Plasmid-mediated Quinolone Resistance Determinants Research Articles

Prevalence of plasmid-mediated quinolone resistance genes in extended-spectrum beta-lactamase producing Klebsiella pneumoniae isolates in northern Iran

Plasmid-mediated quinolone resistance (PMQR) in extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae (K. pneumoniae) contributes to treatment failures, extended hospital stays, and increased mortality percentages. We aimed to determine the prevalence of PMQR genes in ESBL-producing K. pneumoniae isolates from clinical samples in Babol, North of Iran region. This is the first study in this region to investigate this specific association. A total of 95 K. pneumoniae isolates were obtained from hospitalized patients with various clinical infections during March 2022 to February 2023. Disk diffusion and Combination disk method were performed to identification of antimicrobial resistance profiles and ESBL-producing strains. The presence of ESBL and PMQR genes among K. pneumoniae isolates was assessed using polymerase chain reaction (PCR) method. Of the isolates, 68 (71.57 %) were considered as ESBL-producers. The blaTEM, blaSHV and blaCTX-M genes were detected in 74.73 %, 57.89 %, and 41.05 % of K. pneumoniae isolates, respectively. Among the PMQR encoding genes, the highest and lowest frequency was associated to qepA (67.3 %) and qnrA (4.2 %), respectively. The frequency of qnrA, qnrB, qnrS, acc (6′)-Ib-cr, qepA, oqxA, and oqxB genes in 26 MDR-Kp isolates was 11.53 % (n; 3), 69.23 % (n; 18), 65.38 % (n; 17), 73.07 % (n; 19), 80.76 % (n; 21), 84.61 % (n; 22), and 76.92 % (n; 20), respectively. Our result revealed of the 68 ESBL gene-positive isolates, 60 (88.23 %) were positive for the PMQR gene. The co-occurrence of these genes within resistant isolates suggests potential linkage on mobile genetic elements such as plasmids. These findings highlight the significant burden of PMQR determinants in ESBL-producing K. pneumoniae and underscore the urgent need for effective control measures. Implementing robust antimicrobial stewardship programs and strengthening drug-resistance surveillance and control protocols are crucial to prevent the spread of resistant isolates.

Antimicrobial susceptibility and virulence gene analysis of Shigella species causing dysentery in Iranian children: Implications for fluroquinolone resistance

Shigella species significantly impact global health due to their role in diarrheal diseases. A 2019–2022 cross-sectional study on 432 stool samples from pediatric patients in Mashhad, Iran, identified Shigella spp. and tested their susceptibility to 12 antimicrobials by the disk diffusion method. The presence of virulence factors, namely ipaH, virA, stx1, and stx2, as well as plasmid-mediated quinolone resistance (PMQR) genes, including qnrA, qnrB, qnrC, qnrD, and qnrS, were ascertained through the utilization of polymerase chain reaction techniques. Sequencing of 15 isolates detected mutations within quinolone resistance-determining regions (QRDRs) at the gyrA and parC genes, indicating fluoroquinolone (FQ) resistance. 19.2 % (83/432) of stool samples contained Shigella, primarily S. sonnei (77.1 %), followed by S. flexneri (21.6 %) and S. boydii (1.2 %). Most isolates were from children under five (55.4 %). All strains had the ipaH gene, lacked stx1 and stx2, and 86.7 % had virA. High resistance was noted for ampicillin and tetracycline (84.3 % each), trimethoprim-sulfamethoxazole (81.9 %), and azithromycin (60.2 %). 87.1 % of isolates were multidrug-resistant (MDR). The most common PMQR genes were qnrA and qnrS (41 % each). The qnrD gene, prevalent in 36.1 % of cases, is reported in Iran for the first time. The most common PMQR profile was qnrADS (15.7 %). Resistance to nalidixic acid and ciprofloxacin was 45.8 % and 12 %, respectively. The Shigella isolates exhibited mutations in the gyrA (at codons 83, 87, and 211) and parC (at codons 80, 84, 93, 126, 128, 129, and 132) genes. The D87Y mutation in the gyrA gene was the most common in Shigella isolates, occurring in 73 % of cases. The F93S and L132T mutations in the parC gene were unique to this study. Empirical FQ therapy in patients infected with MDR Shigella, possessing PMQR determinants and/or mutations in the QRDRs of gyrA and parC, may escalate the risks of secondary diseases, extended treatment duration, therapeutic failure, and resistance spread. Consequently, the necessity for continuous surveillance and genetic testing to detect FQ-resistant Shigella strains is of paramount importance.

Wide distribution of plasmid mediated quinolone resistance gene, qnrS, among Salmonella spp. isolated from canal water in Thailand.

