Multi-drug resistant Vibrio cholerae O1 variant El Tor isolated in northern Vietnam between 2007 and 2010

Abstract

Since 2007, there has been a re-emergence of cholera outbreaks in northern Vietnam. To understand the molecular epidemiological relatedness and determine the antibiotic susceptibility profiles of responsible V. cholerae O1 outbreak strains, a representative collection of 100 V. cholerae O1 strains was characterized. V. cholerae O1 strains isolated from diarrhoeal patients in northern Vietnam between 2007 and 2010 were investigated for antibiotic susceptibility and characterized by using phenotypic and genotypic tests, including PFGE analysis. Ten clinical V. cholerae O1 isolates from Bangladesh and Zimbabwe were included for comparison. The results revealed that all isolates were resistant to co-trimoxazole and nalidixic acid, 29 % were resistant to tetracycline and 1 % were resistant to azithromycin. All strains were susceptible to ampicillin–sulbactam, doxycycline, chloramphenicol and ciprofloxacin and 95 % were susceptible to azithromycin. MIC values did show reduced susceptibility to fluoroquinolones and 63 % of the strains were intermediately resistant to tetracycline. The isolates expressed phenotypic traits of both serogroup O1 Ogawa and El Tor and harboured an rstR El Tor and ctxB classical biotype. Among the outbreak isolates, only a single PFGE pattern was observed throughout the study period. This study shows that multi-drug resistant V. cholerae altered El Tor producing classical CT strains are now predominant in northern Vietnam.

Drug response and genetic properties of Vibrio cholerae associated with endemic cholera in north-eastern Thailand, 2003–2011

“…Most of the V. cholerae O1 isolated in Thailand between 2003 and 2011 were resistant to SXT, a recommended first-line drug for children with acute diarrhoea. In Thailand, TE and norfloxacin were the most frequently used drugs for treatment of cholera (Supawat et al, 2009), but the data presented in this study on the emergence of MDR V. cholerae in Thailand, together with the increasing incidence of cholera caused by MDR V. cholerae in Africa, Asia, and South America (Glass et al, 1980;Goel et al 2011;Ibarra & Alvarado, 2007;Mandomando et al, 2007;Tran et al, 2012) indicate that drugs should not be administered without having sensitivity patterns first determined, considering that drug response patterns change frequently and can vary spatio-temporally.…”

“…However, antibiotic therapy has faced challenges related to the rapid emergence and spread of V. cholerae strains resistant to multiple antimicrobial agents, such as TE, ampicillin (AMP), kanamycin, streptomycin, SXT, nalidixic acid, E and most recently to ciprofloxacin and norfloxacin (Mhalu et al, 1979;Glass et al, 1980;Jain et al, 2011). In this study, V. et al, 1980;Goel et al 2011;Ibarra & Alvarado, 2007;Mandomando et al, 2007;Tran et al, 2012) indicate that drugs should not be administered without having sensitivity patterns first determined, considering that drug response patterns change frequently and can vary spatio-temporally.…”

“…However, V. cholerae O1 strains isolated during 2007 in north-east Thailand were all resistant to four antibiotics, E, TE, SXT and AMP, although the patterns changed in 2010-2011, as all except three strains were sensitive to TE, with the rest either sensitive to either all or resistant to one, two or three of the antibiotics. MDR V. cholerae strains isolated from cholera patients in Vietnam between 2008 and 2010 were resistant to four antibiotics, namely E, AMP, TE and SXT (Tran et al, 2012), as occurred in Khon Kaen, Thailand, in 2007. Although Thailand shares its border with Vietnam and despite the fact that the resistant V. cholerae strains occurring in the two countries showed similar resistance patterns, it is highly unlikely that the resistant strains emerged in one of the two countries and were transmitted to the other, since resistant strains were present in Thailand in 2007 but not in 2010 when resistant strains were reported in Vietnam (Tran et al, 2012).…”

“…MDR V. cholerae strains isolated from cholera patients in Vietnam between 2008 and 2010 were resistant to four antibiotics, namely E, AMP, TE and SXT (Tran et al, 2012), as occurred in Khon Kaen, Thailand, in 2007. Although Thailand shares its border with Vietnam and despite the fact that the resistant V. cholerae strains occurring in the two countries showed similar resistance patterns, it is highly unlikely that the resistant strains emerged in one of the two countries and were transmitted to the other, since resistant strains were present in Thailand in 2007 but not in 2010 when resistant strains were reported in Vietnam (Tran et al, 2012). Most of the V. cholerae O1 isolated in Thailand between 2003 and 2011 were resistant to SXT, a recommended first-line drug for children with acute diarrhoea.…”

“…However, antibiotic therapy has faced challenges related to the rapid emergence and spread of V. cholerae strains resistant to multiple antimicrobial agents, such as TE, ampicillin (AMP), kanamycin, streptomycin, SXT, nalidixic acid, E and most recently to ciprofloxacin and norfloxacin (Mhalu et al, 1979;Glass et al, 1980;Jain et al, 2011). In this study, V. et al, 1980;Goel et al 2011;Ibarra & Alvarado, 2007;Mandomando et al, 2007;Tran et al, 2012) indicate that drugs should not be administered without having sensitivity patterns first determined, considering that drug response patterns change frequently and can vary spatio-temporally.In recent years, V. cholerae O1 ET has shown a shift in ctxB from genotype 3 (found in ET strains of the seventh pandemic and the Latin American epidemic) to genotype 1 (found in strains of CL biotype worldwide and the US Gulf Coast ET strains). Atypical ET possessing CL biotype CTX was first reported in Asia at the start of this century (Nair et al, 2006;Raychoudhuri et al, 2008;Morita et al, 2010) and subsequently in Africa and Central America (Alam et al, 2010), including Haiti (Chin et al, 2011Hasan et al, 2012).…”