Plasmid-mediated Quinolone Resistance Genes Research Articles

Antimicrobial resistance and genetic background of non-typhoidal Salmonella enterica strains isolated from human infections in São Paulo, Brazil (2000-2019).

Salmonella enterica causes Salmonellosis, an important infection in humans and other animals. The number of multidrug-resistant (MDR) phenotypes associated with Salmonella spp. isolates is increasing worldwide, causing public health concern. Here, we aim to characterize the antimicrobial-resistant phenotype of 789 non-typhoidal S. enterica strains isolated from human infections in the state of São Paulo, Brazil, along 20years (2000-2019). Among the non-susceptible isolates, 31.55, 14.06, and 13.18% were resistant to aminoglycosides, tetracycline, and β-lactams, respectively. Moreover, 68 and 11 isolates were considered MDR and Extended Spectrum β-Lactamase (ESBL) producers, respectively, whereas one isolate was colistin-resistant. We selected four strains to obtain a draft of the Genome Sequence; one S. Infantis (ST32), one S. Enteritidis (ST11), one S. I 4,[5],12:i:- (ST19), and one S. Typhimurium (ST313). Among them, three presented at least one of the following antimicrobial resistance genes (AMR) linked to mobile DNA: blaTEM-1B, dfrA1, tetA, sul1, floR, aac(6')-laa, and qnrE1. This is the first description of the plasmid-mediated quinolone resistance (PMQR) gene qnrE1 in a clinical isolate of S. I 4,[5],12:i:-. The S. Typhimurium is a colistin-resistant isolate, but did not harbor mcr genes, but it presented mutations within the mgrB, pmrB, and pmrC regions that might be linked to the colistin-resistant phenotype. The virulence pattern of the four isolates resembled the virulence pattern of the highly pathogenic S. Typhimurium UK-1 reference strain in assays involving the in vivo Galleria mellonella model. In conclusion, most isolates studied here are susceptible, but a small percentage present an MDR or ESBL-producer and pathogenic phenotype. Sequence analyses revealed plasmid-encoded AMR genes, such as β-lactam and fluoroquinolone resistance genes, indicating that these characteristics can be potentially disseminated among other bacterial strains.

The rate of frequent co-existence of plasmid-mediated quinolone resistance (PMQR) and extended-spectrum β-lactamase (ESBL) genes in Escherichia coli isolates from retail raw chicken in South Korea.

Since plasmid-encoded antibiotic resistance facilitates the emergence of antibiotic-resistant bacteria, the increasing prevalence of Escherichia coli harboring plasmid-mediated quinolone resistance (PMQR) and extended-spectrum β-lactamase (ESBL) genes is a public health concern. The objective of this study is to investigate the co-existence of PMQR and ESBL genes in E. coli isolates from retail raw chicken in South Korea. Among 67 ESBL-producing E. coli isolates from 40 retail raw chicken, more than half of them carried PMQR genes, including qnrS, aac(6')-Ib-cr, and oqxAB. The qnrS was predominantly (91.4%) detected in E. coli isolates carrying both PMQR and ESBL. The aac(6')-Ib-cr was detected in seven ESBL-producing E. coli strains, and 85.7% of the aac(6')-Ib-cr-positive strains also carried qnrS. Moreover, the strains co-harboring qnrS and aac(6')-Ib-cr exhibited increased resistance to ciprofloxacin and kanamycin. These results demonstrate that PMQR genes are frequently detected in ESBL-producing E. coli isolates from retail raw chicken in South Korea.

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.

The prevalence of plasmid-mediated quinolone resistance genes among Escherichia coli strains isolated from urinary tract infections in southwest Iran.

The extensive and inappropriate use of quinolones, which are frequently used as an effective treatment for urinary tract infection (UTI) patients, has led to resistance to these antibiotics. This study was designed to determine the prevalence of quinolones resistance and the presence of plasmid-mediated quinolone resistance (PMQR) genes among extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates. One hundred and fourteen E. coli isolates were collected from patients' urine samples. The susceptibility of isolates to selected antibiotics was tested by the Kirby-Bauer disk diffusion method. ESBL-producing isolates were identified phenotypically using a combination disk test. Using specific primers, the frequency of aac (6')-Ib, qnrA, qnrB, qnrC, qnrD, qnrS, and qepA genes was investigated by polymerase chain reaction (PCR). Among 26 ESBL-producing isolates, the highest resistance rate was observed toward nalidixic acid (80.8%) and ciprofloxacin (61.5%), respectively. Ninety-seven (85%) of all isolates harbored at least one PMQR gene, the most frequent one being aac(6')-Ib-cr variant (47.4%). Coexistence of aac(6')-Ib-cr variant and qnrB were the most broadly distributed genotype among quinolone resistance isolates. Notably, none of the isolates contained the qnrC, qnrD, and qepA genes. Our results highlight the significant prevalence of PMQR genes in ESBL-producing E. coli isolates in this region. Also, the aac (6')-Ib-cr variant was the most frequent gene, particularly in ESBL positive isolates. A regular periodic monitoring program is needed to control and hinder the more spread of antibiotic resistance phenomenon and contributed genes among UTI-causing E. coli isolates.

