Virulence Gene Profiles of Multidrug-Resistant Pseudomonas aeruginosa Isolated From Iranian Hospital Infections

Silver nanoparticle with potential antimicrobial and antibiofilm efficiency against multiple drug resistant, extensive drug resistant Pseudomonas aeruginosa clinical isolates

BACKGROUND

The study aims to investigate the effect of combining silver nanoparticles (AGNPs) with different antibiotics on multi-drug resistant (MDR) and extensively drug resistant (XDR) isolates of Pseudomonas aeruginosa (P. aeruginosa) and to investigate the mechanism of action of AGNPs.

METHODS

AGNPs were prepared by reduction of silver nitrate using trisodium citrate and were characterized by transmission electron microscope (TEM) in addition to an assessment of cytotoxicity. Clinical isolates of P. aeruginosa were collected, and antimicrobial susceptibility was conducted. Multiple Antibiotic Resistance (MAR) index was calculated, and bacteria were categorized as MDR or XDR. Minimum inhibitory concentration (MIC) of gentamicin, ciprofloxacin, ceftazidime, and AGNPs were determined. The mechanism of action of AGNPs was researched by evaluating their effect on biofilm formation, swarming motility, protease, gelatinase, and pyocyanin production. Real-time PCR was performed to investigate the effect on the expression of genes encoding various virulence factors.

RESULTS

TEM revealed the spherical shape of AGNPs with an average particle size of 10.84 ± 4.64 nm. AGNPS were safe, as indicated by IC50 (42.5 µg /ml). The greatest incidence of resistance was shown against ciprofloxacin which accounted for 43% of the bacterial isolates. Heterogonous resistance patterns were shown in 63 isolates out of the tested 107. The MAR indices ranged from 0.077 to 0.84. Out of 63 P. aeruginosa isolates, 12 and 13 were MDR and XDR, respectively. The MIC values of AGNPs ranged from 2.65 to 21.25 µg /ml. Combination of AGNPs with antibiotics reduced their MIC by 5-9, 2-9, and 3-10Fold in the case of gentamicin, ceftazidime, and ciprofloxacin, respectively, with synergism being evident. AGNPs produced significant inhibition of biofilm formation and decreased swarming motility, protease, gelatinase and pyocyanin production. PCR confirmed the finding, as shown by decreased expression of genes encoding various virulence factors.

CONCLUSION

AGNPs augment gentamicin, ceftazidime, and ciprofloxacin against MDR and XDR Pseudomonas isolates. The efficacy of AGNPs can be attributed to their effect on the virulence factors of P. aeruginosa. The combination of AGNPs with antibiotics is a promising strategy to attack resistant isolates of P. aeruginosa.

Probiotics in Dermatology: An Evidence-based Approach

Probiotics are viable microorganisms that confer health benefits when administered to the host in adequate amounts. Over the past decade, there has been a growing demand for the use of oral and topical probiotics in several inflammatory conditions such as atopic dermatitis, psoriasis, acne vulgaris, etc., although their role in a few areas still remains controversial. The objective of this article is to shed light on understanding the origin and implications of microbiota in the pathophysiology of these dermatological conditions and the effect of probiotic usage. We have conducted a comprehensive search of the literature across multiple databases (PubMed, EMBASE, MEDLINE, and Google Scholar) on the role of probiotics in dermatological disorders. Commensal microbes of the skin and gastrointestinal tract play an important role in both health and disease. Increased use of probiotics has asserted a good safety profile, especially in this era of antibiotic resistance. With the advent of new products in the market, the indications, mechanism of action, efficacy, and safety profile of these agents need to be validated. Further studies are required. Oral and topical probiotics may be tried as a treatment or prevention modality in cutaneous inflammatory disorders, thus facilitating decreased requirement for topical or systemic steroids and antimicrobial agents. Tempering microbiota with probiotics is a safe and well-tolerated approach in this era of antimicrobial resistance.

Interesting Cytokine Profile Caused by Clinical Strains of Pseudomonas aeruginosa MDR Carrying the exoU Gene

Pseudomonas aeruginosa is an opportunistic pathogen in HAIs with two facets: the most studied is the high rate of antimicrobial resistance, and the less explored is the long list of virulence factors it possesses. This study aimed to characterize the virulence genes carried by strains as well as the profile of cytokines related to inflammation, according to the resistance profile presented. This study aims to identify the virulence factors associated with MDR strains, particularly those resistant to carbapenems, and assess whether there is a cytokine profile that correlates with these characteristics. As methodology species were identified by classical microbiological techniques and confirmed by molecular biology, resistance levels were determined by the minimum inhibitory concentration and identification of MDR strains. Virulence factor genotyping was performed using PCR. In addition, biofilm production was assessed using crystal violet staining. Finally, the strains were cocultured with PBMC, and cell survival and the cytokines IL-1β, IL-6, IL-10, IL-8, and TNF-α were quantified using flow cytometry. Bacteremia and nosocomial pneumonia in adults are the most frequent types of infection. In the toxigenic aspect, genes corresponding to the type III secretion system were present in at least 50% of cases. In addition, PBMC exposed to strains of four different categories according to their resistance and toxicity showed a differential pattern of cytokine expression, a decrease in IL-10, IL-6, and IL-8, and an over-secretion of IL-1b. In conclusion, the virulence genes showed a differentiated appearance for the two most aggressive exotoxins of T3SS (exoU and exoS) in multidrug-resistant strains. Moreover, the cytokine profile displays a low expression of cytokines with anti-inflammatory and proinflammatory effects in strains carrying the exoU gene.

Molecular investigation of LasA, LasB, and PIV genes in clinical isolates of Pseudomonas aeruginosa in Mazandaran Province, North Iran

AIMS

Pseudomonasaeruginosa plays an important role in hospital infections caused by several virulence factors, such as elastase and proteases. This study aimed to evaluate the prevalence of LasA, LasB, and PIV genes, encoding these enzymes, in clinical isolates of P.aeruginosa.

High prevalence of multidrug-resistant Pseudomonas aeruginosa carrying integron and exoA, exoS, and exoU genes isolated from burn patients in Ahvaz, southwest Iran: A retrospective study

Background

Pseudomonas aeruginosa as an opportunistic pathogen produces several virulence factors. This study evaluated the relative frequency of exoenzymes (exo) A, U and S genes and integron classes (I, II, and III) among multi-drug-resistant clinical P. aeruginosa isolates from burn patients in Ahvaz, southwest of Iran.

Methods

In this cross-sectional study P. aeruginosa isolates were recovered from 355 wound samples. The antimicrobial susceptibility test was done by disk agar diffusion method on Muller-Hinton agar according to the Clinical and Laboratory Standards Institute. MDR isolates were defined if they showed simultaneous resistance to 3 antibiotics. Extensively drug-resistant was defined as nonsusceptibility to at least one agent in all but two or fewer antimicrobial categories. The presence of class I, II, and III integrons and virulence genes was determined using a PCR assay on extracted DNA.

Results

Overall, 145 clinical P. aeruginosa isolates were confirmed with biochemical and PCR tests. Overall, 35% (52/145) of the isolates were taken from males and 64% (93/145) from female hospitalized burn patients. The highest resistance rates of P. aeruginosa isolates to antibiotics were related to piperacillin 59% (n = 86/145) and piperacillin-tazobactam 57% (n = 83/145). A total of 100% of isolates were resistant to at least one antibiotic. MDR and XDR P. aeruginosa had a frequency of 60% and 29%, respectively. The prevalence of integron classes I, II, and III in P. aeruginosa was 60%, 7.58%, and 3.44%, respectively. IntI was more common in MDR and XDR P. aeruginosa isolates. In addition, 70(48%) of P. aeruginosa isolates did not harbor integron genes. Besides, exoA, exoS, and exoU in P. aeruginosa had a frequency of 55%, 55%, and 56%, respectively.

