Prevalence of ESBL and AmpC genes in E. coli isolates from urinary tract infections in the north of Iran

Phenotypic and Genotypic Identification of Four Cases of Plasmid-Mediated AmpC β-Lactamases-Producing Escherichia coli Admitted to a Tertiary Centre

We describe four patients with a positive culture of AmpC β-lactamases-producing Escherichia coli (E. coli), despite the fact that our understanding of plasmid-mediated AmpC β-lactamases (pAmpC) is currently limited. Three out of four cases of AmpC β-lactamases-producing Escherichia coli were isolated from a urine sample, and one was from a peritoneal fluid sample. All four isolates are resistant to cefoxitin disc and were subjected to a confirmatory AmpC phenotypic test (AmpC induction test) and monoplex polymerase chain reaction (PCR) for the determination of six pAmpC genotypes (blaDHA, blaEBC, blaMOX, blaFOX, blaACC, and blaCIT). All four E. coli isolates tested negative for the AmpC induction test, while monoplex PCR analysis was positive only for the blaDHA pAmpC genotype and negative for all five other genotypes (blaEBC, blaMOX, blaFOX, blaACC, and blaCIT). A common clinical characteristic across all patients was fever. One patient was treated for perforated sigmoid diverticulitis, while the other three patients were treated for acute pyelonephritis or urinary tract infections (UTIs). Each patient improved significantly and was successfully discharged.

A review of the mechanisms that confer antibiotic resistance in pathotypes of E. coli

The dissemination of antibiotic resistance in Escherichia coli poses a significant threat to public health worldwide. This review provides a comprehensive update on the diverse mechanisms employed by E. coli in developing resistance to antibiotics. We primarily focus on pathotypes of E. coli (e.g., uropathogenic E. coli) and investigate the genetic determinants and molecular pathways that confer resistance, shedding light on both well-characterized and recently discovered mechanisms. The most prevalent mechanism continues to be the acquisition of resistance genes through horizontal gene transfer, facilitated by mobile genetic elements such as plasmids and transposons. We discuss the role of extended-spectrum β-lactamases (ESBLs) and carbapenemases in conferring resistance to β-lactam antibiotics, which remain vital in clinical practice. The review covers the key resistant mechanisms, including: 1) Efflux pumps and porin mutations that mediate resistance to a broad spectrum of antibiotics, including fluoroquinolones and aminoglycosides; 2) adaptive strategies employed by E. coli, including biofilm formation, persister cell formation, and the activation of stress response systems, to withstand antibiotic pressure; and 3) the role of regulatory systems in coordinating resistance mechanisms, providing insights into potential targets for therapeutic interventions. Understanding the intricate network of antibiotic resistance mechanisms in E. coli is crucial for the development of effective strategies to combat this growing public health crisis. By clarifying these mechanisms, we aim to pave the way for the design of innovative therapeutic approaches and the implementation of prudent antibiotic stewardship practices to preserve the efficacy of current antibiotics and ensure a sustainable future for healthcare.

Phylogenetic analysis, biofilm formation, antimicrobial resistance and relationship between these characteristics in Uropathogenic Escherichia coli

BACKGROUND

In the present study, we examine the prevalence of phylogenetic groups, O-serogroups, adhesin genes, antimicrobial resistance, the level of gene expression associated with biofilm formation, and the presence of extended-spectrum beta-lactamase (ESBL) in UPEC strains isolated from both pediatric and adult patients.

METHODS

In this cross-sectional study, 156 UPEC isolates were collected from UTI patients. ESBL-producing isolates were detected using the double-disc synergy (DDS) method, and biofilm formation was assessed through a microplate assay. The presence of O-serogroups, adhesion factors and resistance genes, including ESBLs and PMQR genes, was detected by PCR, and isolates were categorized into phylogenetic groups using multiplex PCR. Additionally, the quantitative real-time PCR method was also used to determine the expression level of genes related to biofilm.

RESULTS

During the study period, 50.6% (79/156) of the samples were obtained from children, and 49.4% (77/156) were from adults. The highest rate of resistance was to NA (91.7%), while FM (10.9%) had the lowest rate of antibiotic resistance. In addition, 67.9% (106/156) of UPEC isolates were ESBL producers. Most of UPEC isolates belonged to phylogenetic group B2 (37.1%). This study revealed that blaCTX-M and qnrS are widely distributed among UPEC isolates. The mean expression levels of fimA genes were significantly higher in non-biofilm producers than in biofilm producers (p < 0.01).

