Molecular identification of plasmid-mediated quinolone resistance genes among klebsiella pneumoniae clinical isolates from southwest Iran

In recent years, the resistance rate to quinolone antibiotics has been increasing in Klebsiella pneumoniae. Plasmid-mediated quinolone resistance (PMQR) genes are one of the factors causing resistance to quinolones. Hence, this study aimed to determine the incidence of PMQR genes in clinical K. pneumoniae isolates from southwest Iran. In total, 96 K. pneumoniae isolates were identified during the study period. Sixty-seven (69.8%) isolates were resistant to at least one quinolone antibiotic. Resistance rates to levofloxacin, norfloxacin, nalidixic acid, ofloxacin, and ciprofloxacin were 50% (48/96), 56.3% (54/96), 60.4% (58/96), 62.5% (60/96), and 68.8% (66/96), respectively. The highest frequencies of PMQR genes were related to qnrS, aac (6')-Ib-cr, and qnrB genes with 85.1% (57/67), 83.6% (56/67) and 65.7% (44/67), respectively. The qnrD, qnrC, qepA, and qnrA were detected in 23.9% (16/67), 19.4% (13/67), 13.4% (9/67), and 6.0% (4/67) of isolates, respectively. This study was the first to report a high-frequency rate of PMQR genes in K. pneumoniae isolates from the clinical setting of Ahvaz, southwest Iran. As a result, antibiotic prescribing policies should be amended to hinder the further spread of PMQR genes in the studied region.

Research advancements on the diversity and host interaction of gut microbiota in chickens

The maintenance of host health and immune function is heavily dependent on the gut microbiota. However, the precise contribution of individual microbial taxa to regulating the overall functionality of the gut microbiome remains inadequately investigated. Chickens are commonly used as models for studying poultry gut microbiota, with high-throughput 16S rRNA sequencing has emerged as a valuable tool for assessing both its composition and functionality. The interactions between the gut's microbial community and its host significantly influence health outcomes, disease susceptibility, and various mechanisms affecting gastrointestinal function. Despite substantial research efforts, the dynamic nature of this microbial ecosystem has led to inconsistencies in findings related to chicken gut microbiota, which is largely attributed to variations in rearing conditions. Consequently, the interaction between the chickens' gut microflora and its host remains inadequately explored. This review highlights recent advances in understanding these relationships, with a specific focus on microbial composition, diversity, functional mechanisms, and their potential implications for improving poultry production.

Prevalence and characterization of quinolone resistance and integrons in clinical Gram-negative isolates from Gaza strip, Palestine

BACKGROUND

Gram-negative bacteria with quinolone resistance and extended-spectrum beta-lactamases (ESBLs) present significant treatment challenges. This study evaluated the prevalence and characteristics of quinolone resistance in Gram-negative strains, investigating the relationship between plasmid-mediated quinolone resistance (PMQR), ESBLs, and integrons.

METHODS AND RESULTS

We collected 146 Gram-negative isolates from patients in three Palestinian hospitals. For quinolone resistance isolates, the presence and characterization of PMQR, β-lactamase genes and integrons were studied by PCR and sequencing. Out of 146 clinical isolates, 64 (43.8%) were resistant to quinolones, with 62 (97%) being multidrug-resistant (MDR) and 33 (51.5%) ESBL-producers. PMQR-encoding genes were present in 45 (70.3%) isolates, including aac(6')-Ib-cr (26.6%), qnrA (18.8%), qnrS1 (20.8%), and qnrB (6.4%). BlaCTX-M genes were detected in 50% (32/64) of isolates, with blaCTX-M-15 being the most common. BlaTEM-1, blaSHV-1 and blaVIM genes were found in 13, 6, and 4 isolates, respectively. Class I integrons were found in 31/64 (48%) of isolates, with 14 containing gene cassettes conferring resistance to trimethoprim (dhfr17, dfrA12, dfrA1) and aminoglycosides resistance genes (aadA1, aadA2, aadA5, and aadA6).

CONCLUSIONS

This study found a high rate of quinolone resistance, ESBL and integrons in clinical Gram-negative isolates from our hospitals. Urgent measures are crucial, including implementing an antimicrobial resistance surveillance system, to control and continuously monitor the development of antimicrobial resistance.

Antibiotic resistance and virulence profiles of Proteus mirabilis isolated from broiler chickens at abattoir in South Africa

BACKGROUND

Proteus mirabilis has been identified as an important zoonotic pathogen, causing several illnesses such as diarrhoea, keratitis and urinary tract infections.

OBJECTIVE

This study assessed the prevalence of P. mirabilis in broiler chickens, its antibiotic resistance (AR) patterns, ESBL-producing P. mirabilis and the presence of virulence genes.

METHODS

A total of 26 isolates were confirmed as P. mirabilis from 480 pooled broiler chicken faecal samples by polymerase chain reaction (PCR). The disk diffusion method was used to evaluate the antibacterial susceptibility test, while nine virulence genes and 26 AR genes were also screened by PCR.

RESULTS

All 26 P. mirabilis isolates harboured the ireA (siderophore receptors), ptA, and zapA (proteases), ucaA, pmfA, atfA, and mrpA (fimbriae), hlyA and hpmA (haemolysins) virulence genes. The P. mirabilis isolates were resistant to ciprofloxacin (62%) and levofloxacin (54%), while 8 (30.7%) of the isolates were classified as multidrug resistant (MDR). PCR analysis identified the blaCTX-M gene (62%), blaTEM (58%) and blaCTX-M-2 (38%). Further screening for AMR genes identified mcr-1, cat1, cat2, qnrA, qnrD and mecA, 12%, 19%, 12%, 54%, 27% and 8%, respectively for P. mirabilis isolates. The prevalence of the integron integrase intI1 and intI2 genes was 43% and 4%, respectively.