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.

Multidrug-Resistant Klebsiella pneumoniae Complex From Clinical Dogs and Cats in China: Molecular Characteristics, Phylogroups, and Hypervirulence-Associated Determinants.

Klebsiella pneumoniae complex is an increasingly important bacterial pathogen that is capable of causing severe organs and life-threatening disease. This study aimed to investigate the multidrug resistance, phylogroups, molecular characterization, and hypervirulence-associated determinants of the complex, which were isolated from clinical diseased dogs and cats. A total of 35 K. pneumoniae complex (2.3%; 95% confidence interval, 1.6–3.2) isolates were identified from 1,500 samples, all of which were collected randomly from veterinary hospitals in the 12 regions across China. Antimicrobial susceptibility testing showed that isolates were extremely resistant to amoxicillin–clavulanate (82.9%) and trimethoprim–sulfamethoxazole (77.1%). The rate of multidrug-resistant reached an astonishing 82.9% and found a carbapenemase-producing strain carrying IncX3-blaNDM−5 derived a cat from Zhejiang. The prevalence rates of extended-spectrum β-lactamase gene blaCTX−M and plasmid-mediated quinolone resistance gene aac(6')Ib-cr were 51.4% and 45.7%, respectively. The resistance gene aph(3')-Ia of isolates from cats was more significantly (p < 0.05) prevalent than that from dogs. Likewise, K. pneumoniae complex harbored hypervirulence-associated genes ybt (11.4%), iuc (5.7%), and iroB (2.9%). Three (8.6%) of the 35 isolates were determined as hypermucoviscous by the string test. Lipopolysaccharide serotype O1v2 had the highest percentage of 25.7%, but capsular serotypes presented diversity distribution among the isolates. The core–genome phylogenetic tree demonstrated most of the isolates belonged to the KpI phylogroup (91.4%). Multilocus sequence typing analysis identified 25 different STs; ST15 and ST37 were the most abundant accounting for isolates, followed by ST307, ST656, ST1408, and ST4566. In addition, the prevalence of IncFIB-type plasmid for cat isolates was significantly higher (p < 0.05) than that for dogs. Sequences of IncX3 in blaNDM−5-positive strain contained regions showing >99% nucleotide sequence identity to the reference plasmid pNDM-MGR194 from the human.

Water quality and antimicrobial resistant profile of Escherichia coli isolated from dug wells used for domestic purposes

The rapid spread of antimicrobial resistance (AMR) poses a significant threat to public safety. The use of water containing resistant bacteria could increase the risk of spreading AMR. This study assessed the quality of 143 dug wells used for domestic purposes in some communities in Nigeria and determined the resistance profile of isolated &lt;em&gt;Escherichia coli (E. coli)&lt;/em&gt;. The Microbact&lt;sup&gt;TM&lt;/sup&gt; identification kit was used to identify the isolates, and the susceptibility profile was evaluated using the Kirby-Bauer disc diffusion method. The combination disc technique was used to test all isolates for extended spectrum beta lactamase (ESBL) production. Polymerase chain reaction was used to identify ESBL genes, Integrons, and plasmid-mediated quinolone resistance genes. A total of 110 (76.9%) wells were contaminated by coliform bacteria. Of these, 94 (84.45%) wells yielded 202 &lt;em&gt;E. coli&lt;/em&gt; strains. The isolates were commonly resistant to ampicillin (60.9%) but were all susceptible to meropenem. Seventy-seven (38.1%) isolates were multi-drug resistant. Two isolates harbored blaCTX-M and blaTEM separately while four (19%) ciprofloxacin-resistant isolates carried the oqxAB/aac-lb-cr gene. All isolates with resistance genes harbored class 1 and/2 Integrons. Most wells had coliform counts far above the World Health Organization’s recommended limit, indicating that they are unsafe to drink. The presence of multidrug-resistant isolates in well water poses a serious risk to consumers since it might lead to outbreaks of untreatable water-borne diseases.