CONCLUSIONS

The high antibiotic resistance rates in this study highlight the significance of local resistance monitoring and investigating underlying mechanisms. Our findings indicate the dominance of phylogroup B2 and group D as the prevailing phylogenetic groups. Consequently, it is imperative to investigate the epidemiological aspects and characterize UPEC isolates across diverse regions and time frames.

Neonatal intensive care units: extended spectrum β-lactamase genes and biofilm formation by Serratia marcescens

BACKGROUND

The increasing cases of bloodstream infections among children at neonatal intensive care units (NICUs) led this work to investigate biofilm production, antibiotics and the presence of ESβL genes in Serratia marcescens (S. marcescens) strains isolated from blood.

METHODS

Twenty S. marcescens strains were isolated and identified by the VITEK-2 system over 7 months from late 2022 to mid-2023 from Ibn Al-Balady Hospital in Baghdad. Kirby-Bauer test was used to measure antibiotic susceptibility.

RESULTS

The results revealed that 95% of twenty S. marcescens isolates were non-susceptible to Ampicillin and Amoxicillin-clavulanic. Furthermore, S. marcescens isolates showed a high sensitivity rate 70% toward Imipenem. All S. marcescens strains 100% were produced biofilm. This work clarifies that, out of 20 S. marcescens strains, 80% were harbored ESβL genes. The coexistence of blaTEM, blaCTX and blaSHV genes was shown in 43.75% of strains, while 56.25% of S. marcescens strains harbored single ES[Formula: see text]L genes. The biofilm values increase with the accuracy of EsβL genes. Phylogenetic analyses based on the sequence of blaCTX-M and blaTEM were done with closely related genes in the GenBank using MEGA6 software.

CONCLUSIONS

The distribution of blaTEM, blaCTX and blaSHV genes among local S. marcescens strains may be attributed to the indiscriminate use of antibiotics. The results confirmed the spread of ESβL genes in S. marcescens from blood infections among newborn infants.

Molecular detection of plasmid mediated blaTEM, blaCTX-M,and blaSHV genes in Extended Spectrum β-Lactamase (ESBL) Escherichia coli from clinical samples

BACKGROUND

Extended spectrum β-lactamases (ESBLs) are a group of beta-lactamase enzymes that confer resistance to the oxyimino-cephalosporins and monobactams. The emergence of ESBL - producing genes possesses a serious threat for treating infections since it is associated with multi-drug resistance. This study was focused to identify the ESBLs producing genes from Escherichia coli isolates from clinical samples from a referral-level tertiary care hospital in Lalitpur.

METHODS

This was a cross-sectional study conducted from September 2018 to April 2020 at the Microbiology Laboratory of Nepal Mediciti Hospital. Clinical samples were processed, and culture isolates were identified and characterized following standard microbiological techniques. An antibiotic susceptibility test was performed by a modified Kirby-Bauer disc diffusion method as recommended by Clinical and Laboratory Standard Institute guidelines.Extended -spectrum beta-lactamases were phenotypically confirmed by the combined disc method. The ESBL-producing genes bla_TEM, bla_CTX-M and bla_SHV were confirmed by PCR.

RESULTS

Of the 1449 total E. coli isolates, 22.29% (323/1449) isolates were multi-drug resistant (MDR). Among the total MDR E. coli isolates, 66.56% (215/323) were ESBL producers. The maximum number of ESBL E. coli was isolated from urine 90.23% (194) followed by sputum 5.58% (12), swab 2.32% (5), pus 0.93% (2), and blood 0.93% (2). The antibiotic susceptibility pattern of ESBL E. coli producers showed the highest sensitivity toward tigecycline (100%) followed by polymyxin b, colistin and meropenem. Out of 215 phenotypically confirmed ESBL E. coli, only 86.51% (186) isolates were found to be positive by PCR for either bla_TEM or bla_CTX-M genes. Among the ESBL genotypes, the most common were bla_TEM 63.4% (118) followed by bla_CTX-M 36.6% (68).

CONCLUSION

The emergence of MDR and ESBL - producing E. coli isolates with high antibiotic - resistant rates to commonly used antibiotics and increased predominance of major gene types bla_TEM is a serious concern to the clinicians and microbiologists. Periodic monitoring of antibiotic susceptibility and associated genes would help guide the rationale use of antibiotics for treating the predominant pathogen E. coli in the hospitals and healthcare facilities of the communities.

