Epidemiology and Characteristics of Metallo-β-Lactamase-Producing Pseudomonas aeruginosa

Evolutionary insights into NDM variants: Identification and functional analysis of novel NDM-58 in Pseudomonas aeruginosa

The emergence of New Delhi Metallo-β-lactamase (NDM) variants in P. aeruginosa has significantly contributed to carbapenem resistance, posing a global threat to antimicrobial therapy. The catalytic activity of NDM, dependent on Zn (II), is enhanced by specific mutations. In this study, we report the identification and characterization of a novel NDM-58 variant (GenBank: OR081828.1) in P. aeruginosa BA24848, which exhibited resistance to multiple β-lactams, including cephalosporins, carbapenems, and BL/BLI combinations. WGS revealed that NDM-58 harbors a unique P185S substitution. This strain is associated with other ARGs (blaPAO, PME-1, fosA, blaOXA-396, blaOXA-494, blaOXA-50, sul1, dfrA1, qacE, aph(3')-VI, qnrVC1, and cat7), indicating a XDR phenotype. Comparative genomic analysis revealed the presence of MGEs (ISpre2, ISPa6, ISPa2, ISPsy29, IS26, Tn4661, ISPa37, and ISUnCu4) associated with NDM-58, which may facilitate the horizontal transfer of resistance determinants. Structural modeling and molecular dynamics simulations demonstrated that NDM-58 exhibits altered stability and compactness compared to NDM-1, likely influencing its enzymatic activity and resistance profile. Residual conservation analysis revealed that Pro185 is highly conserved, and its substitution to serine may impact protein stability and function. The molecular dynamics analysis indicated that NDM-58 has lower residual fluctuations and increased flexibility, which may enhance its adaptability under varying physiological conditions. Our findings provide novel insights into the evolutionary dynamics of NDM enzymes and the role of genetic environments in their dissemination. Understanding these mechanisms is crucial for developing effective surveillance and mitigation strategies against emerging carbapenem-resistant P. aeruginosa.

Outer membrane permeability of Pseudomonas aeruginosa through β-lactams: new evidence on the role of OprD and OpdP porins in antibiotic resistance

Gram-negative bacteria are a major concern for public health, particularly due to the continuous rise of antibiotic resistance. A major factor that helps the development of resistance is the outer membrane that is essential since it acts as a strong permeability barrier to many antibiotics that are effective against other bacteria. In this study, we determine the specific permeability coefficients for various antibiotics in Pseudomonas aeruginosa strains, which differ from each other for their porin expressions. We showed that OprD and OpdP porins contribute both to internalize meropenem and biapenem. Using qRT-PCR, we demonstrated that their expression is dependent of the various phases of cellular growth. We were able to show how the OpdP porin is less expressed in exponential growth phases, while it tends to be produced when the bacterial culture enters into the latent phase, in an inversely proportional way compared to the OprD porin. The deletion of the OpdP porin, in the presence of meropenem at concentrations equivalent to the MIC values, contributes to the selection of carbapenem-resistant strains. Therefore, the presence of mutations/deletions of the OpdP porin should receive greater consideration from a clinical point of view as the use of meropenem at nonoptimal concentrations could lead to the appearance of resistance phenotypes.IMPORTANCECarbapenem-resistant strains of Pseudomonas aeruginosa are among the major threats to public health. The permeability of the outer membrane for the β-lactam antibiotics is one of the major factors that reduce the activity of the antibiotics. In this study, we measure the low permeability coefficient of the P. aeruginosa outer membrane to β-lactams. The methodology we develop to determine the permeability can be applied to other antibiotic families and/or pathogens.

Current trends in the epidemiology of multidrug-resistant and beta-lactamase-producing Pseudomonas aeruginosa in Asia and Africa: a systematic review and meta-analysis

Pseudomonas aeruginosa continues to be a significant contributor to high morbidity and mortality rates worldwide, particularly due to its role in severe infections such as hospital-acquired conditions, including ventilator-associated pneumonia and various sepsis syndromes. The global increase in antimicrobial-resistant (AMR) P. aeruginosa strains has made these infections more difficult to treat, by limiting the effective drug options available. This systematic review and meta-analysis aim to provide an updated summary of the prevalence of AMR P. aeruginosa over the past 5 years. A systematic search was performed across three major electronic databases-PubMed, ScienceDirect, and Web of Science-yielding 40 eligible studies published between 2018 and 2023. Using a random-effects model, our meta-analysis estimated that the overall prevalence of P. aeruginosa in Asia and Africa over the past 5 years was 22.9% (95% CI [14.4-31.4]). The prevalence rates for multidrug-resistant (MDR) and extensively drug-resistant (XDR) P. aeruginosa strains were found to be 46.0% (95% CI [37.1-55.0]) and 19.6% (95% CI [4.3-34.9]), respectively. Furthermore, the prevalence rates of extended-spectrum β-lactamase- and metallo-β-lactamase-producing P. aeruginosa were 33.4% (95% CI [23.6-43.2]) and 16.0% (95% CI [9.8-22.3]), respectively. Notably, resistance rates to β-lactams used for treating pseudomonal infections were alarmingly high, with rates between 84.4% and 100.0% for cephalosporins, and over 40% of P. aeruginosa isolates showed resistance to penicillins. Our analysis identified the lowest resistance rates for last-resort antimicrobials, with 0.3% (95% CI [0.0-1.3]) resistance to polymyxin B and 5.8% (95% CI [1.5-10.2]) to colistin/polymyxin E. The low resistance rates to polymyxins suggest that these antibiotics remain effective against MDR P. aeruginosa. However, the findings also highlight the critical public health threat posed by antimicrobial-resistant P. aeruginosa, particularly concerning β-lactam antibiotics. This underscores the need for effective and carefully planned intervention strategies, including the development of new antibiotics to address the growing challenge of resistance. Developing robust antibiotic treatment protocols is essential for better management and control of pseudomonal infections globally. Therefore, continued research and international collaboration is vital to tackle this escalating public health challenge. This study protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO), under registration number CRD42023412839.

In-Vitro Activity of Dimercaptosuccinic Acid in Combination with Carbapenems Against Carbapenem-Resistant Pseudomonas aeruginosa

Carbapenenemase producers, particularly the metallo-β-lactamase (MBL) types in Pseudomonas aeruginosa, have emerged as an urgent threat in health care settings. MBLs require zinc at their catalytic site and can be inhibited by dimercaptosuccinic acid (DMSA), a metal chelator known for the treatment of lead and mercury intoxication. Isogenic strains of wild-type and OprD-deleted P. aeruginosa PA14, were constructed, producing the MBLs VIM-2, NDM-1, SPM-1, IMP-1, and AIM-1, or the non-MBL carbapenemases, GES-5 and KPC-2. In addition, 59 previously characterized clinical isolates of P. aeruginosa producing different ß-lactamases (including carbapenemases), and with known outer-membrane porin OprD status, were utilized. Minimal inhibitory concentrations values of imipenem and meropenem, and DMSA combinations were determined, and time-kill assays were performed with PA14 expressing VIM-2. Results indicated a significant additive effect of DMSA (most effective at 3 mM) and carbapenems in recombinant and clinical strains of P. aeruginosa expressing MBLs, in particular against VIM producers, which are the most prevalent carbapenemases in P. aeruginosa. This effect was best evidenced with meropenem and in strains without OprD modification. DMSA shows promising efficacy, particularly in combination therapy with meropenem, for treating infections caused by MBL-producing P. aeruginosa.

Exploiting the fitness cost of metallo-β-lactamase expression can overcome antibiotic resistance in bacterial pathogens

Carbapenems are last-resort antibiotics for treating bacterial infections. The widespread acquisition of metallo-β-lactamases, such as VIM-2, contributes to the emergence of carbapenem-resistant pathogens, and currently, no metallo-β-lactamase inhibitors are available in the clinic. Here we show that bacteria expressing VIM-2 have impaired growth in zinc-deprived environments, including human serum and murine infection models. Using transcriptomic, genomic and chemical probes, we identified molecular pathways critical for VIM-2 expression under zinc limitation. In particular, disruption of envelope stress response pathways reduced the growth of VIM-2-expressing bacteria in vitro and in vivo. Furthermore, we showed that VIM-2 expression disrupts the integrity of the outer membrane, rendering VIM-2-expressing bacteria more susceptible to azithromycin. Using a systemic murine infection model, we showed azithromycin's therapeutic potential against VIM-2-expressing pathogens. In all, our findings provide a framework to exploit the fitness trade-offs of resistance, potentially accelerating the discovery of additional treatments for infections caused by multidrug-resistant bacteria.

Phenotypic and molecular characterization of extended spectrum- and metallo- beta lactamase producing Pseudomonas aeruginosa clinical isolates from Egypt

BACKGROUND

Antimicrobial resistance among Pseudomonas aeruginosa (P. aeruginosa), a leading cause of nosocomial infections worldwide, is escalating. This study investigated the prevalence of extended-spectrum β-lactamases (ESBLs) and metallo-β-lactamases (MBLs) among 104 P. aeruginosa clinical isolates from Alexandria Main University Hospital, Alexandria, Egypt.

METHODS

Antimicrobial susceptibility testing was performed using agar dilution technique, or broth microdilution method in case of colistin. ESBL and MBL prevalence was assessed phenotypically and genotypically using polymerase chain reaction (PCR). The role of plasmids in mediating resistance to extended-spectrum β-lactams was studied via transformation technique using plasmids isolated from ceftazidime-resistant isolates.