Conclusion

It was found that P. aeruginosa as a potent pathogen with strong virulence factors and high antibiotic resistance in the health community can cause refractory diseases in burn patients.

Molecular mechanism of the one-component regulator RccR on bacterial metabolism and virulence

The regulation of carbon metabolism and virulence is critical for the rapid adaptation of pathogenic bacteria to host conditions. In Pseudomonas aeruginosa, RccR is a transcriptional regulator of genes involved in primary carbon metabolism and is associated with bacterial resistance and virulence, although the exact mechanism is unclear. Our study demonstrates that PaRccR is a direct repressor of the transcriptional regulator genes mvaU and algU. Biochemical and structural analyses reveal that PaRccR can switch its DNA recognition mode through conformational changes triggered by KDPG binding or release. Mutagenesis and functional analysis underscore the significance of allosteric communication between the SIS domain and the DBD domain. Our findings suggest that, despite its overall structural similarity to other bacterial RpiR-type regulators, RccR displays a more complex regulatory element binding mode induced by ligands and a unique regulatory mechanism.

Whole genome sequencing of resistance and virulence genes in multi-drug resistant Pseudomonas aeruginosa

BACKGROUND

Pseudomonas aeruginosa is an opportunistic bacterium that causes serious hospital-acquired infections. To assess the risk of clinically isolated P. aeruginosa to human health, we analyzed the resistance and virulence mechanisms of a collection of clinical isolates.

METHODS

This was a retrospective study in which P. aeruginosa isolates collected from January 1, 2018 to August 31, 2019 were analyzed using phenotypic and whole-genome sequencing (WGS) methods. The analysis included 48 clinical samples. Median patient age was 54.0 (29.5) years, and 58.3% of patients were women. Data from the microbiology laboratory database were reviewed to identify P. aeruginosa isolates. All unique isolates available for further testing were included, and related clinical data were collected. Infections were defined as hospital acquired if the index culture was obtained at least 48 h after hospitalization.

RESULTS

High-risk P. aeruginosa clones, including sequence types (STs) ST235 and ST111, were identified, in addition to 12 new STs. The isolates showed varying degrees of biofilm formation ability when evaluated at room temperature, along with reduced metabolic activity, as measured by metabolic staining, suggesting their ability to evade antimicrobial therapy. Most isolates (77.1%) were multidrug resistant (MDR), with the highest resistance and susceptibility rates to beta-lactams and colistimethate sodium, respectively.

CONCLUSIONS

The MDR phenotypes of the examined isolates can be explained by the high prevalence of efflux-mediated resistance- and hydrolytic enzyme-encoding genes. These isolates had high cytotoxic potential, as indicated by the detection of toxin production-related genes.

Diversity of biofilm-specific antimicrobial resistance genes in Pseudomonas aeruginosa recovered from various clinical isolates

Background and Objectives

The resistance of Pseudomonas aeruginosa to antibiotics offers a significant challenge in the treatment of patients. This study aimed to investigate the antimicrobial resistance profile, biofilm-specific antimicrobial resistance genes, and genetic diversity of P. aeruginosa recovered from clinical samples.

Materials and Methods

Totally 47 non-duplicate isolates of P. aeruginosa were recovered from various clinical samples. toxA, algD, ndvB, and tssC1 genes were detected in biofilm-producing isolates. The DNA sequences of the toxA and tssC1 genes were analyzed, by creating phylogenetic trees.

Results

The findings revealed that 30 (63.8%) of the isolates tested positive for Extended spectrum β-lactamase (ESBL), whereas 31 (65.9%) tested positive for Metallo-β-lactamase (MBL) and all of the isolates presented the toxA genes, and 19.1%,17%, 6.3% presented by algD, ndvB and tssC1 genes. Besides, the phylogenetic trees of the toxA and tssC1 gene isolates suggested a genotype that was closely aligned with others. Gene sequencing similarity revealed 99% identity with other isolates deposited in GenBank.

Conclusion

The occurrence of toxA was most prevalent. One isolate was recorded as a novel isolate in the global gene bank as a locally isolated strain from the city of Erbil that has never been identified in global isolates due to genetic variation.

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Antimicrobial Resistance, Genetic Lineages, and Biofilm Formation in Pseudomonas aeruginosa Isolated from Human Infections: An Emerging One Health Concern

Pseudomonas aeruginosa (PA) is a leading nosocomial pathogen and has great versatility due to a complex interplay between antimicrobial resistance and virulence factors. PA has also turned into one the most relevant model organisms for the study of biofilm-associated infections. The objective of the study focused on analyzing the antimicrobial susceptibility, resistance genes, virulence factors, and biofilm formation ability of thirty-two isolates of PA. PA isolates were characterized by the following analyses: susceptibility to 12 antimicrobial agents, the presence of resistance genes and virulence factors in PCR assays, and the quantification of biofilm production as evaluated by two distinct assays. Selected PA isolates were analyzed through multilocus sequence typing (MLST). Thirty PA isolates have a multi-resistant phenotype, and most of the isolates showed high levels of resistance to the tested antibiotics. Carbapenems showed the highest prevalence of resistance. Various virulence factors were detected and, for the quantification of biofilm production, the effectiveness of different methods was assessed. The microtiter plate method showed the highest accuracy and reproducibility for detecting biofilm-producing bacteria. MLST revealed four distinct sequence types (STs) in clinical PA, with three of them considered high-risk clones of PA, namely ST175, ST235, and ST244. These clones are associated with multidrug resistance and are prevalent in hospitals worldwide. Overall, the study highlights the high prevalence of antibiotic resistance, the presence of carbapenemase genes, the diversity of virulence factors, and the importance of biofilm formation in PA clinical isolates. Understanding these factors is crucial for effective infection control measures and the development of targeted treatment strategies.

Prevalence of different virulence factors and their association with antimicrobial resistance among Pseudomonas aeruginosa clinical isolates from Egypt

BACKGROUND

Emergence of multi-drug resistant Pseudomonas aeruginosa, coupled with the pathogen's versatile virulence factors, lead to high morbidity and mortality rates. The current study investigated the potential association between the antibiotic resistance and the production of virulence factors among P. aeruginosa clinical isolates collected from Alexandria Main University Hospital in Egypt. We also evaluated the potential of the phenotypic detection of virulence factors to reflect virulence as detected by virulence genes presence. The role of alginate in the formation of biofilms and the effect of ambroxol, a mucolytic agent, on the inhibition of biofilm formation were investigated.

RESULTS

A multi-drug resistant phenotype was detected among 79.8% of the isolates. The most predominant virulence factor was biofilm formation (89.4%), while DNase was least detected (10.6%). Pigment production was significantly associated with ceftazidime susceptibility, phospholipase C production was significantly linked to sensitivity to cefepime, and DNase production was significantly associated with intermediate resistance to meropenem. Among the tested virulence genes, lasB and algD showed the highest prevalence rates (93.3% and 91.3%, respectively), while toxA and plcN were the least detected ones (46.2% and 53.8%, respectively). Significant association of toxA with ceftazidime susceptibility, exoS with ceftazidime and aztreonam susceptibility, and plcH with piperacillin-tazobactam susceptibility was observed. There was a significant correlation between alkaline protease production and the detection of algD, lasB, exoS, plcH and plcN; pigment production and the presence of algD, lasB, toxA and exoS; and gelatinase production and the existence of lasB, exoS and plcH. Ambroxol showed a high anti-biofilm activity (5% to 92%). Quantitative reverse transcriptase polymerase chain reaction showed that alginate was not an essential matrix component in P. aeruginosa biofilms.

CONCLUSIONS

High virulence coupled with the isolates' multi-drug resistance to commonly used antimicrobials would increase morbidity and mortality rates among P. aeruginosa infections. Ambroxol that displayed anti-biofilm action could be suggested as an alternative treatment option, yet in vivo studies are required to confirm these findings. We recommend active surveillance of antimicrobial resistance and virulence determinant prevalence for better understanding of coregulatory mechanisms.