This research focused on assessing the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants and antimicrobial susceptibility in Salmonella strains isolated from Thai canal water. From 2016 to 2020, 333 water samples were collected from six canals across Bangkok, Thailand. Salmonella spp. was isolated, PMQR genes were detected through polymerase chain reactions, and the antimicrobial susceptibility was examined using the disk diffusion method. The results indicated a 92.2% prevalence of Salmonella spp. in canal water, being serogroups B and C the most frequently detected. Overall, 35.3% of isolates harbored PMQR genes, being qnrS the most prevalent gene (97.2%, n=137/141). Other PMQR genes, including qnrB, qnrD, oqxAB, and aac(6')-Ib-cr, were detected. Notably, six isolates harbored multiple PMQR genes. Furthermore, 9.3% and 3.8% of the overall isolates were resistant to nalidixic acid (NAL) and ciprofloxacin (CIP), respectively. PMQR-positive isolates showed higher rates of non-susceptibility to both NAL (48.2%, n=68/141) and CIP (92.2%, n=130/141) compared to PMQR-negative isolates (NAL: 8.9%, n=23/258; CIP: 11.2%, n=30/258). The high prevalence of Salmonella spp., significant PMQR-positive, and reduced susceptibility isolates in canal water is of public health concern in Bangkok.

β-lactamase and Plasmid-mediated Quinolone Resistance Determinants Among Proteus spp. Isolates at a Tertiary-care Hospital in Kolkata, India

Background: Emerging antibiotic resistance (ABR) in Proteus spp., especially to third-generation cephalosporins (3GCc), carbapenems, and fluoroquinolones, challenges the treatment outcome and infection prevention. Limited studies pose a knowledge gap between them and ABR. Methods: We investigated the in vitro efficacy of therapeutic options and prevalence of β-lac-tamase and plasmid-mediated quinolone resistance (PMQR) traits in 3GC- and/or fluoroquino-lone-nonsusceptible Proteus (P.) spp. (n=27) in Kolkata, India, during 2021–2022. P. mirabilis was commonly isolated (>80%) from superficial and urine samples. The majority of the isolates (48-78%) remained susceptible to piperacillin-tazobactam, meropenem, amikacin, cefoperazone-sulbactam, and cefepime. Results: All isolates showed >0.2 multiple-antibiotic resistance index, with >65% being multi-drug and >30% being extensively drug-resistant. blaTEM (n=9), blaNDM (n=9), and qnrA (n=6) were commonly noted with the co-production of β-lactamases and PMQR in ten (37%) isolates. More than 50% of the isolates were devoid of the tested acquired genes. Conclusion: The study concludes that superbugs dominate, with limited occurrence of plasmid-borne markers in this geographic location.

The Abundance of Plasmid-Mediated Quinolone Resistance Genes in Enterobacter cloacae Strains Isolated from Clinical Specimens in Kermanshah, Iran.

Enterobacter cloacae (E. cloacae) is one of the most common Enterobacteriaceae causing nosocomial infections. Plasmid-mediated quinolone resistance (PMQR) determinants have been considered recently. This study evaluated the abundance of PMQR genes in strains of E. cloacae obtained from clinical samples in Kermanshah, Iran. In this descriptive cross-sectional study, after collecting 113 isolates of E. cloacae, their identity was confirmed using specific biochemical tests. After determining their drug resistance patterns using disc diffusion, the phenotypic frequency of extended-spectrum beta-lactamase (ESBL)-producing isolates was measured by the double-disk synergy test (DDST) method. The isolates were examined for the presence of qnrA, qnrB, qnrS, and aac(6')-Ib-cr genes by the polymerase chain reaction (PCR) assay. The antibiotic resistance rate of E. cloacae isolates varied from 9.7% to 60.2%; among them, 78% were multidrug-resistant (MDR). The highest quinolone resistance was observed in ESBL-producing strains of E. cloacae. The frequency of positive isolates for PMQR and ESBL was 79.6% and 57.5%, respectively. The genes aac(6')-ib-cr (70.8%) and qnrB (38.1%) had the highest frequency among other genes. The number of isolates simultaneously carrying 2 and 3 genes was 64 and 5 isolates, respectively. The obtained results indicate a high degree of quinolone resistance among ESBL-producing E. cloacae strains. Nevertheless, there was a significant relationship between the PMQR gene and ESBL-positive isolates. Therefore, special attention should be paid to molecular epidemiological studies on antibiotic resistance to quinolones and beta-lactamases in these strains.

