systematic review is necessary. Thus, the goals of this review were to summarize what is known about the effects of bacterial QS on the food industry; discuss the current understanding of the catalytic mechanisms of QQ enzymes, including lactonase, acylase, and oxidoreductase; and describe strategies for the engineering and evolution of QQ enzymes for practical use. In particular, this review focuses on the latest progress in the application of QQ enzymes in the field of food. Finally, the current challenges limiting the systematic application of QQ enzymes in the food industry are discussed to help guide the future development of these important enzymes.

Comparison of Virulence-Factor-Encoding Genes and Genotype Distribution amongst Clinical Pseudomonas aeruginosa Strains

Pseudomonas aeruginosa is an opportunistic pathogen encoding several virulence factors in its genome, which is well-known for its ability to cause severe and life-threatening infections, particularly among cystic fibrosis patients. The organism is also a major cause of nosocomial infections, mainly affecting patients with immune deficiencies and burn wounds, ventilator-assisted patients, and patients affected by other malignancies. The extensively reported emergence of multidrug-resistant (MDR) P. aeruginosa strains poses additional challenges to the management of infections. The aim of this study was to compare the incidence rates of selected virulence-factor-encoding genes and the genotype distribution amongst clinical multidrug-sensitive (MDS) and MDR P. aeruginosa strains. The study involved 74 MDS and 57 MDR P. aeruginosa strains and the following virulence-factor-encoding genes: lasB, plC H, plC N, exoU, nan1, pilA, and pilB. The genotype distribution, with respect to the antimicrobial susceptibility profiles of the strains, was also analyzed. The lasB and plC N genes were present amongst several P. aeruginosa strains, including all the MDR P. aeruginosa, suggesting that their presence might be used as a marker for diagnostic purposes. A wide variety of genotype distributions were observed among the investigated isolates, with the MDS and MDR strains exhibiting, respectively, 18 and 9 distinct profiles. A higher prevalence of genes determining the virulence factors in the MDR strains was observed in this study, but more research is needed on the prevalence and expression levels of these genes in additional MDR strains.

Pseudomonas aeruginosa Strains from Both Clinical and Environmental Origins Readily Adopt a Stable Small-Colony-Variant Phenotype Resulting from Single Mutations in c-di-GMP Pathways

A subpopulation of small-colony variants (SCVs) is a frequently observed feature of Pseudomonas aeruginosa isolates obtained from colonized cystic fibrosis lungs. Since most SCVs have until now been isolated from clinical samples, it remains unclear how widespread the ability of P. aeruginosa strains to develop this phenotype is and what the genetic mechanism(s) behind the emergence of SCVs are according to the origin of the isolate. In the present work, we investigated the ability of 22 P. aeruginosa isolates from various environmental origins to spontaneously adopt an SCV-like smaller alternative morphotype distinguishable from that of the ancestral parent strain under laboratory culture conditions. We found that all the P. aeruginosa strains tested could adopt an SCV phenotype, regardless of their origin. Whole-genome sequencing of SCVs obtained from clinical and environmental sources revealed single mutations exclusively in two distinct c-di-GMP signaling pathways, the Wsp and YfiBNR pathways. We conclude that the ability to switch to an SCV phenotype is a conserved feature of P. aeruginosa and results from the acquisition of a stable genetic mutation, regardless of the origin of the strain. IMPORTANCE P. aeruginosa is an opportunistic pathogen that thrives in many environments. It poses a significant health concern, notably because this bacterium is the most prevalent pathogen found in the lungs of people with cystic fibrosis. In infected hosts, its persistence is considered related to the emergence of an alternative small-colony-variant (SCV) phenotype. By reporting the distribution of P. aeruginosa SCVs in various nonclinical environments and the involvement of c-di-GMP in SCV emergence from both clinical and environmental strains, this work contributes to understanding a conserved adaptation mechanism used by P. aeruginosa to adapt readily in all environments. Hindering this adaptation strategy could help control persistent infection by P. aeruginosa.