Enrofloxacin Promotes Plasmid-Mediated Conjugation Transfer of Fluoroquinolone-Resistance Gene qnrS

This study aimed to determine the effect of enrofloxacin (ENR) on the transfer of the plasmid-mediated quinolone resistance (PMQR) gene qnrS from opportunistic pathogen Escherichia coli (E2) to Salmonella Enteritidis (SE211) and to analyze the resistance characteristics of SE211-qnrS isolates. The plasmid carrying qnrS gene of E2 was sequenced by Oxford Nanopore technology. The plasmid carrying qnrS gene belonged to incompatibility group IncY. In vitro, the transfer experiment of IncY plasmid was performed by the liquid medium conjugation method. The conjugation transfer frequency of the IncY plasmid was 0.008 ± 0.0006 in the absence of ENR, 0.012 ± 0.003 in 1/32 MICENR, 0.01 ± 0.008 in 1/8 MICENR, and 0.03 ± 0.015 (Mean±SD) in 1/2 MICENR, respectively. After inoculation of E. coli E2 and SE211, chickens were treated with different doses of ENR (3.03, 10, and 50 mg/kg b.w.) for 7 days consecutively. To screen the SE211-qnrS strains from intestinal tract of chickens, the resistance genes and susceptibility of isolates were identified. The amount of E. coli E2 and the copy number of qnrS gene in the chicken intestinal tract were determined by colony counting and qPCR, respectively. In vivo, more SE211-qnrS strains were isolated from the treated group compared with the untreated group. SE211-qnrS strains not only obtained IncY plasmid, but also showed similar resistance phenotype as E2. In conclusion, ENR treatment can promote the spread of a IncY-resistance plasmid carrying the qnrS fluoroquinolone-resistance gene in Escherichia coli and the development of drug-resistant bacteria.

Clinically healthy household dogs and cats as carriers of multidrug-resistant Salmonella enterica with variable R plasmids

Introduction. Antimicrobial resistance (AMR) is a One Health issue concerning humans, animals and the environment and a unified One Health approach is required to contain this problematic issue. Dogs and cats are popular pet animals and are known to carry many bacterial pathogens that are of public health importance, including Salmonella. However, data on AMR in companion animals is limited.Gap statement. Scant AMR data from bacteria originating from companion animals limits an accurate assessment of the impacts of pet-animal-related AMR on public health.Purpose. This study aimed to phenotypically and genetically investigate AMR in Salmonella isolated from pet dogs and cats in Thailand.Methodology. Salmonella enterica were isolated from pet dogs (n=159) and cats (n=19) in Thailand between 2016 and 2019. All isolates were serotyped. Phenotypic and genotypic antimicrobial resistance was examined. PCR-based replicon typing, replicon sequence typing and plasmid multilocus sequence typing were conducted to characterize plasmids.Results. Seventy-seven serovars were identified, with serovars Weltevreden (9.6%) and Stockholm (9.0%) the most common. Most of the isolates (34.3%) were multidrug-resistant. The serovar Stockholm was an ESBL-producer and carried the β-lactamase genes bla TEM-1 and bla CTX-M-55. The plasmid-mediated quinolone resistance (PMQR) gene, qnrS, was also detected (10.1%). Class 1 integrons carrying the dfrA12-aadA2 cassette array were most frequent (45.9%). Five plasmid replicon types as IncA/C (0.6%), N (1.1%), IncFIIA (28.7%), IncHI1 (2.2%), and IncI1 (3.4%) were identified. Based on the pMLST typing scheme (n=9), plasmids were assigned into five different STs including IncA/C-ST6 (n=1), IncH1-ST16 (n=4), IncI1-ST3 (n=1), IncI1-ST60 (n=1) and IncI1-ST136 (n=1). The ST 16 of IncHI1 plasmid was a novel plasmid ST. Subtyping F-type plasmids using the RST scheme (n=9) revealed four different combinations of replicons including S1:A-:B- (n=4), S1:A-:B22 (n=2), S3:A-:B- (n=1) and S-:A-:B47 (n=1).Conclusions. Our findings highlight the role of clinically healthy household dogs and cats as carriers of AMR Salmonella strains with different R plasmid. The implementation of AMR phenotypes instigation and genotypic monitoring and surveillance programmes in companion animals are imperative as integral components of the One Health framework.