Polluted surface water is a repository of antibiotic-resistant Escherichia coli harbouring Plasmid-Mediated Quinolone Resistance (PMQR) determinants

ABSTRACT We investigated the carriage of PMQR determinants by E. coli from surface water and their antibiotypes. Water samples were collected and analysed from two surface water: Agbowo (AG) and Arulogun (AR) in South-west Nigeria for E. coli, which were identified using PCR detection of uidA. Susceptibility to antibiotics was done using the disc-diffusion method. Detection of PMQR genes in isolates showing complete resistance or intermediate susceptibility to the fluoroquinolone antibiotics was done using primer-specific PCR. Thirty-six E. coli isolates were obtained [AG (20) and AR (16)]. The isolates showed different levels of resistance to the tested antibiotics, with 100% resistance to amoxicillin-clavulanate. None of the isolates was positive for extended spectrum β-lactamase (ESBL) production, but 25 showed complete resistance or intermediate susceptibility to the fluoroquinolone antibiotics. Two isolates each from AG and AR carried qnrA, one isolate carried qnrS, with one each from AG and AR carrying aac(6′)-lb-cr. Four isolates carried oqxAB, but, qnrB and qepA were not detected in any isolate. This study revealed that polluted surface water is a ‘hub’ of antibiotic-resistant E. coli harbouring PMQR genes.

Isolation and Characterization of Cefotaxime and Ciprofloxacin Co-Resistant Escherichia coli in Retail Chicken Carcasses

Transmission of antimicrobial-resistant bacteria to humans through the food chain is of great importance for public health. In this study, it was aimed to isolate and characterize the cefotaxime and ciprofloxacin-resistant Escherichia coli in retail chicken meat samples sold in Hatay. The isolates were subjected to phylogenetic group typing and antimicrobial susceptibility testing. The genetic relatedness of the isolates was determined using Enterobacterial Repetitive Intergenic Consensus Polymerase Chain Reaction (ERIC-PCR) technique. The isolates were also screened for the presence of both antimicrobial and plasmid-mediated quinolone resistance (PMQR) genes by PCR. Cefotaxime and ciprofloxacin co-resistant E. coli isolates with diverse genetic origins were recovered in 42.3% (22/52) of retail chicken carcasses. The E. coli isolates belonged to the phylogenetic group D2 were dominant (40.9%, 9/22), followed by B1 (27.3%, 6/22), B23 (18.2%, 4/22), and A1 (13.6%, 3/22), respectively. Based on dendrogram analysis, the ERIC-PCR method differentiated the isolates into 10 clusters (I-X). The multidrug resistance (MDR) was observed in 81.8% (18/22) of the isolates. PMQR determinants were not identified in any isolates tested. Molecular analysis revealed one or more β-lactamase-encoding genes in all isolates as a single or in combination: blaCTX-M-blaTEM (n=5), blaCMY-2 (n=5), blaCTX-M (n=5), blaCMY-2-blaSHV (n=3), blaCMY-2-blaTEM (n=3), and blaCTX-M-blaCMY-2 (n=1). This study highlights that retail chicken meat is an important reservoir of cefotaxime and ciprofloxacin co-resistant E. coli isolates. It is necessary to evaluate their contribution to the community and hospital infections.

Molecular characterization of PMQR carrying bacteriophages in effluent discharge samples of Azerbaijan hospitals.

Quinolones are one of the most widely used drugs in medicine. Resistance to this agent has been increased significantly among the nosocomial isolates. The objective of this research was to study generalized transduction, as a potential mechanism for plasmid-mediated quinolone resistance (PMQR) genes acquisition among hospital effluent isolates. Discharge samples from hospital effluent were taken from four medical centers in Azerbaijan. Resident phages were enriched against resident enterobacterial hosts using standard phage enrichment protocols. Polymerase chain reaction (PCR) was used to examine phage stocks and bacterial isolates for the presence of PMQR determinants. All positive bacterial isolates for target genes were subjected to transduction assays. Restriction fragment length polymorphism (RFLP) profiles were determined for cluster analysis. A total of 55 pure phage stocks were prepared from 42 effluents. A total of 95 non-duplicated Gram-negative bacteria were isolated. Thirty-two EcoRV-RFLP profiles were determined for the 40 Escherichia coli phage stocks. Twenty-six of 40 (65%) E. coli phages were positive for qnrB (n = 15), qnrD (n = 7), qnrA (n = 3), and qnrC (n = 2) genes. A total of 34 (35.7%) bacterial isolates were recognized to have any PMQR genes including qnrB (n = 23), qnrD (n = 8), qnrA (n = 5), and qnrC (n = 3) genes. Present research provided a strong evidence for potential role of generalized transduction in persistence and circulation of PMQR genes in health care settings of Azerbaijan.

PKpQIL-like plasmid contributes to the dissemination of blaNDM-1 and plasmid mediated quinolone resistance determinants among multi drug resistant Klebsiella pneumoniae in Assiut university hospital, Egypt.