Characterization of Uropathogenic Pseudomonas aeruginosa: Serotypes, Resistance Phenotypes, and Virulence Genotypes

Pseudomonas aeruginosa is a major cause of urinary tract infections. This organism has extended resistance to antimicrobials along with multiple virulence factors, making it difficult to treat. In this study, 49 isolates from urine samples were identified as P. aeruginosa and serotyped by the slide agglutination method. The sensitivity of isolates against 10 antipseudomonal drugs was determined. Phenotypically, lipase, protease, hemolysin, and biofilm production were detected. Genes for the type III secretion system, elastase B, and exotoxin A were detected by PCR. Serotype O11 was the most predominant serotype among test isolates. High levels of resistance were observed against ceftazidime, cefepime, piperacillin, and piperacillin/tazobactam while 10.2% of isolates were resistant to amikacin. MDR was detected in 20.4% of the isolates and was significantly associated with strong biofilm producers. About 95.9% and 63.3% of P. aeruginosa isolates had proteolytic and lipolytic activity, respectively. Among the genes detected, the exoY gene was the most prevalent gene (79.6%), while the exoU gene was the least frequent one (10.2%). toxA and lasB genes were amplified in 63.27% and 75.5% of the isolates, respectively. In addition, the exoU gene was significantly associated with MDR isolates. The high incidence of exoS, exoT, exoY, lasB, and toxA genes in uropathogenic P. aeruginosa implies that these genes can be considered markers for virulent isolates. Furthermore, the coexistence of exoU and exoS genes, even in 6% of isolates, poses a significant treatment challenge because those isolates possess both the invasive and cytotoxic properties of both effector proteins.

Zoonotic diseases of fish and their prevention and control

Fish and aquatic-derived zoonotic diseases have caused considerable problems in the aquaculture industry and fishery worldwide. In particular, zoonotic diseases can pose widespread threats to humans. With the world’s growing population and potential global trade of aquaculture and fish, the risk of environmental contamination and development of fish and aquatic-derived zoonoses in humans are increasing. The important causes of zoonoses include bacteria, parasites, viruses, and fungi. The zoonotic bacterial agents are divided into two main groups: Gram-positive (Mycobacteriaceae, Streptococcaceae, Erysipelothricaceae families) and Gram-negative (Aeromonadaceae, Vibrionaceae, Pseudomondaceae, Enterobacteriaceae, and Hafniaceae families). The premier parasitic agents include cestodes (tapeworm; e.g. Diphyllobothrium spp.), trematodes (fluke; e.g. Opisthorchis spp.), and nematodes (round worm; e.g. Anisakis spp.). In addition, protozoan organisms such as Cryptosporidium spp. are also considered fish-derived zoonotic pathogens. Two groups of fish-associated fungi causing basidiobolomycosis and sporotrichosis also pose a zoonotic risk for humans. The majority of the fish-derived zoonotic diseases are transmitted to humans mainly via the consumption of improperly cooked or raw fish or fish products. Therefore, the incidence of zoonotic diseases can be reduced by properly processing fish and fish products, e.g. by thermal (heat/freezing) treatment. The prevalence of zoonotic agents in fishes varies seasonally and should be regularly monitored to evaluate the prevalence of pathogens in both wild and cultured fish populations. This review focuses on the fish zoonotic agents/diseases and their control and prevention.

In-House Validation of Multiplex PCR for Simultaneous Detection of Shiga Toxin-Producing Escherichia coli, Listeria monocytogenes and Salmonella spp. in Raw Meats

The aim of the study was to perform in-house validation of the developed multiplex PCR (mPCR)-based alternative method to detect Shiga toxin-producing Escherichia coli (STEC), Listeria monocytogenes (L. monocytogenes) and Salmonella spp. in raw meats following the ISO 16140-2: 2016. A comparative study of the developed mPCR against the Bacteriological Analytical Manual (BAM) method was evaluated for inclusivity and exclusivity, sensitivity and the relative level of detection (RLOD). Inclusivity levels for each target bacterium were all 100%, while exclusivity for non-target bacteria was 100%. The sensitivity of the developed mPCR was calculated based on the analysis of 72 samples of raw meat. The sensitivity of the developed mPCR was 100%. The RLOD values of the developed mPCR for STEC, L. monocytogenes and Salmonella spp. were 0.756, 1.170 and 1.000, respectively. The developed mPCR showed potential as a tool for the fast, specific and sensitive detection of the three bacteria in the raw meat industry

Distribution, Diversity and Antibiotic Resistance of Pseudomonas spp. Isolated from the Water Dams in the North of Tunisia