RESULTS

Antimicrobial susceptibility testing revealed alarming resistance rates to carbapenems, cephalosporins, and fluoroquinolones. Using PCR as the gold standard, phenotypic methods underestimated ESBL production while overestimating MBL production. Eighty-five isolates (81.7%) possessed only ESBL encoding genes, among which 69 isolates harbored a single ESBL gene [blaOXA-10 (n = 67) and blaPER (n = 2)]. Four ESBL-genotype combinations were detected: blaPER + blaOXA-10 (n = 8), blaVEB-1 + blaOXA-10 (n = 6), blaPSE + blaOXA-10 (n = 1), and blaPER + blaVEB-1 + blaOXA-10 (n = 1). Three isolates (2.9%) possessed only the MBL encoding gene blaVIM. Three ESBL + MBL- genotype combinations: blaOXA-10 + blaAIM, blaOXA-10 + blaVIM, and blaPER + blaOXA-10 + blaAIM were detected in 2, 1 and 1 isolate(s), respectively. Five plasmid preparations harboring blaVEB-1 and blaOXA-10 were successfully transformed into chemically competent Escherichia coli DH5α with transformation efficiencies ranging between 6.8 × 10 3 and 3.7 × 10 4    CFU/μg DNA plasmid. Selected tested transformants were ceftazidime-resistant and harbored plasmids carrying blaOXA-10.

CONCLUSIONS

The study highlights the importance of the expeditious characterization of ESBLs and MBLs using genotypic methods among P. aeruginosa clinical isolates to hinder the development and dissemination of multidrug resistant strains.

Determination of the presence of carbapenemase enzymes in carbapenem-resistant Pseudomonas aeruginosa isolates by susceptibility test based algorithm

PURPOSE

Phenotypic methods have been proposed for the detection of carbapenemase production. These tests can have slower turnaround times. With the sensitivity-based algorithm described by Gill et al. will be possible to detect the carbapenemase.

METHODS

Carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates from three hospitals between January 2017 and December 2021 were included. The modified carbapenemase-inactivation-method(mCIM) and two algorithms were used, defined as "primary algorithm, i.e. ceftazidime and cefepime non-susceptible in addition to imipenem or meropenem resistance" and "secondary algorithm, i.e. ceftolozane/tazobactam non-susceptible in addition to imipenem or meropenem resistance". PCR testing was performed on all isolates.

RESULTS

256 CRPA isolates were included in the study. When the primary or secondary algorithm criteria were applied, there were 173 isolates that met one or both of them. Of these, 29 were CIM-positive isolates.

CONCLUSION

In our study, the use of the algorithm reduced the need for CIM testing by 32 %.

National Cohort of Compassionate Use of Meropenem-Vaborbactam: No Benefit over Meropenem for Pseudomonas aeruginosa

BACKGROUND

Meropenem-vaborbactam (MEM-VAB) is a novel carbapenem-beta-lactamase-inhibitor combination that demonstrates activity against carbapenem-resistant (CR) Gram-negative bacteria, and more specifically KPC-producers, since vaborbactam is an effective inhibitor of KPC enzymes in vitro. This study aimed to describe the initial uses and efficacy of MEM-VAB for compassionate treatment during the first 21 months following its early access in France.

METHOD

A national multicenter retrospective study was conducted, including all patients who received at least one dose of MEM-VAB between 20 July 2020, and 5 April 2022. Clinical characteristics and outcomes were collected using a standardized questionnaire. The minimum inhibitory concentration (MIC) of antimicrobials, and complete genome sequencing of bacteria were performed when bacterial isolates were available.

RESULTS

Ultimately, 21 patients from 15 French hospitals were included in the study. The main indication for MEM-VAB treatment was respiratory tract infections (n = 9). The targeted bacteria included Pseudomonas aeruginosa (n = 12), Klebsiella pneumoniae (n = 3), Enterobacter spp (n = 3), Citrobacter freundii (n = 1), Escherichia coli (n = 1), and Burkholderia multivorans (n = 1). Overall, no significant advantage of vaborbactam over meropenem alone was observed across all strains of P. aeruginosa in terms of in vitro susceptibility. However, MEM-VAB demonstrated a notable impact, compared to carbapenem alone, on the MIC for the two KPC-3-producing K. pneumoniae and B. multivorans.

CONCLUSIONS

MEM-VAB seems effective as a salvage treatment in compassionate use, but vaborbactam was shown to lack benefits compared to meropenem in treating P. aeruginosa-related infections. Therefore, it is crucial to compare meropenem to MEM-VAB MICs, particularly for P. aeruginosa, before prescribing MEM-VAB.

Antibiotic resistance in Pseudomonas aeruginosa: mechanisms and emerging treatment

Pseudomonas aeruginosa, able to survive on the surfaces of medical devices, is a life-threatening pathogen that mainly leads to nosocomial infection especially in immunodeficient and cystic fibrosis (CF) patients. The antibiotic resistance in P. aeruginosa has become a world-concerning problem, which results in reduced and ineffective therapy efficacy. Besides intrinsic properties to decrease the intracellular content and activity of antibiotics, P. aeruginosa develops acquired resistance by gene mutation and acquisition, as well as adaptive resistance under specific situations. With in-depth research on drug resistance mechanisms and the development of biotechnology, innovative strategies have emerged and yielded benefits such as screening for new antibiotics based on artificial intelligence technology, utilizing drugs synergistically, optimizing administration, and developing biological therapy. This review summarizes the recent advances in the mechanisms of antibiotic resistance and emerging treatments for combating resistance, aiming to provide a reference for the development of therapy against drug-resistant P. aeruginosa.

Characterization of the Chromosomally Located Metallo-β-Lactamase Genes blaIMP-45 and blaVIM-2 in a Carbapenem-Resistant Pseudomonas aeruginosa Clinical Isolate

Objective: Characterization of the multidrug resistance (MDR) region in P. aeruginosa strain PA59 revealed the presence of antibiotic resistance genes, including blaIMP-45 and blaVIM-2, within a complex genetic landscape of mobile genetic elements. Methods: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) strains were isolated from Shanghai Changhai Hospital. Polymerase chain reaction (PCR) was used to detect the β-lactamase genes in the isolated strains. Strains carrying two or more genes were subjected to whole-genome sequencing (WGS) and in-depth bioinformatics analysis. Results: A total of 94 CRPA strains were isolated, among which PA59 was determined to carry blaIMP-45 and blaVIM-2 genes. Compared with single-gene positive or other blaIMP and blaVIM dual-gene positive strains reported, PA59 exhibited a broader range of drug resistance. We discovered a multidrug resistant (MDR)-related region composed of various mobile elements in the PA59 chromosome. This region carried many resistance genes, including the target genes blaIMP-45 and blaVIM-2. By further comparing the mobile elements GI13 and Ph08, we speculated that this integron structure carrying blaIMP-45 and blaVIM-2 was initially integrated into the genomic island or prophage, forming a more complex genetic structure, and then further integrated into the PA59 chromosome through plasmids. Phylogenetic tree analysis showed limited sequence similarity between PA59 and other CRPA strains. Conclusions: This study identified PA59 as the first reported P. aeruginosa strain carrying both blaIMP-45 and blaVIM-2 on the chromosome. The assembly and annotation of the PA59 genome provide valuable insights into the genomic diversity and gene content of this clinically important pathogen, aiding the development of effective strategies against antibiotic resistance.

Multidrug resistance and phylogenetic analyses of Pseudomonas aeruginosa based on the 16S rRNA gene of isolates recovered from clinical samples and their susceptibility to silver-nanoparticle

Background

Pseudomonas aeruginosa is a highly antimicrobial-resistant pathogen with a very narrow range of effective antibacterial agents. Therefore, finding alternative compounds is highly required, such as silver nanoparticles (AgNPs).

Aim

The current study was conducted to identify the multidrug resistance (MDR) profile and perform a phylogenetic analysis on P. aeruginosa isolates recovered from clinical samples (human, cows, cats, and fish) and to study their susceptibility to AgNPs.

Methods

40 samples were subjected to conventional cultivation and biochemical analyses to identify P. aeruginosa. Moreover, these isolates were tested for their antibiotic resistance profile and their response to AgNPs using disk diffusion methods. PCR and Sanger-based sequencing were performed using the 16S rRNA gene as a target.

Results

The results showed that all isolates were resistant to cefixime and sensitive to meropenem. Conversely, the AgNPs were effective in producing larger zones of inhibition. The PCR revealed amplification of the target, and the sequencing and phylogenetic tree of four isolates revealed close similarity with global human sequences from different regions.

Conclusion

The study reveals the MDR characteristics of P. aeruginosa. The isolates are highly susceptible to silver nanoparticles.

PBP-3 directed therapy in VIM-producing Pseudomonas aeruginosa creates bacterial transformers, persisters in disguise

OBJECTIVES

The proliferation of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa represents a significant public health threat. P. aeruginosa undergoes significant phenotypic changes that drastically impair antibiotic efficacy. The objectives of this study were (1) to quantify the time-course of killing of VIM-2-producing P. aeruginosa in response to aztreonam-based therapies (including avibactam for coverage of AmpC), and (2) to document the capacity of P. aeruginosa to undergo morphological transformations that facilitate persistence.