Study of Antimicrobial Resistance, Biofilm Formation, and Motility of Pseudomonas aeruginosa Derived from Urine Samples

Pseudomonas aeruginosa causes urinary tract infections associated with catheters by forming biofilms on the surface of indwelling catheters. Therefore, controlling the spread of the bacteria is crucial to preventing its transmission in hospitals and the environment. Thus, our objective was to determine the antibiotic susceptibility profiles of twenty-five P. aeruginosa isolates from UTIs at the Medical Center of Trás-os-Montes and Alto Douro (CHTMAD). Biofilm formation and motility are also virulence factors studied in this work. Out of the twenty-five P. aeruginosa isolates, 16% exhibited multidrug resistance, being resistant to at least three classes of antibiotics. However, the isolates showed a high prevalence of susceptibility to amikacin and tobramycin. Resistance to carbapenem antibiotics, essential for treating infections when other antibiotics fail, was low in this study, Notably, 92% of the isolates demonstrated intermediate sensitivity to ciprofloxacin, raising concerns about its efficacy in controlling the disease. Genotypic analysis revealed the presence of various β-lactamase genes, with class B metallo-β-lactamases (MBLs) being the most common. The bla_NDM, bla_SPM, and bla_VIM-VIM2 genes were detected in 16%, 60%, and 12% of the strains, respectively. The presence of these genes highlights the emerging threat of MBL-mediated resistance. Additionally, virulence gene analysis showed varying prevalence rates among the strains. The exoU gene, associated with cytotoxicity, was found in only one isolate, while other genes such as exoS, exoA, exoY, and exoT had a high prevalence. The toxA and lasB genes were present in all isolates, whereas the lasA gene was absent. The presence of various virulence genes suggests the potential of these strains to cause severe infections. This pathogen demonstrated proficiency in producing biofilms, as 92% of the isolates were found to be capable of doing so. Currently, antibiotic resistance is one of the most serious public health problems, as options become inadequate with the continued emergence and spread of multidrug-resistant strains, combined with the high rate of biofilm production and the ease of dissemination. In conclusion, this study provides insights into the antibiotic resistance and virulence profiles of P. aeruginosa strains isolated from human urine infections, highlighting the need for continued surveillance and appropriate therapeutic approaches.

The Impact of the Virulence of Pseudomonas aeruginosa Isolated from Dogs

Pseudomonas aeruginosa is a pathogenic bacterium that can cause serious infections in both humans and animals, including dogs. Treatment of this bacterium is challenging because some strains have developed multi-drug resistance. This study aimed to evaluate the antimicrobial resistance patterns and biofilm production of clinical isolates of P. aeruginosa obtained from dogs. The study found that resistance to various β-lactam antimicrobials was widespread, with cefovecin and ceftiofur showing resistance in 74% and 59% of the isolates tested, respectively. Among the aminoglycosides, all strains showed susceptibility to amikacin and tobramycin, while gentamicin resistance was observed in 7% of the tested isolates. Furthermore, all isolates carried the oprD gene, which is essential in governing the entry of antibiotics into bacterial cells. The study also investigated the presence of virulence genes and found that all isolates carried exoS, exoA, exoT, exoY, aprA, algD, and plcH genes. This study compared P. aeruginosa resistance patterns worldwide, emphasizing regional understanding and responsible antibiotic use to prevent multi-drug resistance from emerging. In general, the results of this study emphasize the importance of the continued monitoring of antimicrobial resistance in veterinary medicine.

Prevalence and Antibiotic Resistance Phenotypes of Pseudomonas spp. in Fresh Fish Fillets

In fresh fish products, excessive loads of Pseudomonas can lead to their rapid spoilage. It is wise for Food Business Operators (FBOs) to consider its presence both in whole and prepared fish products. With the current study, we aimed to quantify Pseudomonas spp. in fresh fillets of Salmo salar, Gadus morhua and Pleuronectes platessa. For all three fish species, we detected loads of presumptive Pseudomonas no lower than 10⁴-10⁵ cfu/g in more than 50% of the samples. We isolated 55 strains of presumptive Pseudomonas and carried out their biochemical identification; 67.27% of the isolates were actually Pseudomonas. These data confirm that fresh fish fillets are normally contaminated with Pseudomonas spp. and the FBOs should add it as a "process hygiene criterion" according to EC Regulation n.2073/2005. Furthermore, in food hygiene, it is worth evaluating the prevalence of antimicrobial resistance. A total of 37 Pseudomonas strains were tested against 15 antimicrobials, and they all were identified as being resistant to at least one antimicrobial, mainly penicillin G, ampicillin, amoxicillin, tetracycline, erythromycin, vancomycin, clindamycin and trimethoprim. As many as 76.47% of Pseudomonas fluorescens isolates were multi-drug resistant. Our results confirm that Pseudomonas is becoming increasingly resistant to antimicrobials and thus should be continuously monitored in foods.

oprL Gene Sequencing, Resistance Patterns, Virulence Genes, Quorum Sensing and Antibiotic Resistance Genes of XDR Pseudomonas aeruginosa Isolated from Broiler Chickens

Background

Pseudomonas aeruginosa is incriminated in septicemia, significant economic losses in the poultry production sector, and severe respiratory infections in humans. This study aimed to investigate the occurrence, oprL sequencing, antimicrobial resistance patterns, virulence-determinant, Quorum sensing, and antibiotic resistance genes of P. aeruginosa retrieved from broiler chickens.

Methods

Two hundred samples were collected from 120 broiler chickens from broiler farms at Ismailia Governorate, Egypt. Consequently, the bacteriological examination was conducted and the obtained P. aeruginosa strains were tested for oprL gene sequencing, antibiogram, and PCR screening of virulence, Quorum sensing, and antibiotic resistance genes.

Results

The overall prevalence of P. aeruginosa in the examined birds was 28.3%. The oprL gene sequence analysis underlined that the tested strain expressed a notable genetic identity with various P. aeruginosa strains isolated from different geographical areas in the USA, India, China, Chile, and Ghana. PCR evidenced that the obtained P. aeruginosa strains, carrying virulence-related genes: oprL, toxA, aprA, phzM, and exoS in a prevalence of 100%, 100%, 42.5%, 33.3%, and 25.9%, respectively. Moreover, the recovered P. aeruginosa strains possessed the Quorum sensing genes: lasI, lasR, rhlI, and rhlR in a prevalence of 85.2%, 85.2%, 81.5%, and 81.5%, respectively. Furthermore, 40.7% of the isolated P. aeruginosa were XDR to seven antimicrobial classes, possessing sul1, bla _TEM, tetA, bla _CTX-M, bla _OXA-1, and aadA1 genes.

Conclusion

As we can tell, this is the first report emphasizing the evolution of XDR P. aeruginosa strains from broiler chicken in Egypt, which is supposed to be a serious threat to public health. The emerging XDR P. aeruginosa in poultry frequently harbored the oprL, toxA, and aprA virulence genes, the lasI, lasR, rhlI, and rhlR Quorum sensing genes, and the sul1, bla _TEM, tetA, bla _CTXM, bla _OXA-1, and aadA1 resistance genes.

Prevalence of Quorum Sensing and Virulence Factor Genes Among Pseudomonas aeruginosa Isolated from Patients Suffering from Different Infections and Their Association with Antimicrobial Resistance

Purpose

Antimicrobial resistance and virulence genes play important roles in increasing the severity of Pseudomonas aeruginosa infections, especially in hospitalized patients with high antibiotic pressure. Most genes that encode Pseudomonas aeruginosa virulence factors are controlled and regulated by the quorum sensing (QS) system. The aim of this study was to investigate the frequency of some virulence genes (rhlR, rhlI, lasR, lasI, lasB, toxA, aprA, algD, ExoS, and plcH genes) and their association with antibiotic resistance.