Occurrence of plasmid-mediated quinolone resistance genes in Pseudomonas aeruginosa strains isolated from clinical specimens in southwest Iran: a multicentral study

This study aimed to assess the presence of qnrA, qnrB, qnrC, qnrD, qnrS, qepA, and aac(6′)-Ib-cr determinants as well as quinolone resistance pattern of clinical isolates of P. aeruginosa in Ahvaz, southwest Iran. A total of 185 clinical isolates of P. aeruginosa were collected from 5 university-affiliated hospitals in Ahvaz, southwest Iran. The disk diffusion method was applied to assess the quinolone resistance pattern. The presence of qnrA, qnrB, qnrC, qnrD, qnrS, qepA, and aac(6′)-Ib-cr genes was investigated by the polymerase chain reaction (PCR) method. Overall, 120 (64.9%) isolates were non-susceptible to quinolones. The most and the less quinolone resistance rates were observed against ciprofloxacin (59.4%) and ofloxacin (45.9%), respectively. The prevalence rates of qnr genes were as follows: qnrA (25.8%), qnrB (29.2%), and qnrS (20.8%). The qnrB gene was the most common type of qnr genes. The qnr genes were occurred in 37.5% (n = 45/120) of quinolne-resistant isolates, simultaneously. The qnrC, qnrD, qepA, and aac(6′)-Ib-cr genes were not recognized in any isolates. In conclusion, the ofloxacin was the most effective quinolone. This study was the first to shed light on the prevalence of PMQR genes among P. aeruginosa isolates in southwest Iran.

Plasmid-Mediated Fluoroquinolone Resistance in Pseudomonas aeruginosa and Acinetobacter baumannii.

Introduction Pseudomonas aeruginosa and Acinetobacter baumannii are important pathogens in health care–associated infections. Fluoroquinolone resistance has emerged in these pathogens. In this study, we aimed to determine the occurrence of plasmid-mediated quinolone resistance (PMQR) determinants ( qnrA , qnrB , qnrS , aac(6′)-Ib-cr , oqxAB , and qepA ) by polymerase chain reaction (PCR) and the transmissibility of plasmid-borne resistance determinants in clinical isolates of P. aeruginosa and A. baumannii . Materials and Methods The study included P. aeruginosa (85) and A. baumannii (45) which were nonduplicate, clinically significant, and ciprofloxacin resistant. Antibiotic susceptibility testing was done by disk diffusion method for other antimicrobial agents, namely amikacin, ceftazidime, piperacillin/tazobactam, ofloxacin, levofloxacin, and imipenem. Minimum inhibitory concentration of ciprofloxacin was determined. Efflux pump activity was evaluated using carbonyl-cyanide m-chlorophenylhydrazone (CCCP). The presence of PMQR genes was screened by PCR amplification. Transferability of PMQR genes was determined by conjugation experiment, and plasmid-based replicon typing was performed. Results Resistance to other classes of antimicrobial agents was as follows: ceftazidime (86.9%), piperacillin/tazobactam (73.8%), imipenem (69.2%), and amikacin (63.8%). The minimal inhibitory concentration (MIC)50 and MIC90 for ciprofloxacin were 64 and greater than or equal to 256 µg/mL, respectively. There was a reduction in MIC for 37 (28.4%) isolates with CCCP. In P. aeruginosa , 12 (14.1%) isolates harbored qnrB , 12 (14.1%) qnrS , 9 (10.5%) both qnrB and qnrS , 66 (77.6%) aac(6′)-Ib-cr , and 3 (3.5%) oqxAB gene. In A. baumannii , qnrB was detected in 2 (4.4%), 1 (2.2%) harbored both the qnrA and qnrS , 1 isolate harbored qnrB and qnrS , 21 (46.6%) aac(6′)-Ib-cr , and 1 (2.2%) isolate harbored oqxAB gene. Notably, qepA gene was not detected in any of the study isolates. Conjugation experiments revealed that 12 (9.2%) were transferable. Of the transconjugants, seven (58.3%) belonged to IncFII type plasmid replicon, followed by four (33.3%) IncA/C and one (8.3%) IncFIC type. Conclusion The plasmid-mediated resistance aac(6′)-Ib-cr gene is primarily responsible for mediating fluoroquinolone resistance in clinical isolates of P . aeruginosa and A. baumannii . The predominant plasmid type is IncFII.

