PER-1- and OXA-10-like beta-lactamases in ceftazidime-resistant Pseudomonas aeruginosa isolates from intensive care unit patients in Istanbul, Turkey

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.

Distribution of blaOXA-10, blaPER-1, and blaSHV genes in ESBL-producing Pseudomonas aeruginosa strains isolated from burn patients

Pseudomonas aeruginosa is resistant to a wide range of extended spectrum-lactamases (ESBLs) antibiotics because it produces several kinds of ESBLs. The goal of the current investigation was to identify the bacteria that produce extended spectrum -lactamases and the genes that encode three different ESBLs, such as blaOXA-10, blaPER-1 and blaSHV genes in Pseudomonas aeruginosa isolated from burn patients. In this investigation, 71 Pseudomonas aeruginosa isolates were isolated from burn wounds in Burn and Plastic Surgery Hospital, Duhok City between July 2021 to June 2022. For the purpose of finding the blaOXA-10, blaPER-1, and blaSHV ESBL expressing genes, Polymerase Chain Reaction (PCR) was used. Among 71 Pseudomonas aeruginosa isolates, 26.36% (29/71) were isolated from males and 38.18% (42/71) from females, and 76.06% (54/71) of the isolates were multidrug resistant. They exhibited higher resistance against Piperacillin with resistance rates of 98.59%. Among the ESBL-producing isolates tested, blaOXA-10 was found in 59.26% (32), blaPER-1 was found in 44.44% (24), and blaSHV was found in 11.11% (6). All isolates must undergo antimicrobial susceptibility testing because only a few numbers of the available antibiotics are effective for the treatment of this bacterium. This will prevent the development of resistance in burn units and aids in the management of the treatment plan.

Isolation, Antimicrobial Susceptibility Profile and Detection of Sul1, blaTEM, and blaSHV in Amoxicillin-Clavulanate-Resistant Bacteria Isolated From Retail Sausages in Kampar, Malaysia

Background

Due to the overuse of antibiotics in livestock as a growth-promoting agent, the emergence of multi-antibiotic resistant bacteria is becoming a concern.

Objectives

In this study, we aimed to detect the presence and discover the molecular determinants of foodborne bacteria in retail sausages resistant towards the antibacterial agent amoxicillin-clavulanate.

Methods

Two grams of sausages were chopped into small pieces and transferred into sterile Luria-Bertani (LB) enrichment broths overnight before they were plated on MacConkey agar petri dishes. The bacteria isolated were then screened for amoxicillin-clavulanate resistance, and an antimicrobial susceptibility test of each isolate was performed by using the disc diffusion method. Double synergy and phenotypic tests were carried out to detect the presence of extended spectrum β-lactamase (ESBL). API 20E kit was used to identify the Enterobacteriaceae. All isolates were further examined by polymerase chain reaction (PCR) for resistant genes blaOXA-1, blaOXA-10, plasmid-mediated AmpC (blaCMY and blaDHA), and the chromosome-mediated AmpC, Sul1, blaTEM, and blaSHV genes.

Results

A total of 18 amoxicillin-clavulanate resistant isolates were obtained from seven different types of retail sausages. Only half of them were identified as Enterobacteriaceae, but none were ESBL-producers. All the 18 isolated strains demonstrated resistance towards amoxicillin-clavulanate, penicillin and oxacillin (100%), cefotaxime (71.4%), cefpodoxime (66.7%), and ampicillin (83.3%). blaTEM was the most frequently detected β-lactamase gene. Both plasmid- and chromosomal-bound blaTEM genes were detected in all of the isolated Enterobacteriaceae. blaSHV and Sul1 accounted for 22.2% and 11.1% of the amoxicillin-clavulanate resistant isolates, respectively, whereas blaAMPC, blaCMY, blaDHA, blaOXA-1, and blaOXA-10 were not found in any of the isolates. The only one ESBL-producing bacteria detected in this study was Chryseobacterium meningosepticum, which harbored the blaTEM gene.

Conclusions

The multidrug resistant bacteria that carry antibiotic resistant genes from retail sausages may increase the risk of transmission to humans via the consumption of contaminated sausages. Stricter measures must be taken to address the use of antibiotics in animal agriculture and to consider their potential impact on human health.

Class A and D Extended-Spectrum β-Lactamases in Imipenem Resistant Pseudomonas aeruginosa Isolated From Burn Patients in Iran

Background:

Pseudomonas aeruginosa remains a leading cause of severe wound infection and mortality in burn patients.

Objectives:

The current study aimed to determine the prevalence of Ambler class A and D β-lactamases among P. aeruginosa isolated from infected burn injuries in Tehran, Iran.

