Ahmed, Sabeena

Alam, Khorshed

Faruque, Abu S.G.

Khan, Mohammed G.Y.

Khan, Wasif A.

Luby, Stephen P.

Malek, Mohammad A.

Nair, Gopinath B.

Sack, David A.

Saha, Debasish

Salam, Mohammed A.

Bioline International

J HEALTH POPUL NUTR 2007 Jun;25(2):241-243ISSN 1606-0997 | $ 5.00+0.20©INTERNATIONAL CENTRE FOR DIARRHOEALDISEASE RESEARCH, BANGLADESHOverall, 525 (55%), 420 (44%), 944 (99%), 948 (100%), and no strains from Dhaka and 186 (54%), 165 (48%), 332 (97%), 343 (100%), and no strains from Matlab were resistant to tetra-cycline, erythromycin, trimethoprim-sulpha-methoxazole, furazolidone, and ciprofloxacin respectively. Prior to October 2004, most strains were resistant to trimethoprim-sulphamethoxa-zole and furazolidone but were uniformly sen-sitive to tetracycline, erythromycin, and cipro-floxacin. The first multidrug-resistant strains of V. cholerae (strains resistant to furazolidone, trimethoprim-sulphamethoxazole, tetracycline, and erythro-mycin) were observed in Matlab in October 2004 among the Ogawa serotype, and the iso-lation of such strains increased dramatically to reach 100% by February 2005. In Dhaka, the multidrug-resistant strains appeared one month later in November 2004 among both Ogawa (13%) and Inaba (5%) strains of V. cholerae, and by February 2005, all the Ogawa strains demon-strated the multidrug-resistant phenoytpe. By March 2005, nearly all the El Tor Ogawa isolates, 5 of 6 (83%) at the Matlab Hospital, and 43 of 45 (96%) at the Dhaka Hospital were multidrug-re-sistant. The figure shows the resistance patterns of V. cholerae in Dhaka and Matlab by month and site. Based on the multidrug-resistant phenotype, it appeared that there were two or more clones of V. cholerae O1 in circulation at different time points, and we are in the process of understand-ing the clonality by subjecting representative strains to molecular typing analysis. We deter-mined antimicrobial susceptibility using both disc-diffusion technique and E-test method. In the absence of a reference zone size for V. chol-erae resistance to erythromycin and azithromy-cin, we used the zone size for other organisms to determine the susceptibility (zone of inhibi-tion ≥23 mm for erythromycin and ≥18 mm for azithromycin) of the V. cholerae strains to these drugs. Seventeen of the 35 (49%) V. cholerae strains were resistant to both erythromycin and azithromycin, while the remaining 18 (51%) strains were susceptible to both erythromycin and LETTER-TO-THE-EDITOREmergence of Multidrug-resistant Strain of Vibrio cholerae O1 in Bangladesh and Reversal of Their Susceptibility to Tetracycline after Two YearsCorrespondence and reprint requests should be addressed to:Dr. A.S.G. FaruqueScientist, Clinical Sciences DivisionICDDR,BGPO Box 128, Dhaka 1000(Mohakhali, Dhaka 1212)BangladeshEmail: gfaruque@icddrb.orgFax: (88-02) 988-5657Sir,Cholera is endemic and follows a distinct sea-sonality in Bangladesh (1). Early administration of rehydration therapy using appropriate oral or intravenous fluid(s) saves the lives of patients with cholera. Therapy with an effective antimi-crobial agent significantly shortens the dura-tion of diarrhoea and hospitalization, reduces the volume of watery stool and the requirement of maintenance fluids, and shortens the duration of faecal excretion of Vibrio cholerae reducing transmission of infection to other family mem-bers and nosocomial infections in the clinic set-ting (2). Tetracycline and doxycycline (long-acting tetra-cycline) have long been the antibiotics of choice for treating severe cholera in Bangladesh and in other parts of the world, except for young chil-dren and pregnant women (1,2). Furazolidone, erythromycin, trimethoprim-sulphamethoxazole, and chloramphenicol have also been effective in treating severe cholera caused by strains of V. cholerae susceptible to these agents (3).During October 2004–December 2005, 953 (565 Ogawa and 388 Inaba) and 344 (197 Ogawa and 147 Inaba) strains of V. cholerae O1 isolated from cholera cases admitted to the Dhaka Hospital (urban area) and Matlab Hospital (rural area) of ICDDR,B respectively were examined for sus-ceptibility to tetracycline, erythromycin, trime-thoprim-sulphamethoxazole, furazolidone, and ciprofloxacin. Antimicrobial susceptibility was performed using the disc-diffusion technique on Mueller-Hinton agar (Difco, Detroit, Michigan, USA) with commercial discs (Oxoid, UK) and ap-propriate control strains (4). Faruque ASG et al.Multidrug-resistant Vibrio cholerae O1JHPN242azithromycin. The strains resistant to erythro-mycin exhibited minimum inhibition concen-trations (MICs) of 8 to 32 µg/mL, while the MIC of those susceptible to the drug ranged from 0.25 to 1 µg/mL. The MIC of the strains resistant to azithromycin ranged from 0.75 to 3 µg/mL, while the MIC of those susceptible to the drug was from 0.047 to 0.125 µg/mL. These findings suggest that resistance to erythromycin could be a marker for resistance to azithromycin. Similarly, resistance to tetracycline is considered a proxy indicator for resistance to doxycycline (5). We have, for the first time, encountered this unique, multidrug-resistant pattern, including resistance to erythromycin, among V. cholerae O1 in Bangladesh.Throughout the period of this investigation, all isolates from Matlab and Dhaka were susceptible to ciprofloxacin. The MIC for ciprofloxacin was determined using E-test (AB-BIODISK, Sweden) with the zone size interpretive criteria for sus-ceptibility corresponding to 0.06 µg/mL (5). We noted a consistent increase in the median MIC of V. cholerae O1 strains isolated at the Dhaka Hospital over the years: 0.003 µg/mL in 1994, 0.023 µg/mL in 2001, and 0.38 to 0.5 µg/mL in 2005 (6,7). In a recent study in adults infected with V. cholerae O1, we observed clinical success (resolution of diarrhoea by 48 hours of initia-tion of therapy) rate of 68% with 500-mg 12-hourly dose of ciprofloxacin for three days—a rate substantially lower than that observed with a single one-gramme dose of the drug in an ear-lier study (8). The findings are disturbing since a further in-crease in the MIC may render ciprofloxacin in-effective in the management of cholera caused by such multidrug-resistant strains of V. chol-erae O1. Further studies are being conducted at ICDDR,B to determine the mechanism of resis-tance of these multidrug-resistant strains to cip-rofloxacin. In August 2006, we observed a re-emergence of the Inaba serotype and a sharp reduction in the isolation rate of the Ogawa serotype. In Bangla-desh, such changes in serotypes and the appear-ance of short-lasting, multidrug-resistance, have also been noted in the past (9,10,11). The pro-portion of V. cholerae strains resistant to tetracy-cline decreased substantially (from 75% in Janu-ary 2006 to 10% in August 2006). Resistance to tetracycline persisted for nearly two years, a find-ing that we have not observed earlier (12,13).The current situation clearly demonstrates the need to monitor MIC in areas where cholera is endemic to assess the clinical efficacy of cipro-floxacin in the treatment of cholera. There is also a need to identify effective alterative antimicro-bials for the management of cholera caused by such strains. Through this communication, we would also like to alert our neighbouring coun-tries and the