Natural environment is one of the important reservoirs to disseminate antibiotic resistance, most of the antibiotics resistance researches were focused on clinical isolates. Thus, this work aimed to analyze surface water samples collected from dams and rivers in the north of Tunisia. Pseudomonas species were confirmed using biochemical and molecular identifications. Resistance was studied by testing their susceptibility against 19 antibiotics using the disc diffusion method moreover the virulence factors were studied by PCR targeting 13 genes. 104 isolates were confirmed as Pseudomonas genera distributed into 21 species. The most abundant species is P. aeruginosa (22.11%), followed by P. protegens (12.5%). No resistance phenotypes were observed towards imipenem, meropenem, ceftazidime, colistin, ciprofloxacin and amikacin. A high resistance level was observed against cefoxitin (94.23%), amoxicillin-clavulanic acid (67.31%), nalidixic acid (62.5%), streptomycin (57.69%), ticarcillin (43.27%), fosfomycin (64.42%) and tetracycline (23.08%). A low rate of resistance was observed against cefotaxime (16.35%) and gentamicin (7.69%). The majority (70.19%) of isolates were Multidrug-resistant (MDR). 12 of virulence genes were found in all P. aeruginosa isolates. Our results showed that Pseudomonas isolates could be an important reservoir of antibiotic resistance from environment sites.

Characterization of antimicrobial resistance and virulence genes of Pseudomonas aeruginosa isolated from mink in China, 2011-2020

Pseudomonas aeruginosa strains are potential pathogens that cause respiratory diseases in minks, and caused serious economic loss to mink breeding industry. In this study, we identified antimicrobial resistance and virulence genes in 125 P. aeruginosa isolates from mink in China from 2011 to 2020. The results showed at least one mutation in the gyrA (Thr83Val or Asp87Gly) and parC (Ser87 Leu) genes as well as single mutations in 56 isolates. At least 4-fold reductions in the fluoroquinolone minimum inhibitory concentration values were found when tested in the presence of PAβN in 23 isolates, while 44 isolates were positive for the extended spectrum β-lactamases and 15 antibiotic resistance genes were identified in this population with a prevalence between 1-32%, including qnrA, CTX-M-1G, ermB and C, cmlA, flor, catl, intl1, tetA, B, C, and D as well as sul1, 2, and 3 genes. Interestingly, one isolate carried ten resistance genes. Five virulence genes were detected, where exoS and algD were the most frequently detected (76.8%), which were followed by plcH (76%), lasB (73.6%), and pilB (31.2%). The isolates carrying the antibiotic resistance or virulence genes were genetically variable, suggesting a horizontal spread through the population. Hence, this study provides novel and important data on the resistance and pathogenicity of P. aeruginosa in farmed mink infections. These data provide important insights into the mechanism of fluoroquinolone resistance in P. aeruginosa, highlighting its usefulness in the treatment and control of P. aeruginosa infections in minks.

A Rapid and Sensitive Detection Method for Pseudomonas aeruginosa Using Visualized Recombinase Polymerase Amplification and Lateral Flow Strip Technology

Pseudomonas aeruginosa is a common opportunistic pathogen that causes acute nosocomial necrotizing pneumonia and is the predominant source of chronic lung infections in patients with the genetic disorder cystic fibrosis. Early diagnosis in infected patients and monitoring P. aeruginosa contamination is therefore of great importance in controlling disease spread and development with timely drugs intervention treatment and cut off infection source. Traditional culture-biochemical methods are time consuming and highly dependent on technicians and expensive instruments. To address these challenges, the present study aimed to develop a rapid, sensitive, and specific, on-site detection method for P. aeruginosa based on recombinase polymerase amplification (RPA) combined with lateral flow strip (LFS) technology. The experimental process included screening and modification of primer and probe sets targeting the unique virulence gene elastase B (lasB); specificity detection in 29 strains of P. aeruginosa and 23 closely-related pathogenic bacteria; sensitivity measurements with gradient-diluted P. aeruginosa genomic DNA and probit regression analysis; and clinical application evaluation using 574 patients samples and calculating coincidence rate and kappa index value in comparison with the culture-biochemical method. The P. aeruginosa RPA-LFS assay could complete the amplification process at 37°C constant temperature within 30 min and results could be visualized by the naked eye within 10 min on LFS. The assay displayed high sensitivity with a limit of detection of 3.05 CFU/reaction. It also demonstrated high specificity by showing no cross reaction with other pathogenic bacteria, and rapidness by being completed in less than an hour. Furthermore, when used with clinical samples, the assay had a coincidence rate of 98.26% with the culture-biochemical method and a kappa index value of 0.9433. These data indicate that the RPA-LFS assay represents a major improvement for P. aeruginosa detection, especially in resource-limited areas.

