OBJECTIVES: To characterize the prevalence of plasmid-mediated quinolone resistance determinants qnr and aac(6')-Ib-cr in extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae. METHODS: qnrA, qnrB, qnrS, aac(6')-Ib-cr and ESBL-encoding genes were detected by PCR. MICs of 10 antimicrobial agents were determined by Etest. PFGE was used to investigate the clonality of qnr- and aac(6')-Ib-cr-producing isolates. Conjugation and Southern hybridizations were used to confirm whether qnr, aac(6')-Ib-cr or ESBL-encoding genes were located on plasmids. RESULTS: Twenty-nine (8.0%) of 362 isolates were positive for qnr genes, and the qnrA-, qnrB- and qnrS-type genes were detected alone or in combination in 13 (3.6%), 8 (2.2%) and 9 (2.5%), respectively. Sixty-two (17.1%) isolates were positive for aac(6')-Ib, of which 36 (9.9% of all) had the -cr variant. Conjugation and Southern hybridization revealed that qnrA, aac(6')-Ib-cr and ESBL-encoding genes were always located on the same plasmids. CONCLUSIONS: qnr and aac(6')-Ib-cr genes were detected in 8.0% and 9.9% of ESBL-producing E. coli and K. pneumoniae, respectively. The plasmids carrying the qnr gene could be transferred by conjugation together with ESBL-encoding genes and aac(6')-Ib-cr.
OBJECTIVES: To characterize the prevalence of plasmid-mediated quinolone resistance determinants qnr and aac(6')-Ib-cr in extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae. METHODS: qnrA, qnrB, qnrS, aac(6')-Ib-cr and ESBL-encoding genes were detected by PCR. MICs of 10 antimicrobial agents were determined by Etest. PFGE was used to investigate the clonality of qnr- and aac(6')-Ib-cr-producing isolates. Conjugation and Southern hybridizations were used to confirm whether qnr, aac(6')-Ib-cr or ESBL-encoding genes were located on plasmids. RESULTS: Twenty-nine (8.0%) of 362 isolates were positive for qnr genes, and the qnrA-, qnrB- and qnrS-type genes were detected alone or in combination in 13 (3.6%), 8 (2.2%) and 9 (2.5%), respectively. Sixty-two (17.1%) isolates were positive for aac(6')-Ib, of which 36 (9.9% of all) had the -cr variant. Conjugation and Southern hybridization revealed that qnrA, aac(6')-Ib-cr and ESBL-encoding genes were always located on the same plasmids. CONCLUSIONS: qnr and aac(6')-Ib-cr genes were detected in 8.0% and 9.9% of ESBL-producing E. coli and K. pneumoniae, respectively. The plasmids carrying the qnr gene could be transferred by conjugation together with ESBL-encoding genes and aac(6')-Ib-cr.
Authors: Patricia J Baudry-Simner; Amanpreet Singh; James A Karlowsky; Daryl J Hoban; George G Zhanel Journal: Can J Infect Dis Med Microbiol Date: 2012 Impact factor: 2.471
Authors: Le Thi Minh Vien; Manal Abuoun; Victoria Morrison; Nicholas Thomson; James I Campbell; Martin J Woodward; Nguyen Van Vinh Chau; Jeremy Farrar; Constance Schultsz; Stephen Baker Journal: Antimicrob Agents Chemother Date: 2011-01-31 Impact factor: 5.191
Authors: Maria Sjölund-Karlsson; Jason P Folster; Gary Pecic; Kevin Joyce; Felicita Medalla; Regan Rickert; Jean M Whichard Journal: Antimicrob Agents Chemother Date: 2009-02-17 Impact factor: 5.191
Authors: Le Thi Minh Vien; Stephen Baker; Le Thi Phuong Thao; Le Thi Phuong Tu; Cao Thu Thuy; Tran Thi Thu Nga; Nguyen Van Minh Hoang; James Iain Campbell; Lam Minh Yen; Nguyen Trong Hieu; Nguyen Van Vinh Chau; Jeremy Farrar; Constance Schultsz Journal: J Med Microbiol Date: 2009-08-20 Impact factor: 2.472