METHODS

A well-characterised, clinical VIM-2-producing P. aeruginosa was studied in the hollow fibre infection model (HFIM) over 9 days (7 days of active antibiotic therapy, 2 days of treatment withdrawal) at a 107.5 CFU/mL starting inoculum. HFIM treatment arms included: growth control, aztreonam, ceftazidime/avibactam, aztreonam/ceftazidime/avibactam, polymyxin B, and aztreonam/ceftazidime/avibactam/polymyxin B. In addition, real-time imaging studies were conducted under static conditions to determine the time course of the reversion of persister cells.

RESULTS

There was a pronounced discrepancy between OD620 and bacterial counts obtained from plating methods (hereafter referred to as 'OD-count discrepancy'). For aztreonam monotherapy, observed counts were 0 CFU/mL by 120 h. Despite this, there was a significant OD-count discrepancy compared with the pre-treatment 0 h. Between therapy withdrawal at 168 h and 216 h, all arms with suppressed counts had regrown to the system-carrying capacity. Real-time imaging of the P. aeruginosa filaments after drug removal showed rapid reversion from a long, filamentous phenotype to many individual rods within 2 h.

CONCLUSION

Managing MBL-producing P. aeruginosa requires a multifaceted approach, focused on maximising killing and minimising proliferation of resistant and persistent subpopulations, which will involve eliminating drug-induced phenotypic transformers.

Resistance to ceftazidime-avibactam and other new β-lactams in Pseudomonas aeruginosa clinical isolates: a multi-center surveillance study

New β-lactam-β-lactamase inhibitor combinations represent last-resort antibiotics to treat infections caused by multidrug-resistant Pseudomonas aeruginosa. Carbapenemase gene acquisition can limit their spectrum of activity, and reports of resistance toward these new molecules are increasing. In this multi-center study, we evaluated the prevalence of resistance to ceftazidime-avibactam (CZA) and comparators among P. aeruginosa clinical isolates from bloodstream infections, hospital-acquired or ventilator-associated pneumonia, and urinary tract infections, circulating in Southern Italy. We also investigated the clonality and content of relevant β-lactam resistance mechanisms of CZA-resistant (CZAR) isolates. A total of 120 P. aeruginosa isolates were collected. CZA was among the most active β-lactams, retaining susceptibility in the 81.7% of cases, preceded by cefiderocol (95.8%) and followed by ceftolozane-tazobactam (79.2%), meropenem-vaborbactam (76.1%), imipenem-relebactam (75%), and aztreonam (69.6%). Among non-β-lactams, colistin and amikacin were active against 100% and 85.8% of isolates respectively. In CZAR strains subjected to whole-genome sequencing (n = 18), resistance was mainly due to the expression of metallo-β-lactamases (66.6% VIM-type and 5.5% FIM-1), followed by PER-1 (16.6%) and GES-1 (5.5%) extended-spectrum β-lactamases, mostly carried by international high-risk clones (ST111 and ST235). Of note, two strains producing the PER-1 enzyme were resistant to all β-lactams, including cefiderocol. In conclusion, the CZA resistance rate among P. aeruginosa clinical isolates in Southern Italy remained low. CZAR isolates were mostly metallo-β-lactamases producers and belonging to ST111 and ST253 epidemic clones. It is important to implement robust surveillance systems to monitor emergence of new resistance mechanisms and to limit the spread of P. aeruginosa high-risk clones.

IMPORTANCE

Multidrug-resistant Pseudomonas aeruginosa infections are a growing threat due to the limited therapeutic options available. Ceftazidime-avibactam (CZA) is among the last-resort antibiotics for the treatment of difficult-to-treat P. aeruginosa infections, although resistance due to the acquisition of transferable β-lactamase genes is increasing. With this work, we report that CZA represents a highly active antipseudomonal β-lactam compound (after cefiderocol), and that metallo-β-lactamases (VIM-type) and extended-spectrum β-lactamases (GES and PER-type) production is the major factor underlying CZA resistance in isolates from Southern Italian hospitals. In addition, we reported that such resistance mechanisms were mainly carried by the international high-risk clones ST111 and ST235.

Modification of carbapenemase inhibition test and comparison of its performance with NG-Test CARBA 5 for detection of carbapenemase-producing Enterobacterales

AIMS

Adequately and accurately identifying carbapenemase-producing Enterobacterales (CPE) is vital for selecting appropriate antimicrobial therapy and implementing effective infection control measures. This study aims to optimize the phenotypic detection method of carbapenemase for routine diagnostics in clinical microbiology laboratories.

METHODS AND RESULTS

Carbapenemase genes in 2665 non-duplicate CRE clinical strains collected from various regions of China were confirmed through whole-genome sequencing (WGS). The carbapenemase inhibition test (CIT) was conducted and interpreted using different methods and breakpoints, then compared with the NG-Test CARBA 5 for carbapenemase detection. The diagnostic performance of the CIT method was optimal when the carbapenemase types were determined by comparing the inhibition zone diameters of the imipenem disc with 3-aminophenylboronic acid (APB) plus ethylenediaminetetraacetic acid (EDTA) to those of the imipenem disc with either APB or EDTA alone, with a breakpoint of 4 mm. The overall sensitivities of the current CIT, the modified CIT, and NG-Test CARBA 5 were 91.4%, 94.9%, and 99.9%, respectively. For detecting isolates co-producing Klebsiella pneumoniae carbapenemase (KPC) and metallo-β-lactamases (MBLs), the modified CIT method had higher sensitivity than the current method (70.0% vs. 53.3%), though this difference was not statistically significant (P = 0.063). The NG-Test CARBA 5 showed excellent performance for multi-carbapenemases diagnosis, with sensitivity and specificity of 97.1% and 100%, respectively.

CONCLUSIONS

Optimizing and standardizing the CIT method for clinical use is necessary. It has certain advantages in diagnosing multi-carbapenemase and rare carbapenemase production. However, for identifying common carbapenemase types, the NG-Test CARBA 5 demonstrated superior performance.

Detection of metallo-beta-lactamase-producing genes blaSPM and blaNDM in Pseudomonas aeruginosa isolated from wastewater in Southern Brazil

Pseudomonas aeruginosa is commonly associated with the ability to acquire antimicrobial resistance. The surveillance of resistance genes in various environmental matrices has gained prominence in recent years, being seen as a potential threat to public health. The objective of this study was to investigate genes encoding metallo-beta-lactamases (MBLs), which confer resistance to carbapenems, in wastewater. Fifteen isolates of P. aeruginosa were collected for five months from samples obtained from a municipal wastewater treatment plant in Rio Grande do Sul. These isolates were subjected to disk diffusion testing using 10 different antimicrobials. Phenotypic enzymatic tests for MBLs were conducted, and positive isolates underwent DNA extraction and gene detection using the polymerase chain reaction. The resistance rate to ceftazidime was 100%, cefepime 73.3%, piperacillin-tazobactam 66.67%, imipenem 53.30%, levofloxacin 46.67%, tobramycin 40%, and ciprofloxacin and amikacin 13.33%. Both meropenem and aztreonam resistances were rare accounting for 6.60% of the tested isolates. Among these isolates, 20% were classified as multidrug-resistant and were found to carry the blaNDM and blaSPM genes. The results suggest that evaluating resistance genes in bacteria from urban raw sewage can provide data that assist in surveillance, as this environment can stimulate increased bacterial resistance.

Hospital-acquired and ventilator-associated pneumonia caused by multidrug-resistant Gram-negative pathogens: Understanding epidemiology, resistance patterns, and implications with COVID-19

The ongoing spread of antimicrobial resistance has complicated the treatment of bacterial hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP). Gram-negative pathogens, especially those with multidrug-resistant profiles, including Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Pseudomonas aeruginosa, and Acinetobacter spp., are important culprits in this type of infections. Understanding the determinants of resistance in pathogens causing pneumonia is ultimately stressing, especially in the shadows of the COVID-19 pandemic, when bacterial lung infections are considered a top priority that has become urgent to revise. Globally, the increasing prevalence of these pathogens in respiratory samples represents a significant infection challenge, with major limitations of treatment options and poor clinical outcomes. This review will focus on the epidemiology of HAP and VAP and will present the roles and the antimicrobial resistance patterns of implicated multidrug-resistant (MDR) Gram-negative pathogens like carbapenem-resistant Acinetobacter baumannii (CRAB), carbapenem-resistant Pseudomonas aeruginosa (CRPA), carbapenem-resistant Enterobacterales (CRE), as well as colistin-resistant Gram-negative pathogens and extended-spectrum β-lactamase (ESBL)-producing Enterobacterales. While emerging from the COVID-19 pandemic, perspectives and conclusions are drawn from findings of HAP and VAP caused by MDR Gram-negative bacteria in patients with COVID-19.

Genomic diversity of β-lactamase producing Pseudomonas aeruginosa in Iran; the impact of global high-risk clones

BACKGROUND

Hospital-acquired infections caused by multidrug-resistant Pseudomonas aeruginosa incline hospital stay and costs of treatment that resulted in an increased mortality rate. The frequency of P. aeruginosa high-risk clones producing carbapenemases was investigated in our clinical samples.