Pseudomonas aeruginosa isolates defective in function of the LasR quorum sensing regulator are frequent in diverse environmental niches

The saprophyte Pseudomonas aeruginosa is a versatile opportunistic pathogen causing infections in immunocompromised individuals. To facilitate its adaptation to a large variety of niches, this bacterium exploits population density-dependent gene regulation systems called quorum sensing (QS). In P. aeruginosa, three distinct but interrelated QS systems (las, rhl and pqs) regulate the production of many survival and virulence functions. In prototypical strains, the las system, through its transcriptional regulator LasR, is important for the full activation of the rhl and pqs systems. Still, LasR-deficient isolates have been reported, mostly sampled from the lungs of people with cystic fibrosis, where they are considered selected by the chronic infection environment. In this study, we show that a defect in LasR activity appears to be an actually widespread mechanism of adaptation in this bacterium. Indeed, we found abundant LasR-defective isolates sampled from hydrocarbon-contaminated soils, hospital sink drains and meat/fish market environments, using an approach based on phenotypic profiling, supported by gene sequencing. Interestingly, several LasR-defective isolates maintain an active rhl system or are deficient in pqs system signalling. The high prevalence of a LasR-defective phenotype among environmental P. aeruginosa isolates questions the role of QS in niche adaptation.

Antimicrobial resistance and virulence characteristics in ERIC-PCR typed biofilm forming isolates of P. aeruginosa

Pseudomonas aeruginosa is a serious pathogen particularly in immunocompromised patients. In this work, 103 clinical isolates of P. aeruginosa were collected and classified into weak, moderate, and strong biofilm producers according to their biofilm forming abilities via tissue culture plate method. The antimicrobial resistance and the presence of different virulence genes were investigated via disc diffusion method and polymerase chain reaction respectively. Moreover, ERIC-PCR typing was performed to investigate the genetic diversity among the clinical isolates. No significant correlation was observed between biofilm formation and resistance to each antimicrobial agent. Similar observation was detected concerning the multidrug resistance and biofilm formation. Regarding virulence genes, algD gene was harbored by all isolates (100%). Only pelA and phzM were significantly prevalent in strong biofilm producers. Additionally, the mean virulence score was higher in strong biofilm producers (9.33) than moderate (8.62) and weak (7) biofilm producers. Moreover, there was a significant correlation between the overall virulence score of the isolates and its ability to form biofilm. ERIC-PCR genotyping revealed the presence of 99 different ERIC patterns based on 70% similarity, and the different ERIC patterns were categorized into 8 clusters. 100% similarity indicates the possibility of cross-colonization in P. aeruginosa infections.

Growing emergence of drug-resistant Pseudomonas aeruginosa and attenuation of its virulence using quorum sensing inhibitors: A critical review

A perilous increase in the number of bacterial infections has led to developing throngs of antibiotics for increasing the quality and expectancy of life. Pseudomonas aeruginosa is becoming resistant to all known conventional antimicrobial agents thereby posing a deadly threat to the human population. Nowadays, targeting virulence traits of infectious agents is an alternative approach to antimicrobials that is gaining much popularity to fight antimicrobial resistance. Quorum sensing (QS) involves interspecies communication via a chemical signaling pathway. Under this mechanism, cells work in a concerted manner, communicate with each other with the help of signaling molecules called auto-inducers (AI). The virulence of these strains is driven by genes, whose expression is regulated by AI, which in turn acts as transcriptional activators. Moreover, the problem of antibiotic-resistance in case of infections caused by P. aeruginosa becomes more alarming among immune-compromised patients, where the infectious agents easily take over the cellular machinery of the host while hidden in the QS mediated biofilms. Inhibition of the QS circuit of P. aeruginosa by targeting various signaling pathways such as LasR, RhlR, Pqs, and QScR transcriptional proteins will help in blocking downstream signal transducers which could result in reducing the bacterial virulence. The anti-virulence agent does not pose an immediate selective pressure on growing bacterium and thus reduces the pathogenicity without harming the target species. Here, we review exclusively, the growing emergence of multi-drug resistant (MDR) P. aeruginosa and the critical literature survey of QS inhibitors with their potential application of blocking P. aeruginosa infections.

Lemon Oils Attenuate the Pathogenicity of Pseudomonas aeruginosa by Quorum Sensing Inhibition