Methods

Antimicrobial susceptibility was determined by Kirby-Bauer agar disk diffusion method. A total of 125 clinical isolates of P. aeruginosa were tested for some virulence genes using polymerase chain reaction (PCR).

Results

The highest resistance was observed against cefepime (92.8%). Multi-drug resistant (MDR) P. aeruginosa represented 63.2% of total isolates with high distribution among wound isolates (21/79, 26.3% of MDR isolates). LasB was the most prevalent virulence gene among the tested isolates (89.6%) followed by aprA (85.6%), exoS (84%), algD (80%), toxA (76.8%), and plcH (75.2). Furthermore, a significant association (P < 0.05) among most of the tested virulence genes and MDR isolates was found. The presence of more than 5 virulence genes was highly observed among wound infections, otitis media, and respiratory tract infection isolates.

Conclusion

The complex association of virulence genes including QS system regulating genes with antibiotic resistance indicates the importance of the tested factors in the progression of infections, which is considered a great challenge for the health-care team with the need for specific studies for each area having different antibiotic resistance profiles and the development of effective treatment strategies such as anti-virulent and quorum sensing inhibiting drugs against P. aeruginosa infections.

Prevalence, Antimicrobial Resistance, and Molecular Description of Pseudomonas aeruginosa Isolated from Meat and Meat Products

Resistant and virulent Pseudomonas aeruginosa (P. aeruginosa) bacteria are measured as the major cause of food spoilage and food-borne diseases. This survey assesses the prevalence, antibiotic resistance properties, and virulence factors distribution in P. aeruginosa bacteria isolated from meat and meat products. A total of 370 raw, frozen, and imported bovine meat samples and diverse types of meat product samples were collected from Alborz province, Iran. P. aeruginosa bacteria were identified by culture. Disk diffusion was used to assess the antibiotic resistance of bacteria. Furthermore, the PCR was used to assess the virulence and antibiotic resistance genes. Twenty nine out of 370 (7.83%) samples were contaminated with P. aeruginosa. Imported frozen bovine meat (20%) harbored the highest distribution, while sausage (2%) harbored the lowest. High resistance rates were observed toward ampicillin (89.65%), penicillin (86.20%), tetracycline (82.75%), cefoxitin (37.93%), gentamicin (34.48%), and clindamycin (31.03%). The most commonly detected antibiotic resistance genes were blaDHA (93.10%), blaCTX-M (83.65%), and blaSHV (48.27%). BlaDHA (93.10%), blaCTX-M (83.65%), and blaSHV (48.27%) were the most frequently detected resistance genes. The most commonly detected virulence genes were exoS (75.86%), lasA (68.96%), exoU (58.62%), lasB (51.72%), plcH (48.27%), and algD (44.82%). Meat and meat product samples may be sources of P. aeruginosa, which show an important threat to their consumption. Nevertheless, additional inquiries are obligatory to find supplementary epidemiological properties of P. aeruginosa in meat and meat product samples.

Bacteriophage as a potential therapy to control antibiotic-resistant Pseudomonas aeruginosa infection through topical application onto a full-thickness wound in a rat model

Background

Antibiotic-resistant Pseudomonas aeruginosa (P. aeruginosa) is one of the most critical pathogens in wound infections, causing high mortality and morbidity in severe cases. However, bacteriophage therapy is a potential alternative to antibiotics against P. aeruginosa. Therefore, this study aimed to isolate a novel phage targeting P. aeruginosa and examine its efficacy in vitro and in vivo.

Results

The morphometric and genomic analyses revealed that ZCPA1 belongs to the Siphoviridae family and could infect 58% of the tested antibiotic-resistant P. aeruginosa clinical isolates. The phage ZCPA1 exhibited thermal stability at 37 °C, and then, it decreased gradually at 50 °C and 60 °C. At the same time, it dropped significantly at 70 °C, and the phage was undetectable at 80 °C. Moreover, the phage ZCPA1 exhibited no significant titer reduction at a wide range of pH values (4–10) with maximum activity at pH 7. In addition, it was stable for 45 min under UV light with one log reduction after 1 h. Also, it displayed significant lytic activity and biofilm elimination against P. aeruginosa by inhibiting bacterial growth in vitro in a dose-dependent pattern with a complete reduction of the bacterial growth at a multiplicity of infection (MOI) of 100. In addition, P. aeruginosa-infected wounds treated with phages displayed 100% wound closure with a high quality of regenerated skin compared to the untreated and gentamicin-treated groups due to the complete elimination of bacterial infection.

Conclusion

The phage ZCPA1 exhibited high lytic activity against MDR P. aeruginosa planktonic and biofilms. In addition, phage ZCPA1 showed complete wound healing in the rat model. Hence, this research demonstrates the potential of phage therapy as a promising alternative in treating MDR P. aeruginosa.

Role of Host and Bacterial Lipids in Pseudomonas aeruginosa Respiratory Infections

The opportunistic pathogen Pseudomonas aeruginosa is one of the most common agents of respiratory infections and has been associated with high morbidity and mortality rates. The ability of P. aeruginosa to cause severe respiratory infections results from the coordinated action of a variety of virulence factors that promote bacterial persistence in the lungs. Several of these P. aeruginosa virulence mechanisms are mediated by bacterial lipids, mainly lipopolysaccharide, rhamnolipid, and outer membrane vesicles. Other mechanisms arise from the activity of P. aeruginosa enzymes, particularly ExoU, phospholipase C, and lipoxygenase A, which modulate host lipid signaling pathways. Moreover, host phospholipases, such as cPLA2α and sPLA2, are also activated during the infectious process and play important roles in P. aeruginosa pathogenesis. These mechanisms affect key points of the P. aeruginosa-host interaction, such as: i) biofilm formation that contributes to bacterial colonization and survival, ii) invasion of tissue barriers that allows bacterial dissemination, iii) modulation of inflammatory responses, and iv) escape from host defenses. In this mini-review, we present the lipid-based mechanism that interferes with the establishment of P. aeruginosa in the lungs and discuss how bacterial and host lipids can impact the outcome of P. aeruginosa respiratory infections.

Laboratory diagnosis of urinary tract infections in patients with resistance genes towards antibiotics

Escherichia coli are gram-negative bacteria that cause urinary tract infections (UTIs). UTIs have affected a significant percentage of humans yearly due to bacterial infection. Our study aims to determine the prevalence of resistance genes in E. coli towards sulfamethoxazole. This study included (490) patients with UTIs, and the urine samples were cultured on media. The patients were admitted to the Medical City in Baghdad to treat UTIs. 116 E.coli isolates were isolated from urine specimens, 35 isolates of them were resistant to trimethoprim/sulfamethoxazole, and 81 isolates were sensitive to trimethoprim/sulfamethoxazole; the E. coli isolates were submitted to multiplex PCR to detection some resistance genes (Sul1, sul2) after detected the isolates by PCR depending on 16S rRNA. Our study showed that identified E. coli was (91-99%) depending on the number of the examined samples by the Vitek 2 system. The molecular study included extraction of chromosomal DNA from (53) E. coli isolates; 35 samples were taken resistant to antibiotics, while from the total of 81 sensitive isolates, only 18 sensitive samples were taken from that are the most sensitive to Timethprime/sulfamethoxazole, then identification by 16S rRNA gene. Detection of Sulfonamides resistance genes included sul1 and sul2. The results showed the 16S rRNA gene identification found in all E. coli isolates and the detection of antibiotic resistance genes. The resistant isolates with the Sul1 gene prevalence were 11(31%), while the sensitive isolates with Sul1gene were 1(6%). Moreover, the resisted isolates with Sul2 gene prevalence was 8(23%), while the sensitive isolates with the Sul1 gene were 0(0%). The numbers of the resistant isolates were (11) and (8) that carry the Sul1 gene and Sul2 gene, respectively, while the numbers of the sensitive isolates were (1) and (0), respectively. We can conclude that a high percentage of Sul1 gene and Sul2 genes in E. coil isolated from UTIs were high. Keywords. UTI, Sul1, Sul2, resistant gene, trimethoprim-sulfamethoxazole