Concomitant carriage of blaNDM-1 and plasmid mediated quinolone resistance determinants (PMQRs) by multi drug resistant (MDR) Klebsiella pneumoniae (K. pneumoniae) has increased globally, often related to their presence on transmissible plasmids. In this study, we hypothesized the presence of blaNDM-1 and PMQRs on a single conjugative plasmid that circulates among K. pneumoniae strains isolated from Assiut University Hospital. Twenty-two clinical MDR K. pneumoniae strains harboring both blaNDM-1 and PMQRs were genotyped using pulsed field gel electrophoresis. Horizontal transfer of blaNDM-1 and PMQRs was evaluated by conjugation and trans-conjugants were screened for the presence of both genes and integron by PCR. Trans-conjugant's plasmid DNA bands were purified using agarose gel electrophoresis and different DNA bands were screened for blaNDM-1 and PMQRs. Plasmids carrying blaNDM-1 and PMQRs were typed by PCR based replicon typing. All MDR K. pneumoniae contained class 1 integron and belonged to 15 pulsotypes. BlaNDM-1 and PMQRs were co-transferred in each conjugation process. Multiple replicons (5-9 types) were detected in each trans-conjugant; with IncFIIK and IncFIB-KQ replicons being common among all trans-conjugants. Both blaNDM-1 and PMQRs were detected on a pKpQIL-like multi-replicon plasmid that was present in all K. pneumoniae strains. In view of these results, the presence of blaNDM-1 and PMQRs on pKpQIL-like plasmid that existed in multiple unrelated K. pneumoniae isolates is highly suggestive of the circulation of pKpQIL-like MDR plasmids in our hospitals. Moreover, carriage of integrons by the-circulating MDR plasmids increases the risk of dissemination of antimicrobial resistance among pathogens.

High frequency of NDM-1 and OXA-48 carbapenemase genes among Klebsiella pneumoniae isolates in central Iran

BackgroundThe emergence and distribution of multidrug-resistant (MDR) and carbapenem-resistant Klebsiella pneumoniae (CRKP) has become a global health threat. Therefore, this study aimed to investigate the frequency and antibiotic resistance patterns of MDR, extensively drug-resistant (XDR), and CRKP, as well as the antibiotic resistance genes of Klebsiella pneumoniae (K. pneumoniae) isolates from patients’ infectious samples from central Iran.MethodsThis study examined 546 clinical samples of patients to identify K. pneumoniae. The isolates were investigated for their antibiotic resistance profile, extended-spectrum β-lactamase (ESBL), AMPC β-lactamase, carbapenemase resistance, sulfonamide, tetracycline, plasmid-mediated quinolone resistance (PMQR) along with their resistance genes, integrase, and quaternary ammonium compounds (qac) by polymerase chain reaction (PCR).ResultsOut of 546 clinical samples, 121 (22.1%) cases of K. pneumoniae were identified using culture and PCR methods. The highest antibiotic resistance rates were found for ampicillin (119/121; 98.3%), cotrimoxazole (78/121; 64.4%), and cefixime, cefotaxime, ceftriaxone, and ceftazidime as a group (77/121; 63.6%). Tigecycline, colistin, and fosfomycin were the most effective antimicrobial agents with 98.4%, 96.7%, and 95.9% susceptibility, respectively. The amount of CRKP was 51 (42.1%). All CRKP isolates were MDR. The most abundant genes were blaTEM (77/77; 100%), blaCTX−M1 (76/77; 98.7%), blaSHV (76/77; 98.7%), blaCTX−M15 (73/77; 94.8%) for ESBL; blaCIT 28 (48.3%) and blaCMY−2 26 (44.8%) for AMPC β-lactamase; and blaOXA−48 46 (90.1%) and blaNDM 36 (70.5%) for carbapenemase. Among the PMQR determinants, qnrB (25/52; 48%), qnrS (19/52; 36.5%), and qnrA (11/52; 21.1%) were positive from the isolates. TetA and tetB were recognized in 25 (44.6%) and 17 (30.3%) isolates, respectively. Class 1 and 2 integrons were recognized in 97 (80.1%) and 53 (43.8%) isolates, respectively.ConclusionsDue to the high prevalence of MDR and CRKP in central Iran, tracking and immediate intervention are necessary for control and inhibition of K. pneumoniae resistant isolates. Tigecycline, colistin, and fosfomycin are the best treatment options for treatment of patients with CRKP in this geographical area.

Faecal carriage of ESBL producing and colistin resistant Escherichia coli in avian species over a 2-year period (2017-2019) in Zimbabwe.

