Coexistence of metallo-beta-lactamase-encoding genes in Pseudomonas aeruginosa

Prioritization of Critical Factors for Surveillance of the Dissemination of Antibiotic Resistance in Pseudomonas aeruginosa: A Systematic Review

Pseudomonas aeruginosa is the primary opportunistic human pathogen responsible for a range of acute and chronic infections; it poses a significant threat to immunocompromised patients and is the leading cause of morbidity and mortality for nosocomial infections. Its high resistance to a diverse array of antimicrobial agents presents an urgent health concern. Among the mechanisms contributing to resistance in P. aeruginosa, the horizontal acquisition of antibiotic resistance genes (ARGs) via mobile genetic elements (MGEs) has gained recognition as a substantial concern in clinical settings, thus indicating that a comprehensive understanding of ARG dissemination within the species is strongly required for surveillance. Here, two approaches, including a systematic literature analysis and a genome database survey, were employed to gain insights into ARG dissemination. The genome database enabled scrutinizing of all the available sequence information and various attributes of P. aeruginosa isolates, thus providing an extensive understanding of ARG dissemination within the species. By integrating both approaches, with a primary focus on the genome database survey, mobile ARGs that were linked or correlated with MGEs, important sequence types (STs) carrying diverse ARGs, and MGEs responsible for ARG dissemination were identified as critical factors requiring strict surveillance. Although human isolates play a primary role in dissemination, the importance of animal and environmental isolates has also been suggested. In this study, 25 critical mobile ARGs, 45 critical STs, and associated MGEs involved in ARG dissemination within the species, are suggested as critical factors. Surveillance and management of these prioritized factors across the One Health sectors are essential to mitigate the emergence of multidrug-resistant (MDR) and extensively resistant (XDR) P. aeruginosa in clinical settings.

"Relationship between antibiotic resistance, biofilm formation, virulence factors and source of origin of Pseudomonas aeruginosa environmental isolates with regard to the presence of metallo-β-lactamase-encoding genes"

A total of 557 water samples were evaluated and of these, 23 were positive for the presence of Pseudomonas aeruginosa. Approximately 91.7% of them were weak biofilm formers. Only 4 isolates showed antimicrobial resistance. All isolates presented Twitching motility, a positive result for the production of pyocyanin, alkaline protease, and hemolysins. The genotypic tests showed: lasA, (95.6%) lasB (95.6%), exoS (95.6%), exoT (91.3%), toxA (91.3%), akgO (91.3%), plcN (91.3%) aprA (86.9%), phzM (78.3%), and pvdA (60.9%). For genes encoding metallo-beta-lactamase, it was found: blaVIM (56.6%), blaSPM (4.3%), and blaSIM (47.8%). A strong association was found between the metallo-beta-lactamase producing genes, nine genes of virulence factors and the motility (r = 0.6231). The very close clonal profile suggests a probable similarity between the isolates from different cities. Thus, P. aeruginosa can be present in water supplies with variable virulence capacities and can generate a huge concern for human, animal, and environmental health.

Endemicity of Pseudomonas aeruginosa producing IMP-18 and/or VIM-2 MBLs from the high-risk clone ST111 in Central America

Background

Pseudomonas aeruginosa is an important cause of serious nosocomial infections. Despite the overall genetic diversity of this species, highly conserved clonal complexes (CCs) have been observed among MDR isolates. Many of these CCs are associated with MBL-producing isolates.

Objectives

To evaluate five P. aeruginosa isolates from Central America that carried IMP-18- and/or VIM-2-encoding genes from the SENTRY Antimicrobial Surveillance Program (2017-2018).

Methods

Susceptibility testing was performed by broth microdilution (CLSI). WGS was performed using MiSeq (Illumina) and MinION (Oxford Nanopore). Assembled contigs from short and long reads were combined for in silico screening of resistance genes, MLST, core genome (cg)MLST and SNP analysis.

Results

The P. aeruginosa isolates were collected in Panama and Mexico from patients with urinary tract infections or pneumonia. Isolates were categorized as XDR (CLSI/EUCAST). All isolates belonged to ST111 but carried different combinations of resistance-encoding genes. Transposon-associated MBL genes, blaIMP-18 and/or blaVIM-2, were chromosomally located. blaIMP-18 was detected in an In1666 integron whereas blaVIM-2 was embedded in an In59-like integron. Isolates were closely related based on cgMLST (average allele distance 2-34) and SNP analysis (5-423 different SNPs).

Conclusions

MBL-producing ST111 P. aeruginosa have become endemic in Panama and may have spread to Mexico via clonal dissemination. Recombination events are apparent in the evolution of this CC. Surveillance is warranted to track the expansion and movement of this clone.