The chemical composition of three Citrus limon oils: lemon essential oil (LEO), lemon terpenes (LT) and lemon essence (LE), and their influence in the virulence factors production and motility (swarming and swimming) of two Pseudomonas aeruginosa strains (ATCC 27853 and a multidrug-resistant HT5) were investigated. The main compound, limonene, was also tested in biological assays. Eighty-four compounds, accounting for a relative peak area of 99.23%, 98.58% and 99.64%, were identified by GC/MS. Limonene (59-60%), γ-terpinene (10-11%) and β-pinene (7-15%) were the main compounds. All lemon oils inhibited specific biofilm production and bacterial metabolic activities into biofilm in a dose-dependent manner (20-65%, in the range of 0.1-4 mg mL^-1) of both strains. Besides, all samples inhibited about 50% of the elastase activity at 0.1 mg mL^-1. Pyocyanin biosynthesis decreases until 64% (0.1-4 mg mL^-1) for both strains. Swarming motility of P. aeruginosa ATCC 27853 was completely inhibited by 2 mg mL^-1 of lemon oils. Furthermore, a decrease (29-55%, 0.1-4 mg mL^-1) in the synthesis of Quorum sensing (QS) signals was observed. The oils showed higher biological activities than limonene. Hence, their ability to control the biofilm of P. aeruginosa and reduce the production of virulence factors regulated by QS makes lemon oils good candidates to be applied as preservatives in the food processing industry.

Molecular Detection of Drug-Resistance Genes of blaOXA-23-blaOXA-51 and mcr-1 in Clinical Isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa has caused high rates of mortality due to the appearance of strains with multidrug resistance (MDR) profiles. This study aimed to characterize the molecular profile of virulence and resistance genes in 99 isolates of P. aeruginosa recovered from different clinical specimens. The isolates were identified by the automated method Vitek2, and the antibiotic susceptibility profile was determined using different classes of antimicrobials. The genomic DNA was extracted and amplified by multiplex polymerase chain reaction (mPCR) to detect different virulence and antimicrobial resistance genes. Molecular typing was performed using the enterobacterial repetitive intergenic consensus (ERIC-PCR) technique to determine the clonal relationship among P. aeruginosa isolates. The drug susceptibility profiles of P. aeruginosa for all strains showed high levels of drug resistance, particularly, 27 (27.3%) isolates that exhibited extensively drug-resistant (XDR) profiles, and the other isolates showed MDR profiles. We detected the polymyxin E (mcr-1) gene in one strain that showed resistance against colistin. The genes that confer resistance to oxacillin (bla_OXA-23 and bla_OXA-51) were present in three isolates. One of these isolates carried both genes. As far as we know from the literature, this is the first report of the presence of bla_OXA-23 and bla_OXA-51 genes in P. aeruginosa.

Antibiofilm and antipersister activity of acetic acid against extensively drug resistant Pseudomonas aeruginosa PAW1

Pseudomonas aeruginosa is an ESKAPE pathogen associated with difficult-to-treat burn wound and surgical-site infections. This study aimed to characterise an extensively drug resistant (XDR) P. aeruginosa isolate (designated PAW1) and to investigate the antibiofilm and antipersister effect of acetic acid on PAW1. PAW1 was identified using biotypic (VITEK) and genotypic (16S rDNA) analysis. Minimum inhibitory concentration (MIC) and disc susceptibility testing showed high level resistance against all antibiotics from classes including beta lactams, cephems, carbapenems and fluoroquinolones. It was therefore identified as extensively drug resistant (XDR), showing resistance to all antibiotics except for, aminoglycoside (gentamicin and netilmicin) and lipopeptides (polymyxin B). Time kill assays showed antibiotic tolerant, persister cell formation in presence of 100X MICs of gentamicin and polymyxin B. Other virulence traits such as ability to produce lipase, protease, haemolysin, and siderophores and to form biofilms were additional factors which may contribute to its pathogenicity. PAW1 showed promising susceptibility against acetic acid with MIC and minimum biofilm inhibitory concentration of 0.156% (v/v). Percent viability of PAW1 was dependent on dose and treatment time of acetic acid. 0.625% acetic acid treatment of 5 minutes was effective in killing >90% planktonic cells showing lesser toxicity to L929 cells (IC₅₀ = 0.625%). Biofilm disruption caused due to acetic acid was also dose dependent, showing 40.57% disruption after treatment with 0.625% acetic acid for 5 minutes. FESEM imaging and live dead staining of planktonic and biofilm forms of PAW1 confirmed that acetic acid treatment caused 19.04% of cell shrinkage and disruption of extracellular matrix resulting in killing of cells. Antipersister activity of acetic acid was demonstrated by showing complete killing of PAW1 at 4X MIC. Overall, this study characterised an XDR isolate P. aeruginosa showing resistance and tolerance to various antibiotics. Antipersister and antibiofilm effect of acetic acid demonstrates the importance of forgotten topical agents as an effective strategy to treat XDR pathogens.