Extended spectrum beta-lactamase (ESBL) producing Escherichia coli have become widespread among food producing animals. These strains serve as a reservoir of antibiotic resistance genes (ARGs) and act as a possible source of infection to humans as transmission can occur by direct or indirect contact. This study investigated the faecal carriage of ESBL producing and colistin resistant E. coli in poultry over a 2-year period (2017-2019) from Zimbabwe. A total of 21 ESBL positive isolates from poultry cloacal specimens were selected for whole genome sequencing from animal E. coli isolates bio-banked at the National Microbiology Reference laboratory using phenotypic susceptibility testing results from the National Escherichia coli Surveillance Program to provide representation of different geographical regions and year of isolation. Cloacal swabs were collected from 3000 broiler live birds from farm 1 and from farm 2, 40 backyard chickens and 10 ducks were sampled. Antimicrobial susceptibility and ESBL testing were performed as per Clinical Laboratory Standards Institute guidelines. Whole genome sequencing of ESBL producing isolates was used to determine sequence types (STs), ARGs, and phylogroups. Twenty-one of the included E. coli isolates were confirmed as ESBL producers. Three defined sequence type clonal complexes (CCs) were identified (ST10CC, ST155CC and ST23CC), with ST10CC associated with the most antibiotic resistant profile. The ESBL phenotype was linked to the presence of either cefotaximase-Munich-14 (CTX-M-14) or CTX-M-79. Plasmid mediated quinolone resistant determinants identified were qnrB19 and qnrS1 and one ST10CC isolate from farm 1 broiler chickens harbored a mobile colistin resistance gene (mcr-1). Phylogenetic groups most identified were B1, A and unknown. The avian ESBL producing E. coli belonged to a diverse group of strains. The detection of several ARGs highlights the importance of implementing enhanced control measures to limit the spread in animals, environment, and humans. This is the first report of mcr-1 in Zimbabwe, which further underscores the importance of the One Health approach to control the spread and development of AMR.

Molecular patterns of clinically important fluoroquinolone resistance in multidrug-resistant Klebsiella pneumoniae isolates during nosocomial outbreaks in Shanghai, PR China.

Introduction. The soaring resistance of Klebsiella pneumoniae to fluoroquinolones in PR China has substantially limited the application of these antimicrobials, especially in those clinical settings that were threatened by persistent carbapenem-resistant K. pneumoniae (CRKP), necessitating strict implementation of antimicrobial stewardship and active enhanced surveillance of infection control.Hypothesis. There is interplay between plasmid-mediated quinolone resistance (PMQR) determinants and quinolone resistance-determining region (QRDR) mutations during the acquisition of a clinically important fluoroquinolone resistance (CI-FR) profile in multidrug-resistant K. pneumoniae (MDR-KP) isolates.Aim. To investigate the high-risk CRKP clones responsible for nosocomial spread and analyse the molecular patterns of CI-FR in MDR-KP isolates in a tertiary hospital in Shanghai, PR China.Methodology. A total of 34 isolates, including 30 CRKPs, were molecularly characterized. Investigations included antimicrobial susceptibility tests, multilocus sequence typing (MLST) and wzi genotyping, PCR sequencing and phylogenetic analysis for resistance-associated genes, and clinical information retrieval from medical records.Results. Two high-risk CRKP clones, ST11-wzi64 and ST15-wzi19/wzi24, were identified as being responsible for nosocomial outbreaks in the intensive care unit (ICU) and the neurosurgery department, potentially by the respiratory route. QRDR mutations of both gyrA and parC were detected in isolates of ST15 (S83F/D87A/S80I), ST11 (S83I/D87G/S80I) and ST218 (D87A/S80I), respectively. The PMQR genes, qnrS1, aac(6')-Ib-cr and oqxAB, were present in 32 (94.1 %) of the isolates alone or in combination, co-occurring with genes (bla) encoding β-lactamases, 16S rRNA methylases and putrescine ABC permeases. AcrR, an AcrAB transcriptional repressor, was insertion-inactivated by the IS5-like element in ST11 isolates. The encoding sequences of OmpK35 and OmpK36 genes were associated with specific STs and wzi alleles. ST11, ST15-wzi19 and ST218 isolates had frameshift disruptions in OmpK35 and specific GD insertions at position 134-135 in OmpK36. The 27 isolates with clinically important ciprofloxacin resistance (MICs ≥2 mg l-1) included 25 isolates (ST15, ST11, ST218) with multiple QRDR mutations, plus 1 with only 2 PMQR determinants (ST290-wzi21) and another with an unknown resistance mechanism (ST65-wzi72). Ciprofloxacin-susceptible isolates maintained intact ompK36 genes, including two CRKPs each with ST13-wzi74 (KPC-2 and NDM-1 coproducers) and ST65-wzi72, plus carbapenem-susceptible isolates (ST15-wzi24, ST65-wzi72, ST107-wzi173).Conclusions. Under selective pressures, the accumulation of mutations of three types (QRDR, acrR, ompK36) and the acquisition of resistance-conferring genes have continuously contributed to CI-FR in MDR-KP isolates.

