Department of Microbiology, Institute of National Importance, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Pondicherry, India.
Clin Microbiol Infect. 2012 Mar;18(3):239-45. doi: 10.1111/j.1469-0691.2011.03546.x. Epub 2011 Jun 29.
Typhoid fever is caused by Salmonella enterica serovar Typhi, a major public health concern in developing countries. Recently, there has been an upsurge in the occurrence of bacterial isolates that are resistant to ciprofloxacin, and the emergence of broad spectrum β-lactamases in typhoidal salmonellae constitutes a new challenge for the clinician. A total of 337 blood culture isolates of S. Typhi, isolated from Pondicherry, India, between January 2005 and December 2009, were investigated using phenotypic, molecular and serological methods. Of the 337 isolates, 74 (22%) were found to be multidrug resistant (MDR) and 264 (78%) nalidixic acid resistant (NAR). Isolates with reduced susceptibility to ciprofloxacin possessed single mutations in the gyrA gene. A high rate of resistance (8%) was found to ciprofloxacin. All isolates with a ciprofloxacin MIC ≥ 4 mg/L possessed both double mutations in the QRDR of the gyrA gene and a single mutation in the parC gene. Active efflux pump mechanisms were also found to be involved in ciprofloxacin resistance. Finally, a large number of PFGE patterns (non-clonal genotypes) were observed among the S. Typhi isolates. In conclusion, a high rate of ciprofloxacin resistance was observed in comparison to other endemic areas in blood culture isolates of S. Typhi from Pondicherry, India, with steadily increasing NAR but decreasing MDR isolations over the study period. This is most likely to be due to an increased use of ciprofloxacin as a first-line drug of choice over more traditional antimicrobial agents for the treatment of typhoid fever.
伤寒是由伤寒沙门氏菌血清型 Typhi 引起的，是发展中国家的一个主要公共卫生问题。最近，对环丙沙星耐药的细菌分离株的发生率有所上升，而广谱β-内酰胺酶在伤寒沙门氏菌中的出现给临床医生带来了新的挑战。2005 年 1 月至 2009 年 12 月期间，从印度本地治里分离的 337 株伤寒沙门氏菌血培养分离株，通过表型、分子和血清学方法进行了研究。在 337 株分离株中，发现 74 株（22%）为多药耐药（MDR），264 株（78%）对萘啶酸耐药（NAR）。对环丙沙星敏感性降低的分离株在gyrA 基因中存在单个突变。发现对环丙沙星的耐药率较高（8%）。所有环丙沙星 MIC≥4mg/L 的分离株均在 gyrA 基因 QRDR 中存在双重突变，以及 parC 基因中的单个突变。还发现主动外排泵机制也参与了环丙沙星的耐药性。最后，在伤寒沙门氏菌分离株中观察到大量 PFGE 图谱（非克隆基因型）。总之，与印度本地治里的其他地方性地区相比，在血培养分离株中观察到环丙沙星耐药率较高，在研究期间，NAR 呈稳步上升趋势，而 MDR 分离株呈下降趋势。这很可能是由于在治疗伤寒时，与传统的抗菌药物相比，环丙沙星作为一线药物的使用增加所致。