High prevalence of β-lactam and fluoroquinolone resistance in various phylotypes of Escherichia coli isolates from urinary tract infections in Jiroft city, Iran

BACKGROUND

Urinary tract infection (UTI) is one of the most prevalent infectious diseases with worldwide health threatening. Antimicrobial resistant strains of Escherichia coli (E. coli) are a common cause of UTI which were identified as a treatment challenge. This study aimed to assay the prevalence of common β-lactam resistance genes including bla_TEM, bla_SHV, bla_CTX-M and bla_CMY and phenotypic resistance to commonly used β-lactam and fluoroquinolone antibiotics in UTIs. These factors were evaluated in various phylogenetic groups (phylotypes) of E. coli isolates. Real-time PCR was applied to detect β-lactam resistance genes and conventional PCR was used to determine the phylotypes. Phenotypic resistance against β-lactams (ceftazidime, cefotaxime, aztreonam and ceftriaxone) and fluoroquinolones (ciprofloxacin) were identified by the disc diffusion technique. The ability of extended spectrum β-lactamases (ESBLs) production in E. coli isolates was detected using the combined disc diffusion method.

RESULTS

The prevalence of resistance genes were 89.6% for bla_TEM, 44.3% for bla_CTX-M, 6.6% for bla_SHV and 0.9% for bla_CMY. The two high prevalent phylotypes were B2 (29.2%) and D (17.9%) followed by E (14.1%), F (9.4%), C (6.6%) and 10.3% of isolates were unknown in phylotyping. Disc diffusion results showed high prevalence of antibiotic resistance to cefotaxime (88.6%), aztreonam (83%), ceftireaxon (77.3%), ceftazidime (76.4%) and ciprofloxacin (55.6%). Totally, 52.8% of isolates were found as phenotypical ESBL-producers.

CONCLUSIONS

This study's results confirmed an explosion of antibiotic resistance amongst E. coli isolates from UTI against β-lactams and fluoroquinolones. Findings explain the necessity of deep changes in quantity and quality of drug resistance diagnosis and antibiotic therapy strategies. More studies are suggested to better and confident evaluations.

Bacterial profile and antibiotic susceptibility pattern of uropathogens causing urinary tract infection in the eastern part of Northern India

Urinary tract infection (UTI) is a common infectious disease that affects men and women. It is a significant health concern due to multidrug-resistant (MDR) organisms. Therefore, it is necessary to have a current understanding of the antibiotic susceptibility (AS) pattern of uropathogens to manage UTI effectively. Since the bacterial pathogen causing UTI and its AS vary with time and place, the prevailing AS pattern of the causative agents are essential for empirical antibiotic therapy. This study aims to determine the prevalence and AS of uropathogens isolated from UTI patients in the eastern part of Northern India. The study was carried out between November 2018 and December 2019. Clean catch midstream urine samples were collected and processed using standard guidelines for microbiological procedures. Positive microbiological cultures were found in 333 of the 427 patients, where 287 were gram-negative bacteria (GNB), and 46 were gram-positive bacteria (GPB). Females had a higher prevalence of UTI (60.7%) than males (39.3%) (p = 0.00024). The most susceptible age group in females was 18–50 years as compared to males, whereas at the age of 51–80 years and >80 years males were more susceptible than females (p = 0.053). The most prevalent pathogen identified were Escherichia coli (55.0%), followed by Proteus sp. (6.9%), Klebsiella pneumoniae (6.6%), Pseudomonas aeruginosa (6.3%), of which 96.0% were MDR bacteria. The susceptibility pattern of our study also revealed that amikacin, gentamycin and imipenem were the most effective drugs against GNB. In contrast, nitrofurantoin, vancomycin, and chloramphenicol were the most effective drugs against GPB. According tothe findings, MDR pathogens are very much prevalent. Since UTI is one of the most frequent bacterial diseases, proper management necessitates extensive investigation and implementation of antibiotic policy based on AS patterns for a particular region.

Relationship Between Antibiotic Resistance, Biofilm Formation, and Biofilm-Specific Resistance in Escherichia coli Isolates from Ningbo, China

Purpose

Methods

Results

Conclusion