CONCLUSIONS

The rise of ciprofloxacin and levofloxacin resistance, as well as MDR strains, is a public health threat that points to a challenge in the treatment of infections caused by these zoonotic bacteria. Furthermore, because ESBL-producing P. mirabilis has the potential to spread to humans, the presence of blaCTX -M -producing P. mirabilis in broilers should be kept under control. This is the first study undertaken to isolate P. mirabilis from chicken faecal samples and investigate its antibiotic resistance status as well as virulence profiles in South Africa.

Characterization of Escherichia coli strains isolated from geese by detection of integron-mediated antimicrobial resistance

OBJECTIVES

Current research shows that the resistance of Escherichia coli (E. coli) is mainly related to integron gene cassettes. To assess the resistance of E. coli of goose origin and the carriage of its integron genes in four farms in Heilongjiang Province, antibiotic resistance phenotypes and the presence of various types of integrons were investigated.

METHODS

In this study, test strains were sampled and isolated from the farms, and 109 test strains were tested for drug sensitivity of 15 different antimicrobial drugs by the Kb disc diffusion method. Polymerase chain reaction was used to detect E. coli in three types of integrase genes (intI1, intI2, and intI3) and for sequencing analysis of the class I integron gene cassette.

RESULTS

Susceptibility test results show that more than 70% of tested strains exhibit resistant phenotypes to ampicillin, amoxicillin, imipenem, tetracycline, and doxycycline. The detection rate of class I integrons was 68.91%, while class II integrons and class III integrons were not detected. The detection rate of class I integrin gene cassette was 7.42%. Sequence analysis showed that strains carried different integron gene cassettes: dfrA17-aadA5, dfrA1-aadA1, dfrA27-arr-3, and aminoglycoside 3''-nucleotidyltransferase.

CONCLUSIONS

Results suggest that the detection rate of class I integrons is highly correlated with their drug resistance. Class I integrons provide a valuable guide to studying the spread and the expression of resistance genes and thus finding effective measures to prevent bacterial resistance.

Prevalence and characterisation of antimicrobial resistance genes and class 1 and 2 integrons in multiresistant Escherichia coli isolated from poultry production

A global increase in the populations of drug resistant bacteria exerts negative effects on animal production and human health. Our study has been focused on the assessment of resistance determinants in relation to phenotypic resistance of the 74 commensal E. coli isolates present in different ecological environments. The samples were collected from poultry litter, feces, and neck skin. Among the microorganisms isolated from the poultry litter (group A), the highest resistance was noted against AMP and DOX (100%). In the E. coli extracts from the cloacal swabs (group B), the highest resistance was observed against AMP (100%) and CIP (92%). The meat samples (group C) were characterized by resistance to AMP (100%) and STX (94.7%). Genes encoding resistance to β-lactams (bla_TEM, bla_CTX-M), fluoroquinolones (qnrA, qnrB, qnrS), aminoglycosides (strA-strB, aphA1, aac(3)-II), sulfonamides (sul1, sul2, sul3), trimethoprim (dfr1, dfr5, dfr7/17) and tetracyclines (tetA, tetB) were detected in the studied bacterial isolates. The presence of class 1 and 2 integrons was confirmed in 75% of the MDR E. coli isolates (plasmid DNA), of which 60% contained class 1 integrons, 15% contained class 2 integrons, and 11.7% carried integrons of both classes. Thus, it may be concluded that integrons are the common mediators of antimicrobial resistance among commensal multidrug resistant Escherichia coli at important stages of poultry production.

Characterization of Integrons and Quinolone Resistance in Clinical Escherichia coli Isolates in Mansoura City, Egypt

Escherichia coli is a common pathogen in both humans and animals. Quinolones are used to treat infections caused by Gram-negative bacteria, but resistance genes emerged. Only scarce studies investigated the association between plasmid-mediated quinolone resistance (PMQR) genes and integrons in clinical isolates of E. coli. The current study investigated the prevalence of quinolone resistance and integrons among 134 clinical E. coli isolates. Eighty (59.70%) isolates were quinolone-resistant, and 60/134 (44.77%) isolates were integron positive with the predominance of class I integrons (98.33%). There was a significant association between quinolone resistance and the presence of integrons (P < 0.0001). Isolates from Urology and Nephrology Center and Gastroenterology Hospital were significantly quinolone-resistant and integron positive (P ≤ 0.0005). Detection of PMQR genes on plasmids of integron-positive isolates showed that the active efflux pump genes oqxAB and qepA had the highest prevalence (72.22%), followed by the aminoglycoside acetyltransferase gene (aac(6′)-Ib-cr, 66.67%) and the quinolone resistance genes (qnr, 61.11%). Amplification and sequencing of integrons' variable regions illustrated that no quinolone resistance genes were detected, and the most predominant gene cassettes were for trimethoprim and aminoglycoside resistance including dfrA17, dfrB4, and dfrA17-aadA5. In conclusion, this study reported the high prevalence of PMQR genes and integrons among clinical E. coli isolates. Although PMQR genes are not cassette-born, they were associated with integrons' presence, which contributes to the widespread of quinolone resistance in Egypt.