METHODS

In this cross-sectional study, 155 non-repetitive P. aeruginosa isolates were included from different medical centers of Iran. Antibiotic susceptibility testing was determined, and the presence of β-lactamases were sought by phenotypic and genotypic methods. The clonal relationship of all isolates was investigated, and multi-locus sequence typing (MLST) was used for finding the sequence types of carbapenemase-producers.

RESULTS

The agent with highest percent susceptibility rate was recorded for colistin (94.9%). MOX and FOX were found both as low as 1.95% (3/155). The most frequent narrow spectrum β-lactamase was SHV with 7.7% (12/155) followed by PER, OXA-1, and TEM with the frequency of 7.1% (11/155), 3.2% (5/155), and 1.3% (2/155), respectively. Carbapenemases were detected in 28 isolates (18%). The most frequent carbapenemase was IMP with 9% (14/155) followed by NDM, 8.4% (13/155). OXA-48 and VIM were also detected both per one isolate (0.65%). MLST of carbapenem resistant P. aeruginosa isolates revealed that ST244, ST664, ST235, and ST357 were spread in subjected clinical settings. REP-PCR uncovered high genomic diversity in our clinical setting.

CONCLUSION

Clonal proliferation of ST235 strain plays a key role in the propagation of MDR pattern in P. aeruginosa. Our data showed that high-risk clones has distributed in Iran, and programs are required to limit spreading of these clones.

Epidemiology of Pseudomonas aeruginosa in diabetic foot infections: a global systematic review and meta-analysis

Pseudomonas aeruginosa is one of the most common causes of diabetic foot infection globally. This study aimed to determine the global distribution of P. aeruginosa isolated from diabetic foot ulcer infection. PRISMA procedure was used to perform the current systematic review and meta-analysis. The Web of Science, MEDLINE/PubMed, Scopus, and other databases were searched for studies published in English from 2000 to 2022. Data was analyzed using the Comprehensive Meta-Analysis software (CMA). Keywords and MESH phrases included Pseudomonas aeruginosa, diabetic foot ulcer, P. aeruginosa, and diabetic foot infection. As a result of this review, 16.6% of diabetic foot wound infections were caused by P. aeruginosa. About 37.9% of strains were multidrug resistant (MDR). P. aeruginosa infection rates in diabetic foot ulcers ranged from 0.5 to 100% globally. In total, the prevalence rates of P. aeruginosa in diabetic foot ulcer infection from Asia, Africa, and Western countries were reported at 18.5%, 16.3%, and 11.1%, respectively. Data have shown that the prevalence of P. aeruginosa, particularly MDR strains, isolated from diabetic foot ulcer infection was relatively high; inherent resistance to antibiotics is also high; the wound either does not heal or if it does, it will be delayed. Therefore, timely treatment is essential.

Network meta-analysis of antibiotic resistance patterns in gram-negative bacterial infections: a comparative study of carbapenems, fluoroquinolones, and aminoglycosides

Introduction

Antimicrobial resistance poses a grave global threat, particularly with the emergence of multidrug-resistant gram-negative bacterial infections, which severely limit treatment options. The increasing global threat of antimicrobial resistance demands rigorous investigation, particularly concerning multidrug-resistant gram-negative bacterial infections that present limited therapeutic options. This study employed a network meta-analysis, a powerful tool for comparative effectiveness assessment of diverse antibiotics. The primary aim of this study was to comprehensively evaluate and compare resistance patterns among widely used antibiotic classes, namely carbapenems, fluoroquinolones, and aminoglycosides, for combating gram-negative pathogens.

Methods

We searched PubMed, Web of Sciences, Scopus, Scholarly, Medline, Embase, and Cochrane databases up to August 27, 2023. Studies showing antibiotic resistance in clinical isolates of Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii exposed to carbapenems, fluoroquinolones, and aminoglycosides were included. This study determined treatment-specific resistance percentages and ranked these treatments based on resistance using a random-effects network meta-analysis technique. To investigate the impact of the study and pathogen features, subgroup and meta-regression analyses were performed. Risk ratios and 95% confidence intervals (CIs) were calculated using a network meta-analysis (NMA) incorporating both direct and indirect evidence. Clinical improvement, cure, microbiological eradication, and death from any cause were the primary outcomes. Nephrotoxicity was a secondary result.

Results

The analysis included 202 publications and 365,782 gram-negative isolates. The NMA included data from 20 studies and 4,835 patients. Carbapenems had the lowest resistance rates throughout the pathogen spectrum, with resistance percentages of 17.1, 22.4, and 33.5% for Enterobacteriaceae, P. aeruginosa, and A. baumannii, respectively. For the same infections, aminoglycosides showed resistance rates of 28.2, 39.1, and 50.2%, respectively. Fluoroquinolones had the highest resistance rates at 43.1, 57.3, and 65.7%, respectively. Unexpectedly, resistance to all three antibiotic classes has increased over time, with multidrug resistance being the most prevalent.

Conclusion

This extensive network meta-analysis provides an overview of the patterns of resistance throughout the world and how they are changing. The most effective choice is still carbapenems, but the increasing resistance highlights the critical need for multimodal therapies to protect antibiotic effectiveness against these powerful gram-negative infections.

Domestically Acquired NDM-1-Producing Pseudomonas aeruginosa, Southern California, USA, 2023

We describe a case of New Delhi metallo-β-lactamase 1-producing carbapenem-resistant Pseudomonas aeruginosa (CRPA) in a transplant patient with multiple hospitalizations in California, USA. Whole-genome sequencing revealed the isolate was genetically distinctive, despite ≈95% similarity to other global strains. The patient's lack of international travel suggests this CRPA was acquired domestically.

Integration of phenotypic, qPCR and genome sequencing methodologies for the detection of antimicrobial resistance and virulence in clinical isolates of a tertiary hospital, India

The emergence of antimicrobial resistance (AMR) and virulence in clinical isolates is a significant public health concern. The rapid and accurate detection of these traits in clinical isolates is essential for effective infection control and treatment. We demonstrated the integration of multiple detection methodologies, including phenotypic testing, quantitative polymerase chain reaction (qPCR), and genome sequencing, to detect AMR and virulence in clinical isolates. One hundred sixty-two gram-negative bacterial clinical isolates were selected for this study from the Shri Vinoba Bhave Civil Hospital, Silvassa, a tertiary government hospital. Antimicrobial susceptibility was detected by determining the Minimum Inhibitory Concentration (MIC) using Vitek-2, whereas the combined disk (CD) method was used for phenotypic detection of carbapenemase activity. The highest sensitivity rates were obtained for antibiotics colistin 87.93%, amikacin 67.52%, tigecycline 63.39%, nitrofurantoin 60.87%, and gentamycin 56.08%. The most resistant antibiotics were ceftazidime (71.93%), ciprofloxacin (67.95%) and trimethoprim/sulfamethoxazole (65.56%). Approximately 46.91% (76) of all the isolates were MBL isolates. The qPCR results confirmed the presence of blaNDM-1 in 29.01% of the isolates. The blaNDM-1 harbouring isolates in descending order, were Acinetobacter, Enterobacter cloacae, and Klebsiella pneumoniae. Klebsiella and Acinetobacter isolates were extensively drug-resistant. Whole genome sequencing performed on one of the Klebsiella pneumoniae isolates revealed the presence of many virulence factors, which increased the pathogenicity of the clinical isolates. The results showed that antimicrobial resistance, including carbapenem resistance, blaNDM-1, and virulence factors, was highly prevalent among isolates from tertiary clinical hospitals. The integration of multiple detection methodologies can potentially improve the detection of AMR and virulence in clinical isolates, leading to better patient outcomes and a reduced spread of these essential traits.

The Prevalence of Metallo-Beta-Lactamese-(MβL)-Producing Pseudomonas aeruginosa Isolates in Brazil: A Systematic Review and Meta-Analysis

The purpose of the current study is to describe the prevalence of Pseudomonas aeruginosa (PA)-producing MβL among Brazilian isolates and the frequency of blaSPM-1 in MβL-PA-producing isolates. From January 2009 to August 2023, we carried out an investigation on this subject in the internet databases SciELO, PubMed, Science Direct, and LILACS. A total of 20 papers that met the eligibility requirements were chosen by comprehensive meta-analysis software v2.2 for data retrieval and analysis by one meta-analysis using a fixed-effects model for the two investigations. The prevalence of MβL-producing P. aeruginosa was 35.8% or 0.358 (95% CI = 0.324-0.393). The studies' differences were significantly different from one another (x2 = 243.15; p < 0.001; I2 = 92.18%), so they were divided into subgroups based on Brazilian regions. There was indication of asymmetry in the meta-analyses' publishing bias funnel plot; so, a meta-regression was conducted by the study's publication year. According to the findings of Begg's test, no discernible publishing bias was found. blaSPM-1 prevalence was estimated at 66.9% or 0.669 in MβL-PA isolates (95% CI = 0.593-0.738). The analysis of this one showed an average heterogeneity (x2 = 90.93; p < 0.001; I2 = 80.20%). According to the results of Begg's test and a funnel plot, no discernible publishing bias was found. The research showed that MβL-P. aeruginosa and SPM-1 isolates were relatively common among individuals in Brazil. P. aeruginosa and other opportunistic bacteria are spreading quickly and causing severe infections, so efforts are needed to pinpoint risk factors, reservoirs, transmission pathways, and the origin of infection.

