Virulence factor profiles, phylogenetic background, and antimicrobial resistance pattern of lactose fermenting and nonlactose fermenting Escherichia coli from extraintestinal sources.

Context: In recent years, nonlactose fermenting (NLF) Escherichia coli have been increasingly isolated in the microbiology laboratory, but their clinical significance has not yet been clearly elucidated. Aims: To characterize the lactose fermenting (LF) and NLF isolates on the basis of their virulence factors, phylogenetic background, and drug resistance property. Settings and Design: This descriptive study was carried out in a multi‑specialty tertiary care hospital. Subjects and Methods: Three hundred nonrepeat E. coli isolates from inpatients were studied. Isolates were differentiated as LF and NLF on the basis of colony characteristics on MacConkey’s agar. Possession of virulence and drug resistance genes was determined by multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR methods. Antibiotic sensitivity testing was performed by disk diffusion method. Results: Of 300 isolates 39 (13%) were NLF isolates. Maximum number of NLF isolates belonged to phylogroups B2 and D when compared with LF isolates. The incidence of iutA, hlyA, and neuC genes were significantly higher in NLF isolates. The presence of drug resistance genes such as AmpC gene, SHV, and CTXM were higher in LF isolates. Conclusions: LF isolates demonstrated a higher antimicrobial resistance and NLF isolates possessed higher virulence properties. The microbiology laboratory should report lactose fermentation profile as it may help the physician to initiate appropriate treatment.

Molecular characterization and clinical significance of New Delhi metallo-beta-lactamases-1 producing Escherichia coli recovered from a South Indian tertiary care hospital.

Context: The increased rate of infection by New Delhi metallo-beta-lactamases-1 (NDM1) producing Escherichia coli is a major concern since they show a high rate of drug resistance and are responsible for mortality and morbidity. Aims: To characterize the NDM1 producing E. coli isolates and their impact on patients’ clinical outcome. Settings and Design: This descriptive study was carried out in a multi-specialty tertiary care hospital. Materials and Methods: Three hundred nonrepeat strains of E. coli from inpatients were included in the study. Modifi ed Hodge test and metallo-beta-lactamases (MBL) e-test were performed to detect carbapenemase and MBL activity. Polymerase chain reaction (PCR) technique was performed to detect NDM1. NDM1 positive isolates were further tested for plasmid mediated AmpC, blaCTX, blaSHV, blaTEM genes and also for phylogrouping by PCR methods. Treatment and patients’ clinical outcome were also analyzed. Results: Out of 300 isolates, 21 (7%) were MBL producers by phenotypic methods. Of this, 17 (81%) were NDM1 positives, among the NDM1 producers 6 (35%) isolates were belongs to phylogroups D followed by A 5 (29%), B1 4 (24%) and B2 2 (12%), 15 (88%) isolates were blaCTX-M positive suggestive of extended-spectrum beta lactamase producing strain and 7 (47%) were positive with CIT type of AmpC. With the follow-up of the patients, it was found that 12 (71%) recovered and 3 (18%) developed relapses, and mortality was seen in 2 (12%) patients. Conclusions: NDM1 producing isolates showed a high degree of drug resistance but can be treated with suitable antimicrobials, in the majority. Early detection and choice of appropriate antibiotics may help in reducing mortality and morbidity.

Genomic analysis and clinical importance of Escherichia coli isolate from patients with sepsis.