Patients and Methods:

Bacteriological samples were taken from burn patients with clinical symptoms of burn infection. Fifty Gram-negative, oxidase-positive, catalase- positive bacilli, grown at 42ºC and production of pigment on Mueller-Hinton agar were identified as P. aeruginosa. All of the 50 isolates were examined for antibiotic susceptibility via disk diffusion method, and production of Ambler class A and and D β-lactamases by phenotypic screening test. The presence of Ambler class A and D β-lactamases was confirmed by polymerase chain reaction technique.

Results:

The results showed that the majority of isolates (88%) were multi-drug resistant. Out of these 50 imipenem resistant isolates, 7 (14%), 18 (36%), 18 (36%) and 18 (36%) strains were positive for bla_PER, bla_OXA-10, bla_TEM and bla_SHV genes alone or in combination, respectively. None of the isolates possessed bla_KPC or bla_GES genes.

Conclusions:

The current study highlights that the high level of resistance to many antibacterial agents and a gradual increase in the degree of PER, OXA-10, SHV and TEM ESBLs among the majority of imipenem resistant P. aeruginosa isolated from patients with burn infection is an enormous threat in burn centers in Iran.

Genetic characterization of Pseudomonas aeruginosa-resistant isolates at the university teaching hospital in Iran

Background:

Pseudomonas aeruginosa is an opportunistic pathogen that is commonly responsible for nosocomial infections. The aim of this study was to perform a genotyping analysis of the Pseudomonas aeruginosa-resistant isolates by the multilocus sequence typing (MLST) method at the university teaching hospital in Iran.

Materials and Methods:

Antimicrobial susceptibility was analyzed for P. aeruginosa isolates. Ceftazidime-resistant (CAZ_res) isolates with a positive double-disc synergy test were screened for the presence of extended-spectrum β-lactamase-encoding genes. Phenotypic tests to detect the metallo-β-lactamase strains of P. aeruginosa were performed on imipenem-resistant (IMP_res) isolates. Selected strains were characterized by MLST.

Results:

Of 35 P. aeruginosa isolates, 71%, 45% and 45% of isolates were CAZ_res, IMP_res and multidrug resistant (MDR), respectively. Fifty-seven percent of the isolates carried the bla_OXAgroup-1. All the five typed isolates were ST235. Isolates of ST235 that were MDR showed a unique resistance pattern.

Conclusion:

This study shows a high rate of MDR P. aeruginosa isolates at the university teaching hospital in Iran. It seems MDR isolates of P. aeruginosa ST235 with unique resistance pattern disseminated in this hospital.

Spread of extended-spectrum β-lactamase genes of blaOXA-10, blaPER-1 and blaCTX-M in Pseudomonas aeruginosa strains isolated from burn patients

BACKGROUND

Pseudomonas aeruginosa is resistant to many antibiotics due to production of different classes of extended spectrum β-lactamases (ESBLs). Prevalence of ESBLs among P. aeruginosa has been increased in recent years, demonstrate a serious health problem especially in burn units worldwide.

OBJECTIVE

Present study was designed to determine the ESBL producing strains and identify the genes encoding three different ESBLs of bla PER-1, bla OXA-10 and bla CTX-M genes in P. aeruginosa isolates from burn patients.

METHODS

In total 185 clinical isolates of P. aeruginosa were collected from infectious wounds of hospitalized burn patients. Antimicrobial susceptibility testing and phenotypic detection of ESBL were performed by disk diffusion method and Double disk Synergy Test (DDST). Polymerase Chain Reaction (PCR) was done for detection of bla OXA-10, bla PER-1 and bla CTX-M ESBL encoding genes.

RESULTS

In total, 176 (95.13%) isolates were multidrug resistant. The DDST demonstrated 96 (51.9%) isolates as putative ESBL producers with 100% or highly resistance to ofloxacin, cephalexin, aztreonam (97.57%) and ceftriaxone (91.6%). By PCR amplification, bla PER-1, bla OXA-10 and bla CTX-M genes were detected in 52 (54.16%), 66 (68.75%) and 1 (1.04%) isolates of ESBL producers respectively. Forty-three isolates (44.79%) were simultaneously positive for both bla OXA-10 and bla PER-1 related genes.

CONCLUSION

The rate of ESBL producing P. aeruginosa was notable in present study. Since there are only limited effective antibiotics against the bacterium, therefore all isolates must be investigated by antimicrobial susceptibility testing, which limits resistance development in burn units and helps the management of treatment strategy.