Genomic Characterization of IMP-Producing Pseudomonas aeruginosa in Bulgaria Reveals the Emergence of IMP-100, a Novel Plasmid-Mediated Variant Coexisting with a Chromosomal VIM-4

Multidrug-resistant (MDR) Pseudomonas aeruginosa infections represent a major public health concern and require comprehensive understanding of their genetic makeup. This study investigated the first occurrence of imipenemase (IMP)-carrying P. aeruginosa strains from Bulgaria. Whole genome sequencing identified a novel plasmid-mediated IMP-100 allele located in a a novel In4886 integron embedded in a putative Tn7700 transposon. Two other closely related chromosomal IMP variants, IMP-13 and IMP-84, were also detected. The IMP-producers were resistant to last-line drugs including cefiderocol (CFDC) (two out of three) and susceptible to colistin. The IMP-13/84 cassettes were situated in a In320 integron inserted in a Tn5051-like transposon as previously reported. Lastly, the p4782-IMP plasmid rendered the PA01 transformant resistant to CFDC, suggesting a transferable CFDC resistance. A variety of virulence factors associated with adhesion, antiphagocytosis, iron uptake, and quorum sensing, as well as secretion systems, toxins, and proteases, were confirmed, suggesting significant pathogenic potential consistent with the observed strong biofilm formation. The emergence of IMP-producing MDR P. aeruginosa is alarming as it remains unsusceptible even to last-generation drugs like CFDC. Newly detected IMP-100 was even located in a CFDC-resistant XDR strain.

Virtual Screening of Potential RoxS Inhibitors and Evaluation of Their Antimicrobial Activity in Combination with Antibiotics against Clinically Resistant Bacteria

Pseudomonas aeruginosa with difficult-to-treat resistance has been designated as an urgent or serious threat by the CDC in the United States; therefore, novel antibacterial drugs and combination strategies are urgently needed. The sensor kinase RoxS is necessary for the aerobic growth of Pseudomonas aeruginosa. This study aimed to screen candidate RoxS inhibitors and evaluate their efficacy in treating multi-drug-resistant and extensively drug-resistant Pseudomonas aeruginosa in combination with meropenem and amikacin to identify promising combination strategies. RoxS protein structures were constructed using homology modeling and potential RoxS inhibitors, including Ezetimibe, Deferasirox, and Posaconazole, were screened from the FDA-approved ZINC drug database using molecular docking and molecular dynamics simulations. MIC and checkerboard assays were used to determine the in vitro antimicrobial efficacy of the three drugs in combination with antibiotics. The results of in vitro experiments showed an additive effect of 100 μg/mL Deferasirox or 16 μg/mL Posaconazole in combination with meropenem and a synergistic effect of 1.5 μg/mL Deferasirox and amikacin. In summary, these three drugs are potential inhibitors of RoxS, and their combination with meropenem or amikacin is expected to reverse the resistance of P. aeruginosa, providing new combination strategies for the treatment of clinically difficult-to-treat Pseudomonas aeruginosa.

Endemic High-Risk Clone ST277 Is Related to the Spread of SPM-1-Producing Pseudomonas aeruginosa during the COVID-19 Pandemic Period in Northern Brazil

Pseudomonas aeruginosa is a high-priority bacterial agent that causes healthcare-acquired infections (HAIs), which often leads to serious infections and poor prognosis in vulnerable patients. Its increasing resistance to antimicrobials, associated with SPM production, is a case of public health concern. Therefore, this study aims to determine the antimicrobial resistance, virulence, and genotyping features of P. aeruginosa strains producing SPM-1 in the Northern region of Brazil. To determine the presence of virulence and resistance genes, the PCR technique was used. For the susceptibility profile of antimicrobials, the Kirby-Bauer disk diffusion method was performed on Mueller-Hinton agar. The MLST technique was used to define the ST of the isolates. The exoS+/exoU- virulotype was standard for all strains, with the aprA, lasA, toxA, exoS, exoT, and exoY genes as the most prevalent. All the isolates showed an MDR or XDR profile against the six classes of antimicrobials tested. HRC ST277 played a major role in spreading the SPM-1-producing P. aeruginosa strains.

Drug-resistant bacteria in the critically ill: patterns and mechanisms of resistance and potential remedies

Antimicrobial resistance in the intensive care unit is an ongoing global healthcare concern associated with high mortality and morbidity rates and high healthcare costs. Select groups of bacterial pathogens express different mechanisms of antimicrobial resistance. Clinicians face challenges in managing patients with multidrug-resistant bacteria in the form of a limited pool of available antibiotics, slow and potentially inaccurate conventional diagnostic microbial modalities, mimicry of non-infective conditions with infective syndromes, and the confounding of the clinical picture of organ dysfunction associated with sepsis with postoperative surgical complications such as hemorrhage and fluid shifts. Potential remedies for antimicrobial resistance include specific surveillance, adequate and systematic antibiotic stewardship, use of pharmacokinetic and pharmacodynamic techniques of therapy, and antimicrobial monitoring and adequate employment of infection control policies. Novel techniques of combating antimicrobial resistance include the use of aerosolized antibiotics for lung infections, the restoration of gut microflora using fecal transplantation, and orally administered probiotics. Newer antibiotics are urgently needed as part of the armamentarium against multidrug-resistant bacteria. In this review we discuss mechanisms and patterns of microbial resistance in a select group of drug-resistant bacteria, and preventive and remedial measures for combating antibiotic resistance in the critically ill.

Making a chink in their armor: Current and next-generation antimicrobial strategies against the bacterial cell envelope

Gram-negative bacteria are uniquely equipped to defeat antibiotics. Their outermost layer, the cell envelope, is a natural permeability barrier that contains an array of resistance proteins capable of neutralizing most existing antimicrobials. As a result, its presence creates a major obstacle for the treatment of resistant infections and for the development of new antibiotics. Despite this seemingly impenetrable armor, in-depth understanding of the cell envelope, including structural, functional and systems biology insights, has promoted efforts to target it that can ultimately lead to the generation of new antibacterial therapies. In this article, we broadly overview the biology of the cell envelope and highlight attempts and successes in generating inhibitors that impair its function or biogenesis. We argue that the very structure that has hampered antibiotic discovery for decades has untapped potential for the design of novel next-generation therapeutics against bacterial pathogens.

Isolation and Characterization of Pseudomonas aeruginosa Phages with a Broad Host Spectrum from Hospital Sewage Systems and Their Therapeutic Effect in a Mouse Model

This study aimed to isolate and characterize phages as an alternative treatment of multidrug- or pan-drug-resistant Pseudomonas aeruginosa. Phage titers and bacterial densities correlated, with the phages disappearing after bacteria were eliminated. We isolated phages in filtered sewage water by a double-layered agar spot test. Fifty-eight P. aeruginosa strains were used to screen the host spectrum of the 14 phages isolated. Random amplification of polymorphic DNA-typing polymerase chain reaction was used to analyze the genomic homologies of the 58 host bacteria strains and four phages with a broad host spectrum. Transmission electron microscopy was used to observe the morphology of the four phages with a broad host spectrum. Mice with intraabdominal P. aeruginosa infection were used as an in vivo animal model to investigate the therapeutic effect of the selected phage. Four virulent phages with a broad host spectrum specific to P. aeruginosa strains were isolated. They were all double-stranded DNA viruses and belonged to four different genotypes. The test curve showed that phage I had the highest adsorption rate, the shortest latent period, and the largest burst size. The infected mouse model indicated that small doses of phage I could prevent the death of infected mice. Phage titers and bacterial densities correlated, with phages disappearing after bacteria were eliminated. Phage I was the most effective and promising treatment of drug-resistant P. aeruginosa.

Mechanisms of Antibiotic and Biocide Resistance That Contribute to Pseudomonas aeruginosa Persistence in the Hospital Environment

Pseudomonas aeruginosa is an opportunistic bacterial pathogen responsible for multiple hospital- and community-acquired infections, both in human and veterinary medicine. P. aeruginosa persistence in clinical settings is worrisome and is a result of its remarkable flexibility and adaptability. This species exhibits several characteristics that allow it to thrive under different environmental conditions, including the ability to colonize inert materials such as medical equipment and hospital surfaces. P. aeruginosa presents several intrinsic mechanisms of defense that allow it to survive external aggressions, but it is also able to develop strategies and evolve into multiple phenotypes to persevere, which include antimicrobial-tolerant strains, persister cells, and biofilms. Currently, these emergent pathogenic strains are a worldwide problem and a major concern. Biocides are frequently used as a complementary/combination strategy to control the dissemination of P. aeruginosa-resistant strains; however, tolerance to commonly used biocides has also already been reported, representing an impediment to the effective elimination of this important pathogen from clinical settings. This review focuses on the characteristics of P. aeruginosa responsible for its persistence in hospital environments, including those associated with its antibiotic and biocide resistance ability.

Molecular characterizations of antibiotic resistance, biofilm formation, and virulence determinants of Pseudomonas aeruginosa isolated from burn wound infection

BACKGROUND

Burn injuries result in disruption of the skin barrier against opportunistic infections. Pseudomonas aeruginosa is one of the main infectious agents colonizing burn wounds and making severe infections. Biofilm production and other virulence factors along with antibiotic resistance limit appropriate treatment options and time.