Addition time plays a major role in the inhibitory effect of chitosan on the production of Pseudomonas aeruginosa virulence factors

Pseudomonas aeruginosa is a gram-negative bacterium capable of forming persistent biofilms that are extremely difficult to eradicate. The species is most infamously known due to complications in cystic fibrosis patients. The high mortality of cystic fibrosis is caused by P. aeruginosa biofilms occurring in pathologically overly mucous lungs, which are the major cause facilitating the organ failure. Due to Pseudomonas biofilm-associated infections, remarkably high doses of antibiotics must be administered, eventually contributing to the development of antibiotic resistance. Nowadays, multidrug resistant P. aeruginosa is one of the most terrible threats in medicine, and the search for novel antimicrobial drugs is of the utmost importance. We have studied the effect of low molecular weight chitosan (LMWCH) on various stages of P. aeruginosa ATCC 10145 biofilm formation and eradication, as well as on production of other virulence factors. LMWCH is a well-known naturally occurring agent with a vast antimicrobial spectrum, which has already found application in various fields of medicine and industry. LMWCH at a concentration of 40 mg/L was able to completely prevent biofilm formation. At a concentration of 60 mg/L, this agent was capable to eradicate already formed biofilm in most studied times of addition (2-12 h of cultivation). LMWCH (50 mg/L) was also able to suppress pyocyanin production when added 2 and 4 h after cultivation. The treatment resulted in reduced formation of cell clusters. LMWCH was proved to be an effective antibiofilm agent worth further clinical research with the potential to become a novel drug for the treatment of P. aeruginosa infections.

Prevalence of enterotoxin genes (SEA to SEE) and antibacterial resistant pattern of Staphylococcus aureus isolated from clinical specimens in Assiut city of Egypt

Background

Infections in communities and hospitals are mostly caused by Staphylococcus aureus strains. This study aimed to determine the prevalence of five genes (SEA, SEB, SEC, SED and SEE) encoding staphylococcal enterotoxins in S. aureus isolates from various clinical specimens, as well as to assess the relationship of these isolates with antibiotic susceptibility. Traditional PCR was used to detect enterotoxin genes, and the ability of isolates expressing these genes was determined using Q.RT-PCR.

Results

Overall; 61.3% (n = 46) of the samples were positive for S. aureus out of 75 clinical specimens, including urine, abscess, wounds, and nasal swabs. The prevalence of antibiotic resistance showed S. aureus isolates were resistant to Nalidixic acid, Ampicillin and Amoxicillin (100%), Cefuroxime (94%), Ceftriaxone (89%), Ciprofloxacin (87%), Erythromycin and Ceftaxime (85%), Cephalexin and Clarithromycin (83%), Cefaclor (81%), Gentamicin (74%), Ofloxacin (72%), Chloramphenicol(59%), Amoxicillin/Clavulanic acid (54%), while all isolates sensitive to Imipinem (100%). By employing specific PCR, about 39.1% of isolates were harbored enterotoxin genes, enterotoxin A was the most predominant toxin in 32.6% of isolates, enterotoxin B with 4.3% of isolates and enterotoxin A and B were detected jointly in 2.1% of isolates, while enterotoxin C, D and E weren’t detected in any isolate.

Conclusion

This study revealed a high prevalence of S. aureus among clinical specimens. The isolates were also multidrug resistant to several tested antibiotics. Enterotoxin A was the most prevalent gene among isolates. The presence of antibiotic resistance and enterotoxin genes may facilitate the spread of S. aureus strains and pose a potential threat to public health.

Clinical Specimens are the Pool of Multidrug- resistant Pseudomonas aeruginosa Harbouring oprL and toxA Virulence Genes: Findings from a Tertiary Hospital of Nepal

The multidrug- or extensively drug-resistant (MDR/XDR) Pseudomonas aeruginosa carrying some virulence genes has become a global public health threat. However, in Nepal, there is no existing report showing the prevalence of oprL and toxA virulence genes among the clinical isolates of P. aeruginosa. Therefore, this study was conducted for the first time in the country to detect the virulence genes (oprL and toxA) and antibiotic susceptibility pattern of P. aeruginosa. A total of 7,898 clinical specimens were investigated following the standard microbiological procedures. The antibiotic susceptibility testing was examined by the modified disc diffusion method, and virulence genes oprL and toxA of P. aeruginosa were assessed using multiplex PCR. Among the analyzed specimens, 87 isolates were identified to be P. aeruginosa of which 38 (43.68%) isolates were reported as MDR. A higher ratio of P. aeruginosa was detected from urine samples 40 (45.98%), outpatients' specimens 63 (72.4%), and in patients of the age group of 60–79 years 36 (41.37%). P. aeruginosa was more prevalent in males 56 (64.36%) than in female patients 31 (35.63%). Polymyxin (83.90%) was the most effective antibiotic. P. aeruginosa (100%) isolates harboured the oprL gene, while 95.4% of isolates were positive for the toxA gene. Identification of virulence genes such as oprL and toxA carrying isolates along with the multidrug resistance warrants the need for strategic interventions to prevent the emergence and spread of antimicrobial resistance (AMR). The findings could assist in increasing awareness about antibiotic resistance and suggest the judicious prescription of antibiotics to treat the patients in clinical settings of Nepal.

Groundwater, soil and compost, as possible sources of virulent and antibiotic-resistant Pseudomonas aeruginosa

Pseudomonas aeruginosa is a major public health concern all around the world. In the frame of this work, a set of diverse environmental P. aeruginosa isolates with various antibiotic resistance profiles were examined in a Galleria mellonella virulence model. Motility, serotypes, virulence factors and biofilm-forming ability were also examined. Molecular types were determined by pulsed-field gel electrophoresis (PFGE). Based on our results, the majority of environmental isolates were virulent in the G. mellonella test and twitching showed a positive correlation with mortality. Resistance against several antibiotic agents such as Imipenem correlated with a lower virulence in the applied G. mellonella model. PFGE revealed that five examined environmental isolates were closely related to clinically detected pulsed-field types. Our study demonstrated that industrial wastewater effluents, composts, and hydrocarbon-contaminated sites should be considered as hot spots of high-risk clones of P. aeruginosa.

Non-thermal Plasma Treatment of ESKAPE Pathogens: A Review

The acronym ESKAPE refers to a group of bacteria consisting of Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. They are important in human medicine as pathogens that show increasing resistance to commonly used antibiotics; thus, the search for new effective bactericidal agents is still topical. One of the possible alternatives is the use of non-thermal plasma (NTP), a partially ionized gas with the energy stored particularly in the free electrons, which has antimicrobial and anti-biofilm effects. Its mechanism of action includes the formation of pores in the bacterial membranes; therefore, resistance toward it is not developed. This paper focuses on the current overview of literature describing the use of NTP as a new promising tool against ESKAPE bacteria, both in planktonic and biofilm forms. Thus, it points to the fact that NTP treatment can be used for the decontamination of different types of liquids, medical materials, and devices or even surfaces used in various industries. In summary, the use of diverse experimental setups leads to very different efficiencies in inactivation. However, Gram-positive bacteria appear less susceptible compared to Gram-negative ones, in general.