Prevalence of Plasmid-Mediated Quinolone Resistance Genes and Molecular Typing of Klebsiella pneumoniae Isolates from Blood Cultures in Milad Hospital, Tehran, Iran, Within 2018 - 2019

Background: Plasmid-mediated quinolone resistance (PMQR) determinants are commonly characterized in Klebsiella pneumoniae isolates worldwide and complicate the treatment of infections caused by this bacterium. Objectives: This study aimed to investigate the prevalence of PMQR determinants and molecular typing of blood isolates of K. pneumoniae in Milad hospital in Tehran, Iran, within 2018 - 2019. Methods: A total of 100 K. pneumoniae isolates were tested for susceptibility to quinolones using the disk diffusion method. The minimum inhibitory concentrations (MICs) of ciprofloxacin (CIP) and levofloxacin (LEV) were determined using the microdilution broth method. The PMQR determinants were detected by polymerase chain reaction (PCR) assay, and the genetic relationship between the isolates was assessed using enterobacterial repetitive intergenic consensus (ERIC)-PCR. Results: The resistance rates of the isolates to LEV, CIP, nalidixic acid, and norfloxacin were determined to be 62, 46, 29, and 23%, respectively. Eighty-one isolates were resistant to at least one tested quinolone. A high-level CIP and LEV resistance (MIC > 32 mg/L) was observed in 15 (18.51%) and 36 (44.44%) isolates, respectively. The PMQR genes were detected in 71 (87.65%) isolates. The oqxAB, qnrS, qnrD, qnrB, aac(6')-Ib-cr, qnrA, qepA, and qnrC genes were detected in 71 (87.65%), 30 (37%), 25 (30.8%), 24 (29.6%), 18 (22.2%), 17 (21%), 17 (21%), and 8 (9.9%) isolates, respectively. The ERIC-PCR revealed 64 genotypes among quinolone-resistant isolates. Conclusions: The high prevalence of PMQR genes observed in this study is a significant concern for public health since they can contribute to the spread of fluoroquinolone resistance among clinical isolates. The ERIC-PCR revealed high heterogeneity among the studied isolates, indicating that they emerged from different sources.

Prevalence of Plasmid-Mediated Quinolone Resistance (PMQRs) Determinants and Whole Genome Sequence Screening of PMQR-Producing E. coli Isolated from Men Undergoing a Transrectal Prostate Biopsy.

Fluoroquinolones (FQs) are recommended as prophylaxis for men undergoing transrectal prostate biopsy (TRUS-Bx). Recent studies suggest a significant share of FQ-resistant rectal flora in post-TRUST-Bx infections. Methods: 435 Enterobacterales isolates from 621 patients attending 12 urological departments in Poland were screened by PCR for PMQR genes. PMQR-positive isolates were tested for quinolone susceptibility and investigated by whole genome sequencing (WGS) methods. Results: In total, 32 (7.35%) E. coli strains with ciprofloxacin MIC in the range 0.125–32 mg/L harbored at least one PMQR gene. qnrS and qnrB were the most frequent genes detected in 16 and 12 isolates, respectively. WGS was performed for 28 of 32 PMQR-producing strains. A variety of serotypes and sequence types (STs) of E. coli was noticed. All strains carried at least one virulence gene. AMR genes that encoded resistance against different classes of antibiotics were identified. Additionally, five of 13 ciprofloxacin-susceptible E. coli had alterations in codon 83 of the GyrA subunits. Conclusion: This study provides information on the common presence of PMQRs among E. coli, which may explain the cause for development of post-TRUS-Bx infections. High numbers of virulence and antimicrobial resistance genes detected show a potential for analysed strains to develop infections.

Changes in the characteristics of community-onset fluoroquinolone-resistant Escherichia coli isolates causing community-acquired acute pyelonephritis in South Korea.

This study aimed to examine the changes in the characteristics of community-onset fluoroquinolone-resistant (FQ-R) Escherichia coli isolates causing community-acquired acute pyelonephritis (APN) in South Korea. Blood or urine samples were prospectively collected from patients aged ≥15 years with community-acquired APN who were admitted to one of the eight Korean hospitals included in this study between September 2017 and August 2018. Phylogenetic typing, multilocus sequence typing, and molecular characterization of β-lactamase resistance and plasmid-mediated quinolone resistance (PMQR) determinants were performed. The data were compared with those from a previous study with the same design conducted in 2010-2011. A total of 300 and 346 isolates were identified in 2010-2011 and 2017-2018, respectively. Among them, 76 (22.0%) and 77 (25.7%) FQ-R isolates were identified in 2010-2011 and 2017-2018, respectively. A significantly higher antimicrobial resistance against third-to fourth-generation cephalosporins, including cefotaxime (23.9% vs. 77.9%, P<0.001), were observed among FQ-R isolates in 2017-2018 than among those in 2010-2011. A higher proportion of ST131 isolates (27.6% vs. 66.2%, P<0.001), as well as isolates that had extended-spectrum β-lactamase (ESBL)/plasmid-mediated AmpC β-lactamase (PABL) (23.7% vs. 79.2%, P<0.001), was observed in 2017-2018 than in 2010-2011. Further, more PMQR determinants (11.8% vs. 40.8%, P<0.001) were observed in 2017-2018 than in 2010-2011. Among uropathogenic FQ-R E. coli isolates in South Korea, the prevalence of ST131 and the proportion of isolates containing ESBL and/or PMQR determinants have increased.