MATERIALS AND METHODS

Wound samples were collected from hospitalized burn patients. P. aeruginosa isolates and related virulence factors identified by the standard biochemical and molecular methods. Antibiotic resistance patterns were determined by the disc diffusion method and β-lactamase genes were detected by polymerase chain reaction (PCR) assay. To determine the genetic relatedness amongst the isolates, enterobacterial repetitive intergenic consensus (ERIC)-PCR was also performed.

RESULTS

Forty P. aeruginosa isolates were identified. All of these isolates were biofilm producers. Carbapenem resistance was detected in 40% of the isolates, and bla_TEM (37/5%), bla_VIM (30%), and bla_CTX-M (20%) were the most common β-lactamase genes. The highest resistance was detected to cefotaxime, ceftazidime, meropenem, imipenem and piperacillin, and 16 (40%) isolates were resistant to these antibiotics. The minimum inhibitory concentrations (MIC) of colistin was lower than 2 μg/mL and no resistance was observed. Isolates were categorized to 17 MDR, 13 mono-drug resistance, and 10 susceptible isolates. High genetic diversity was also observed among the isolates (28 ERIC types) and most carbapenem-resistant isolates were classified into four main types.

CONCLUSION

Antibiotic resistance, particularly carbapenem resistance was considerable among the P. aeruginosa isolates colonizing burn wounds. Combining carbapenem resistance with biofilm production and virulence factors would result in severe and difficult-to-treat infections.

Evidence-Based Treatment of Pseudomonas aeruginosa Infections: A Critical Reappraisal

Multidrug-resistant (MDR)/extensively drug-resistant (XDR) Pseudomonas aeruginosa is emerging as a major threat related to adverse patient outcomes. The goal of this review is to describe evidence-based empiric and targeted treatment regimens that can be exploited when dealing with suspected or confirmed infections due to MDR/XDR P. aeruginosa. P. aeruginosa has inherent resistance to many drug classes, the capacity to form biofilms, and most importantly, the ability to quickly acquire resistance to ongoing treatments. Based on the presence of risk factors for MDR/XDR infections and local epidemiology, where large proportions of strains are resistant to classic beta-lactams, the recommended empirical treatment for suspected P. aeruginosa infections is based on ceftolozane-tazobactam or ceftazidime-avibactam. Where local epidemiology indicates low rates of MDR/XDR and there are no risk factors, a third or fourth generation cephalosporin can be used in the context of a "carbapenem-sparing" strategy. Whenever feasible, antibiotic de-escalation is recommended after antimicrobial susceptibility tests suggest that it is appropriate, and de-escalation is based on different resistance mechanisms. Cefiderocol and imipenem-cilastatin-relebactam withstand most resistance mechanisms and may remain active in cases with resistance to other new antibiotics. Confronting the growing threat of MDR/XDR P. aeruginosa, treatment choices should be wise, sparing newer antibiotics when dealing with a suspected/confirmed susceptible P. aeruginosa strain and choosing the right option for MDR/XDR P. aeruginosa based on specific types and resistance mechanisms.

The Intriguing Carbapenemases of Pseudomonas aeruginosa: Current Status, Genetic Profile, and Global Epidemiology

Worldwide, Pseudomonas aeruginosa remains a leading nosocomial pathogen that is difficult to treat and constitutes a challenging menace to healthcare systems. P. aeruginosa shows increased and alarming resistance to carbapenems, long acknowledged as last-resort antibiotics for treatment of resistant infections. Varied and recalcitrant pathways of resistance to carbapenems can simultaneously occur in P. aeruginosa, including the production of carbapenemases, broadest spectrum types of β-lactamases that hydrolyze virtually almost all β-lactams, including carbapenems. The organism can produce chromosomal, plasmid-encoded, and integron- or transposon-mediated carbapenemases from different molecular classes. These include Ambler class A (KPC and some types of GES enzymes), class B (different metallo-β-lactamases such as IMP, VIM, and NDM), and class D (oxacillinases with carbapenem-hydrolyzing capacity like OXA-198) enzymes. Additionally, derepression of chromosomal AmpC cephalosporinases in P. aeruginosa contributes to carbapenem resistance in the presence of other concomitant mechanisms such as impermeability or efflux overexpression. Epidemiologic and molecular evidence of carbapenemases in P. aeruginosa has been long accumulating, and reports of their existence in different geographical areas of the world currently exist. Such reports are continuously being updated and reveal emerging varieties of carbapenemases and/or new genetic environments. This review summarizes carbapenemases of importance in P. aeruginosa, highlights their genetic profile, and presents current knowledge about their global epidemiology.

A case report: Intermittent catheterization combined with rehabilitation in the treatment of carbapenem-resistant Klebsiella pneumoniae catheter-associated urinary tract infection

Catheter-related urinary tract infections, especially those caused by multidrug-resistant (MDR) bacteria, are extremely difficult to treat due to limited therapeutic choices. Therefore, removing catheters as soon as possible is pivotal to successful treatment. Herein, we report a case of catheter-related urinary tract infection caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). Intermittent catheterization was used to reduce biofilm occurrence and exercise bladder function on the basis of an active and adequate anti-infection strategy. Simultaneously, combined with acupuncture treatment and strengthening the patient’s pelvic floor muscle training to improve urinary retention, the catheter was eventually removed to obtain autonomous urination in this patient, and this led to the successful treatment for a CRKP catheter-related urinary tract infection.

Phenotypic and genotypic investigation of metallo-β-lactamases in Pseudomonas aeruginosa clinical isolates in Bushehr, Iran

Objectives

Production of metallo-β-lactamases (MBLs) is an important mechanism of resistance to carbapenems. This study aimed to detect the MBL-producing Pseudomonas aeruginosa clinical isolates and to investigate the presence of bla _VIM, bla _IMP, bla _SPM, bla _NDM, bla _GIM, bla _AIM, and bla _SIM genes in these isolates in Bushehr, Iran.

Materials and Methods

A total of 169 P. aeruginosa clinical isolates were collected from three hospitals in Bushehr. The modified carbapenem inactivation method (mCIM) was used for the phenotypic detection of carbapenemase production. A combination disk test (CDT) was performed for the phenotypic detection of MBL production. To investigate the presence of bla _VIM, bla _IMP, bla _SPM, bla _NDM, bla _GIM, bla _AIM, and bla _SIM genes, PCR and sequencing was carried out.

Results

Based on the results of mCIM, 40 (23.7%) of 169 isolates were carbapenemase producers. CDT revealed that 26 (15.4%) isolates were MBL producers. bla _IMP, bla _NDM, and bla _VIM genes were found in 18 (69.2%), 8 (30.8%), and 1 (3.8%) of the MBL-producing isolates, respectively. Coexistence of bla _IMP and bla _NDM was observed in 2 (7.7%) MBL-producing isolates. Among all 169 P. aeruginosa isolates, 23 (13.6%) harbored bla _NDM, 18 (10.6%) carried bla _IMP, and 1 (0.6%) carried the bla _VIM gene. bla _SPM, bla _GIM, bla _AIM, and bla _SIM were not found in the present study.

Conclusion

bla _NDM, bla _IMP, and bla _VIM genes were detected in this study, which could be a warning sign about the prevalence of these genes among P. aeruginosa clinical isolates in our region. Proper monitoring and detection of MBL-producing isolates are essential steps to prevent the spread of these isolates.

Molecular characterization and antibiogram of the carbapenemase gene variants in clinical strains of Pseudomonas aeruginosa

BACKGROUND

Carbapenemase-producing Pseudomonas aeruginosa (CPPA) is a substantial clinical concern because it jeopardizes therapeutic choices. This study characterizes the gene variants of CPPA and report its antibiogram.

METHODS

CPPA was isolated prospectively from diverse clinical sources in a tertiary care setting using a routine microbiological approach. Carbapenem-resistant P. aeruginosa strains were phenotypically identified using the modified carbapenem inactivation (mCIM) method. Minimum inhibitory concentration (MIC) breakpoints of several antibacterial drug groups were determined using broth microdilution methods and the MicroScan WalkAway plus system. Carbapenemase gene variants bla_NDM, bla_VIM, bla_OXA,bla_GES, and bla_IMP were amplified using polymerase chain reaction (PCR), and the purified gene products were sequenced.

RESULTS

Seventy-one P. aeruginosa-infected cases were found, with 47 (66.2%) carrying CPPA; 46.8% of the latter were significantly associated with intensive care units (p = 0.03). CPPA was frequently detected in wound swabs (13; 27.7%), sputum (11; 23.4%), and blood (9; 19.1%). All strains were multidrug-resistant (MDR), and several were extensively drug-resistant. MIC₅₀ and MIC₉₀ breakpoints of all antibiotics, except colistin, were within the resistance range. MIC₉₀ breakpoints of aztreonam, amikacin, cefepime, and piperacillin-tazobactam were > 512 µg/mL. The multiple antibiotic resistance index (MARI) was remarkably high, with a range of 0.38-0.92. The most commonly detected carbapenemase genes were bla_VIM (74%), bla_NDM-1 (19%), bla_OXA-23 (14.9%), and bla_GES (10.6%), while 12 of 47 strains co-harbored different combinations of carbapenemase gene variants.

CONCLUSION

A large proportion of CPPA strains carried the bla_VIM gene variant, indicating intimidating health problems and emphasizing the need for extensive surveillance and antibiotic stewardship.

