Gupta Ruchi, Gaind Rajni, Wain John, Deb Monorama, Singh Laishram Chandreshwor, Basir Seemi Farhat
Department of Biosciences, Jamia Millia Islamia, New Delhi 110025, India; Department of Microbiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi 110029, India.
Department of Microbiology, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi 110029, India.
Biomol Detect Quantif. 2015 Jan 20;2:30-34. doi: 10.1016/j.bdq.2015.01.003. eCollection 2014 Dec.
To establish the relative importance of serovar Typhi with non-classical quinolone resistance.
Eight hundred and ninety-one isolates of Typhi, isolated between 2004 and 2011, were tested for antibiotic susceptibility determination using disc diffusion and E-test. The mechanisms of fluoroquinolone resistance were studied in a sub-set of the NAL (nalidixic acid susceptible) isolates by wave nucleic acid fragment analysis of PCR products from , , and and from the plasmid borne determinants: ,B,S; aac(6')-Ib-cr and . To assess genetic relatedness multi-locus variable number tandem repeat analysis was carried out using five loci.
Eighty isolates with a nalidixic acid MIC of <32 mg/L (NAL) and a ciprofloxacin MIC of >0.064 mg/L CIP (ciprofloxacin reduced susceptibility) were found. In 36 NAL CIP isolates two distinct genotypes were identified when compared with 16 susceptible controls: Group B ( = 34), mutation in at codon 464, NAL MIC of 3-12 mg/L and CIP MIC of 0.064-0.5 mg/L.; and Group C, mutation in at codon 83 ( = 2) NAL MIC of 16 mg/L and CIP MIC of 0.25-0.38 mg/L. Group B isolates were found in different strain backgrounds as defined by MLVA.
The use of nalidixic acid to screen for reduced susceptibility to fluoroquinolones in Typhi misses CIP-NAL isolates, an established phenotype in India.
确定具有非经典喹诺酮耐药性的伤寒杆菌血清型的相对重要性。
对2004年至2011年间分离出的891株伤寒杆菌进行检测，采用纸片扩散法和E试验测定抗生素敏感性。通过对来自gyrA、gyrB、parC和parE以及质粒携带决定簇：qnrA、qnrB、qnrS；aac(6')-Ib-cr和qepA的PCR产物进行波核酸片段分析，研究了氟喹诺酮耐药机制。为评估遗传相关性，使用五个位点进行多位点可变数目串联重复分析。
发现80株菌株，其萘啶酸MIC<32mg/L（萘啶酸敏感，NAL），环丙沙星MIC>0.064mg/L（环丙沙星敏感性降低，CIP）。在36株NAL CIP菌株中，与16株敏感对照相比，鉴定出两种不同的基因型：B组（n = 34），gyrA第464位密码子突变，萘啶酸MIC为3 - 12mg/L，环丙沙星MIC为0.064 - 0.5mg/L；C组，gyrA第83位密码子突变（n = 2），萘啶酸MIC为16mg/L，环丙沙星MIC为0.25 - 0.38mg/L。B组菌株存在于由多位点可变数目串联重复分析定义的不同菌株背景中。
使用萘啶酸筛选伤寒杆菌对氟喹诺酮的敏感性降低会遗漏CIP - NAL菌株，这是印度一种已确定的表型。