Carriage of plasmid-mediated qnr determinants and quinolone efflux pump (qepA) by ciprofloxacin-resistant bacteria recovered from Urinary Tract Infection (UTI) samples

BackgroundBacterial resistance to commonly-used antibiotics has been on the increase especially in the clinical settings. This study focused on the detection of plasmid-mediated quinolone resistance (PMQR) determinants in ciprofloxacin-resistant bacteria recovered from Urinary Tract Infection (UTI) samples.ResultsAlready characterized isolates from urine samples of UTI-diagnosed in- and out- patients were obtained from the culture pool of the Department of Medical Microbiology and Parasitology, University College Hospital (UCH), Ibadan, Nigeria. A total of seventy-three ciprofloxacin-resistant isolates were used in this study. Of the 73 UTI isolates, 43 carried at least one of the four PMQR genes targeted and they belonged to eight bacterial genera namely: Escherichia (25), Klebsiella (10), Pseudomonas (2), Proteus (2) and one isolate each belonging to Enterobacter, Acinetobacter, Citrobacter and Salmonella genera. qnrA was detected in 10.9% (8/73) of the isolates while the occurrence of qnrB and qnrS was 32.9% (24/73) and 20.5% (15/73), respectively. The quinolone efflux pump (qepA) was detected in 9/73 (12.3%) of the isolates. Thirty of the isolates carried only one PMQR gene, while thirteen carried two PMQR genes. There was no carriage of more than two PMQR genes in the forty-three isolates from which PMQR genes were detected.ConclusionThis study reports the carriage of PMQR determinants by eight of the nine Gram-negative bacterial genera from urinary sources in patients attending the University College Hospital, Ibadan over the four-month period of study. This is quite worrisome as it suggests a high contribution of UTI cases to the burden of quinolone resistance. There is a need for more studies of this nature in other hospitals in Nigeria, to develop a database on the contribution of UTI cases to quinolone resistance.

Virulence traits and plasmid-mediated quinolone resistance among Aggregatibacter actinomycetemcomitans from Iraq: Low rate of highly virulent JP2 genotype

Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is an important causative agent of periodontitis acting by employment of a series of virulence factors. Our aim was to evaluate the virulence traits and plasmid-mediated quinolone resistance of A. actinomycetemcomitans isolates in Iraq. A total of 1580 samples were collected from dental caries (n = 1190) and periodontitis (n = 390) among which 200 samples were positive. The antibiotic susceptibility pattern and biofilm formation were performed. The antibiotic resistance and virulence determinants were screened using polymerase chain reaction (PCR) technique. The ltx3 and ltx4 primers were used for identification of highly virulent JP2 type. A. actinomycetemcomitans was identified among dental caries (n = 114) and periodontitis (n = 86) samples. The JP2 type was identified in six periodontitis samples. Sixty (30% of) isolates were multidrug-resistant (MDR). Eighty-four (42% of) A. actinomycetemcomitans isolates formed strong biofilms and 44% of them had moderate-level biofilms. The detected virulence genes included ltxA (96%), cdtB (64%), qseB (62%), qseC (58%) and rcpA (58%). There was a significant relation between the existence of ltxA (42%, p = 0.041) and rcpA (64%, p = 0.022) genes and the biofilm formation. The JP2 genotype was identified in six adolescents with periodontitis. The rate of qnrA, qnrB, qnrC, qnrD, qnrS and aac(6′)-Ib-cr plasmid-mediated quinolone resistance genes included 22%, 18%, 16%, 16%, 14% and 0%, respectively. The qnrA (66.7%) and qnrB (53.4%) genes were significantly detected higher in MDR strains. Herein, A. actinomycetemcomitans from dental caries and periodontitis had relatively high rate of resistance to β-lactams but low resistance levels to quinolones. Moreover, most of the resistant isolates carried the qnrA-S genes. A majority of them had ltxA gene, half of them contained all the virulence genes and JP2 genotype was found in six isolates from periodontitis. Furthermore, half of the isolates produced biofilms which was significantly related to the ltxA and rcpA genes. Screening of virulence genes and antibiotic resistance pattern determination contribute to the control, diagnosis and eradication of these isolates.

Phenotypic and molecular characterization of β-lactamase and plasmid-mediated quinolone resistance genes in Klebsiella oxytoca isolated from slaughtered pigs in Thailand.

