Laboratory of Molecular Genetics of Microorganisms, Oswaldo Cruz Institute (IOC), Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, Brazil.
PLoS Negl Trop Dis. 2013;7(2):e2049. doi: 10.1371/journal.pntd.0002049. Epub 2013 Feb 14.
The current millennium has seen a steep rise in the number, size and case-fatalities of cholera outbreaks in many African countries. Over 40,000 cases of cholera were reported from Nigeria in 2010. Variants of Vibrio cholerae O1 El Tor biotype have emerged but very little is known about strains causing cholera outbreaks in West Africa, which is crucial for the implementation of interventions to control epidemic cholera.
METHODOLOGY/PRINCIPAL FINDINGS: V. cholerae isolates from outbreaks of acute watery diarrhea in Nigeria from December, 2009 to October, 2010 were identified by standard culture methods. Fifteen O1 and five non-O1/non-O139 strains were analyzed; PCR and sequencing targeted regions associated with virulence, resistance and biotype were performed. We also studied genetic interrelatedness among the strains by multilocus sequence analysis and pulsed-field gel electrophoresis. The antibiotic susceptibility was tested by the disk diffusion method and E-test. We found that multidrug resistant atypical El Tor strains, with reduced susceptibility to ciprofloxacin and chloramphenicol, characterized by the presence of the SXT element, and gyrA(Ser83Ile)/parC(Ser85Leu) alleles as well CTX phage and TCP cluster characterized by rstR(ElTor), ctxB-7 and tcpA(CIRS) alleles, respectively, were largely responsible for cholera outbreaks in 2009 and 2010. We also identified and characterized a V. cholerae non-O1/non-O139 lineage from cholera-like diarrhea cases in Nigeria.
CONCLUSIONS/SIGNIFICANCE: The recent Nigeria outbreaks have been determined by multidrug resistant atypical El Tor and non-O1/non-O139 V. cholerae strains, and it seems that the typical El Tor, from the beginning of seventh cholera pandemic, is no longer epidemic/endemic in this country. This scenario is similar to the East Africa, Asia and Caribbean countries. The detection of a highly virulent, antimicrobial resistant lineage in Nigeria is worrisome and points to a need for vaccine-based control of the disease. This study has also revealed the putative importance of non-O1/non-O139 V. cholerae in diarrheal disease in Nigeria.
在本世纪，许多非洲国家的霍乱爆发数量、规模和病死率都急剧上升。2010 年，尼日利亚报告了超过 4 万例霍乱病例。埃尔托生物型霍乱弧菌的变体已经出现，但对于造成西非霍乱爆发的菌株知之甚少，这对于实施控制流行霍乱的干预措施至关重要。
方法/主要发现：2009 年 12 月至 2010 年 10 月，从尼日利亚急性水样腹泻爆发中分离出霍乱弧菌，采用标准培养方法进行鉴定。分析了 15 株 O1 和 5 株非 O1/非 O139 株；进行了与毒力、耐药性和生物型相关的 PCR 和测序。我们还通过多位点序列分析和脉冲场凝胶电泳研究了菌株之间的遗传相关性。采用纸片扩散法和 E 试验检测抗生素敏感性。我们发现，具有 SXT 元件、对环丙沙星和氯霉素敏感性降低、CTX 噬菌体和 TCP 簇特征分别为 rstR(ElTor)、ctxB-7 和 tcpA(CIRS)等位基因的多药耐药非典型埃尔托菌株是 2009 年和 2010 年霍乱爆发的主要原因。我们还鉴定并描述了一种来自尼日利亚霍乱样腹泻病例的非 O1/非 O139 霍乱弧菌谱系。
结论/意义：最近尼日利亚的爆发是由多药耐药非典型埃尔托和非 O1/非 O139 霍乱弧菌菌株引起的，似乎从第七次霍乱大流行开始，典型埃尔托弧菌在该国已不再流行/地方性。这种情况类似于东非、亚洲和加勒比国家。在尼日利亚检测到一种高毒力、抗微生物耐药的谱系令人担忧，表明需要基于疫苗来控制该疾病。本研究还表明，非 O1/非 O139 霍乱弧菌在尼日利亚腹泻病中的重要性。