Biotyping of isolates of Pseudomonas aeruginosa isolated from human infections by RAPD and ERIC-PCR

Pseudomonas aeruginosa is a significant mortality factor due to nosocomial infections in humans. P. aeruginosa has been known with severe infections, high incidence, and multiple drug resistance. The present study aims to rapidly diagnose and biotype the isolates of P. aeruginosa isolated from human infections in Shiraz hospitals and health centers. Ninety six different isolates were collected from skin, urine, sputum, blood, wound, central vein blood, body fluids and burn wounds between January 2016 and February 2017. After phenotypic confirmation, isolates were examined by PCR for molecular confirmation. Ninety three isolates were verified as P. aeruginosa in molecular analysis. Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR and Random Amplified Polymorphic DNA (RAPD) were done for 67 isolates. In ERIC-PCR, the patterns obtained included 2–11 bands. The RAPD patterns obtained with primers 272 and 208 consisted of 3–11 and 1–12 bands respectively. Based on dice similarity coefficient of greater than 80%, 38, 45 and 38 groups were identified in ERIC, RAPD 272 and RAPD 208 respectively. The results showed that the isolates of P. aeruginosa have a high polymorphism apparently because of the high genetic variation.

Molecular identification and Virulence factors of Pseudomonas aeruginosa isolated from operation hall

This study aimed to determine the P.aeruginosa that causes contamination to operation hall in hospitals by detecting of pathogenisity markers ..Moreover, the virulence factors  of predominant species were detected phenotypically  by using   routine  techniques, that responsible for pathogenicity.  Fifteen  samples were collected from different sites of operation hall during  two months  2022 in AL-Hussein  hospital/ karbala City. The identification of P.aeruginosa isolates depended on colonial morphology, microscopic examination and biochemical tests as a primary identification. The final identification was confirm by PCR  technique from different sites  .The  results  obtained  by  the  PCR  tests were twenty two isolates of P.aeruginosa  were  detected , which  distributed  into :(9) earth, (8) wall, and (10) beds. The  study  investigated  the  virulence  factors  of  P.aeruginosa, which  had  the  ability  to  produce capsule, biofilm , adhesion ,protease, bacteriocin ,haemolysin and   β-lactamase  and gelatinase .             The  results  revealed  variation  in  the  resistance of bacteria to some antibiotics,..P.aeruginosa exhibited high resistance (96%) to Cefotaxime, but absolute susceptibility to Ciproflaxacin and Gentamycin and high susceptibility to Amikacin.Ceftiaxone,and Azithromycin.

Identification, antibiotic resistance, and virulence profiling of Aeromonas and Pseudomonas species from wastewater and surface water

Aquatic environments are hotspots for the spread of antibiotic-resistant bacteria and genes due to pollution caused mainly by anthropogenic activities. The aim of this study was to evaluate the impact of wastewater effluents, informal settlements, hospital, and veterinary clinic discharges on the occurrence, antibiotic resistance profile and virulence signatures of Aeromonas spp. and Pseudomonas spp. isolated from surface water and wastewater. High counts of Aeromonas spp. (2.5 (± 0.8) - 3.3 (± 0.4) log₁₀ CFU mL^-1) and Pseudomonas spp. (0.6 (± 1.0) - 1.8 (± 1.0) log₁₀ CFU mL^-1) were obtained. Polymerase chain reaction (PCR) and MALDI-TOF characterization identified four species of Aeromonas and five of Pseudomonas. The isolates displayed resistance to 3 or more antibiotics (71% of Aeromonas and 94% of Pseudomonas). Aeromonas spp. showed significant association with the antibiotic meropenem (χ² = 3.993, P < 0.05). The virulence gene aer in Aeromonas was found to be positively associated with the antibiotic resistance gene blaOXA (χ² = 6.657, P < 0.05) and the antibiotic ceftazidime (χ² = 7.537, P < 0.05). Aeromonas recovered from both wastewater and surface water displayed high resistance to ampicillin and had higher multiple antibiotic resistance (MAR) indices close to the hospital. Pseudomonas isolates on the other hand exhibited low resistance to carbapenems but very high resistance to the third-generation cephalosporins and cefixime. The results showed that some of the Pseudomonas spp. and Aeromonas spp. isolates were extended-spectrum β-lactamase producing bacteria. In conclusion, the strong association between virulence genes and antibiotic resistance in the isolates shows the potential health risk to communities through direct and indirect exposure to the water.

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.

The Effect of Silver Nanoparticles on Pyocyanin Production of Pseudomonas aeruginosa Isolated From Clinical Specimens

BACKGROUND

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen causing a wide range of human infections. The organism is resistant to a wide range of antibiotics. The purpose of this study was to investigate the effect of AgNPs on pyocyanin pigment production of P. aeruginosa bacteria isolated from clinical specimens.

METHODS

In this study, 15 clinical isolates of P. aeruginosa were collected from different specimens of hospitalized patients. P. aeruginosa was detected by biochemical and molecular (detection of pbo1 gene by colony PCR method) methods and the MIC and MBC of AgNPs were determined by agar dilution method. Inhibition of P. aeruginosa pyocyanin production at AgNPs concentrations of 0, 0.3, 0.5, 1 and 1.5 mg/ml of was studied with OD of 520 nm.

RESULTS

The mean MIC and MBC of AgNPs were 1.229 and 1.687 mg/ml, respectively. Pyocyanin production was investigated for all isolates at different concentrations of nanoparticles, and their comparison showed that with increasing nanoparticle concentration, pyocyanin production significantly decreased (p<0.05).

CONCLUSION

According to the results of this study, AgNPs had an inhibitory effect on P. aeruginosa and its pigment production and with increasing nanoparticles concentration, pigment production decreased; therefore, it seems that the nanoparticles can be used to treat and prevent diseases caused by P. aeruginosa.

Molecular characterization of polymorphisms among Pseudomonas aeruginosa strains isolated from burn patients' wounds

Pseudomonas aeruginosa is one of the most common reasons for nosocomial infections. Given the high morbidity and mortality, as well as the cost of management, particularly in developing countries, burn injuries are considered important health concerns. Owing to the increased rate of resistance against antibiotics, this study aimed to isolate Pseudomonas aeruginosa strains from burn patient's wounds by analyzing antibiotic susceptibility and genetic profiling. In this regard, we explored the relationship between the nucleotide sequence and antibiotic susceptibility. In this cross-sectional study, 107 isolates of P. aeruginosa were collected from a major burn center in Tehran, Iran. The isolates were characterized with standard biochemical tests and examined by applying the Disk Diffusion method to find the patterns of sensitivity, and their genetic relationship was revealed by RAPD-PCR method. According to the antibiogram results, most of the isolates were resistant to 3 or more antibiotics tested and the most sensitivity was related to the Colistin antibiotic. RAPD-PCR method revealed a high polymorphism among P. aeruginosa isolates in Tehran. There was no significant association between the genotype groups and antibiotic susceptibility profiles. We evaluated the pattern of resistance to pathogenic organisms and identified multi-drug resistant organisms. Currently, Colistin antibiotic is the most suitable treatment option for burned patients. RAPD-PCR is a genotyping method with high efficiency for typing and categorizing different isolates of MDR-P. aeruginosa.

Carbapenem-Resistant Pseudomonas aeruginosa Strains-Distribution of the Essential Enzymatic Virulence Factors Genes

Pseudomonas aeruginosa is one of the most commonly isolated bacteria from clinical specimens, with increasing isolation frequency in nosocomial infections. Herein, we investigated whether antimicrobial-resistant P. aeruginosa strains, e.g., metallo-beta-lactamase (MBL)-producing isolates, may possess a reduced number of virulence genes, resulting from appropriate genome management to adapt to a changing hospital environment. Hospital conditions, such as selective pressure, may lead to the replacement of virulence genes by antimicrobial resistance genes that are crucial to survive under current conditions. The study aimed to compare, using PCR, the frequency of the chosen enzymatic virulence factor genes (alkaline protease-aprA, elastase B-lasB, neuraminidases-nan1 and nan2, and both variants of phospholipase C-plcH and plcN) to MBL distribution among 107 non-duplicated carbapenem-resistant P. aeruginosa isolates. The gene encoding alkaline protease was noted with the highest frequency (100%), while the neuraminidase-1 gene was observed in 37.4% of the examined strains. The difference in lasB and nan1 prevalence amongst the MBL-positive and MBL-negative strains, was statistically significant. Although P. aeruginosa virulence is generally more likely determined by the complex regulation of the virulence gene expression, herein, we found differences in the prevalence of various virulence genes in MBL-producers.

