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.

Urinary tract infection due to Enterobacter sakazakii.

Enterobacter sakazakii is a rare but important cause of necrotizing enterocolitis, bloodstream infection and central nervous system infections in humans, with mortality rates of 40-80%. It has not been reported to cause urinary tract infection. We report a case of urinary tract infection due to E. sakazakii in a 63-year-old lady with chronic renal failure.

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.