A Plasmid Carrying blaIMP-56 in Pseudomonas aeruginosa Belonging to a Novel Resistance Plasmid Family

bla_IMP and bla_VIM are the most detected plasmid-encoded carbapenemase genes in Pseudomonas aeruginosa. Previous studies have reported plasmid sequences carrying bla_IMP variants, except bla_IMP-56. In this study, we aimed to characterize a plasmid carrying bla_IMP-56 in a P. aeruginosa strain isolated from a Mexican hospital. The whole genome of P. aeruginosa strain PE52 was sequenced using Illumina Miseq 2 × 150 bp, with 5 million paired-end reads. We characterized a 27 kb plasmid (pPE52IMP) that carried bla_IMP-56. The phylogenetic analysis of RepA in pPE52IMP and 33 P. aeruginosa plasmids carrying resistance genes reported in the GenBank revealed that pPE52IMP and four plasmids (pMATVIM-7, unnamed (FDAARGOS_570), pD5170990, and pMRVIM0713) were in the same clade. These closely related plasmids belonged to the MOB_P11 subfamily and had similar backbones. Another plasmid (p4130-KPC) had a similar backbone to pPE52IMP; however, its RepA was truncated. In these plasmids, the resistance genes bla_KPC-2, bla_VIM variants, aac(6′)-Ib4, bla_OXA variants, and bla_IMP-56 were inserted between phd and resolvase genes. This study describes a new family of plasmids carrying resistance genes, with a similar backbone, the same RepA, and belonging to the MOB_P11 subfamily in P. aeruginosa. In addition, our characterized plasmid harboring bla_IMP-56 (pPE52IMP) belongs to this family.

Carbapenem Combinations for Infections Caused by Carbapenemase-Producing Pseudomonas aeruginosa: Experimental In Vitro and In Vivo Analysis

In the context of difficult-to-treat carbapenem-resistant Pseudomonas aeruginosa infections, we evaluated imipenem, meropenem, and doripenem combinations against eleven carbapenemase-producing P. aeruginosa isolates. According to the widespread global distribution of high-risk clones and carbapenemases, four representative isolates were selected: ST175 (OXA-2/VIM-20), ST175 (VIM-2), ST235 (GES-5), and ST111 (IMP-33), for efficacy studies using a sepsis murine model. Minimum inhibitory concentration (mg/L) ranges were 64–256 for imipenem and 16–128 for meropenem and doripenem. In vitro, imipenem plus meropenem was synergistic against 72% of isolates and doripenem plus meropenem or imipenem against 55% and 45%, respectively. All combinations were synergistic against the ST175, ST235, and ST155 clones. In vivo, meropenem diminished the spleen and blood bacterial concentrations of four and three isolates, respectively, with better efficacy than imipenem or doripenem. The combinations did not show efficacy compared with the more active monotherapies, except for imipenem plus meropenem, which reduced the ST235 bacterial spleen concentration. Mortality decreased with imipenem plus meropenem or doripenem for the ST175 isolate. Results suggest that carbapenem combinations are not an alternative for severe infections by carbapenemase-producing P. aeruginosa. Meropenem monotherapy showed in vivo efficacy despite its high MIC, probably because its dosage allowed a sufficient antimicrobial exposure at the infection sites.

The biogenesis of β-lactamase enzymes

The discovery of penicillin by Alexander Fleming marked a new era for modern medicine, allowing not only the treatment of infectious diseases, but also the safe performance of life-saving interventions, like surgery and chemotherapy. Unfortunately, resistance against penicillin, as well as more complex β-lactam antibiotics, has rapidly emerged since the introduction of these drugs in the clinic, and is largely driven by a single type of extra-cytoplasmic proteins, hydrolytic enzymes called β-lactamases. While the structures, biochemistry and epidemiology of these resistance determinants have been extensively characterized, their biogenesis, a complex process including multiple steps and involving several fundamental biochemical pathways, is rarely discussed. In this review, we provide a comprehensive overview of the journey of β-lactamases, from the moment they exit the ribosomal channel until they reach their final cellular destination as folded and active enzymes.

Association of multidrug resistance behavior of clinical Pseudomonas aeruginosa to pigment coloration

Pseudomonas aeruginosa is an adaptable bacterial pathogen that infects a variety of organs, including the respiratory tract, vascular system, urinary tract, and central nervous system, causing significant morbidity and mortality. As the primary goal of this study, we wanted to determine how pigment color production differed between clinical strains of P. aeruginosa, and whether or not that variation was associated with multidrug resistance or the ability to form biofilms. We screened in total 30.1% of yellow, 39.8% green and 30.1% of no pigment-producing P. aeruginosa strains from a total of 143 various clinical isolates. Yellow pigment-producing strains presented significant resistance to antibiotics groups, including β-lactam (91.5%), aminoglycosides (70.5%), and carbapenems (51.9%) compared to green and non-pigmented strains. Notably, 16.3% of yellow pigment-producing strains were resistant to colistin which is used as a last-resort treatment for multidrug-resistant bacteria, whereas only 2.3% of non-pigmented and 1.8% of green pigmented strains were resistant to colistin. Aside from that, yellow pigment-producing strains were frequent producers of enzymes belonging to the lactamase family, including ESBL (55.6%), MBL (55.6%), and AmpC (50%). Compared to the green groups (7.14%) and non-pigmented groups (28.5%), they had a higher frequency of efflux positive groups (64.2%). Notably, when compared to non-pigmented groups, green pigment-producing strains also displayed antibiotic susceptibility behavior similar to yellow pigment-producing strains. The majority of yellow pigment-producing strains outperformed the green and non-pigmented strains in terms of MIC levels when compared to the other two groups of strains. Despite the fact that previous studies have demonstrated a direct correlation between multidrug resistance behaviors and biofilm production, no such statistically significant association between pigment and biofilm formation was found in our investigation. Our research has demonstrated that the correlation of bacterial pigments on their susceptibility to antimicrobial agents. Yellow pigment-producing P. aeruginosa strains posed a significant problem due to the lack of alternative agents against such transformed strains, which may be associated with the development of multidrug resistance.

Genotyping of Extended Spectrum Beta-Lactamase-Producing Pseudomonas aeruginosa Isolated from People with Nosocomial Infections

Background: Pseudomonas aeruginosa nosocomial infections are among major problems associated with increased mortality and mobility among patients. Objectives: The aim of this research was to determine the molecular epidemiology of extended spectrum beta-lactamase (ESBL)-producing P. aeruginosa genotypes isolated from patients with nosocomial infections. Methods: One hundred forty-six clinical isolates of Pseudomonas spp. were obtained from a tertiary referral hospital. Phenotypic identification and PCR detection of gyrB were used to characterize P. aeruginosa. Extended spectrum beta-lactamases in samples were identified using the disk approximation test and the combination disk test (CDT). The blaSHV and blaTEM genes were detected by PCR. The strains were typed by the pulse field gel electrophoresis (PFGE), repetitive element sequence (Rep)-PCR, and enterobacterial repetitive intergenic consensus (ERIC)–PCR methods. Results: A total of 134 (91.78%) P. aeruginosa isolates were separated, 41.79% of whom were related to nosocomial infections. The extended spectrum beta-lactamase analysis test revealed that 5.97% and 66.41% of the isolates harbored the blaSHV and blaTEM genes, respectively. Enterobacterial repetitive intergenic consensus PCR, Rep-PCR, and PFGE each showed 56, 55, and 55 different patterns, respectively. Pulse-field gel electrophoresis indicated that pulso types C3 were dominant. Conclusions: The associations between ESBL production, blaSHV and blaTEM positivity, and ERIC, Rep-PCR, and PFGE patterns were not significant (P ≥ 0.05). Among nosocomial infections, a relatively high prevalence of ESBL-producing P. aeruginosa isolates was observed in the Kurdistan province of Iran. Periodic review of antibiotic resistance and molecular characterization of P. aeruginosa isolates is recommended to prevent the spread of nosocomial infections in hospitals.

Prevalence and Molecular Characterization of Metallo β-Lactamase Producing Gram-Negative Pathogens Causing Eye Infections

Purpose:

Metallo β-lactamases (MβL) production is a worldwide problem, particularly in gram-negative bacteria. As scanty data is available on the prevalence of MBL, the present study is being undertaken to determine the prevalence, antibacterial sensitivity patterns, and molecular characterization of MβL associated resistant genes in gram-negative bacteria isolated from ocular infections.

Material and Methods

At a tertiary eye care center in south India, 359 gram-negative pathogens, 200 isolates from eye infections, and 159 isolates from normal flora of the eye were studied. A gold standard microbiology method was used to identify the isolates. An antibiotic double disc synergy test and a combination disc test were used to detect MβL production. Multiplex PCR was used to investigate the molecular characteristics of the MβL encoding genes blaVIM, blaIMP, and blaNDM.

Results

Of the 359 gram-negative bacterial pathogens, Pseudomonas aeruginosa 108 (30.1%) and Enterobacter agglomerans 46 (12.8%) were commonly isolated. High prevalence of P. aeruginosa 81% (17 strains) was detected as an MβL producer and it shows 100% resistance to 2nd and 3rd generation cephalosporins and meropenem. Multiplex PCR detected only the blaVIM gene in 56 (28%) of various eye infections and 27 (17%) of normal flora of the gram-negative bacteria (GNB). The blaVIM gene is detected predominantly in 51.8% of keratitis and 21.4% of postoperative endophthalmitis. High prevalence of the gene was detected in P. aeruginosa 42.9% (24 of 56) and Alcaligens denitrificans 10.7% (6 of 56) from eye infections. Whereas, in the control group, P. aeruginosa and E. coli each had 14.8% (4 of 27) that were shown positive.

