Characteristics of Klebsiella Pneumonia St4 Coharboring Qnrb1, Aac-Ib-Cr, CTX-M-15 and SHV 11 in A Tunisian Hospital

Abstract

Background: Multiresistant Klebsiella pneumonia are predominant cause of hospital acquired infection. This work describes the molecular epidemiology of these isolates in Tunisian Hospital. Methods: Between October 2010 and June 2013, 50 non-duplicated clinical K.pneumoniae were selected based on nalidixic acid (NA) resistance and were characterized. Isolates were identified using APi 20E system. Susceptibility testing was determined using the disc diffusion method and the micro dilution technique to determine the MIC of ciprofloxacin. PMQR and ESBL genes were detected by PCR and positive results were confirmed by direct sequencing of PCR products. Multilocus sequence typing (MLST) was performed to determine the genetic relationship among isolates. Conjugation and transformation were done to know if PMQR and ESBL were carried with one or two plasmids. Results: 20 PMQR harboring K.pneumoniae representing 40% of all NA resistant isolates were characterized. Among PMQR positive K.pneumoniae 13 were resistant to amoxicillin, amoxicillin/clavulanic acid, ticarcilline, piperacillin, cefaloridine, cefotaxime (CTX) and ceftazidime. The rate of resistance to gentamicin, tobramycin and amikacin were 85%, 95% and 25% respectively. Out of 20 K.pneumoniae (60%) were qnr positive (1 qnrA6 and 11 qnrB1) and (60%) were aac-Ib-cr positive. 33.3% harbored the aac-Ib-cr and qnrB1 determinants. Out of all PMQR positive strains, 65% harbored ctx-M-15 gene. It was associated to shv11 in three cases and tem1 in two cases. The predominant types were ST4 (35%) and ST15 (20%). ST 101(15%) and ST 147 (10%) come in second order. one case of each ST14,ST86,ST336 and ST307 were also observed. qnrB1, aac-Ib-cr, Ctx-m-15 can be carried with more than one plasmid in the same bacteria. Conclusion: The co-existing of different genes conferring resistance among the same and different family of antibiotics is a big threat to patient because it limits the therapeutic process. This phenomenon is a problem of concern that needs to improve the resistance surveillance of multi gene carrying K pneumonia.