Molecular epidemiology and mechanisms of antimicrobial resistance in Pseudomonas aeruginosa isolates causing burn wound infection in Iran

In this study, the contributions of different resistance mechanisms in Pseudomonas aeruginosa isolates were investigated among burned patients. The real-time reverse transcription polymerase chain reaction was performed to determine the expression level of mexY, ampC, and oprD for isolates. Also the isolates were typed by multilocus sequence typing (MLST). Seventy-five per cent of clinical isolates were multidrug resistant. The bla(OXA group-I) and blaPER alleles were identified in 28 and 10 P. aeruginosa isolates, respectively. The majority of bla(PER) positive isolates belonged to the same MLST clone and was identified as ST235. The types of remaining isolates were ST360 and ST861. Among 10 bla(PER) positive isolates, eight isolates demonstrated reduced oprD expression and mexY overexpression. Our data further highlight the epidemic potential of the international clone ST235. According to the results, different resistant mechanisms identified among ST235 isolates that were resistant to ceftazidime, imipenem, ciprofloxacin, and amikacin.

Detection of Pseudomonas aeruginosa isolates of the international clonal complex 11 carrying the blaPER-1 extended-spectrum β-lactamase gene in Greece

OBJECTIVES

The extended-spectrum β-lactamase (ESBL) PER-1 initially disseminated among Pseudomonas aeruginosa strains in Turkey. Despite reports from other European countries, such strains have not been detected in Greece until now. We describe the first bla(PER-1)-positive P. aeruginosa isolates from Greece and their genetic environment.

METHODS

From January 2008 to December 2009, 287 consecutive non-duplicate P. aeruginosa isolates with reduced susceptibility or resistance to ceftazidime (MIC >8 mg/L) were screened for ESBL production with a modified boronic acid-based double-disc synergy test. Phenotypically ESBL-positive isolates were subjected to agar dilution, PFGE and multilocus sequence typing (MLST). Broad-spectrum bla genes were identified by PCR and sequencing. Plasmid analysis and conjugation experiments were performed. The location of the bla(PER-1) gene was detected by Southern blotting and its genetic environment was characterized using inverse PCR.

RESULTS

Five isolates were phenotypically positive for ESBL production, exhibited resistance to cefepime, ceftazidime, aztreonam and meropenem, and carried the bla(PER-1) gene. MLST showed that they belonged to sequence type (ST) 235, which belongs to the international clonal complex 11. Four isolates had the same PFGE pattern. Southern blotting revealed the chromosomal location of the bla(PER-1) gene. Analysis of the bla(PER-1) flanking regions showed identity to transposon Tn1213 downstream and 1406 bp upstream of bla(PER-1). Further upstream, an orfA gene and ISPa12 were identified; both were truncated by the insertion of IS6100.

CONCLUSIONS

This study confirmed the presence of PER-1-producing P. aeruginosa strains in Greece. The chromosomal location of bla(PER-1), as part of a truncated transposon, suggests clonal expansion rather than horizontal gene transfer.

In vitro activity of avibactam (NXL104) in combination with β-lactams against Gram-negative bacteria, including OXA-48 β-lactamase-producing Klebsiella pneumoniae

The objective of this study was to investigate the in vitro antibacterial activity of avibactam (formerly NXL104) in combination with imipenem, cefepime or ceftazidime against Gram-negative bacteria. Bacterial isolates included: Pseudomonas aeruginosa harbouring PER-1 β-lactamase (n=14); Acinetobacter baumannii harbouring PER-1, OXA-51 and OXA-58 (n=20); carbapenem-non-susceptible Klebsiella pneumoniae (n=25) and Escherichia coli (n=1) harbouring OXA-48; carbapenem-non-susceptible E. coli (n=1) harbouring both IMP-1 metallo-β-lactamase and extended-spectrum β-lactamase (ESBL); carbapenem-non-susceptible Serratia marcescens (n=1); and carbapenem-susceptible E. coli (n=20) and K. pneumoniae isolates (n=12) with CTX-M-15 ESBL. Minimum inhibitory concentrations (MICs) of imipenem, cefepime and ceftazidime were determined in combination with 4 mg/L avibactam by the Clinical and Laboratory Standards Institute (CLSI) method on Mueller-Hinton agar. Imipenem/avibactam and ceftazidime/avibactam displayed limited potency against A. baumannii isolates, whereas cefepime/avibactam and ceftazidime/avibactam were active against P. aeruginosa. Klebsiella pneumoniae isolates with OXA-48 β-lactamase were resistant to imipenem [MIC for 90% of the organisms (MIC(90)) ≥4 mg/L]. MIC(90) values for the combination of avibactam 4 mg/L with imipenem, cefepime and ceftazidime were in the susceptible range for all strains (MIC(90)≤0.5mg/L). All E. coli and K. pneumoniae isolates with CTX-M-15 β-lactamase were inhibited at ≤1 mg/L for combinations with avibactam and 100% were susceptible by CLSI breakpoint criteria to imipenem, cefepime and ceftazidime. In conclusion, combinations of imipenem, cefepime and ceftazidime with avibactam may present a promising therapeutic strategy to treat infections due to K. pneumoniae with OXA-48 enzyme as well as K. pneumoniae and E. coli with CTX-M-15 enzyme.

