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 bla TEM, bla SHV and bla CTX-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.

Upregulation of pmrA, pmrB, pmrC, phoQ, phoP, and arnT genes contributing to resistance to colistin in superbug Klebsiella pneumoniae isolates from human clinical samples in Tehran, Iran

Background

Antibiotic resistance in Klebsiella pneumoniae isolates, particularly resistance to colistin, has become a growing concern. This study seeks to investigate the upregulation of specific genes (pmrA, pmrB, pmrC, phoQ, phoP, and arnT) that contribute to colistin resistance in K. pneumoniae isolates collected from human clinical samples in Tehran, Iran.

Methods

Thirty eight K. pneumoniae isolates were obtained and subjected to antibiotic susceptibility testing, as well as evaluation for phenotypic AmpC and ESBL production according to CLSI guidelines. The investigation of antibiotic resistance genes was conducted using polymerase chain reaction (PCR), whereas the quantification of colistin resistance related genes expressions was performed via Real-Time PCR.

Results

The highest and lowest antibiotics resistance were observed for cefotaxime 33 (86.8%) and minocycline 8 (21.1%), respectively. Twenty-four (63.2%) and 31 (81.6%) isolates carried AmpC and ESBLs, respectively. Also, antibiotic resistance genes containing blaNDM, blaIMP, blaVIM, blaSHV, blaTEM, blaCTXM, qnrA, qnrB, qnrS, and aac(6')-Ib were detected in K. pneumoniae isolates. Only 5 (13.1%) isolates were resistant to colistin and the MIC range of these isolates was between 4 and 64 μg ml-1. Upregulation of the pmrA, pmrB, pmrC, phoQ, phoP, and arnT genes was observed in colistin-resistant isolates. The colistin-resistant isolates were found to possess a simultaneous presence of ESBLs, AmpC, fluoroquinolone, aminoglycoside, and carbapenem resistant genes.

Conclusions

This study reveals escalating antibiotic resistance in K. pneumoniae, with notable coexistence of various resistance traits, emphasizing the need for vigilant surveillance and innovative interventions.

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.

Isolation and characterization of chromium (VI) tolerant bacteria from tannery effluents

BACKGROUND

The tannery industry is a potent environment polluting agent worldwide. Chromium (VI) is a major heavy metal in tannery effluents and their accumulation in soil and water is a serious environmental problem. This study investigates the capacity of indigenous bacteria isolated from tannery effluents for tolerance to chromium (VI).

METHODS

The chromium tolerance of isolates assessed through both agar dilution and broth microdilution methods. Isolates were identified by morphological and biochemical analysis. The tolerance of isolates to cadmium, nickel, lead, and vanadium and also their multidrug-resistant (MDR) profile were determined. Then the top isolate was characterized via 16S rRNA sequencing and its growth temperature and pH were optimized. Finally, the kinetic of chromium biosorption and chromium removal efficiency was determined using a Nutrient broth medium and wastewater containing 20 mg/L chromium, respectively.

RESULTS

Of 32 screened chromium tolerant isolates, 14 isolates with higher chromium tolerance were selected for further study. 78.57% of isolates represented simultaneous MDR and Multi Heavy Metal tolerance (MHMT) phenotypes and MDR indices of 0.2-1 indicating their source from niches with high antibiotic contamination. However, there was no significant correlation between MDR and MHMT phenotypes among isolates. The top isolate was identified as Lactococcus lactis and showed optimal growth at pH 6 and 25 °C. The maximum chromium biosorption occurred at the end of the exponential phase upon optimized conditions and the approximate chromium removal efficiency of 52.5% was obtained.

CONCLUSION

The isolated bacteria specifically L. lactis after more evaluations, may show the potential for bioremediation of chromium from tannery effluents.

Fluoroquinolone resistance contributing mechanisms and genotypes of ciprofloxacin- unsusceptible Pseudomonas aeruginosa strains in Iran: emergence of isolates carrying qnr/aac(6)-Ib genes

BACKGROUND

Fluoroquinolones (FQs) including ciprofloxacin (CIP) are key antibiotics for the treatment of Pseudomonas aeruginosa infections, but resistance to FQs is developing as a result of chromosomal mutations or efflux pump effects. Plasmid-mediated quinolone resistance (PMQR) has been recently reported in the Enterobacteriaceae family. This study aimed to investigate the mechanisms of CIP insusceptibility in P. aeruginosa isolates from ICU patients and to characterize their genotypes.

METHODS

A total of 40 ciprofloxacin unsusceptible (CIP-US) P. aeruginosa isolates from Tehran hospitals were recruited in this study. A broth microdilution assay was performed to find acquired resistance profiles of the isolates. All isolates were screened for target-site mutations (gyrA and parC), PMQR genes, and efflux pumps (mexB, D, Y, and E) expression. Clonality was determined by random amplified polymorphic DNA (RAPD)-PCR, and genotyping was performed on 5 selected isolates by analyzing 7 loci in the existing multilocus sequence typing scheme.

RESULTS

Thirty-eight out of 40 CIP-US isolates (95%) were categorized as MDR. Seven (17.5%) had gyrA mutation in codons 83, and no mutation was detected in parC; 77.5% of the isolates were positive for PMQR genes. Among PMQR genes, qnrB (30%), qnrC (35%), and qnrD (30%) predominated, while qnrA, qnrS, and aac(6)-Ib genes were harbored by 20.5%, 12.5%, and 15% of the isolates respectively. Efflux pump protein expression was observed in 35% of the isolates. After RAPD-PCR, 19 different genotypes were yielded, and 5 of them were classified into sequence types (STs): 773, 1160, 2011, 2386, and 359.

CONCLUSION

In this first-time study on P. aeruginosa CIP-US strains from Iranian ICU patients, three main CIP unsusceptibility mechanisms were investigated. A single mutation in one CIP target enzyme could explain high CIP resistance. qnr genes in the isolates can be considered as a CIP-unsusceptibility mechanism among studied isolates. Efflux pumps have more contribution in multidrug resistance than CIP susceptibility. CIP-US isolates of this study have not spread from distinct clonal strains and probably emerged from different sources. STs identified for the first time in this study in Iran should be considered as emerging MDR strains.

Symptoms, risk factors, diagnosis and treatment of urinary tract infections

Urinary tract infection (UTI) is a common microbial infection found in all ages and sexes which involves inflammation of the urinary tract. These infections can range from simple bladder inflammation, that is, cystitis, to severe cases of uroseptic shock. UTI ranks as the number 1 infection that leads to a prescription of antibiotics after a doctor's visit. These infections are sometimes distressing and even life threatening, and both males (12%) and females (40%) have at least one symptomatic UTI throughout their lives. Diagnostic failures in case of bacterial infections are the main contributing factor in improper use of antibiotics, delay in treatment and low survival rate in septic conditions. So, early diagnosis and appropriate therapy with antibiotics are the most significant requirements for preventing complicated UTI conditions such as urosepsis. This review article summarises the symptoms of the UTIs and the associated risk factors to it. The various conventional and recent diagnostic methods were also discussed in this review, along with treatment therapies with or without antibiotics.