Context: Escherichia coli is a major cause of bloodstream infections and death due to sepsis. Bacteremic isolates harbor a signifi cantly greater repertoire of virulence factors (VFs) in contrast with commensal E. coli isolates. Aims: The aim was to determine the relationships between E. coli VFs, phylogenetic groups, and their clinical importance. Settings and Design: This descriptive study was carried out in a multi-specialty tertiary care hospital. Materials and Methods: Escherichia coli isolates from consecutive episodes of bacteremia in 100 patients were screened for their VFs, phylogenetic group, and their effect on patient’s clinical outcome. Virulence genes of all isolates were determined by multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR methods. Estimation of risk of death was calculated using APACHE score II calculator. Results: Of the 100 patients, the most common predisposing factors were diabetes (42%), followed by carcinoma (23%). On analysis of the VF genes of the isolates, a majority of strains (88%) were possessing the fi mH gene followed by iutA (76%), papC (44%), cnf1 (16%), hlyA (16%) and neuC (5%) respectively. Phylogenetic analysis revealed that 25 (25%) isolates belonged to phylogroup A, 8(8%) strains to group B1, 30 (30%) were from group B2 and 37 (37%) were from group D. The incidence of iutA gene was signifi cant in higher APACHE II score group. Conclusions: Our fi ndings indicate that virulent as well as commensal strains are capable of causing sepsis. Host related predisposing factors, adherence factors, and iron uptake are essential for the survival of the sepsis inducing strains.

Characterization of plasmid mediated AmpC producing Escherichia coli clinical isolates from a tertiary care hospital in South India.

Context: Plasmid mediated AmpC (pAmpC) β-lactamase producing Escherichia coli are an emerging problem worldwide as they are now exhibiting resistance to multiple classes of antibiotics and are a major cause of therapeutic failure. Aims: The aim of this study was to characterize pAmpC β-lactamase producing extraintestinal E. coli, their phylogenetic distribution, resistance pattern, treatment options, and impact on patient’s clinical outcome. Settings and Design: This descriptive study was carried out in a multi-specialty tertiary care hospital. Materials and Methods: A total of 300 clinically signifi cant, non-repeat isolates were studied. AmpC disk test was used for phenotypic AmpC-β- lactamase detection. Molecular types of pAmpC were determined by a multiplex polymerase chain reaction (PCR). Phylogenetic analysis was performed by triplex PCR methods. Metallo-beta-lactamase (MBL) detection was done by E test. Antibiogram, treatment, and clinical outcome were collected in a structured proforma. Results: Although 95 isolates (32%) were phenotypically positive for AmpC, PCR detected CIT type of AmpC gene in only 37 isolates. Majority of strains were from phylogroup A (85%) and B1 (58%) which are considered as commensal groups. Co-production of ESBL’s was observed in 33 strains and 5 strains were found to be MBL producers. Most widely prescribed antibiotics were 3rd generation cephalosporins (30%), carbapenems (19%) and aminoglycosides (16%). Conclusions: Plasmid mediated AmpC producing isolates were found to exhibit a high degree of drug resistance, and they mainly belonged to commensal strains possibly due to misuse of antibiotics. Proper antibiotic policy is required to limit the spread of pAmpC producers or else it will lead to a therapeutic dead end in the near future.

Effect of trace elements on surface hydrophobicity and adherence of Escherichia coli to uroepithelial cells.

Trace elements have significant effect on the physiology of bacteria. Variation in the concentration of trace elements may affect the expression of virulence by microorganisms. The effect of trace elements on hydrophobicity and adherence of E.coli to uroepithelial cells was studied. Increasing concentrations of Ca2+, Mg2+, Fe3+ and Zn2+ significantly decreased the surface hydrophobicity. Toxic trace elements like Co2+, Cu2+, Mn2+ and Ni2+ did not alter surface hydrophobicity. With regards to adherence of E.coli to uroepithelial cells, only Mg2+ had significant effect. Toxic trace elements decreased the rate of cell adherence. The pathogenic strains of E.coli showed higher surface hydrophobicity and better cell adherence compared to the nonpathogenic strains. There was good correlation between surface hydrophobicity and cell adherence at higher concentrations (0.1 to 0.2mM) of Fe2+ and Zn2+. The results indicated that trace elements can significantly affect surface hydrophobicity and adherence of E.coli to uroepithelial cells. Such effect may have a significant impact on the initial stages of bacterial infection.