region of circulation of this new multidrug-resistant strain of V. cholerae O1. ACKNOWLEDGEMENTSThe study was funded by ICDDR,B and Govern-ment of Bangladesh through IHP-HNPRP.Fig. Resistance patterns of V. cholerae O1 in Dhaka and Matlab by month and siteSep Oct Nov Dec Jan Feb Mar% resistant Dhaka Ogawa Matlab Ogawa Dhaka Inaba Matlab Inaba 01020304050607080901002004 2005Faruque ASG et al.Multidrug-resistant Vibrio cholerae O1Volume 25 | Number 2 | June 2007 243REFERENCES1. Sack DA, Sack RB, Nair GB, Siddique AK. Cholera. Lancet 2004;363:223-33.2. Greenough WB, 3rd, Gordon RS, Jr., Rosenberg IS, Davies BI, Benenson AS. Tetracycline in the treat-ment of cholera. Lancet 1964;41:355-7.3. World Health Organization. Guidelines for cholera control. Geneva: World Health Organization, 1993. 46 p.4. National Committee for Clinical Laboratory Stan-dards. Performance standards for antimicrobial disc susceptibility tests. 4th ed. Approved standard M2-A5. Villanova, PA: National Committee for Clini-cal Laboratory Standards, 1990. 65 p.5. Koplan JP, Hughes JM, Cohen ML, Samba EM, Ka-bore AB, Bopp CA et al. Laboratory methods for the diagnosis of epidemic dysentery and cholera. Atlanta, GA: Centers for Disease Control and Pre-vention, 1999. 71 p.6. Khan WA, Bennish ML, Seas C, Khan EH, Ronan A, Dhar U et al. Randomized controlled compari-son of single-dose ciprofloxacin and doxycycline for cholera caused by Vibrio cholerae O1 or O139. Lancet 1996;348:296-300.7. Saha D, Khan WA, Karim MM, Chowdhury HR, Salam MA, Bennish ML. Single-dose ciprofloxa-cin versus 12-dose erythromycin for childhood cholera: a randomised controlled trial. Lancet 2005; 366:1085-93.8. Salam MA, Saha D, Karim MM, Khan WA, Ahmed S. The quest for new drug in the treatment of chol-era in adults: evaluation of efficacy of rifaximin in a randomized, controlled clinical trial (abstract). In: 40th Joint Meeting of the US-Japan Cholera and Other Bacterial Enteric Infections Panel, Bos-ton, USA (30 November–2 December 2005). Bos-ton: Organizer, 2005:218.9. Siddique AK, Zaman K, Majumder Y, Islam Q, Bashir I, Mutsuddy P et al. Simultaneous outbreaks of contrasting drug resistant classic and El Tor Vibrio cholerae O1 in Bangladesh. Lancet 1989;2:350.10. Urassa WK, Mhando YB, Mhalu FS, Mjonga SJ. An-timicrobial susceptibility pattern of Vibrio cholerae O1 strains during two cholera outbreaks in Dar es Salaam, Tanzania. East Afr Med J 2000;77:350-3.11. Zachariah R, Harries AD, Arendt V, Nchingula D, Chimtulo F, Courteille O et al. Characteristics of a cholera outbreak, patterns of Vibrio cholerae and antibiotic susceptibility testing in rural Malawi. Trans R Soc Trop Med Hyg 2002;96:39-40.12. Glass RI, Huq I, Alim ARMA, Yunus M. Emergence of multiply antibiotic-resistant Vibrio cholerae in Bangladesh. J Infect Dis 980;142;939-42.13. Glass RI, Huq MI, Lee V, Threlfall EJ, Khan MR, Alim ARMA et al. Plasmid-borne multiple drug re-sistance in Vibrio cholerae serogroup O1, biotype El Tor: evidence for a point-source outbreak in Bangladesh. J Infect Dis 1983;147:204-9.  Abu S.G. Faruque, Khorshed Alam, Mohammad A. Malek, Mohammed G.Y. Khan, Sabeena Ahmed, Debasish Saha, Wasif A. Khan, Gopinath B. Nair, Mohammed A. Salam, Stephen P. Luby, and David A. SackICDDR,BGPO Box 128Dhaka 1000(Mohakhali, Dhaka 1212)Bangladesh

Emergence of Multidrug-resistant Strain of Vibrio cholerae  O1 in
Bangladesh and Reversal of Their Susceptibility to Tetracycline After
Two Years

Emergence of Multidrug-resistant Strain of Vibrio cholerae O1 in Bangladesh and Reversal of Their Susceptibility to Tetracycline After Two Years

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