Characterization of the virulence of Pseudomonas aeruginosa strains causing ventilator-associated pneumonia

Background

The objective of this study was to evaluate the virulence of P. aeruginosa ventilator-associated pneumonia (VAP) strains (cases) in terms of biofilm production and other phenotypic and genotypic virulence factors compared to P. aeruginosa strains isolated from other infections (controls).

Methods

Biofilm production was tested to assess biomass production and metabolic activity using crystal violet binding assay and XTT assay, respectively. Pigment production (pyocyanin and pyoverdine) was evaluated using cetrimide agar. Virulence genes were detected by conventional multiplex PCR and virulence was tested in an in vivo model in Galleria mellonella larvae.

Results

We did not find statistically significant differences between VAP and no-VAP strains (p > 0.05) regarding biofilm production. VAP strains had no production of pyocyanin after 24 h of incubation (p = 0.023). The distribution of virulence genes between both groups were similar (p > 0.05). VAP strains were less virulent than non-VAP strains in an in vivo model of G. mellonella (p < 0.001).

Conclusion

The virulence of VAP-Pseudomonas aeruginosa does not depend on biofilm formation, production of pyoverdine or the presence of some virulence genes compared to P. aeruginosa isolated from non-invasive locations. However, VAP strains showed attenuated virulence compared to non-VAP strains in an in vivo model of G. mellonella.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12879-020-05534-1.

Emerging MDR-Pseudomonas aeruginosa in fish commonly harbor oprL and toxA virulence genes and blaTEM, blaCTX-M, and tetA antibiotic-resistance genes

This study aimed to investigate the prevalence, antibiogram of Pseudomonasaeruginosa (P.aeruginosa), and the distribution of virulence genes (oprL,exoS, phzM, and toxA) and the antibiotic-resistance genes (bla_TEM, tetA, and bla_CTX-M). A total of 285 fish (165 Oreochromisniloticus and 120 Clariasgariepinus) were collected randomly from private fish farms in Ismailia Governorate, Egypt. The collected specimens were examined bacteriologically. P. aeruginosa was isolated from 90 examined fish (31.57%), and the liver was the most prominent infected organ. The antibiogram of the isolated strains was determined using a disc diffusion method, where the tested strains exhibited multi-drug resistance (MDR) to amoxicillin, cefotaxime, tetracycline, and gentamicin. The PCR results revealed that all the examined strains harbored (oprL and toxA) virulence genes, while only 22.2% were positive for the phzM gene. On the contrary, none of the tested strains were positive for the exoS gene. Concerning the distribution of the antibiotic resistance genes, the examined strains harbored bla_TEM, bla_CTX-M, and tetA genes with a total prevalence of 83.3%, 77.7%, and 75.6%, respectively. Experimentally infected fish with P.aeruginosa displayed high mortalities in direct proportion to the encoded virulence genes and showed similar signs of septicemia found in the naturally infected one. In conclusion, P.aeruginosa is a major pathogen of O.niloticus and C.gariepinus.oprL and toxA genes are the most predominant virulence genes associated with P.aeruginosa infection. The bla_CTX-M,bla_TEM, and tetA genes are the main antibiotic-resistance genes that induce resistance patterns to cefotaxime, amoxicillin, and tetracycline, highlighting MDR P.aeruginosa strains of potential public health concern.

High prevalence of atypical virulotype and genetically diverse background among Pseudomonas aeruginosa isolates from a referral hospital in the Brazilian Amazon

Pseudomonas aeruginosa is an opportunistic pathogen causing different types of infections, particularly in intensive care unit patients. Characteristics that favor its persistence artificial environments are related to its high adaptability, wide arsenal of virulence factors and resistance to several antimicrobial classes. Among the several virulence determinants, T3SS stands as the most important due to the clinical impact of exoS and exoU genes in patient’s outcome. The molecular characterization of P. aeruginosa isolates helps in the comprehension of transmission dynamics and enhance knowledge of virulence and resistance roles in infection process. In the present study, we investigated virulence and resistance properties and the genetic background of P. aeruginosa isolated from ICUs patients at a referral hospital in Brazilian Amazon. A total of 54 P. aeruginosa isolates were characterized by detecting 19 virulence-related genes, antimicrobial susceptibility testing, molecular detection of β-lactamase-encoding genes and genotyping by MLST and rep-PCR. Our findings showed high prevalence of virulence-related markers, where 53.7% of the isolates presented at least 17 genes among the 19 investigated (P = 0.01). The rare exoS⁺/exoU⁺ cytotoxic virulotype was detected in 55.6% of isolates. Antimicrobial susceptibility testing revealed percentages of antibiotic resistance above 50% to carbapenems, cephalosporins and fluoroquinolones associated to MDR/XDR isolates. Isolates harboring both bla_SPM-1 and bla_OXA genes were also detected. Genotyping methods demonstrated a wide genetic diversity of strains spread among the different intensive care units, circulation of international MDR/XDR high-risk clones (ST111, ST235, ST244 and ST277) and emergence of seven novel MLST lineages. Finally, our findings highlight the circulation of strains with high virulence potential and resistance to antimicrobials and may be useful on comprehension of pathogenicity process, treatment guidance and establishment of strategies to control the spread of epidemic P. aeruginosa strains.

Whole-genome sequence of multi-drug resistant Pseudomonas aeruginosa strains UY1PSABAL and UY1PSABAL2 isolated from human broncho-alveolar lavage, Yaoundé, Cameroon

Pseudomonas aeruginosa has been implicated in a wide range of post-operation wound and lung infections. A wide range of acquired resistance and virulence markers indicate surviving strategy of P. aeruginosa. Complete-genome analysis has been identified as efficient approach towards understanding the pathogenicity of this organism. This study was designed to sequence the entire genome of P. aeruginosa UY1PSABAL and UY1PSABAL2; determine drug-resistance profiles and virulence factors of the isolates; assess factors that contribute toward stability of the genomes; and thereafter determine evolutionary relationships between the strains and other isolates from similar sources. The genomes of the MDR P. aeruginosa UY1PSABAL and UY1PSABAL2 were sequenced on the Illumina Miseq platform. The raw sequenced reads were assessed for quality using FastQC v.0.11.5 and filtered for low quality reads and adapter regions using Trimmomatic v.0.36. The de novo genome assembly was made with SPAdes v.3.13 and annotated using Prokka v.2.1.1 annotation pipeline; Rapid Annotation using Subsytems Technology (RAST) server v.2.0; and PATRIC annotation tool v.3.6.2. Antimicrobial resistance genes and virulence determinants were searched through the functional annotation data generated from Prokka, RAST and PATRIC annotation pipelines; In addition to ResFinder and Comprehensive Antibiotic Resistance Database (CARD) which were employed to determine resistance genes. The PHAge Search Tool Enhanced Release (PHASTER) web server was used for the rapid identification and annotation of prophage sequences within bacterial genome. Predictive secondary metabolites were identified with AntiSMASH v.5.0. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and cas genes regions were also investigated with the CRISPRone and CRISPRFinder server. The genome sizes of 7.0 and 6.4 Mb were determined for UY1PSABAL and UY1PSABAL2 strains with G+C contents of 66.1% and 66.48% respectively. β-lactamines resistance genes blaPAO, aminoglycoside phosphorylating enzymes genes aph(3')-IIb, fosfomycine resistance gene fosA, vancomycin vanW and tetracycline tetA were among identified resistance genes harboured in both isolates. UY1PSABAL bore additional aph(6)-Id, aph(3'')-Ib, ciprofloxacin-modifying enzyme crpP and ribosomal methylation enzyme rmtB. Both isolates were found harbouring virulence markers such as flagella and type IV pili; and also present various type III secretion systems such as exoA, exoS, exoU, exoT. Secondary metabolites such as pyochelin and pyoverdine with iron uptake activity were found within the genomes as well as quorum-sensing systems, and various fragments for prophages and insertion sequences. Only the UY1PSABAL2 contains CRISPR-Cas system. The phylogeny revealed a very close evolutionary relationship between UY1PSABAL and the similar strain isolated from Malaysia; the same trend was observed between UY1PSABAL2 and the strain from Chinese origin. Complete analyses of the entire genomes provide a wide range of information towards understanding pathogenicity of the pathogens in question.