Molecular Detection of Antibiotic-Resistant Genes in Pseudomonas aeruginosa from Nonclinical Environment: Public Health Implications in Mthatha, Eastern Cape Province, South Africa

Evaluation of resistant profiles and detection of antimicrobial-resistant genes of bacterial pathogens in the nonclinical milieu is imperative to assess the probable risk of dissemination of resistant genes in the environment. This paper sought to identify antibiotic-resistant genes in Pseudomonas aeruginosa from nonclinical sources in Mthatha, Eastern Cape, and evaluate its public health implications. Samples collected from abattoir wastewater and aquatic environment were processed by membrane filtration and cultured on CHROMagarTM Pseudomonas medium. Species identification was performed by autoSCAN-4 (Dade Behring Inc., IL). Molecular characterization of the isolates was confirmed using real-time polymerase chain reaction (rPCR) and selected isolates were further screened for the possibility of harboring antimicrobial resistance genes. Fifty-one Pseudomonas species were recovered from abattoir wastewater and surface water samples, out of which thirty-six strains were Pseudomonas aeruginosa (70.6%). The P. aeruginosa isolates demonstrated resistance to aztreonam (86.1%), ceftazidime (63.9%), piperacillin (58.3%), cefepime (55.6%), imipenem (50%), piperacillin/tazobactam (47.2%), meropenem (41.7%), and levofloxacin (30.6%). Twenty out of thirty-six P. aeruginosa displayed multidrug resistance profiles and were classified as multidrug-resistant (MDR) (55.6%). Most of the bacterial isolates exhibited a high Multiple Antibiotic Resistance (MAR) Index ranging from 0.08 to 0.69 with a mean MAR index of 0.38. In the rPCR analysis of fifteen P. aeruginosa isolates, 14 isolates (93.3%) were detected harboring bla SHV, six isolates (40%) harbored bla TEM, and three isolates (20%) harbored bla CTX-M, being the least occurring ESBL. Results of the current study revealed that P. aeruginosa isolates recovered from nonclinical milieu are resistant to frontline clinically relevant antipseudomonal drugs. This is concerning as it poses a risk to the environment and constitutes a public health threat. Given the public health relevance, the paper recommends monitoring of multidrug-resistant pathogens in effluent environments.

Characterization of Pseudomonas aeruginosa isolated from various environmental niches: New STs and occurrence of antibiotic susceptible "high-risk clones"

The aim of this study was to investigate the antimicrobial phenotypes, major virulence factors, and the molecular typing of 66 P. aeruginosa isolates collected from various sources: human patients and hospital environment, raw milk, poultry meat, chicken/sheep fecal samples, wastewater, thermal water, and seawater. All isolates, except one, were susceptible to all tested antibiotics. exoA, lasB, rhlR, and lasR genes were harbored by 60 isolates. Forty-six, 18, and 2 isolates amplified exoS, exoU, and exoS+exoU genes, respectively. Twenty-one isolates showed high elastase and pigment production. The PFGE typing identified 26 pulsotypes. Some pulsotypes included isolates from different environmental niches and areas. Twelve selected isolates were typed by MLST and eight different STs were found, three of them were new. Our results highlighted the dissemination of some clones amongst different settings and the occurrence of antibiotic susceptible 'high-risk clones' that might be very harmful when acquiring genes encoding antibiotic resistance.

Biofilm Production and Antimicrobial Resistance of Clinical and Food Isolates of Pseudomonas spp

Due to its ubiquity, ability to form biofilms, and acquire resistance mechanisms, Pseudomonas spp. become one of the major challenge for healthcare settings and food industry. The aims of this study were to assess the biofilm production of Pseudomonas spp. recovered from clinical and food specimens and to evaluate their antimicrobial resistance. A total of 108 isolates of Pseudomonas spp. were included in the study, 48 being clinical isolates recovered from patients admitted to four tertiary care hospitals throughout Serbia and 60 were isolated from the bulk tank milk samples and meat carcasses. Biofilm production was analyzed by microtiter plate assay. Antimicrobial susceptibility was evaluated by disk diffusion method according to the CLSI guidelines, while class A and B β-lactamases encoding genes were screened by PCR. A total of 98 (90.7%) strains were biofilm producers (moderate producer: 68, 69.4%; strong producer: 8, 8.2%). Although a slightly higher percentage of clinical isolates were biofilm producers (91.7%) compared to food isolates (90%), statistical significance was not observed (P > 0.05). The proportion of carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates was significantly higher among clinical (42%) isolates compared to food (1.7%) Pseudomonads (P < 0.05). The bla_PER and bla_NDM genes were found in ESBL (seven isolates) and MBL (two isolates) production, respectively. In the present study, we confirmed that biofilm formation was highly present in both clinical and food Pseudomonas spp. irrespective of the prior existence of resistance genes. Additionally, clinical settings pose a major reservoir of MDR Pseudomonas spp. and especially CRPA isolates.

