title: Prevalence and antibacterial resistance patterns of extended-spectrum beta-lactamase producing Gram-negative bacteria isolated from ocular infections.
abstract: OBJECTIVE
  Extended-spectrum beta-lactamases (ESBLs) mediated resistance is more prevalent worldwide, especially among Gram-negative bacterial isolates, conferring resistance to the expanded spectrum cephalosporins. As limited data were available on the prevalence of ESBLs in this area, the current study was undertaken to determine the prevalence, antibacterial resistance patterns, and molecular detection and characterization of ESBL encoding resistance genes among ocular Gram-negative bacterial isolates from ocular infections.
  
  
  METHODS
  A prospective study was done on 252 ocular Gram-negative bacterial isolates recovered from ocular infections during a study period from February 2011 to January 2014. All isolates were subjected to detection of ESBLs by cephalosporin/clavulanate combination disc test and their antibacterial resistance pattern was studied. Molecular detection and characterization of ESBL encoding blaTEM -, blaSHV , blaOXA -, and blaCTX-M (phylogenetic groups 1, 2, 9, and 8/25) resistance genes by multiplex polymerase chain reaction and DNA sequence analysis.
  
  
  RESULTS
  Of all Gram-negative bacteria, Pseudomonas aeruginosa (44%) was the most common strain, followed by Enterobacter agglomerans and Klebsiella pneumoniae each (10%). Among the 252, 42 (17%) were ESBL producers. The major source of ESBL producers were corneal scraping specimens, highest ESBL production was observed in P. aeruginosa 16 (38%) and Escherichia coli 7 (16.6%). Among ESBL-producing genes, the prevalence of blaTEM -gene was the highest (83%) followed by blaOXA -gene (35%), blaSHV -gene (18.5%), and blaCTX-M-1 -gene (18.5%) alone or together.
  
  
  CONCLUSIONS
  The higher rate of prevalence of ESBLs-encoding genes among ocular Gram-negative bacteria is of great concern, as it causes limitation to therapeutic options. This regional knowledge will help in guiding appropriate antibiotic use which is highly warranted.
authors.affiliation: Department of Microbiology and Molecular Biology, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India.
authors.forename: G
authors.initials: G
authors.lastname: Rameshkumar
authors.affiliation: Department of Glaucoma, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India.
authors.forename: R
authors.initials: R
authors.lastname: Ramakrishnan
authors.affiliation: Department of Intraocular Lens and Cataract Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India.
authors.forename: C
authors.initials: C
authors.lastname: Shivkumar
authors.affiliation: Department of Paediatric Ophthalmology and Adult Strabismus Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India.
authors.forename: R
authors.initials: R
authors.lastname: Meenakshi
authors.affiliation: Department of Cornea and Refractive Surgery Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India.
authors.forename: V
authors.initials: V
authors.lastname: Anitha
authors.affiliation: Department of Retina - Vitreous Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India.
authors.forename: Y C
authors.initials: YC
authors.lastname: Venugopal Reddy
authors.affiliation: Department of Orbit, Oculoplasty and Ocular Oncology Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Tirunelveli, Tamil Nadu, India.
authors.forename: V
authors.initials: V
authors.lastname: Maneksha
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000235:genetics; D015818:Eye Infections, Bacterial / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006090:Gram-Negative Bacteria / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D015995:Prevalence; D011446:Prospective Studies; D055815:Young Adult; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000378:metabolism*; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D047090:beta-Lactams; D001618:beta-Lactamases