Genotypes and cephalosporin susceptibility in extended-spectrum beta-lactamase producing enterobacteriaceae in the community

  • Daniel Maina Aga Khan University Hospital, Nairobi, Kenya
  • Gunturu Revathi Aga Khan University Hospital, Nairobi, Kenya
  • Samuel Kariuki Medical Research Institute, Nairobi, Kenya
  • Hastings Ozwara Institute of Primate Research, Nairobi, Kenya
Keywords: ESBL-producing Enterobacteriaceae, genotype, MIC

Abstract

Introduction:  Infections from extended spectrum beta lactamases (ESBLs) producing enterobacteriaceae are increasingly being reported in the community setting. These infections are often multidrug resistant, with clinical and epidemiological implications, and necessitate surveillance measures based on local data. In the present study ESBLs genotypes were correlated with susceptibility to cephalosporins among ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates acquired in the community.

Methodology:  We investigated 28 E. coli and 24 K. pneumoniae isolates by PCR for the presence of blaSHV, blaCTX-M, and blaTEM. Minimum inhibitory concentration (MIC) for cephalosporins was determined by use of E-tests.

Results:  blaCTX-M was detected in 46 (88.5%), blaSHV in 13 (25%) and blaTEM in18 (34.6%) of the isolates. Nineteen (36.5%) isolates had more than one genotype detected. Urine specimens provided most of the ESBL-producing isolates (71%) followed by respiratory specimens (11%). MIC50 for cefotaxime, ceftazidime, and ceftriaxone were at 60μg/ml, 13μg/ml, and 139μg/ml, respectively. There was a statistically significant association (p-value = 0.017) between blaSHV and resistance to ceftazidime. Though other associations could be seen among the genotypes and susceptibility profiles of the three drugs, they were not statistically significant. Twenty-four (52.2%) of the blaCTX-M isolates were sensitive and nine (19.6%) resistant to ceftazidime. For cefotaxime, 29 (63%) of blaCTX-M isolates were resistant and two (4.3%) were sensitive.

Conclusion:  The predominant ESBL genotype in the local community-acquired infections is blaCTX-M , most of which involved the urinary tract.  ESBL genes elevated MICs for the cephalosporins, but only blaSHV could predict resistance to ceftazidime.

Author Biographies

Daniel Maina, Aga Khan University Hospital, Nairobi, Kenya

Resident, Clinical Pathology

Deparment of Pathlogy

 

Gunturu Revathi, Aga Khan University Hospital, Nairobi, Kenya

Assistant Professor in Clinical Microbiology

Department of Pathology

Samuel Kariuki, Medical Research Institute, Nairobi, Kenya

Chief Research Scientist and Head,

Centre for Microbiology

Hastings Ozwara, Institute of Primate Research, Nairobi, Kenya

Senior Research Scientist and Head,

Tropical Infections Department

Published
2011-11-30
How to Cite
1.
Maina D, Revathi G, Kariuki S, Ozwara H (2011) Genotypes and cephalosporin susceptibility in extended-spectrum beta-lactamase producing enterobacteriaceae in the community. J Infect Dev Ctries 6:470-477. doi: 10.3855/jidc.1456
Section
Original Articles