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.

Genetic diversity and molecular analysis of metallo beta lactamases among imipenem resistant clinical isolates of Pseudomonas aeruginosa from Peshawar, Pakistan

Objectives

Pseudomonas aeruginosa is an opportunistic pathogen with remarkable adaptation ability to thrive in diverse environmental conditions. This study aimed at phenotypic and molecular analysis of metallo beta lactamases (blaIMP, blaVIM, blaNDM-1 and blaSPM-1) and genetic diversity analysis among imipenem resistant clinical isolates of Pseudomonas aeruginosa.

Methods

This study was conducted from May 2017 to June 2018. The study included 187 Pseudomonas aeruginosa isolates collected from different clinical specimens from Peshawar, Pakistan. The isolates were analyzed for resistance to imipenem. Combined disc test (CDT) was then performed for phenotypic detection of metallo beta lactamases among imipenem resistant isolates of Pseudomonas aeruginosa. Molecular detection of metallo beta lactamases genes i.e. blaIMP, blaVIM, blaNDM-1 and blaSPM-1 was analyzed through polymerase chain reaction. Genetic diversity was determined through RAPD-PCR.

Results

MBL production was observed in 76% (n=19) isolates. The occurrence of MBL genes blaIMP, blaNDM-1 and blaVIM was 68% (n=17), 48% (n=12), and 4% (n=1) respectively. The blaSPM-1 gene was not detected. High genetic diversity was observed in current study. Out of 182 isolates 171 isolates showed different RAPD profiles (93.95% polymorphism); 160 were unique RAPD strains and based on similarity coefficient ≥ 80%, 22 isolates were clustered into 11 distinct clones.

Conclusion

A high prevalence of blaIMP and blaNDM-1 among imipenem resistant isolates of Pseudomonas aeruginosa is alarming that calls for proper control and prevention strategies. RAPD technique was found to be a good genotyping technique when limited resources are available.

Incidence and Molecular Characterization of Carbapenemase Genes in Association with Multidrug-Resistant Clinical Isolates of Pseudomonas aeruginosa from Tertiary Healthcare Facilities in Southwest Nigeria

Pseudomonas aeruginosa, resistant to multiple antibacterial agents including carbapenems, is of great global public health concern. There is limited data available regarding incidence of Metallo-Beta Lactamase producing P. aeruginosa, their molecular basis of resistance in particular carbapenem resistance and any genetic relatedness among circulating clinical isolates in Southwest Nigeria. Four hundred and thirty P. aeruginosa isolates were collected from seven tertiary care hospitals (predominantly from wound, ear, and urinary tract infections) and verified by PCR targeting oprI and oprL. Antibiotic susceptibility using 16 selected antibiotics and MBL screening was performed. The integrons (class 1, 2 and 3) and carbapenemase genes- bla_GES, bla_NMC-A, bla_BIC-1, bla_SME, bla_IMP, bla_VIM, bla_SPM, bla_NDM, bla_AIM, bla_DIM, bla_SIM, bla_GIM, bla_OXA-48, bla_OXA-58 were detected by PCR and were sequenced. Quantitative real-time polymerase chain reaction was used to quantify expression levels of eight efflux pump genes, ampC cephalosporinase and outer membrane porin, oprD. The isolates were genotyped using Enterobacterial Repetitive Intergenic Consensus sequence Polymerase Chain Reaction (ERIC-PCR). Four hundred and thirty P. aeruginosa isolates were subjected to antibiotic susceptibility testing, revealing that 109 (25.4%) isolates were multidrug-resistant, 47 (10.9%) were extensively drug-resistant and 25 (5.8%) were pandrug-resistant. MBL was seen in 17.0% (73/430) isolates. MBL-encoding genes; bla_VIM-5 and bla_NDM-1 were detected in 86.3% (63/73) isolates, with bla_VIM-5 and bla_NDM-1 in 35.6% (26/73) and 38.4% (28/73), respectively, whereas co-occurrence of bla_VIM-5 and bla_NDM-1 was found in 12.3% (9/73). Forty-one (56.2%) carbapenem-resistant P. aeruginosa strains carried class 1 integrons, while co-occurrence of class 1 and 2 integrons was seen in 12.3%. qPCR results indicated that MexXY-OprM was highly expressed pump in 58.9%, ampC upregulated in 26.0%, while oprD porin was downregulated in 65.8% isolates. ERIC-PCR results suggest that carbapenem-resistant strains exhibit genetic heterogeneity. The high incidence of MBL-encoding genes and integrons in diversified clinical P. aeruginosa from southwestern Nigeria is of great concern. The co-occurrence of bla_VIM-5 and bla_NDM-1 as well as resistance in general manifesting a gradient based on genotypic variation suggests that there is a strong need for efficient surveillance programs and antibiotic stewardship.

