title: Screening of ocular enterobacteriaceae isolates for presence of chromosomal blaNDM-1 and ESBL genes: a 2-year study at a tertiary eye care center.
abstract: OBJECTIVE
  Since, to our knowledge, there are no reports on the prevalence of the blaNDM-1 gene among ocular isolates of Enterobacteriaceae, and only limited information on the prevalence of extended spectrum beta-lactamases (ESBLs) among ocular bacterial isolates are available, our study was undertaken.
  
  
  METHODS
  A prospective study was done on 74 Enterobacteriaceae isolates from patients presenting with clinical suspicion of bacterial ocular infections during a period from January 2010-December 2011. All isolates were subjected to detection of ESBLs by double disc synergy and screened for the presence of CTX-M -I, II, III, and IV groups, and OXA, TEM, SHV, blaNDM-1 genes by PCR.
  
  
  RESULTS
  Of 74 ocular Enterobacteriaceae isolates 57 (77%) were ESBL producers tested by the double disc diffusion test. PCR-based DNA sequencing of these 57 ocular isolates showed the presence of CTX-M-15 (14.0%), blaOXA-1 (5.2%), blaSHV-1 (8.7%), and blaTEM-1 (7.0%) types. The blaNDM-1 was absent among these ocular isolates. The most widely disseminated ESBL gene among ocular isolates was CTX-M-15. Phenotypic and genotypic results showed 100% correlation.
  
  
  CONCLUSIONS
  To our knowledge, this is the first extensive study performed to genotype ESBL-producing ocular Enterobacteriaceae isolates. The isolation of ESBL-producing Enterobacteriaceae organisms predominantly from conjunctival specimens indicates community-acquired infections/colonization by these bacteria in the conjunctiva of the patients, and cases are not related to hospital-acquired infections because of the short stay of ophthalmic patients in the hospitals. A shift in the resistance rates of ceftazidime from 37.5% to 79.7% over the years proves the increase in drug resistance among ocular clinical isolates.
authors: L & T Microbiology Research Centre, Kamalnayan Bajaj Research Centre, Vision Research Foundation, Sankara Nethralaya, Chennai, India.
authors: Murali
authors: M
authors: Sowmiya
authors: Jambulingam
authors: J
authors: Malathi
authors: Hajib Naraharirao
authors: HN
authors: Madhavan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004755:Enterobacteriaceae / Q000235:genetics* / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000235:genetics*; D015818:Eye Infections, Bacterial / Q000235:genetics* / Q000382:microbiology; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011446:Prospective Studies; D017422:Sequence Analysis, DNA; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases; C552864:beta-lactamase NDM-1