Enhanced Antibacterial Activity of Silver Nanoparticles Combined with Hydrogen Peroxide Against Multidrug-Resistant Pathogens Isolated from Dairy Farms and Beef Slaughterhouses in Egypt

Purpose

The last few decades have witnessed a rapid and global increase in multidrug-resistant bacteria (MDR) emergence.

Methods

The aim of the current study is to isolate the most common MDR bacteria from dairy farms and beef slaughterhouses followed by evaluation of their antimicrobial resistance pattern and assessment of the antibacterial activity of AgNPs-H₂O₂ as an alternative to conventional antibiotics. In this regard, 200 samples were collected from two dairy farms and one beef slaughterhouse located in Dakhliya Governorate, Egypt.

Results

Interestingly, out of 120 collected samples from dairy farms, the prevalence of the isolated strains was 26.7, 23.3, 21.7, 16.7, and 11.7% for S. typhimurium, E. coli O157:H7, L. monocytogenes, K. pneumoniae and P. aeruginosa, respectively. Meanwhile, the overall prevalence was 30, 25, 22.5, 17.5, and 5% for E. coli O157:H7, L. monocytogenes, S. typhimurium, P. aeruginosa, and K. pneumoniae, respectively, for the 80 samples collected from a beef slaughterhouse. The antimicrobial susceptibility pattern elucidated that all isolated strains exhibited resistance to at least four of the tested antimicrobials, with multiple-antibiotic resistance index values (MAR) ranging between 0.44 and 0.88. Furthermore, the commercial AgNPs-H₂O₂ product was characterized by transmission electron microscopy (TEM) and zeta potential that showed spherical particles with a surface charge of -0.192 mV. The antimicrobial activity of synergized nano-silver (AgNP) with H₂O₂ product toward MDR strains was assessed via measuring minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and time-kill curve.

Conclusion

The present data report high prevalence rates of MDR pathogens in dairy farms and abattoirs. More importantly, AgNPs-H₂O₂ exerted broad-spectrum bactericidal activity toward MDR bacterial strains, suggesting their promising usage as safe, ecofriendly, cost-effective antibacterial agents. To our knowledge, this study is a pioneer in investigating the potential alternative antimicrobial role of silver nanoparticles for control of multiple drug-resistant pathogens in Egypt.

An African perspective on the prevalence, fate and effects of carbapenem resistance genes in hospital effluents and wastewater treatment plant (WWTP) final effluents: A critical review

This article provides an overview of the antibiotic era and discovery of earliest antibiotics until the present day state of affairs, coupled with the emergence of carbapenem-resistant bacteria. The ways of response to challenges of antibiotic resistance (AR) such as the development of novel strategies in the search of new antibiotics, designing more effective preventive measures as well as the ecology of AR have been discussed. The applications of plant extract and chemical compounds like nanomaterials which are based on recent developments in the field of antimicrobials, antimicrobial resistance (AMR), and chemotherapy were briefly discussed. The agencies responsible for environmental protection have a role to play in dealing with the climate crisis which poses an existential threat to the planet, and contributes to ecological support towards pathogenic microorganisms. The environment serves as a reservoir and also a vehicle for transmission of antimicrobial resistance genes hence, as dominant inhabitants we have to gain a competitive advantage in the battle against AMR.

Virulence Constitution of Multi-Drug-Resistant Pseudomonas aeruginosa in Upper Egypt

Purpose

Ventilator-associated pneumonia caused by Pseudomonas aeruginosa (P. aeruginosa) is a major health-care problem. In this study, we explored the epidemiology of virulence determinants among multi-drug-resistant (MDR) clinical P. aeruginosa isolates from hospitalized patients with ventilator-associated pneumonia in intensive care units in Upper Egypt.

Patients and Methods

MDR P. aeruginosa isolates were screened for the presence of eight virulence factors and typed by ERIC-PCR.

Results

A total of 39 clinical MDR isolates were selected out of 173 isolated P. aeruginosa showing a combination of adhesion and cytotoxicity virulence patterns, with the detection of aprA, exoU, exoS, lasB, algD, toxA in 74.3%, 58.9%, 46.1%, 41.2%, 30.7%, 20.5% of the isolates, respectively. The MDR isolates were grouped into 13 different virulence profiles according to the pattern of virulence gene distribution. exoU genotype was more predominant among the P. aeruginosa isolates with more than 48% of the isolates harboring this gene alone, 7% harboring both exoU and exoS and 43.5% harboring exoS gene. An intermediate degree of diversity was detected by ERIC-PCR typing where the isolates were clustered in 7 major groups, indicating possible cross-infection within the hospital.