Molecular characterization of NDM-1-producing Pseudomonas aeruginosa isolates from hospitalized patients in Iran

Background

The emergence of carbapenem-resistant Pseudomonas aeruginosa is one of the most important challenges in a healthcare setting. The aim of this study is double-locus sequence typing (DLST) typing of bla_NDM-1 positive P. aeruginosa isolates.

Methods

Twenty-nine bla_NDM-1 positive isolates were collected during three years of study from different cities in Iran. Modified hodge test (MHT), double-disk synergy test (DDST) and double-disk potentiation test (DDPT) was performed for detection of carbapenemase and metallo-beta-lactamase (MBL) producing bla_NDM-1 positive P. aeruginosa isolates. The antibiotic resistance genes were considered by PCR method. Clonal relationship of bla_NDM-1 positive was also characterized using DLST method.

Results

Antibiotic susceptibility pattern showed that all isolates were resistant to imipenem and ertapenem. DDST and DDPT revealed that 15/29 (51.8%) and 26 (89.7%) of bla_NDM-1 positive isolates were MBL producing isolates, respectively. The presence of bla_OXA-10,bla_VIM-2, bla_IMP-1 and bla_SPM genes were detected in 86.2%, 41.4%, 34.5% and 3.5% isolates, respectively. DLST typing results revealed the main cluster were DLST 25-11 with 13 infected or colonized patients.

Conclusions

The presence of bla_NDM-1 gene with other MBLs encoding genes in P. aeruginosa is a potential challenge in the treatment of microorganism infections. DLST showed partial diversity among 29 bla_NDM-1 positive isolates.

Genetic Basis of Antimicrobial Resistant Gram-Negative Bacteria Isolated From Bloodstream in Brazil

Multidrug-resistant microorganisms are a well-known global problem, and gram-negative bacilli are top-ranking. When these pathogens are associated with bloodstream infections (BSI), outcomes become even worse. Here we applied whole-genome sequencing to access information about clonal distribution, resistance mechanism diversity and other molecular aspects of gram-negative bacilli (GNB) isolated from bloodstream infections in Brazil. It was possible to highlight international high-risk clones circulating in the Brazilian territory, such as CC258 for Klebsiella pneumoniae, ST79 for Acinetobacter baumannii and ST233 for Pseudomonas aeruginosa. Important associations can be made such as a negative correlation between CRISPR-Cas and K. pneumoniae CC258, while the genes bla_TEM, bla_KPC and bla_CTX−M are highly associated with this clone. Specific relationships between A. baumannii clones and bla_OXA−51 variants were also observed. All P. aeruginosa ST233 isolates showed the genes bla_VIM and bla_OXA486. In addition, some trends could be identified, where a new P. aeruginosa MDR clone (ST3079), a novel A. baumannii clonal profile circulating in Brazil (ST848), and important resistance associations in the form of bla_VIM−2 and bla_IMP−56 being found together in one ST233 strain, stand out. Such findings may help to develop approaches to deal with BSI and even other nosocomial infections caused by these important GNB.

Prevalence of metallo-β-lactamase genes among Pseudomonas aeruginosa isolated from various clinical samples in China

Background

Pseudomonas aeruginosa is an opportunistic pathogen which is associated with nosocomial infections and causes various diseases including urinary tract infection, pneumonia, soft-tissue infection and sepsis. The emergence of P. aeruginosa-acquired metallo-β-lactamase (MBL) is most worrisome and poses a serious threat during treatment and infection control. The objective of this study was to identify antibiotic susceptibility, phenotypic detection of MBL production and to determine the prevalence of MBL genes in carbapenem-resistant P. aeruginosa isolated from different clinical samples.

Methods

A total of 329 non-duplicate P. aeruginosa isolated from various clinical samples from two hospitals in China between September 2017 and March 2019 were included in this study. Phenotypic detection of MBL was performed by the combined detection method using imipenem and imipenem-ethylenediaminetetraacetic acid (EDTA) discs. MBL-encoding genes including bla VIM-1 , bla VIM-2 , bla IMP-1 , bla IMP-2 , bla SPM-1 , bla SIM , bla NDM-1 and bla GIM were detected by polymerase chain reaction (PCR).