BEL-2, an extended-spectrum beta-lactamase with increased activity toward expanded-spectrum cephalosporins in Pseudomonas aeruginosa

A Pseudomonas aeruginosa isolate recovered in Belgium produced a novel extended-spectrum ss-lactamase, BEL-2, differing from BEL-1 by a single Leu162Phe substitution. That modification significantly altered the kinetic properties of the enzyme, increasing its affinity for expanded-spectrum cephalosporins. The bla(BEL-2) gene was identified from a P. aeruginosa isolate clonally related to another bla(BEL-1)-positive isolate.

Minor extended-spectrum beta-lactamases

Extended-spectrum beta-lactamases (ESBLs) are usually plasmid-mediated enzymes that confer resistance to a broad range of beta-lactams. Initially, resistance to third-generation cephalosporins in Gram-negative rods was mainly due to the dissemination of TEM- and SHV-type ESBLs, which are point mutants of the classic TEM and SHV enzymes with extended substrate specificity. During the last ten years, CTX-M-type ESBLs have become increasingly predominant, but less frequent class A beta-lactamases have also been described, including SFO, BES, BEL, TLA, GES, PER and VEB types. While several of these latter are rarely identified, or are very localised, others are becoming locally prevalent, or are increasingly isolated worldwide. In addition, mutations can extend the spectrum of some OXA-type beta-lactamases to include expanded-spectrum cephalosporins, and several of these enzymes are considered to be ESBLs.

In vitro activities of various antibiotics, alone and in combination with colistin methanesulfonate, against Pseudomonas aeruginosa strains isolated from cystic fibrosis patients

BACKGROUND

The in vitro activities of various antibiotics, either alone or in combination with colistin methanesulfonate, were assessed using Pseudomonas aeruginosa strains isolated from cystic fibrosis patients.

METHODS

Except for colistin methanesulfonate, minimum inhibitory concentrations were determined by microbroth dilution technique as described by the Clinical and Laboratory Standards Institute (CLSI); for colistin methanesulfonate, a modified method of the CLSI was used. Minimum bactericidal concentrations were determined as described by the CLSI. The in vitro activities of antibiotics in combination were determined by microbroth checkerboard technique, and results were interpreted by fractional inhibitory concentration index.

RESULTS

According to MIC values, 100, 98, 96 and 84% of the isolates were found susceptible to amikacin, colistin methanesulfonate, meropenem and ceftazidime, respectively. The minimum bactericidal concentrations were generally equal to or twice as high as those of the minimum inhibitory concentrations. With a fractional inhibitory concentration index of < or =0.5 as borderline, synergistic interactions were more frequent with combinations where amikacin was involved than with those with colistin methanesulfonate. No antagonism was observed.

CONCLUSION

The findings of this study may play a useful role in selecting the appropriate combinations when a single agent is inadequate to treat cystic fibrosis patients with P. aeruginosa infections.

Molecular epidemiology of PER-1 extended spectrum beta-lactamase among gram-negative bacteria isolated at a tertiary care hospital

The bla(PER-1) presence was sought by PCR in 289 ceftazidime resistant Gram-negative bacteria isolated at Dokuz Eylul University Hospital (Turkey) between 1998 and 2003. PER-1 production rates were 32.3, 33.9, 14.9 and 37.9% in the 1998-2000 period, 2001, 2002 and 2003, respectively. bla(PER-1) was detected in 46.2 and 35.9% of ceftazidime-resistant Pseudomonas aeruginosa and Acinetobacter baumannii isolates, respectively. ERIC-PCR results revealed that dissemination of two endemic clones for both P. aeruginosa (X and Y) and A. baumannii (A and B) was responsible for the high prevalence. Results of the conjugation tests and plasmid curing experiments suggested that bla(PER-1) was located on the chromosome in the representative strains. It was also shown for the first time that bla(PER-1) in a clinical isolate was associated with class-1 integron which could facilitate dissemination of bla(PER-1) among bacteria.

