Changing characteristics of Vibrio cholerae: emergence of multidrug resistance and non-O1, non-O139 serogroups.

The serogroups and antimicrobial susceptibility patterns of V. cholerae isolated in Hubli, India during the years 2000 to 2004 were monitored. A total of 256 V. cholerae isolates were obtained during the study period, of which 129 (50.4%) belonged to serogroup O1 while the O139 and non-O1, non-O139 serogroups constituted 61 (23.8%) and 66 (25.8%) isolates, respectively. V. cholerae O1 Ogawa was the predominant isolate during the first 2 years of the study. However, this was replaced by V. cholerae non-O1, non-O139 serogroups in the following years. The V. cholerae, which was susceptible to most enteric antimicrobials in 2000, was found to be multidrug resistant in subsequent years, with the development of fluroquinolone resistance since 2002. Surveillance of the epidemiological and microbiological characteristics of V. cholerae provides useful information for managing cholera cases. The V. cholerae non-O1, non-O139 serogroups coupled with multiple antimicrobial resistance may form a group of emerging diarrheal pathogens in the tropics.

A cólera no Estado do Rio Grande do Norte--Brasil--perfil sorológico e de sensibilidade do Vibrio cholerae a diferentes antimicrobianos / Cholera in Rio Grande do Norte State--Brazil: sorology and sensitivity of Vibrio cholerae to different antimicrobials

PURPOSE: The emergence of multiple resistance to antimicrobials in Vibrio cholerae isolated in the state of Ceará, Brazil, alerted researchers in this area to the sensitivity to antimicrobials of strains isolated in Rio Grande do Norte (RN), Brazil. METHODS: One hundred and four strains of V. cholerae of human origin, isolated by Laboratório Central de Saúde Pública Dr. Almino Fernandes, were serologically typified and evaluated for in vitro sensitivity to eight antibiotics belonging to different groups (polymyxine, tetracycline, chloramphenicol, nitrofurantoin, sulphazotrin, pefloxacine, erythromycine, ampicillin). The strains were collected from patients suspected of contracting choleric diarrhea in the year 1999, in Natal/RN/Brazil. RESULTS: From the sample total, 100 were identified as V. cholerae, serogroup O:1, biotype El Tor, with 99 (95.3%) belonging to serovar Ogawa and only 1 (0.9%) to serovar Inaba. The 4 remaining were characterized as non O:1 V. cholerae, with 3 (2.9%) biochemically identified as Heiberg type I and 1 (0.9%) as type II. All the V. cholerae serogroup O:1 strains were sensitive to tetracycline, chloramphenicol, sulphazotrin, pefloxacine, erythromycine and resistant to polymyxine. In relation to nitrofurantoin, only 1 was sensitive. Only 1 was resistant to ampicillin. The non O:1 V. cholerae strains were resistant to polymyxine. CONCLUSIONS: The results showed sensitivity in 100% of the V. cholerae serogroup O:1 strains to tetracycline, an elective drug in the treatment of cholera, and an absence of multiple resistant strains in our environment. An interesting finding was the frequency of serovar Ogawa in 1999, considering the greater incidence of serovar Inaba in other years of cholera outbreaks in RN.

Quinolone susceptibility of Vibrio cholerae O1 & O139 isolates from Vellore.

BACKGROUND & OBJECTIVES: Vellore is an endemic area for cholera. The relative prevalence of clinical cases of Vibrio cholerae O1 and O139 has been fluctuating. Few studies have examined the susceptibility of local isolates to quinolones. The objective of the present study was to look at quinolone susceptibility and determine MIC of ciprofloxacin to representative clinical isolates of V. cholerae O1 and O139 in Vellore, obtained between 1997 and 1999. METHODS: Antimicrobial susceptibility testing of V. cholerae strains was performed by disc diffusion technique and MIC determination by E test. RESULTS: Five of 30 O1 and all the O139 serogroup isolates were susceptible to nalidixic acid. All isolates of both serogroups were sensitive to norfloxacin. All isolates of both serogroups gave MIC results in the susceptible range to ciprofloxacin; the MICs being lower for V. cholerae O139 (MIC50 = 0.004 microgram/ml and MIC90 = 0.047 microgram/ml) than for O1 serogroup (MIC50 = 0.38 microgram/ml and MIC90 = 0.5 microgram/ml). INTERPRETATION & CONCLUSION: V. cholerae O1 and O139 show differences in quinolone susceptibility, the reason for this is not clear. This could be because of longer exposure of the O1 serogroup to quinolone antimicrobials as compared to the O139 serogroup.