Results

Of the 329 P. aeruginosa, majority of the isolates were resistant to imipenem (77.5%) followed by meropenem (64.7%). Of the 270 P. aeruginosa isolates tested, 149 (55.2%) isolates were found to be positive for MBL detection. Of the different samples, 57.8% (n = 26) of P. aeruginosa isolated from blood were found to be positive for MBL production. Of the various MBL genes, bla IMP-1 (28.2%) was the most predominant gene detected followed by bla VIM-2 (18.8%), bla VIM-1 (16.1%), bla NDM-1 (9.4%), bla IMP-2 (6.7%), bla SIM (6.0%), bla SPM-1 (4.0%) and bla GIM (1.3%) genes.

Conclusions

The high resistance of P. aeruginosa toward imipenem and meropenem and the high prevalence of bla IMP-1 and bla VIM-2 set the alarm on the increasing, perhaps the increased, carbapenem resistance. In addition to routine antibiotic susceptibility testings, our results emphasize the importance of both the phenotypic and genotypic MBL detection methods in routine practice for early detection of carbapenem resistance and to prevent further dissemination of this resistant pathogen.

Detection of carbapenemase-producing Pseudomonas aeruginosa by phenotypic and genotypic methods in a tertiary care hospital of East India

BACKGROUND:

Carbapenemase-producing Pseudomonas aeruginosa is a serious threat in hospital infection due to its multidrug resistance.

AIM:

The aim of the study was to determine the frequency of carbapenem resistance in clinical isolates of Pseudomonas aeruginosa and detect the presence of carbapenemase enzymes in carbapenem-resistant P. aeruginosa (CRPA) isolates by phenotypic and genotypic methods.

MATERIAL AND METHODS:

Double-disk synergy test [DDST] and combined disk synergy test [CDST]) was performed in CRPA isolates and the prevalence of ^blaKPC, ^blaNDM-1, ^blaIMP, ^blaVIM, ^blaSIM, ^blaSPM, ^blaGIM, and ^blaOXA-48 was determined.

RESULTS:

Of 559 isolates included in the study, a total of 102 isolates were resistant to carbapenem that accounted for overall 18.24% (102/559) prevalence. Of these 102 isolates, 89 (87.25%) isolates were positive by DDST and 95 (93.17%) isolates were positive by CDST. Of 102 CRPA isolates, ^blaVIM was detected in 30 isolates (30/102, 29.1%), followed by ^blaNDM-1 in 29 (29/102, 28.4%) isolates and ^blaSIM and ^blaGIM in 6 isolates each (6/102, 5.8%). A combination of two carbapenemase genes was detected in 12 isolates, with six (6/102, 5.88%) CRPA isolates harboring with both ^blaVIM and ^blaNDM-1 genes. Four isolates were found to harbor a combination of three carbapenem-resistant genes.

CONCLUSION:

A high rate of carbapenemase production was observed in P. aeruginosa. Coproducers of multiple carbapenemases are also a cause of concern. An in-depth understanding of molecular mechanisms of resistance will be helpful in optimizing patient management and hospital infection control.

Resistance profile of genetically distinct clinical Pseudomonas aeruginosa isolates from public hospitals in central Pakistan

INTRODUCTION

Pseudomonas aeruginosa (member of ESKAPE group) is predominantly responsible for emerging nosocomial infections and poses serious health concern due to ever-increasing drug resistance trends. The current study investigates the prevalence of such highly resistant P. aeruginosa in major hospital settings and further characterizes and compares them for genetic heterogeneity.

MATERIALS AND METHODS

Samples of patients (n=108) with wound infections, bacteremia and burn injuries from major hospitals of Rawalpindi and Islamabad during 2017 to 2018 were collected for the present study. The samples were processed in the COMSATS Microbiology and Public Health lab and screened for the P. aeruginosa by routinely used biochemical tests, drug susceptibility tests and rapid molecular approaches.

RESULTS

The results suggested that most of the isolates (88/108) are indeed P. aeruginosa (81.4%) underpinning the need of its active surveillance in hospital settings. Further analysis suggested that 32 of these 88 microbes are multi-drug resistance (36.3%), 16 (18.1%) are extensively drug resistance and 4 (4.5%) are pan-drug resistance. Moreover, double disc synergistic test suggested that 16 (18.1%) are positive for metallo-β-lactamase production. Molecular screening confirmed that 2 (12.5%) and 3 (18.75%) of these 16 isolates are positive for VIM and NDM gene respectively while all the studied isolates were positive for AmpC β-lactamase. PAP17 isolate harbors both VIM and NDM genes. ERIC PCR profiling showed that majority of MDR bacteria fall in cluster II and III similarly XDR bacteria also fall in cluster II and III while PDR bacteria fall in cluster IV.

