title: Multi-drug carbapenem-resistant Klebsiella pneumoniae infection carrying the OXA-48 gene and showing variations in outer membrane protein 36 causing an outbreak in a tertiary care hospital in Riyadh, Saudi Arabia.
abstract: OBJECTIVE
  To investigate the genes of antibiotic resistance among isolates from the first reported carbapenem-resistant Klebsiella pneumoniae (CRKP) outbreak in a tertiary care hospital, Riyadh, Saudi Arabia.
  
  
  METHODS
  Antimicrobial susceptibility testing was performed on bacterial isolates using the Microscan Walkaway system (Siemens, Germany) and was confirmed by Etest (AB Biodisk, Sweden). bla-CTX-M, -SHV, -TEM, -OXA-48, OXA-A,B,C,D, -KPC, -NDM, -VIM, -IMP, integron 1, and outer membrane proteins(Omp)-35 and Omp-36 were investigated by PCR amplification and direct sequencing of PCR products. Isolates were sequence-typed by multilocus sequence typing (MLST).
  
  
  RESULTS
  All isolates were resistant to cefotaxime, ceftazidime, cefepime, ciprofloxacin, and piperacillin-tazobactam, and 91% (21 out of 23) were resistant to amikacin and gentamicin. All isolates except two from a single patient were resistant to one of the carbapenems. CTX-M and SHV genes were detected in all isolates, CTX-M-15 and SHV-1 types being predominant among these extended-spectrum beta-lactamases (ESBLs). TEM-1 was found in all except one isolate (isolate 3). Significantly, the OXA-48 gene was also found in all isolates. OXA-D-gene was found in three out of 23 isolates. KPC, NDM, OXA-A, -B, -C, VIM, and IMP genes were absent in all isolates. Disruption of the Omp-36 gene due to insertion of transposon IS903 and/or IS4 was detected in four out of 23 isolates, and some unique variations were also observed in this gene, including an insertion of two amino acids in the L3 region of Omp-36 in one isolate (isolate 3) and a mutation resulting in a premature stop codon in another isolate (isolate 25). MLST revealed ST29 to be the predominant sequence type (17 out of 23 isolates, 74%). Three were ST709 and one each was ST37 and ST111; one isolate had an unknown ST.
  
  
  CONCLUSIONS
  This is probably the first reported outbreak of multidrug/carbapenem-resistant Klebsiella infection involving the OXA-48 gene from Saudi Arabia. Although the presence of ESBLs such as OXA, CTX-M, TEM, and SHV are predictable reasons for resistance, variations in the Omp-36 gene might also have precipitated this phenomenon. Disruption of the Omp-36 sequence by large insertional elements, the insertion of two amino acids in a very crucial part of this protein, and the presence of a premature stop codon in one isolate might have rendered this protein incomplete and non-functional. The study also demonstrated that more than one type of clone was responsible for this reported apparent outbreak and that ST29, a clone not reported from this region before, was the major clone responsible.
authors.affiliation: King Abdullah International Medical Research Center (KAIMRC), Riyadh.
authors.forename: Taher
authors.initials: T
authors.lastname: Uz Zaman
authors.affiliation: King Abdullah International Medical Research Center (KAIMRC), Riyadh.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Aldrees
authors.affiliation: King Saud bin Abdulaziz University for Health Sciences, WHO Collaborating Center and GCC Center for Infection Control; Department of Pathology, King Abdulaziz Medical City, Riyadh.
authors.forename: Sameera M
authors.initials: SM
authors.lastname: Al Johani
authors.affiliation: King Abdullah International Medical Research Center (KAIMRC), Riyadh.
authors.forename: Maha
authors.initials: M
authors.lastname: Alrodayyan
authors.affiliation: Department of Pathology, King Abdulaziz Medical City, Riyadh.
authors.forename: Faizah A
authors.initials: FA
authors.lastname: Aldughashem
authors.affiliation: King Abdullah International Medical Research Center (KAIMRC), Riyadh; King Saud bin Abdulaziz University for Health Sciences, WHO Collaborating Center and GCC Center for Infection Control; Department of Infection Prevention and Control, King Abdulaziz Medical City, Riyadh; Department of Pediatrics, King Abdulaziz Medical City, Riyadh, PO Box 22490, Riyadh 11426, Saudi Arabia. Electronic address: balkhyh@ngha.med.sa.
authors.forename: Hanan H
authors.initials: HH
authors.lastname: Balkhy
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry; D015780:Carbapenems / Q000494:pharmacology*; D004196:Disease Outbreaks; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D014644:Genetic Variation; D006801:Humans; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D012529:Saudi Arabia; D062606:Tertiary Care Centers; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D015780:Carbapenems; D001618:beta-Lactamases; C108449:oxacillinase
keywords: Carbapenem resistance; Extended-spectrum beta-lactamases; Klebsiella pneumoniae; Outer membrane protein; Saudi Arabia