title: Molecular characterisation of Klebsiella oxytoca strains isolated from patients with antibiotic-associated diarrhoea.
abstract: OBJECTIVE
  Colitis is a common complication after treatment with antibiotics such as β-lactams, quinolones, and aminoglycosides. Recently, Klebsiella oxytoca has been implicated in this type of diarrhoea. The prevalence and characterisations of K. oxytoca isolated from patients with antibiotic-associated diarrhoea were investigated. The K. oxytoca isolates were also tested for cytotoxin production.
  
  
  METHODS
  This study was conducted from May 2011 to Dec 2013. Faecal samples were collected from hospitalised patients receiving antibiotic treatment. Initial cultivation was performed on specific media. The clinical isolates were confirmed by polymerase chain reaction (PCR) using the specific K. oxytoca polygalacturonase (pehX) gene. The double-disc diffusion test was used to detect extended-spectrum beta-lactamase (ESBL)-producing strains. Tracking of ESBL-encoding genes was performed via PCR. The organism was cultured on Hep-2 cell lines for cytotoxin production.
  
  
  RESULTS
  Out of 331 samples collected from patients, 40 were confirmed molecularly to be clinical isolates of K. oxytoca. Fourteen (35%) ESBL-producing strains were isolated using the double-disc diffusion method. Among the molecularly confirmed K. oxytoca isolates, seven (17.5%) tested positive for the blaSHV gene, 12 (30%) for blaTEM, 10 (25%) for blaCTX-M, three (7.5%) for blaOXA, nine (22.5%) for blaCTX-M-15, and seven (17.5%) for blaTEM-1. Five (12%) isolates showed cytotoxin activity below 30%, 12 (30%) strains showed moderate cytotoxin activity between 30% and 60%, and 23 (58%) strains showed cytotoxin activity ⩾60%.
  
  
  CONCLUSIONS
  The cytotoxin-producing K. oxytoca is found to be one of the causes of antibiotic-induced colitis. Discontinuing treatment and allowing normal intestinal flora to be established or prescribing appropriate medication after antibiogram can help patients with antibiotic-induced haemorrhagic colitis in a timely manner.
authors.affiliation: Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Mohammad Yousef
authors.initials: MY
authors.lastname: Alikhani
authors.affiliation: Microbiology Research Center & Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Fereshteh
authors.initials: F
authors.lastname: Shahcheraghi
authors.affiliation: Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Khodaparast
authors.affiliation: Department of Microbiology, Osmania University, Hyderabad, Andhra Pradesh (AP), India; Department of Microbiology, Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Amir Sasan
authors.initials: AS
authors.lastname: Mozaffari Nejad
authors.affiliation: Department of Virology, Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Mojgan K
authors.initials: MK
authors.lastname: Moghadam
authors.affiliation: Microbiology Research Center & Department of Microbiology, Pasteur Institute of Iran, Tehran, Iran. Electronic address: mousavi@pasteur.ac.ir.
authors.forename: Sayed Fazlollah
authors.initials: SF
authors.lastname: Mousavi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000009:adverse effects* / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D003092:Colitis / Q000209:etiology; D003603:Cytotoxins / Q000378:metabolism; D003967:Diarrhea / Q000139:chemically induced* / Q000382:microbiology; D052978:Disk Diffusion Antimicrobial Tests; D005243:Feces / Q000382:microbiology; D005260:Female; D006801:Humans; D007223:Infant; D007710:Klebsiella Infections / Q000150:complications / Q000201:enzymology / Q000382:microbiology*; D041121:Klebsiella oxytoca / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D055815:Young Adult; D001618:beta-Lactamases / Q000096:biosynthesis; D047090:beta-Lactams / Q000009:adverse effects* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003603:Cytotoxins; D047090:beta-Lactams; D001618:beta-Lactamases
keywords: Antibiotic-associated colitis; Cytotoxin; Klebsiella oxytoca