Conclusion

The emerging MβLs mediated resistance among P. aeruginosa is a challenging task for ophthalmologists, especially in patients with endophthalmitis and bacterial keratitis. This local knowledge will aid in advising appropriate antibiotic use and avoiding unnecessary antibiotic prescriptions, which are highly warranted.

The first report of the blaIMP-10 gene and complete sequence of the IMP-10-encoding plasmid p12NE515 from Pseudomonas aeruginosa in China

OBJECTIVE

To investigate a detailed genomic characterization of the bla_IMP-10-carrying plasmid p12NE515 from a Pseudomonas aeruginosa isolate in China.

METHODS

Plasmid p12NE515 was subjected to whole-genome sequencing and the complete sequence was compared with related plasmid sequences. Transferability of plasmid, carbapenemase activity and bacterial susceptibility profiles were determined to assess p12NE515-mediated resistance phenotypes.

RESULTS

P. aeruginosa 12NE515 was identified as a less common sequence type of ST1976. p12NE515 harboring bla_IMP-10 possessed a backbone identical to plasmid p60512-IMP (carrying bla_IMP-1), but the accessory resistance regions differed. Only one accessory module, Tn7339, was carried in p12NE515, and this transposon was an insertion sequence-mediated transposition unit generated by the insertion of a novel class 1 integron, In1814, at the downstream end of ISPa17. Here, bla_IMP-10 together with aacA7 was located in In1814, being at evolution stage III of Tn402-associated integron due to truncation of the tni module.

CONCLUSION

This study is the first to determine the complete sequence of a bla_IMP-10-carrying plasmid, and this is also the first report of a bla_IMP-10-producing strain in China. The prevalence of the bla_IMP-10 gene and the genetic characterization of the bla_IMP-10-carrying plasmid should be analyzed to provide deeper insight into the transmission mechanism of antimicrobial resistance genes.

Emergence of Carbapenem-Resistant ST244, ST292, and ST2446 Pseudomonas aeruginosa Clones in Burn Patients in Yunnan Province

INTRODUCTION

The prevalence of carbapenem-resistant Pseudomonas aeruginosa is increasing persistently, particularly in burn ward isolates. Here, we investigate the prevalence of carbapenem-resistant Pseudomonas aeruginosa in a burn ward of a provincial-level hospital at Kunming, Yunnan province, China.

METHODS

A total of 118 P. aeruginosa strains were isolated from 57 hospitalized patients, and their MICs were measured. Carbapenem-resistant isolates were selected for multilocus sequence typing (MLST). Carbapenem-resistance mechanisms were identified by examining carbapenemase genes and OprD protein and Carba-NP testing. Representative isolates were further characterized by de novo sequencing for carbapenemase molecular background.

RESULTS

Among 118 P. aeruginosa isolates, 54 (54/118,45.8%) were carbapenem-resistant Pseudomonas aeruginosa, and 3 genotypes were found (ST292, ST244, and ST2446). Non-carbapenemase-producing ST292 was the most prevalent ST, followed by ST2446 and ST244. A novel 13-bp oprD deletion was found in the ST292 clone, which formed the truncated outer membrane protein and may cause carbapenem resistance. ST244 and ST2446 harbored blaIMP-45 and blaIMP-87, respectively. blaIMP-45 is located in a megaplasmid, together with aac(6')-Ib3, blaOXA-1, catB3, qnrVC6, armA, msr(E), mph(E), aph(3')-Ia, tetC/tetR, aac(6')-Ib3, floR, mexC-mexD-oprJ, fosA and lead to extensive drug resistance. ST2446 contains a carbapenem-resistant gene blaIMP-87 on the chromosome and is acquired by a novel gene cassette array (blaIMP-87-ant(2")-Ia-blaOXA-10-aac(6')-Ib3) of class 1 integron.

DISCUSSION

For the first time, ST244, ST292 and ST2446 are reported emerging in burn patients, with distinctive carbapenem-resistance mechanisms, respectively. The obtained results highlight the need to surveillance carbapenem-resistant isolates in burn patients.

Therapeutic Strategies for Emerging Multidrug-Resistant Pseudomonas aeruginosa

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa isolates are frequent causes of serious nosocomial infections that may compromise the selection of antimicrobial therapy. The goal of this review is to summarize recent epidemiologic, microbiologic, and clinical data pertinent to the therapeutic management of patients with infections caused by MDR/XDR-P. aeruginosa. Historically, conventional antipseudomonal β-lactam antibiotics have been used for the empiric treatment of MDR/XDR-P. aeruginosa. Owing to the remarkable capacity of P. aeruginosa to confer resistance via multiple mechanisms, these traditional therapies are often rendered ineffective. To increase the likelihood of administering empiric antipseudomonal therapy with in vitro activity, a second agent from a different antibiotic class is often administered concomitantly with a traditional antipseudomonal β-lactam. However, combination therapy may pose an increased risk of antibiotic toxicity and secondary infection, notably, Clostridioides difficile. Multiple novel agents that demonstrate in vitro activity against MDR-P. aeruginosa (e.g., β-lactam/β-lactamase inhibitor combinations and cefiderocol) have been recently granted US Food and Drug Administration (FDA) approval and are promising additions to the antipseudomonal armamentarium. Even so, comparative clinical data pertaining to these novel agents is sparse, and concerns surrounding the scarcity of antibiotics active against refractory MDR/XDR-P. aeruginosa necessitates continued assessment of alternative therapies. This is particularly important in patients with cystic fibrosis (CF) who may be chronically colonized and suffer from recurrent infections and disease exacerbations due in part to limited efficacious antipseudomonal agents. Bacteriophages represent a promising candidate for combatting recurrent and refractory infections with their ability to target specific host bacteria and circumvent traditional mechanisms of antibiotic resistance seen in MDR/XDR-P. aeruginosa. Future goals for the management of these infections include increased comparator clinical data of novel agents to determine in what scenario certain agents may be preferred over others. Until then, appropriate treatment of these infections requires a thorough evaluation of patient- and infection-specific factors to guide empiric and definitive therapeutic decisions.

Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy

Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).

Escherichia coli ST471 Producing VIM-4 Metallo-β-Lactamase in Colombia

An Escherichia coli isolate sequence-type 471 (ST471) producing Verona integron-encoded metallo-β-lactamases (VIM)-4 was recovered from a rectal swab in a patient without travel records with osteomyelitis in Colombia. The isolate carried a class 1 integron-borne bla_VIM-4 gene with a 170-bp duplication in the 3′ end of the gene, preceded by an aac(6′)-Ib gene. The genetic environment of bla_VIM-4, bla_CMY-2, and sul2 genes showed similarities to the backbone of pKKp4, an IncA/C-type plasmid from a Klebsiella pneumoniae strain carrying bla_VIM-4 recovered in Kuwait. This is the first report of bla_VIM-4 in Enterobacterales in South America. Our results suggest that bla_VIM-4 gene was found on an IncA/C-type plasmid that could play a role in the spread of VIM-4 carbapenemase in Colombia.

Epidemiology, Molecular Characteristics, and Virulence Factors of Carbapenem-Resistant Pseudomonas aeruginosa Isolated from Patients with Urinary Tract Infections

Purpose

Pseudomonas aeruginosa is an important pathogen that causes urinary tract infections. Carbapenems are the drugs of choice for the treatment of P. aeruginosa infections. However, the emergence and spread of carbapenem-resistant P. aeruginosa (CRPA) is a serious global health threat. In this study, we investigated the epidemiology, molecular characteristics, drug resistance, and virulence factors of CRPA isolated from urine samples.

Methods

A total of 124 P. aeruginosa isolates were obtained from urine samples collected between March 2020 and February 2021. Clonal relatedness was evaluated using multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). We performed antimicrobial susceptibility tests and investigated the presence of carbapenemase genes and virulence factors in CRPA isolates.

Results

The carbapenem resistance rate of the isolated P. aeruginosa was 46.7% (59/124). A total of 54 (91.5%) out of the 59 CRPA isolates were identified as multidrug-resistant. The majority of the CRPA isolates (81.4%, 48/59) harbored carbapenemase genes, such as bla_IMP-6 or bla_NDM-1. In an epidemiological analysis using MLST, 88.1% of CRPA isolates were confirmed to be ST773 (50.8%, 30/59) or ST235 (37.3%, 22/59). The CRPA isolates harboring bla_IMP-6 and bla_NDM-1 belonged to ST235 (PFGE pulsotypes E1-E18, F) and ST773 (PFGE pulsotypes H1-H2, I1-I16) subtypes, respectively. The studied CRPA isolates simultaneously harbored 10 to 14 virulence factors of the 16 virulence factors examined. Nine virulence factor genes (toxA, exoT, plcH, plcN, phzM, phzS, lasB, aprA, and algD) were identified in all CRPA isolates.

Conclusion

Our study shows that P. aeruginosa ST235 harboring bla_IMP-6 and ST773 harboring bla_NDM-1—known internationally as high-risk clones with multiple virulence factors—are widely spread in the study area. These findings suggest that continuous monitoring is necessary to prevent the further spread of carbapenemase-producing CRPA.