Molecular Characterization of Quinolone Resistance Determinants in Non-Typhoidal Salmonella Strains Isolated in Tehran, Iran

Background: Quinolone resistant Salmonella serotypes have been reported in recent years and have become increasingly widespread worldwide. Objectives: We evaluated the molecular mechanism of quinolone resistance in non-typhoidal Salmonella strains isolated from clinical samples in Tehran, Iran. Methods: The present study included the Salmonella isolates originated from hospitalized individuals and outpatients in Tehran, Iran. Serotyping of nalidixic acid-resistant Salmonella isolates was done by slide agglutination method. Then, the quinolone resistance-determining region (QRDR) of topoisomerase gene gyrA and the plasmid-mediated quinolone resistance (PMQR) determinants were detected using the polymerase chain reaction (PCR) method. Restriction fragment length polymorphism (RFLP) analysis was also employed to determine the possible mutation in the gyrA gene of those strains. Mutant strains were detected by enzymatic digestion, and their PCR products were sequenced immediately. Results: Amongst 141 isolates, 60% showed nalidixic acid resistance, whereas none of them were ciprofloxacin-resistant. The commonly prevalent serotypes were S. Enteritidis and S. Infantis. Of 85 nalidixic acid-resistant strains, 17 (20%) isolates harbored the qnrS gene. However, PCR analysis of the quinolone-resistant strains did not detect qnrA and qnrB genes. PCR-RFLP and sequencing analysis of the QRDRs of the gyrA gene indicated that 16 (18.8%) isolates had mutant patterns, and the most common point mutation was serine to phenylalanine at position 83. Conclusions: Our results demonstrated that point mutations in gyrA and the existence of plasmid-mediated gene qnrS were important mechanisms of quinolone resistance in non-typhoidal Salmonella strains isolated from human origin. Other alternative mechanisms of resistance, such as alterations in the expression of efflux pumps, should be studied to provide greater insight into the molecular mechanism of quinolone-resistant non-typhoidal Salmonella isolates.

Plasmid-mediated quinolone resistance determinants in fluoroquinolone-nonsusceptible Escherichia coli isolated from patients with urinary tract infections in a university hospital, 2009–2010 and 2020

ObjectivesThis study aimed to characterize the plasmid-mediated quinolone resistance (PMQR) in fluoroquinolone nonsusceptible E. coli (FQNSEC) isolated from patients with urinary tract infections (UTIs) in 2019–2010 and 2020. MethodsA total of 844 E. coli isolates were collected from UTI patients at National Cheng Kung University Hospital. The antimicrobial susceptibility of E. coli isolates to 21 antibiotics was determined by disk diffusion tests. The distribution of phylogenetic groups, virulence factor, and PMQR genes was determined by PCR. Conjugation assays were performed to investigate the transferability of qnr genes from FQNSEC isolates to E. coli C600. ResultsWe found 211 (41.9%) and 152 (44.7%) E. coli isolates were FQNSEC in 2009–2010 and 2020, respectively. Phylogenetic group B2 was dominant in FQNSEC isolates (52.34%), followed by group F (10.47%), group B1 (9.64%), and group D (9.64%). FQNSEC isolates were more resistant to 17 of 19 tested antimicrobial agents, compared to the fluoroquinolone susceptible E. coli. PMQR screening results showed 34, 22, and 10 FQNSEC isolates containing aac(6′)-Ib-cr, qnr genes, and efflux pump genes (qepA or oqxAB), respectively. PMQR E. coli isolates were more nonsusceptible to gentamicin, amoxicillin, ampicillin/sulbactam, imipenem, cefazolin, cefuroxime, cefmetazole, ceftriaxone, ceftazidime, and cefepime compared to non-PMQR FQNSEC. Moreover, 16 of 22 qnr-carrying plasmids were transferrable to the recipient C600. ConclusionHere, we reported the high prevalence of MDR- and XDR-E. coli in FQNSEC isolates. Moreover, qnr-carrying plasmids were highly transferable and led to the resistance to other classes of antibiotics in the transconjugants.

Characterization of plasmid-mediated quinolone resistance genes and extended-spectrum beta-lactamases in non-typhoidal Salmonella enterica isolated from broiler chickens.