Antimicrobial resistance pattern, genetic distribution of ESBL genes, biofilm-forming potential, and virulence potential of Pseudomonas aeruginosa isolated from the burn patients in Tehran Hospitals, Iran

Introduction

according to the studies performed, researchers considered Pseudomonas aeruginosa (P. aeruginosa) as the major cause of infectious diseases like burn and wound infection that makes it one of the most threatening opportunistic pathogens. The present research aimed at investigating antimicrobial resistance, biofilm-forming abilities, and frequency of the genes contributed to bla_VEB-1, bla_PER-1, and bla_PSE-1 genes and virulence of P. aeruginosa separated from the burn infections in Tehran, Iran.

Methods

we evaluated the resistance of 156 P. aeruginosa isolates to fifteen antimicrobial agents and generation of the ESBL and MBL enzymes phenotypically based on the CLSI instructions. Moreover, the biofilm forming potential has been assayed in a microtitre plate. In addition, PCR has been used to examine the frequency of virulence-and biofilm-related genes. Furthermore, the PCR of bla_VEB-1, bla_PSE-1, and bla_PER-1 genes has been amplified.

Results

according to the results, 72.2% of P. aeruginosa isolates have been MDR and 35.6% and 55.5% have been positive for producing MBL and ESBL, respectively. Moreover, 67.8% have been positive for forming biofilms. It has been found that 15.3% isolates are ESBL-positive; from among them 60% belong to the females and 40% belong to the males. In addition, one and two isolates respectively harbored the bla_VEB-1and bla_PER-1genes.

Conclusion

the present research outputs indicated the higher frequency of the multi drug resistance and higher percent of the virulence-related genes in the clinical P. aeruginosa isolates in Iran.

Coordination of las regulated virulence factors with Multidrug-Resistant and extensively drug-resistant in superbug strains of P. aeruginosa

Successful pathogenicity often resulted from a complicated association between virulence and antibiotic resistance in Pseudomonas aeruginosa infections. Therefore, the current study aimed to investigate the relationship between the las system and antibiotic resistance. Seventy-three (73) P. aeruginosa isolates were collected from burn wounds (26.02%), blood cultures (30.13%), catheters (12.32%), and urine culture (31.50%). Among the 73 collected isolates, 22 isolates were considered as multi-drug resistant (MDR) and 11 isolates as extensively-drug resistant (XDR). Furthermore, phenazines and LasA protease were detected among 21.91% and 32.87% of isolates, respectively. Quantitative real-time PCR assessment of KPC, MBL, and lasI/R indicated that resistance and virulence factors are more expressed in XDR strains than MDR strains. Also, the expression level of KPC and MBL reduced in non-biofilm forming strains. However, increased expression levels of lasI, lasR, and the KPC genes were observed in LasA and LasB protease producing strains. Interestingly, 16 known sequence types (including ST108, ST260, ST217) and three novel STs (ST2452, ST2427, and ST2542) were characterized among the collected isolates, which are related to the virulence and resistance. In MDR-XDR strains, a strong correlation between lasI/R and the variants of antibiotic resistance genes was found. In conclusion, the pathogenicity of P. aeruginosa may increase the prevalence of antibiotic-resistant strains.

Risk of type III secretion systems in burn patients with Pseudomonas aeruginosa wound infection: A systematic review and meta-analysis

PURPOSE

The pathogenesis of Pseudomonas aeruginosa is multifactorial and attributed to the production of several cell-associated and extracellular virulence factors including those implicated in adherence, iron uptake, exoenzymes (Exo) and exotoxins. The present study aimed to determine the prevalence of type III secretion systems (T3SS) effectors in Iranian burn patients with P. aeruginosa wound infection.

METHODS

A systematic search was conducted to identify papers published by Iranian authors in the Web of Science, PubMed, Scopus, Embase, and Google Scholar electronic databases during the period of January, 2000 to December, 2018. Publications which met our inclusion criteria were selected for data extraction and analysis by Comprehensive Meta-Analysis Software. The inclusion criteria were articles that include burn patients with a wound infection caused by P. aeruginosa, and reported the prevalence of aimed exoenzymes.

RESULTS

Ten publications were selected out of 15 full-text reviewed articles with the inclusion criteria. Of ten studies, the pooled prevalence of ExoS producing isolates was estimated at 57.1% (95% CI: 40.3-72.5%). Five studies reported the prevalence of ExoU and ExoT, from which, the pooled prevalence of ExoU and ExoT producing isolates was estimated at 51.4% (95% CI: 31.4-70.9%) and 86.4% (95% CI: 48.1-97.8%), respectively. Four studies reported the prevalence of ExoY, from which, the pooled prevalence of ExoY producing isolates was estimated at 79.0% (95% CI: 48.6-93.8%).

CONCLUSION

Our results showed a remarkable prevalence of T3SS-positive genotype in patients with burn injuries. These findings provided attractive targets for new therapeutic strategies for burn patients who were infected with cytotoxin-producing P. aeruginosa.

Occurrence of blaTEM and blaCTXM Genes and Biofilm-Forming Ability among Clinical Isolates of Pseudomonas aeruginosa and Acinetobacter baumannii in Yaoundé, Cameroon

Background: Pseudomonas aeruginosa (PSA) and Acinetobacter baumannii (ACB) are non-fermentative bacteria mostly associated with nosocomial infections in humans. Objective: This study aimed to determine the antimicrobial resistance profiles and virulence gene of PSA and ACB previously isolated from humans in selected health facilities in Yaoundé, Cameroon. Methods: A total of 77 and 27 presumptive PSA and ACB isolates, respectively, were collected from the Yaoundé teaching hospital. These isolates were previously isolated from various samples including pus, blood and broncho-alveolar lavage. The identities of the isolates were determined through polymerase chain reaction (PCR) amplification of PSA and ACB specific sequences. Antimicrobial susceptibility testing (AST) was performed using the Kirby–Bauer disc diffusion method. Phenotypical expression of AmpC β-lactamases (AmpC), extended spectrum β-lactamases (ESBLs) and metallo β-Lactamases (MBLs) were determined using the combined disc method. Bacterial genomes were screened for the presence of β-lactamases bla_TEM and bla_CTXM genes using specific PCR. The pathogenicity of PSA and ACB was assessed through amplification of the lasB, exoA, pslA and exoS as well as OmpA and csuE virulence genes, respectively. Results: Of the 77 presumptive PSA isolates, a large proportion (75 to 97.4%) were positively identified. All (100%) of the presumptive 27 ACB harbored the ACB-specific ITS gene fragment by PCR. Twenty five percent of the PSA isolates produced ESBLs phenotypically while more than 90% of these isolates were positive for the lasB, exoA, pslA and exoS genes. A large proportion (88%) of the ACB isolates harboured the OmpA and csuE genes. bla_TEM and bla_CTXM were detected in 17 and 4% of PSA, respectively, while a much higher proportion (70 and 29%) of the ACB isolates possessed these resistance determinants respectively. Conclusion: Our findings reveal the occurrence of both virulence and drug-resistant determinants in clinical PSA and ACB isolates from patients in health care settings in Yaoundé, Cameroon, thus suggesting their role in the pathological conditions in patients.