Conclusion

Our results highlight the increased frequency of virulent P. aeruginosa isolates with a shift to the more virulent cytotoxic exoU genotype. Further hospital infection-control measures are mandatory to control the hospital cross-transmission of these highly virulent isolates. This study could vastly be a help to develop efficient treatment policies against P. aeruginosa induced ventilator-associated pneumonia.

Serotypes and virulence genes of Pseudomonas aeruginosa isolated from mink and its pathogenicity in mink

In this study, 20 P. aeruginosa strains were isolated from 112 farmed mink exhibiting hemorrhagic pneumonia in mideastern Shandong province, China. Serotype G (18/20) was the dominant serotype among the isolates with prevalence in mink, followed by serotype B (1/20), serotype C (1/20). The 9 virulence-associated genes of P. aeruginosa were tested using PCR. The prevalence of the virulence genes for the isolates were algD 95% (19/20), plcH 85% (17/20), exoY 80% (16/20), aprA 75% (15/20), lasB 70% (14/20), exoS 65% (13/20), exoT 60% (12/20) and toxA 60% (12/20), respectively. The 20 isolates were negative for exoU gene. The isolates exhibited multidrug resistance and cross resistance, using antimicrobial disc susceptibility assays. The animal experiments demonstrated that LD50% of the P.aeruginosa-CS-2 in the intratracheally challenged mink was 2.2 × 10^7.0 CFU, and 6.8 × 10^4.0 CFU in the intraperitoneally challenged mink. It implied that both the inoculation doses and the routes of inoculation could have influences on the pathogenicity of P. aeruginosa in mink. Therefore, the evolutionary and epidemiological surveillance of P. aeruginosa in mink should be further strengthened for public health.

Grapefruit essential oils inhibit quorum sensing of Pseudomonas aeruginosa

Citrus essential oils are used in food to confer flavor and aromas. The citrus essential oils have been granted as GRAS and could be used as antimicrobial additives to control bacterial quorum sensing from potential food bacterial pathogens. The chemical composition and inhibitory activity of Citrus paradisi (grapefruit) essential oils obtained by cold-pressed method (EOP) and cold-pressed method followed by steam distillation, against Pseudomonas aeruginosa were determined. The GC-MS analyses of the oil indicated the amount of the essential oil components was highest with D-limonene in both cases. However, the extraction method modified the chemical composition. EOP had higher amount of coumarins and flavonoid as well as less oxygenated terpenoids. At 0.1 mg/mL essential oils were not able to modify the bacterial development but inhibited the P. aeruginosa biofilm production between 52% and 55%, sessile viability between 45% and 48%, autoinducer production and elastase activity between 30% and 56%. Limonene was less effective at inhibiting P. aeruginosa than the essential oils, suggesting a synergistic effect of the minor components. According to our results, grapefruit essential oils could be used as a food preservative to control P. aeruginosa virulence.

Frequency and antibiogram of multi-drug resistant pseudomonas aeruginosa in a Tertiary Care Hospital of Pakistan

Objective:

To determine pathogen burden and susceptibility pattern of multi-drug resistant (MDR) Pseudomonas aeruginosa isolates from clinical specimens in Karachi.

Methods:

It was In-vitro Clinical study, conducted in department of Pharmacology, Ziauddin University, and isolates were collected from various specimens such as pus, tracheal aspiration, wound swab, blood and urine in Microbiology department of Ziauddin Hospital, Nazimabad campus, Karachi. The antibiotic susceptibility pattern was determined by Kirby Bauer Disc diffusion method. Samples were processed as per procedures defined by Clinical and Laboratory Standards Institute (CLSI) guidelines 2018.

Results:

About 55% were found to be multi drug resistant P. aeruginosa. Majority of the isolates (35.4%) were recovered from the age range 60-80 years. Maximum number of MDR P. aeruginosa was isolated from pus (33.1%) followed by tracheal aspiration (20.6%). Highest sensitivity was seen by colistin (100%) followed by ceftolozane/tazobactam (60%). Least sensitivity was observed with imipenem (19%). However, increase trend of resistance was seen among all antipesudomonal drugs.

Conclusion:

Increasing frequency of infections due to MDR P. aeruginosa is an emerging threat in our set up which can be prevented by prescribing antibiotics judiciously. Consistent lab detection and surveillance regarding this resistant pathogen is compulsory for providing effective health care to community.