Background and Aim:Over recent years, antimicrobial-resistant Klebsiella species in humans, animals, food animals, food products, and agricultural environments have been the center of attention due to its role in the evolution of antimicrobial resistance. The emergence of resistance to fluoroquinolones and cephalosporins of third and higher generations in Klebsiella oxytoca has not received much attention in animal husbandry compared to that in Klebsiella pneumoniae. Reports on K. oxytoca are limited in the study area. Therefore, we investigated the antimicrobial susceptibility and resistance genes in K. oxytoca isolated from slaughtered pigs in Thailand.Materials and Methods:Microbiological examination was conducted on 384 Klebsiella spp. isolates recovered from slaughtered pigs in ten provinces of Thailand. Seventy-two K. oxytoca isolates (18.75%) were examined for antimicrobial-resistant genes (β-lactamase [blaTEM, blaCTX-M, and blaSHV]) and fluoroquinolone-resistant genes (qnrA, qnrB, qnrC, qnrD, qnrS, oqxAB, aac(6’)-Ib-cr, and qepA).Results:The most common genotype was blaCTX-M (58/72, 80.55%), followed by blaTEM with blaCTX-M (7/72, 9.72%) and blaTEM (6/72, 8.33%). The most common blaCTX-M group was blaCTX-M-1 (19/58, 32.76%), followed by blaCTX-M-9 (1/58, 1.72%). Plasmid-mediated quinolone resistance genes were identified in 13 (18.05%) isolates: qnrS (16.70%) and qnrB (1.4%). All 13 isolates had qnrS transferable to an Escherichia coli recipient, whereas qnrB was not detected in any transconjugants. Either blaCTX-M or blaTEM harbored by one K. oxytoca strain was transferable to an E. coli recipient. Analysis of antimicrobial susceptibility revealed that more than 90% of the blaCTX-M-carrying K. oxytoca isolates were susceptible to chloramphenicol, trimethoprim, ceftazidime, cefepime, cefotaxime, amoxicillin-clavulanic acid, piperacillin–tazobactam, and fosfomycin. All K. oxytoca isolates (13) harboring qnr were susceptible to carbapenem and ceftriaxone; however, 43 (74.13%) of the K. oxytoca isolates harboring blaCTX-M exhibited extended-spectrum β-lactamase activity. Most of the K. oxytoca isolates from pigs were highly resistant to ampicillin, azithromycin, and gentamicin.Conclusion:To prevent further transmission of Klebsiella spp. Between food animals and humans, strict control of antibiotic use in clinical and livestock settings is necessary along with routine disinfection of the livestock environment and efforts to increase awareness of antimicrobial resistance transmission.

A qnr-plasmid allows aminoglycosides to induce SOS in Escherichia coli.

The plasmid-mediated quinolone resistance (PMQR) genes have been shown to promote high-level bacterial resistance to fluoroquinolone antibiotics, potentially leading to clinical treatment failures. In Escherichia coli, sub-minimum inhibitory concentrations (sub-MICs) of the widely used fluoroquinolones are known to induce the SOS response. Interestingly, the expression of several PMQR qnr genes is controlled by the SOS master regulator, LexA. During the characterization of a small qnrD-plasmid carried in E. coli, we observed that the aminoglycosides become able to induce the SOS response in this species, thus leading to the elevated transcription of qnrD. Our findings show that the induction of the SOS response is due to nitric oxide (NO) accumulation in the presence of sub-MIC of aminoglycosides. We demonstrated that the NO accumulation is driven by two plasmid genes, ORF3 and ORF4, whose products act at two levels. ORF3 encodes a putative flavin adenine dinucleotide (FAD)-binding oxidoreductase which helps NO synthesis, while ORF4 codes for a putative fumarate and nitrate reductase (FNR)-type transcription factor, related to an O2-responsive regulator of hmp expression, able to repress the Hmp-mediated NO detoxification pathway of E. coli. Thus, this discovery, that other major classes of antibiotics may induce the SOS response could have worthwhile implications for antibiotic stewardship efforts in preventing the emergence of resistance.

High carriage of plasmid-mediated quinolone resistance (PMQR) genes by cefotaxime-resistant Escherichia coli recovered from surface-leaking sanitary sewers.

There is a rapid rise in the incidence of quinolone resistant bacteria in Nigeria. Most studies in Nigeria have focused on isolates from the clinical settings, with few focusing on isolates of environmental origin. This study aimed to investigate the antibiogram and carriage of plasmid-mediated quinolone resistance (PMQR) genes by quinolone-resistant isolates obtained from a pool of cefotaxime-resistant Escherichia coli (E. coli) recovered from sewage leaking out of some surface-leaking sanitary sewers in a University community in Nigeria. Isolation of E. coli from the sewage samples was done on CHROMagar E. coli, after enrichment of the samples was done in Brain Heart Infusionbroth amended with 6µg/mL of cefotaxime. Identification of presumptive E. coli was done using molecular methods (detection of uidA gene), while susceptibility to antibiotics was carried out using thediscdiffusion method. Detection of PMQR genes (qnrA, qnrB, qnrS, aac(6')-lb-cr, qepA and oqxAB) was carried out using primer-specific PCR. A total of 32 non-repetitive cefotaxime-resistant E. coli were obtained from the sewage, with 21 being quinolone-resistant. The quinolone-resistant isolates showed varying level of resistance to the tested antibiotics, with imipenem being the only exception with 0% resistance. The PMQR genes: aac(6')-lb-cr, qnrA, qnrB, qnrS and qepA and oqxAB were detected in 90.5%, 61.9%, 47.6%, 38.1%, 4.8% and 0% respectively of the isolates. The findings of this study showed a high level of resistance to antibiotics and carriage of PMQR genes by quinolone-resistant E. coli obtained from the leaking sanitary sewers, suggesting a potential environmental and public health concern.