Background and Aim:Antibiotic-resistant Salmonella is a public health concern. Fluoroquinolones and extended-spectrum beta-lactams are widely used for the treatment of Salmonella infections. This study focused on the detection of plasmid-mediated quinolone resistance (PMQR) and extended-spectrum beta-lactamase (ESBL) genes among multidrug-resistant (MDR) Salmonella enterica isolated from broilers.Materials and Methods:A total of 40 non-typhoidal S. enterica isolates were collected from 28 broiler chicken farms in four Iraqi Governorates. These isolates were examined for their susceptibility to 10 antimicrobial agents by disk-diffusion method followed by polymerase chain reaction assay for the detection of PMQR determinants and ESBLs genes.Results:Salmonella strains revealed high levels of resistance to the following antibiotics: Nalidixic acid 100%, levofloxacin (LEV) 97.5%, amoxicillin-clavulanic acid 95.0%, tetracycline 92.5%, and nitrofurantoin 80.0%. Otherwise, all isolates were susceptible to cefotaxime and ceftriaxone. All isolates were MDR, with 15 different profiles observed. Among 38 amoxicillin/clavulanic acid-resistant Salmonella isolates, 20 (52.6%) had the blaTEM gene, while blaSHV, blaCTX-M, and blaOXA genes were not detected. Only 5 (12.8%) out of 39 LEV-resistant isolates were positive for qnrB, three of which had blaTEM. No qnrC or qnrD, qnrS, aac(6`)-Ib-cr, qunA, and oqxAB genes were found in any of the tested isolates.Conclusion:This study demonstrates that broiler chickens may be considered a potential source for spreading MDR non-typhoidal Salmonella and ESBL traits in poultry production. Therefore, it is important to continuously monitor ESBL and PMQR genes to avoid the spread of resistant strains in the food chain and impact public health.

Investigation of plasmid-mediated quinolone resistance genes in carbapenem resistant Enterobacterales

Fluoroquinolones, are effective agents both against gram-positive and gram-negative bacteria. Quinolones show bactericidal effect as a result of inhibition of DNA gyrase and topoisomerase IV enzymes. Main quinolo resistance mechanisms are chromosomal mutations in these enzymes and decreased intracellular accumulation due to efflux pumps or decreased membrane uptake. Recently a new quinolone resistance mechanism mediated by plasmids has been defined. These plasmids carry genes called as qnr. Qnr genes do not cause quinolone resistance but they cause decreased quinolone susceptibility and lead to higher minimum inhibitory concentrations. Currently there are qnrA, qnrB, qnrC, qnrD and qnrS genes. This study was aimed to investigate the presence of plasmid-mediated quinolone resistance determinants in carbapenem resistant Enterobacterales isolates. A total 154 carbapenem resistant Enterobacterales isolates were included in the study. Presence of qnrA, qnrB, qnrC, qnrD and qnrS genes were investigated by multiplex polymerase chain reaction (PCR) method. The results of the PCR amplification revealed that qnrA was detected in two isolates (E6, E85) (1.29%), qnrB was detected in 12 isolates (8.4%) (E32, E43, E46, E61, E62, E84, E94, E149, E 166, E167, E177, E179) and qnrS was detected in six isolates (E15, E25, E57, E63, E70, E80) (4.54%). And one isolate (E9) was both positive for qnrB and qnrS. QnrC and qnrD were not detected in any isolates. Transferable quinolone resistance due to the dissemination of qnr genes may have important impacts in terms of infection control and treatment problems. Survey of plasmid mediated quinolone resistance will help to determine the size of the issue and guide the measures that should be taken to avoid escalation of resistance and dissemination problem.

Investigation of plasmid-mediated quinolone resistance genes among clinical isolates of Klebsiella pneumoniae in southwest Iran.

BackgroundExtensive and inappropriate use of quinolones has led to growing resistance rates to these broad‐spectrum antibiotics. The present study purposed to investigate the prevalence of plasmid‐mediated quinolone resistance (PMQR) genes in Klebsiella pneumoniae clinical isolates.MethodNinety‐two non‐repetitive K. pneumoniae clinical isolates were confirmed by standard microbiological methods. Antibacterial susceptibility of isolates toward seven agents from the quinolone family was evaluated by the disc diffusion method. Ciprofloxacin minimum inhibitory concentrations (MICs) were determined using the standard agar dilution method. PCR amplification was used to detect the existence of PMQR genes in the studied isolates.ResultsIn the present study, significant quinolones' resistance (40%) was observed in K. pneumoniae isolates, and most of the strains were resistant to nalidixic acid (94.6%) and ofloxacin (45.6%). MIC analysis showed 15 strains were resistant to 6–128 μg/ml of ciprofloxacin, and five were intermediately‐resistant. PMQR genes were detected in 88% of all isolates. Acc(6’)‐Ib‐cr was constituted half of the total PMQR genes detected among ciprofloxacin non‐susceptible isolates. Of 20 ciprofloxacin non‐susceptible isolates, 65% (n = 13) harbored multiple PMQR determinants, and 15 strains were determined as integron carriage.ConclusionThe findings of this study indicated considerable resistance against quinolones, which could be correlated with the extensive and inappropriate use of this class of antibiotics as empirical treatment.