Risk Factor Analysis in Clinical Isolates of ESBL and MBL (Including NDM-1) Producing Escherichia coli and Klebsiella Species in a Tertiary Care Hospital.

BACKGROUND

Extended-spectrum β-lactamase (ESBL) and metallo-β-lactamase (MBL) producing Gram negative organisms are emerging as a worldwide public health concern.

AIM

To elucidate risk factors for infection with ESBL and MBL (also NDM-1) producing E. coli and Klebsiella spp.

MATERIALS AND METHODS

A prospective observational study was conducted from November 2010 to March 2012. ESBL production was detected using ESBL E-test, MBL by MBL E-test and NDM-1 by polymerase chain reaction (PCR). Risk factors analysed includes age, sex, clinical specimen, type of infection, duration of hospital stay prior to collection of sample, admitting ward, antimicrobial susceptibility, previous antibiotics used, co-morbid illnesses like diabetes mellitus, immunodeficiency, low birth weight, respiratory/neurological/cardiac/haematological/liver diseases, malignancy, urinary or central venous catheter, ventilatory support, surgical procedures and dialysis.

STATISTICAL ANALYSIS

z-test or Fisher's exact test.

RESULTS

E. coli - ESBL producing isolates E. coli revealed female preponderance, equal incidence of hospital and community acquired infections, mostly from surgical wards, isolated from urine, age group among females >20-30 years and among males >28 days-1 year. They showed high resistance to cephalosporins, monobactam, penicillin but low resistance to carbapenems and aminoglycosides. Co-morbid conditions observed were surgery, urinary catheterisation, haematological disease, ventilatory support, diabetes mellitus and neurological disease. MBL producing strains were mainly from females, surgical wards, (including both NDM-1 isolates), hospital acquired infections, isolated from body fluids (NDM-1 positive), female genital tract specimen and urine (one NDM-1 positive). NDM-1 positive isolates belonged to age groups >5-10 year and >0-28 days and underwent surgery and urinary catheterisation. Klebsiella spp.- ESBL producing isolates showed female preponderance, hospital acquired infections, from surgical wards, high resistance levels to cephalosporins, fluoroquinolones, monobactam, but low levels to carbapenems, among males isolated from pus in age group >0-28 days and >28 days -1 year and among females from urine in >20-30 years, no significant difference when correlated with risk factors. MBL (NDM-1) producing isolates were mainly from females with age range 0 days to 70 years, mainly admitted to ICU/postoperative wards with urinary catheter in-situ, ventilatory support, surgery, diabetes mellitus, haematological and neurological disease.

CONCLUSION

Risk factors for infections due to ESBL and MBL producing Gram Negative Bacteria (GNB) should be clearly identified to reduce their spread and to optimise antibiotic use.