High levels of gut carriage of antimicrobial-resistant Escherichia coli in community settings in Rio de Janeiro, Brazil.

The prevalence and risk factors for gut carriage of antimicrobial-resistant Escherichia coli among individuals living in the community in Rio de Janeiro, Brazil, are unknown. The aim of this study was to determine the prevalence of colonization with antimicrobial-resistant E. coli, including isolates producing ESBL and harboring plasmid-mediated quinolone resistant (PMQR) genes in this community. We performed a cross-sectional study and analyzed fecal specimens of individuals attending outpatient clinics in the city from January 2015 to July 2019. We investigated susceptibility to antimicrobial agents by disc diffusion tests and used PCR to determine ESBL types, PMQR, and the virulence genes that characterize an isolate as extraintestinal pathogenic E. coli (ExPEC). Among the 623 subjects, 212 (34%) carried an isolate resistant to at least one of the tested antimicrobial agents, with the highest frequencies of resistance to ampicillin (26%), trimethoprim-sulfamethoxazole (19%), cefazolin (14%), and ciprofloxacin (CIP, 9%). In addition, 13% (81) of subjects carried a multidrug-resistant-E. coli (MDR-E), including 47 (8% of all isolates) ESBL-producing E. coli (ESBL-E), mainly of CTX-M-8 (15, 32%) and CTX-M-15 (9, 20%) types. PMQR genes were present in 7% (42) of all isolates, including 60% (32) of the 53 resistant to CIP. Previous use of antimicrobial agents, particularly fluoroquinolones, was a risk factor for colonization with MDR-E (25%, 20/81 vs 13%, 70/542, p = 0.01), ESBL-E (28%, 13/47, vs 13%, 77/576, p = 0.01), and resistance to CIP (26%, 14/53, vs 12%, 70/570, p = 0.01). The most pathogenic phylogroups B2, C, and D were 37% of the MDR-E, 30% of the ESBL-E, 38% of the CIP-resistant, and 31% of PMQR gene carrying E. coli isolates. We show that carriage of MDR-E (mostly ESBL-E) reached high levels in the community in Rio de Janeiro, increased by the selection of antimicrobial agents. Much of the resistant E. coli isolates are potential pathogenic strains. The widespread use of antimicrobial agents during the COVID-19 pandemic in Brazil may have worsened this picture.

Public health implications of plasmid-mediated quinolone and aminoglycoside resistance genes in Escherichia coli inhabiting a major anthropogenic river of India.

Abstract Presence of antimicrobial resistance (AMR) genes in Escherichia coli inhabiting anthropogenic rivers is an important public health concern because plasmid-mediated AMR genes can easily spread to other pathogens by horizontal gene transfer. Besides β-lactams, quinolones and aminoglycosides are the major antibiotics against E. coli. In the present study, we have investigated the presence of plasmid-mediated quinolone resistance (PMQR) and aminoglycoside resistance genes in E. coli isolated from a major river of northern India. Our results revealed that majority of the strains were phenotypically susceptible for fluoroquinolones and some aminoglycosides like amikacin, netilmicin, tobramycin and gentamicin. However, 16.39% of the strains were resistant for streptomycin, 8.19% for kanamycin and 3.30% for gentamicin. Of the various PMQR genes investigated, only qnrS1 was present in 24.59% of the strains along with ISEcl2. Aminoglycoside-resistance genes like strA-strB were found to be present in 16.39%, aphA1 in 8.19% and aacC2 in only 3.30% of the strains. Though, no co-relation was observed between phenotypic resistance for fluorquinolones and presence of PMQR genes, phenotypic resistance for streptomycin, kanamycin and gentamicin exactly co-related with the presence of the genes strA-strB, aphA1 and aacC2, respectively. Moreover, all the AMR genes discerned in aquatic E. coli were found to be situated on conjugative plasmids and, thus easily transferrable. Our study accentuates the importance of routine surveillance of urban rivers to curtail the spread of AMR genes in aquatic pathogens.