CONCLUSION

This study revealed that majority of the isolates are multi drug resistant MDR and extensively drug resistant (XDR). However, the presence of some pan drug resistant (PDR) isolates among such small sample size screened is of utmost concern. Molecular typing of extremely resistant P. aeruginosa revealed high genetic diversity. Therefore, we suggest that regular monitoring and surveillance of such highly resistant P. aeruginosa in hospital settings will help to control their transmission and hence reduce the disease burden.

Comparative Study of CDST & Multiplex PCR to Detect MBL Producing Gram-Negative Bacilli among VAP Patients Admitted in a Public Medical College Hospital of Bangladesh

Background: Ventilator-associated pneumonia (VAP) is the most common nosocomial infection in intensive care units (ICU), which accounts for 25% of all ICU infection. Documenting carbapenem-resistant gram-negative bacilli is very important as these strains may often cause outbreaks in the ICU setting and are responsible for the increased mortality and morbidity or limiting therapeutic options. The classical phenotypic method cannot provide an efficient means of diagnosis of the metallo-β-lactamases (MBLs) producer. Polymerase chain reaction (PCR) assays have lessened the importance of the phenotypic approach by detecting metallo-β-lactamase resistance genes such as New Delhi metallo-β-lactamase (NDM), Imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), Sao Paulo metallo-β-lactamase (SPM), Germany Imipenemase (GIM). Objective: To compare the results of the Combined Disc Synergy Test (CDST) with that of the multiplex PCR to detect MBL-producing gram-negative bacilli. Materials and Method: A total of 105 endotracheal aspirates (ETA) samples were collected from the ICU of a public school in Bangladesh. This cross-sectional study was carried out in the Department of Microbiology, Chittagong for quantitative culture, CDST test, and multiplex PCR for bla_IMP, bla_VIM, bla_NDM genes of MBL producers. Results: Among the 105 clinically suspected VAP cases, the quantitative culture was positive in 95 (90%) and among 95 g-negative bacilli isolated from VAP patients, 46 (48.42%) were imipenem resistant, 30 (65.22%) were MBL producers by CDST, 21 (45.65%) were identified as MBL producers by multiplex PCR. Conclusion: PCR was highly sensitive and specific for the detection of MBL producers.

An update on antimicrobial resistance and the role of newer antimicrobial agents for Pseudomonas aeruginosa

Infections due to Pseudomonas aeruginosa is a major health concern, especially hospital-acquired infections, in critically ill individuals. Antimicrobial resistance (AMR) increases the morbidity and mortality rates associated with pseudomonal infections. In this review, we aim to address two major aspects of P. aeruginosa. The first part of the review will focus on the burden of AMR and its prevailing mechanisms seen in India, while the second part will focus on the challenges and approaches in the management with special emphasis on the role of newer antimicrobial agents.

Prevalence and Mechanisms of Carbapenem Resistance Among Acinetobacter baumannii Clinical Isolates in Egypt

The increasing number of carbapenem-resistant Acinetobacter baumannii clinical isolates is a major concern, which restricts therapeutic options for treatment of serious infections caused by this emerging pathogen. The aim of this work is to assess the antimicrobial resistance profile and identify the molecular mechanisms involved in carbapenem resistance in A. baumannii isolated from different clinical sources in Mansoura University Hospitals, Egypt. Antimicrobial susceptibility testing has shown that resistance to carbapenem has dramatically increased (98%) with concomitant elevated levels of resistance to quinolones, trimethoprim/sulfamethoxazole, and aminoglycosides. Polymyxin B and colistin are considered the last resort. Random amplified polymorphic DNA (RAPD) typing method revealed great diversity among A. baumannii isolates. Coexistence of diverse intrinsic and acquired carbapenem-hydrolyzing β-lactamases has been detected in the tested isolates: Ambler class A: bla_KPC (56%) and bla_GES (48%), and Ambler class B: bla_NDM (30%), bla_SIM (28%), bla_VIM (20%), and bla_IMP (10%). Most isolates (94%) carried bla_OXA-23-like and bla_OXA-51-like simultaneously. bla_OXA-23-like was preceded by ISAba1 providing a potent promoter activity for its expression. Sequencing analysis revealed that ISAba1 has been also inserted in carbapenem resistance-associated outer membrane protein (OMP) (carO) gene in three isolates, two of which were clonal based on RAPD typing, leading to interruption of its expression as confirmed by SDS-PAGE analysis of OMP fractions. Carbapenem resistance genes are widely distributed among A. baumannii clinical isolates from different clinical sources. Therefore, enhanced infection control measures, effective barriers, and rational use of antimicrobials should be enforced in hospitals for minimizing the widespread resistance to carbapenems and all other antibiotics.