Outbreak of Pseudomonas aeruginosa infections with PER-1 extended-spectrum beta-lactamase in Warsaw, Poland: further evidence for an international clonal complex

Forty-one Pseudomonas aeruginosa isolates with extended-spectrum beta-lactamases (ESBLs) from a hospital in Warsaw, Poland, were analyzed. Thirty-seven isolates from several wards were collected over 9 months in 2003 and 2004. The isolates were recovered from patients with multiple types of infections, mostly respiratory tract and postoperative wound infections. All 41 isolates produced the PER-1 ESBL, originally observed in Turkey but recently also identified in several countries in Europe and the Far East. The bla(PER-1) gene resided within the Tn1213 composite transposon, which was chromosomally located. Pulsed-field gel electrophoresis and multilocus sequence typing (MLST) revealed the presence of three separate clones among the isolates. Two of these, corresponding to sequence types (STs) ST244 and ST235, were responsible for parallel outbreaks. Apart from PER-1, all the isolates produced OXA-2 oxacillinase. ST235 isolates additionally expressed a novel enzyme, OXA-74, differing by one amino acid from the OXA-17 ESBL identified originally in PER-1- and OXA-2-positive P. aeruginosa isolates from Ankara, Turkey, in 1992. These earlier Ankara isolates with PER-1, OXA-2, and OXA-17 were also classified into ST235, which is a single-locus variant of two other STs, ST227 and ST230. ST227, ST230, and ST235 all correspond to the recently described clonal complex BG11, which seems to be internationally distributed, having spread in Turkey, Greece, Italy, Hungary, Poland, Sweden, and much of Russia. It is associated with various beta-lactamases, including PER-1 and VIM metalloenzymes. This work further demonstrates the value of MLST of P. aeruginosa.

Occurrence of PER-1 producing clinical isolates of Pseudomonas aeruginosa in Japan and their susceptibility to doripenem

The acquisition of resistance by extended-spectrum beta-lactamases (ESBL) has been reported primarily for Enterobacteriaceae, but there are few reports on the isolation of ESBL-producing Pseudomonas aeruginosa. PER-1-type ESBL producing P aeruginosa has been found in various regions around the world but there are no reports of clinical isolates in Japan. During our susceptibility surveillance studies over a 10 year period, we found four clinical isolates resistant to ceftazidime due to production of PER-1. They were resistant to ceftazidime but susceptible in the presence of clavulanic acid, a class A beta-lactamase inhibitor. The strains had the ability to hydrolyze ceftazidime. They also had the gene for PER-1-type ESBL. This is the first report of the isolation of PER-1 producing strains in Japan. These four strains were resistant to ceftazidime, cefepime and aztreonam with MICs of 64 microg/ml or more, but were more susceptible to carbapenem antibiotics. In particular, doripenem, which is a novel carbapenem antibiotic, showed good antibacterial activity with a MIC of 2 or 4 microg/ml, which was more potent than meropenem and imipenem. Doripenem also showed good therapeutic efficacy against a systemic infection of mice with a PER-1 producing strain, and was also more potent in vivo than imipenem or meropenem.

Genetic analysis of a multiresistant strain of Pseudomonas aeruginosa producing PER-1 beta-lactamase

A multiresistant strain of Pseudomonas aeruginosa, PA2345, belonging to serotype O:1, was isolated at the Teaching Hospital of Besançon, France. Resistance to beta-lactams, including third-generation cephalosporins, depended upon a chromosomally-located composite transposon carrying the bla(PER-1) gene encoding extended-spectrum beta-lactamase PER-1. PA2345 was unrelated genotypically to two previous PER-1-producing isolates of P. aeruginosa. Sequence analysis of the transposon in PA2345 revealed the presence of two insertion sequences (ISPa23 and ISPa24) with very different predicted transposases (TnpA1, TnpA2), which were both bordered by closely related 16-bp inverted repeats. High resistance of PA2345 to aminoglycosides was caused, in part, by a chromosomal class-I integron containing gene cassettes aadB, encoding an ANT(2'') enzyme, and aadA11, encoding a new ANT(3'') enzyme with 281 amino-acids that conferred elevated resistance to streptomycin and spectinomycin. Stable overproduction of efflux system MexXY contributed to resistance to amikacin, while mutations in the quinolone resistance-determining regions of gyrA and parC accounted for the high resistance of PA2345 to fluoroquinolones. The study indicates that multidrug resistance in P. aeruginosa might arise from sequential acquisition of a variety of mechanisms provided by both horizontal gene transfers and mutations in chromosomal genes.