Antimicrobial susceptibility and molecular characterization of Salmonella enterica serovar Indiana from foods, patients, and environments in China during 2007–2016

Salmonella enterica serovar Indiana has become a widely prevalent non-typhoidal serovar in China in recent years. To improve the understanding of antimicrobial resistance and genetic bias in this emerging pathogen, a total of 214 S . Indiana isolates from foods, patients, and the environments in China from 2007 to 2016 were characterized for antimicrobial susceptibility, antimicrobial resistance-determining factors, and molecular typing. It was found that 208 (97.2%) exhibited resistance to ciprofloxacin, and 102 (47.7%) isolates to ceftriaxone. Ciprofloxacin resistance increased from 82.4% in 2007–2008 to 100.0% in 2015–2016. Ceftriaxone resistance increased from 29.4% in 2007–2008 to 47.1% in 2015–2016. In particular, the proportion of multidrug-resistant (MDR) S. Indiana isolates increased from 64.7% in 2007–2008 to 91.4% in 2015–2016. Mutations in the quinolone resistance determining region (QRDR) ( gyr A and par C), plasmid-mediated quinolone resistance (PMQR) genes [ aac(6’)-Ib-cr , oqx AB, qnr A, qnr S, qnr B and qep A], extended-spectrum beta-lactamase (ESBL) genes ( bla OXA , bla CTX-M , bla TEM , bla CMY and bla VEB ), and class I integrons were identified in these S. Indiana isolates, along with transposon units of ΔIS Ecp1 - bla CTX-M-65 -IS 903B , IS Ecp1 -IS Vsa5 - bla CTX-M-14 -IS 903B , and IS Ecp1 - bla CTX-M-55/15 -Δ orf 477. To our knowledge, the ESBL gene bla VEB was identified in Salmonella for the first time. Diverse plasmid types (IncHI2, IncN, IncA/C, IncFIB, IncI1 and IncFII) were identified in these isolates, among which IncHI2-type plasmid (49.1%) was the most common type in S . Indiana. Multilocus sequence typing (MLST) showed a single ST17 in S . Indiana. Pulsed-field gel electrophoresis (PFGE) results showed that there was a genotypic diversity, and some clones might have existed in S . Indiana between patients and foods for several years. These findings suggested that the frequent emergence of S . Indiana isolates with resistance to ciprofloxacin and ceftriaxone would pose a huge threat to food safety and public health. ∙ Ciprofloxacin and ceftriaxone co-resistant isolates were found. ∙ESBLs genes, PMQR genes with mutations in QRDR and class I integrons were observed. ∙ bla VEB was identified in Salmonella for the first time. ∙IS Ecp1 , IS Vsa5 and IS 903B was adjacent to bla CTX-M. ∙ST17 and genotypic diversity were identified in S. Indiana.

Plasmid-mediated quinolone resistance determinants in clinical bacterial pathogens isolated from the Western Region of Ghana: a cross-sectional study.

quinolones are critically important antibiotics that are reserved for treating very severe infections caused by multidrug-resistant bacterial pathogens. However, their indiscriminate uses have resulted in an increased number of resistant strains in many parts of the world including Ghana. We determined the quinolone resistance profile of Gram-negative bacterial pathogens and characterized the underlying molecular determinants of resistance. Gram-negative pathogens obtained from clinical specimens at three hospital laboratories were tested for resistance to quinolones and other commonly used antibiotics. ESBL production among the Enterobacterial isolates was confirmed using the combined disc diffusion method. We then used PCR to determine seven types of plasmid-mediated quinolone resistance genes present in the isolates resistant to nalidixic acid and ciprofloxacin. in this study, 29.5% of the isolates were resistant to ciprofloxacin, with the highest of 50% among E. coli resistance to the other quinolones was levofloxacin (24.4%), norfloxacin (24.9%), and nalidixic acid (38.9%). Significant proportions of the quinolone-resistant isolates were ESBL producers (P-values < 0.001). The aac(6´)-Ib-cr, qnrS, oqxA, and qepA genes were present in 43 (89.6%), 27 (56.3%), 23 (47.9%), and one (2.1%) of the isolates, respectively. None of the isolates tested positive to qnrA, qnrB, and oqxB genes. The presence of the aac(6´)-Ib-cr gene positively correlated with resistance to ceftriaxone, cefotaxime, and gentamicin (P-values < 0.05). high proportions of Gram-negative bacterial isolates were resistant to quinolones and most of these isolates possessed multiple PMQR genes. There is a need to implement measures to limit the spread of these organisms.