title: A study on the aac-(61)-lb-cr gene prevalence among ciprofloxacin-resistant strains of uropathogenicEnterobacteriaceae.
abstract: BACKGROUND
  Urinary tract infections (UTIs) are very common. Indiscriminate use of antibiotics has led to the development of resistance to most of the commonly used antibiotics including quinolones.
  
  
  OBJECTIVE
  This study aimed to find out the prevalence of ciprofloxacin resistance among the uropathogenicEnterobacteriaceae, to determine the virulence factors of these isolates, and to detect the aac-(61)-lb-cr gene among those isolates with minimal inhibitory concentrations (MICs) of ciprofloxacin >256 mcg/ml.
  
  
  METHODS
  Urine samples reaching the microbiology laboratory were processed, pathogens belonging to theEnterobacteriaceaefamily were isolated from those with significant bacteriuria, and antibiotic sensitivity testing was performed according to the CLSI guidelines. MIC of ciprofloxacin for the isolates resistant to ciprofloxacin was determined by using theE-test, and virulence factors such as hemagglutination, hemolysis, and mucoid colonies were analyzed. aac-(61)-lb-cr gene was analyzed by polymerase chain reaction for those isolates with MIC > 256 mcg/ml.
  
  
  RESULTS
  Escherichia coliwas the most common isolate (62%) with the highest ciprofloxacin resistance (68%). Fourteen percent of them had MIC > 256 mcg/ml and all of these isolates harbored the aac-(61)-lb-cr gene.
  
  
  CONCLUSIONS
  Plasmid-mediated drug resistance can rapidly spread and lead to selection of drug-resistant mutants if not controlled.
authors.affiliation: Department of Microbiology, Chettinad Hospital and Research Institute, Kelambakkam, Chennai, Tamil Nadu, India.
authors.forename: Nirupa
authors.initials: N
authors.lastname: Soundararajan
authors.affiliation: Department of Microbiology, Chettinad Hospital and Research Institute, Kelambakkam, Chennai, Tamil Nadu, India.
authors.forename: Priyadarshini
authors.initials: P
authors.lastname: Shanmugam
authors.affiliation: Department of Microbiology, Chettinad Hospital and Research Institute, Kelambakkam, Chennai, Tamil Nadu, India.
authors.forename: Caroline
authors.initials: C
authors.lastname: Devanbu
authors.affiliation: Department of Microbiology, Chettinad Hospital and Research Institute, Kelambakkam, Chennai, Tamil Nadu, India.
authors.forename: Shameem Banu Abdul
authors.initials: SB
authors.lastname: Sattar
keywords: Aac-(61)-lb-cr gene; ciprofloxacin resistance; plasmid-mediated quinolone resistance; urinary tract infections