title: Observations on Citrobacter species from a tertiary care health center with special reference to multi-drug resistance and presence of CTX-M gene.
abstract: BACKGROUND
  Citrobacter is an important nosocomial pathogen and its multi-drug resistant (MDR) isolates are increasingly being reported across the globe. They are known to produce extended spectrum beta lactamase (ESBL) and harbor CTX-M gene.
  
  
  OBJECTIVE
  The aim was to isolate Citrobacter sp. from clinical specimens, analyze their MDR status and look for the presence of CTX-M gene.
  
  
  METHODS
  In this prospective study, Citrobacter isolates positive for ESBL on screening, were confirmed by combined disc method along with minimum inhibitory concentration (MIC) for cefotaxime. In selected cefotaxime resistant isolates, multiplex polymerase chain reaction was done for blaCTX-M gene.
  
  
  RESULTS
  Of 146 Citrobacter sp. isolated, most (73%) were from admitted patients and hospital stay of >72 h and prior antibiotic intake were the most common associated factors. Maximum isolates were from pus (41.1%). Citrobacter freundii was the commonest species (49%) followed by Citrobacter koseri (28%); 79 were ESBL producers. Seventy were cefotaxime resistant as shown by MIC. blaCTX-M gene was detected in 15/40 of these isolates, all belonged to CTX-M group 1.
  
  
  CONCLUSIONS
  Overall incidence of Citrobacter in our setup is low, but they were mostly MDR, and ESBL production was high, which is a cause of concern. blaCTX-M gene detection is important because of its rapid transmission to other bacterial species.
authors.forename: Sneha
authors.initials: S
authors.lastname: Mohan
authors.affiliation: Department of Microbiology, King George's Medical University, Lucknow, Uttar Pradesh, India.
authors.forename: Jyotsna
authors.initials: J
authors.lastname: Agarwal
authors.forename: Richa
authors.initials: R
authors.lastname: Srivastava
authors.forename: Mastan
authors.initials: M
authors.lastname: Singh
mesh_terms: D002954:Citrobacter / Q000145:classification / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification*; D024901:Drug Resistance, Multiple, Bacterial; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology; D005144:F Factor; D006801:Humans; D015994:Incidence; D008826:Microbial Sensitivity Tests; D011446:Prospective Studies; D062606:Tertiary Care Centers; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases