霍乱弧菌O1和O139血清型I类整合子的扩增与分布研究

目的扩增霍乱弧菌不同血清型I类整合子基因片段,并分析I类整合子在霍乱弧菌O1和O139血清型中的分布. 方法收集霍乱弧菌O1和O139血清型40株,根据GenBank资料设计PCR引物,扩增霍乱弧菌I类整合子基因片段,并用限制性酶切分析法进行鉴定,分析I类整合子在不同血清型的分布情况. 结果从霍乱弧菌O1和O139血清型中均能扩增约800 bp的基因片段,扩增片段经Pst I酶切后可获得671和127 bp的片段,经HindIII酶切后可获得580、160和58 bp的片段,经HindIII 和Pst I酶切后可获得453、160、127和58 bp的片段,I类整合子在O139血清型霍乱弧菌中分布多于O1血清型. 结论 I类整合子与霍乱散发菌株耐药性的传递、血清型的分布有密切的联系.     

Expanding multiple antibiotic resistance among clinical strains of Vibrio cholerae isolated from 1992-7 in Calcutta, India

Antimicrobial susceptibilities of Vibrio cholerae strains isolated from cholera patients admitted to the Infectious Diseases Hospital, Calcutta, India for 6 years were analysed to determine the changing trends; 840 V. cholerae strains isolated in 1992-1997 were included in this study. Among V. cholerae serogoup O1 and O139, ampicillin resistance increased from 1992 (35 and 70%, respectively) to 1997 (both serogroups 100%). Resistance to furazolidone and streptomycin was constantly high among V. cholerae O1 strains with gradual increase in resistance to other drugs such as ciprofloxacin, co-trimoxazole, neomycin and nalidixic acid. V. cholerae O139 strains exhibited susceptibilities to furazolidone and streptomycin comparable with those of O1 strains. However, after initial increase in resistance to chloramphenicol and co-trimoxazole, all the V. cholerae O139 strains became susceptible to these two drugs from 1995 onwards. Both V. cholerae O1 and O139 remained largely susceptible to gentamicin and tetracycline. V. cholerae non-O1, non-O139 strains, in contrast, exhibited high levels of resistance to virtually every class of antimicrobial agents tested in this study especially from 1995. Kruskal-Wallis one-way analysis showed that V. cholerae O1 Ogawa serogroup exhibited significant yearly increase in resistance to nine antibiotics followed by non-O1 non-O139 and O139 strains to six antibiotics and two antibiotics respectively. Interesting observation encountered in this study was the dissipation of some of the resistant patterns commonly found among V. cholerae non-O1 non-O139 or O1 serogroups to the O139 serogroup and vice versa during the succeeding years.     

Multiply antibiotic-resistant Vibrio cholerae O1 biotype El Tor strains emerge during cholera outbreaks in Zambia

Antibiotic resistance data, made available from laboratory records during eight cholera outbreaks between 1990 and 2004 showed Vibrio cholerae serogroup O1 to have a low level of resistance (2-3%) to tetracycline during 1990-1991. Resistance increased for tetracycline (95%), chloramphenicol (78%), doxycycline (70%) and trimethoprim-sulphamethoxazole (97%) in subsequent outbreaks. A significant drop in resistance to tetracycline and chloramphenicol followed the adoption of a national policy to replace tetracycline with erythromycin for treating cholera. Sixty-nine strains from cholera outbreaks in Zambia between 1996 and 2004, were examined for antibiotic resistance and basic molecular traits. A 140 MDa conjugative, multidrug-resistant plasmid was found to encode tetracycline resistance in strains from 1996/1997 whereas strains from 2003/2004 were resistant to furazolidone, but susceptible to tetracycline, and lacked this plasmid. PCR revealed 25 of 27 strains from 1996/1997 harboured the intl1 class 1 integron but lacked SXT, a conjugative transposon element. Similar screening of 42 strains from 2003/2004 revealed all carried SXT but not the intl1 class 1 integron. All 69 strains, except two, one lacking ctxA and the other rstR and thus presumably truncated in the CTX prophage region, were positive for important epidemic markers namely rfbO1, ctxA, rstR2, and tcpA of El Tor biotype. Effective cholera management is dependent on updated reports on culture and sensitivity to inform the choice of antibiotic. Since the emergence of antibiotic resistance may significantly influence strategies for controlling cholera, continuous monitoring of epidemic strains is crucial.     

Class I integrons and SXT elements in El Tor strains isolated before and after 1992 Vibrio cholerae O139 outbreak,Calcutta, India

We examined the distribution of class I integrons and SXT elements in Vibrio cholerae O1 El Tor strains, isolated in Calcutta, India, before and after the V. cholerae O139 outbreak in 1992. Class I integrons, with aadA1 gene cassette, were detected primarily in the pre-O139 strains; the SXT element was found mainly in the post-O139 strains.     

Fluoroquinolone-resistant Vibrio cholerae isolated during a cholera outbreak in India

During the cholera epidemic of 2002 in and around Hubli, south India, Vibrio cholerae strains resistant to fluoroquinolones were isolated. Among the isolates of V. cholerae non-O1, non-O139 serogroups, 55.9% and 47.1% were resistant to norfloxacin and ciprofloxacin, respectively. However, only 12.5% of the O1 serogroup strains were resistant to both norfloxacin and ciprofloxacin. Though the O139 serogroup strains were susceptible to these antibiotics, they exhibited multidrug resistance. Emergence of fluoroquinolone-resistant V. cholerae that also exhibited multidrug resistance is of great significance in the epidemiology and control of cholera.     

A high proportion of Vibrio cholerae strains isolated from children with diarrhoea in Bangkok, Thailand are multiple antibiotic resistant and belong to heterogenous non-O1, non-O139 O-serotypes.

Results of a surveillance on cholera conducted with patients seen at the Children Hospital in Bangkok, Thailand from August 1993 to July 1995 are presented. Annually, isolation rates for Vibrio cholerae varied between 1.7 and 4.4% of patients with diarrhoea. V. cholerae O1 serotype Ogawa accounted for between 31 and 47% of patients cultured positive for V. cholerae, whereas the O139 serotype dominated in early 1994 after which it disappeared. Non-O1, non-0139 strains were isolated at similar rates as serotype O1 in 1993 and 1994, but accounted for 69% of V. cholerae culture positive specimens in 1995. However, the annual proportion of the isolation of non-O1, non-O139 strains showed little variation and remained low between 1.0 and 1.3%. Serotyping of 69 epidemiological unrelated non-O1, non-O139 strains produced 37 different O-serotypes. BglI ribotyping of serotypes containing more than two strains demonstrated a high degree of heterogeneity within and between serotypes, except seven serotype O37 strains which showed an identical ribotype suggesting clonality. None of the 69 strains hybridized with a cholera toxin probe and only two strains hybridized with a heat-stable enterotoxin probe. Susceptibility testing to 12 antibiotics showed that 40 of 69 (58%) non-O1, non-O139 strains were resistant to colistin, streptomycin and sulphisoxazole and 28 of 69 (41%) were multiple antibiotic resistant (MAR; > or = 4 antibiotics). Although 26 of 69 (38%) strains contained one or more plasmids, the plasmids were of low molecular weights and did not seem to encode antibiotic resistance. The results of the present study showed that a high proportion of heterogenous MAR V. cholerae non-O1, non-O139 strains were isolated from children at the hospital. With reference to the emergence of V. cholerae O139 in 1992, we suggest that non-O1, non-O139 strains should be monitored carefully to detect new serotypes with a possible epidemic potential, but also to determine the development and mechanism of antibiotic resistance.     

2005年-2010年武汉市霍乱弧菌监测分析

目的:对2005年-2010年霍乱弧菌监测中分离的25株疑似菌株进行系统鉴定。方法:分离培养、血清学试验、系统生化鉴定(VITEK32)、PCR检测其分型及毒素基因、药敏试验。结果:25株菌鉴定为霍乱弧菌的有21株,与霍乱弧菌发生交叉凝集4株;病例监测主要为O139霍乱弧菌、外环境监测主要为O1群霍乱弧菌;病例监测菌株携带霍乱弧菌毒素基因(ctxAB)、其他菌株均不携带霍乱弧菌毒素基因(ctxAB)。药敏实验结果对诺氟沙星和环丙沙星敏感,对其他抗生素有不同程度的耐药。结论:武汉市霍乱弧菌在病例监测中主要为O139群霍乱弧菌产毒株、外环境监测中主要为O1群霍乱弧菌非产毒株,不同型别菌株存在不同程度耐药性。     

耐碳青霉烯类肺炎克雷伯菌耐药基因检测及同源性

目的探讨耐碳青霉烯类肺炎克雷伯菌(CRKP)耐药基因型及同源性。方法收集某院2015年9月—2016年2月临床标本分离的38株CRKP,采用聚合酶链反应(PCR)方法检测耐药基因型,脉冲场凝胶电泳(PFGE)分析菌株同源性。结果 38株CRKP主要来源于重症监护病房(ICU)及外科重症监护病房(SICU),分别占39.48%、34.21%。38株CRKP均检出blaKPC和blaSHV耐药基因,6株检出blaCTX耐药基因。PFGE显示共分成A、B、C、D4个谱型,其中以C型为主(65.78%,25/38)。A型菌株中菌株14、15、16携带blaKPC-2型、blaSHV型、blaCTX-M-15耐药基因,此3株细菌均是SICU患者分离的,菌株14和15分离自同一天,菌株16分离时间延后一周;C型菌株中,菌株10、18、25、28的同源性为100%,菌株10、18分离自ICU患者,菌株25、28分离自神经内一科患者(均从ICU转出),均是在ICU住院期间检出,且分离时间相差1 d。结论该院CRKP耐药基因型以blaKPC及blaSHV为主,存在克隆株医院内流行。     

鸡来源产超广谱β-内酰胺酶大肠埃希菌携带整合子基因的研究

目的 分析鸡肠道内共生的产超广谱β-内酰胺酶(ESBLs)大肠埃希菌整合子携带状况以及其与多重耐药性的关系.方法 从甘肃、湖北、北京、四川地区养殖场鸡粪便标本中分离的大肠埃希菌,肉汤稀释法检测菌株的耐药性,WHONET软件进行耐药性分析;筛选出的ESBLs菌株进行整合子的PCR检测和基因测序. 结果 通过药敏试验从鸡粪中分离的224株大肠埃希菌中共检出产ESBLs的菌株54株,分离率为24.1%.产ESBLs的菌株中I类整合子的携带率为63.0%,I类整合子可变区发现的耐药基因有addA1、aadA2、aadA5、aadA22,dfrA12、dfrA17、dfrI,aar-3,分别介导氨基糖苷类、磺胺类抗生素以及利福平的耐药性.aadA22是在国内菌株中首次报道.Ⅱ类整合子携带率为5.6%,携带的耐药基因包括sat、ereA、aadA1.Ⅲ类整合子酶阳性的有3株菌,但其可变区未检出任何耐药基因. 结论 I类整合子主要介导氨基精苷类抗生素和甲氧嘧啶的耐药性,在大肠埃希菌ESBLs菌株的多重耐药性中具有重要的作用,加强养殖动物大肠埃希菌耐药性以及整合子携带状况的监测,对防止耐药菌株的广泛传播,改善临床抗生素的疗效具有重要意义.     

Genetic diversity and antibiotic resistance of clinical and environmental Vibrio Cholerae suggests that many serogroups are reservoirs of resistance

Vibrio cholerae is an important human pathogen and the cause of cholera. Since genetic variation and antibiotic resistance of strains have implications for effective treatment of the disease, we examined the genetic diversity and antibiotic resistance profile in 92 clinical strains (serogroup O1) and 56 environmental strains (O1 antigen, 42 strains; non-O1 antigen, 14 strains) isolated in Brazil between 1991 and 1999. Clinical and environmental O1 strains showed greater drug resistance compared to environmental non-O1 strains. Nearly all clinical O1 strains were resistant to one or more antibiotics while half of the environmental O1 and non-O1 strains were resistant to one or more antibiotics. No plasmids or class 1 integrons were detected in the strains by PCR analysis. Multilocus enzyme electrophoresis analysis (MLEE) suggests most of the O1 strains belong to a single (South American) clone that is related but different to seventh-pandemic strains isolated from other parts of the world. Our results show that there is a close genetic relationship between clinical and environmental O1 strains and that many serogroups and the environment can be a reservoir for antibiotic resistance.     

Changes in Vibrio cholerae O1 strains isolated in Romania during 1977-95.

Six hundred and twenty-four Vibrio cholerae O1 strains, 623 serotype Ogawa and one serotype Inaba, isolated in Romania between 1977-95 were tested to detect all changing traits concerning serogroup, serotype, biotype, phage type and resistotype patterns and subsequently, the possible epidemiological relationship among these strains. Biotyping revealed one classical, 580 eltor strains and 43 intermediary variants. When tested with Mukerjee phages, 546 (87%) strains were sensitive and 78 (13%) resistant. One phage type (M4) dominated during 1977-90, two phage types (M4 and M5) exhibited the same high frequencies during 1991, a diversity of types occurred during 1993-4 whereas in 1995, two phage types (M4 and M5) showed similar distributions again. Five patterns of drug susceptibility were successively described during 1977-95. The most prominent changes in Vibrio cholerae O1 strains were noticed during 1993-4: the highest number of non-typable strains and intermediary variants, the widest spectrum of phage types and of multidrug resistance. In 1995, the strains reverted to the previous typable forms but a new drug resistance pattern was noticed.     

Incidence and molecular analysis of Vibrio cholerae associated with cholera outbreak subsequent to the super cyclone in Orissa,India

An epidemiological study was carried out to find out the aetiological agent for diarrhoeal disorders in the cyclone and flood affected areas of Orissa, India. Rectal swabs collected from 107 hospitalized diarrhoea patients were bacteriologically analysed to isolate and identify the various enteropathogens. Detection of toxic genes among E. coli and V. cholerae was carried out by polymerase chain reaction (PCR) assay. Of the 107 rectal swabs analysed, 72.3% were positive for V. cholerae O1 Ogawa, 7.2% for V. cholerae O139, 1.2% for E. coli (EAggEC) and 1.2% for Shigella flexneri type 6. Using multiplex PCR assay it was found that all V. cholerae isolates were ctxA positive and El Tor biotype. Strains of V. cholerae O1 were observed to be resistant to nalidixic acid, furazolidone, streptomycin, co-trimoxazole and ampicillin. Except for nalidixic acid, the resistance pattern for O139 was identical to that of O1 strains. Representative strains of V. cholerae were further characterized by randomly amplified polymorphic DNA (RAPD) analysis and ribotyping. Both O1 and O139 V. cholerae strains exhibited the R3 pattern of ribotype and belonged to a similar pattern of RAPD compared with that of Calcutta strains. Early bacteriological and epidemiological investigations have revealed the dominance of V. cholerae O1 among the hospitalized patients in cyclone affected areas of Orissa. Drinking water scarcity and poor sanitation were thought to be responsible for these diarrhoeal outbreaks. Timely reporting and implementation of appropriate control measures could contain a vital epidemic in this area.     

2010年湖南省霍乱弧菌病原学特征及溯源分析

目的分析2010年湖南省霍乱弧菌分离株的病原学特征,比较霍乱疫情分离株与常规监测分离株之间的克隆相关性,追溯传染源。方法对疫情与监测分离到的42株霍乱弧菌进行常规生物分型和PCR检测毒力基因,对23株代表株进行药敏试验,对18株代表株通过脉冲场凝胶电泳(PFGE)获得电泳图谱,利用BioNumerics软件对图谱进行聚类分析,探讨菌株间的相关性。结果 2010年从湖南省霍乱疫情中分离10株霍乱弧菌均为O139群,ctxA阳性率100%。常规监测分离霍乱弧菌32株,其中O1群15株,全部为ctxA阴性株;O139群17株,ctxA阳性率94.11%。23株霍乱弧菌耐药结果显示强力霉素、复方新诺明的耐药率分别为47.83%、56.52%,发现1株对诺氟沙星、环丙沙星耐药。PFGE方法显示有5种脉冲场凝胶电泳图谱,相似率在82%~100%之间,甲鱼中分离的O139群霍乱弧菌与霍乱疫情分离菌株之间高度同源。结论湖南省霍乱弧菌存在紧密相关的流行克隆群;被O139群霍乱弧菌污染的甲鱼很可能是湖南省霍乱疫情发生的主要传染来源,海、水产品的监测是霍乱防控的重点;要密切关注对诺氟沙星、环丙沙星的耐药变化。     

Vibrio cholerae O1 lineages driving cholera outbreaks during seventh cholera pandemic in Ghana

In recent years, the frequency of cholera epidemics across Africa has increased significantly with thousands of people dying each year. However, there still exists a lack of information concerning the Vibrio cholerae O1 lineages driving early and contemporary epidemics since the seventh cholera pandemic started in the continent. This compromises the understanding of the forces determining the epidemiology of cholera in Africa and its control. This study aimed to analyze a collection of V. cholerae O1 strains from the beginning of the seventh cholera pandemic in Ghana and to compare them with recent isolates to understand the evolution of the cholera epidemic in Ghana. V. cholerae O1 strains were characterized by means of Multilocus Sequence Analysis (MLSA), genes from the virulence core genome (VCG), and genes related to the choleragenic phenotype. Our results revealed two major clusters of Ghanaian V. cholerae O1 strains, El Tor and Amazonia/Ghana. Concerning the virulence genes, all strains harbored the set of VCG and most were positive for VSP-II genomic island. The ctxB gene of the contemporary strains was characterized as Altered El Tor. The strains from 1970 to 1980 were susceptible to all antibiotics tested, except for the Amazonia/Ghana cluster that was resistant to aminoglycosides and carried the class 2 integron with the sat2-aadA1 arrangement. This study showed that distinct V. cholerae O1 were the determinants of cholera outbreaks in Ghana. Thus, in endemic regions, such as Africa, cholera can be caused by various V. cholerae O1 genotypes.     

Antimicrobial resistance and class 1 integrons in pathogenic Escherichia coli from dairy farms

The goal of this study was to assess the prevalence of antimicrobial resistance and class 1 integrons, including integron-associated genes, in 24 Escherichia coli isolates from dairy farms. Escherichia coli isolates (n = 14) from dairy cows with mastitis (ECDM), Shiga toxin-producing (STEC) O157:H7 from cull dairy cow fecal samples (n = 9) and bulk tank milk (n = 1) were evaluated for sensitivity to 19 antimicrobial agents used commonly in human and/or veterinary medicine. Multiplex PCR was used to determine presence of genes associated with class 1 integrons (intI1, qacEDelta1, and sulI1). Class 1 integrons were found only in eight of 10 isolates (one STEC O157:H7 and seven ECDM) that demonstrated antimicrobial resistance, and seven of these were resistant to two or more antimicrobial agents. Eight of 10 STEC O157:H7 and six of 14 ECDM were susceptible to all commonly used antibiotics. Five ECDM demonstrated multiple resistances to four or more antibiotics. Most of the 24 isolates examined exhibited resistance against sulfamethoxazole, followed by streptomycin and tetracycline. STEC O157:H7 strains had less prevalence of antibiotic resistance and integron carriage than ECDM. The multiplex PCR method developed for detection of intI1, qacEDelta1, and sulI1 can be used routinely for monitoring presence of these genes. Class 1 integrons were found in eight of 10 E. coli strains that demonstrated antimicrobial resistance; seven of these were resistant to two or more antibiotics. It appears that integrons played a role in the incidence of antimicrobial resistance of the strains used in this study.     

Vibrio cholerae resistant to 2,4-diamino-6,7-diisopropylpteridine (O/129) isolated from patients with enteritis in Ceará, Brazil

This paper reports the characterization of clinical Vibrio cholerae resistant to vibriostatic agent O/129, using classical and plasmid analysis. In a study conducted during December 1991-September 1993, two of 7,058 V. cholerae strains, obtained from patients suspected to have cholera in the State of Ceará, northeast Brazil, were resistant to 150 micrograms of the vibriostatic agent O/129 (2,4-diamino-6,7-diisopropylpteridine). One strain was identified as V. cholerae O1 El Tor Inaba and the other one as serogroup O22. Only one O1 strain harboured a plasmid of 147 kb transferable to Escherichia coli K12, and five strains of V. cholerae O1 and non-O1 were sensitive to O/129 and plasmid-negative at a frequency between 8 x 10(-2) and 3.6 x 10(-5). Additionally, O/129-resistant strains of V. cholerae O1 and O22 were resistant to trimethoprim/sulphamethoxazole.     

鲍氏不动杆菌多药耐药与Ⅰ类整合子相关性的研究

目的 探讨鲍氏不动杆菌的多药耐药与I类整合子的相关性.方法 收集39株医院感染多药耐药鲍氏不动杆菌株及41株非多药耐药鲍氏不动杆菌株,以纸片扩散法敏感试验(K-B法)检测其耐药表型,以聚合酶链反应(PCR)方法检测Ⅰ类整合子的分布情况,分析Ⅰ类整合子与细菌耐药表型的相关性.结果 鲍氏不动杆菌对多种抗菌药物的耐药率均较高,除对亚胺培南、头孢哌酮/舒巴坦、环丙沙星、阿米卡星、哌拉西林/他唑巴坦敏感率较高外,对其他抗菌药物的耐药率均>40.0%;多药耐药鲍氏不动杆菌中Ⅰ类整合子阳性率为82.1%,非多药耐药菌株阳性率为26.8%,多药耐药菌与非多药耐药菌株Ⅰ类整合子阳性率差异有统计学意义(X~2=24.6,P<0.01);比较研究Ⅰ类整合子阳性菌株耐药表型与Ⅰ类整合子阴性菌株耐药表型发现,除了对亚胺培南敏感率均较高,对氨曲南均耐药,两者耐药率之间差异无统计学意义外,对其他抗菌药物耐药率差异均有统计学意义(P<0.05).结论 Ⅰ类整合子的表达与鲍氏不动杆菌多药耐药密切相关.     

湖南省2005年-2010年霍乱疫情分离株的毒力基因PCR及PFGE分型分析

目的:了解2005年-2010年湖南省霍乱疫情分离到的O139群霍乱弧菌菌株的病原学特征,研究疫情分离株之间的克隆相关性。方法:采用K-B法进行药敏试验;聚合酶链反应(PCR)检测ctxAB毒力基因;脉冲场凝胶电泳对疫情分离代表株进行PFGE分型分析。结果:33株霍乱弧菌对强力霉素、复方新诺明的耐药率较高,分别为39.39%和75.76%,对环丙沙星、诺氟沙星以及丁胺卡那100%敏感;毒力基因的PCR结果显示为所有疫情分离的O139霍乱弧菌均为产毒株,即霍乱肠毒素基因ctxAB阳性;24株分离自2005年和2010年的7起疫情里的O139霍乱弧菌进行PFGE分型及聚类分析后,共分为3个PFGE带型,所有菌株的带型相似率在83%～100%之间。结论:湖南省2005年-2010年霍乱疫情以O139群为主,引起疫情的全部为产毒株,不同年份不同地区之间霍乱疫情的分离菌株之间存在着紧密相关的流行克隆群,对分离菌株进行耐药性监测和进一步的分子分型分析,有助于霍乱的主动监测和传染来源的追踪。     

1984-2002年重庆市59株O_1群霍乱临床分离株耐药性及分子分型研究

目的分析重庆市1984-2002年O1群霍乱临床分离株的耐药性和菌株的相关性。方法对59株O1群霍乱临床分离株(小川型20株,稻叶型39株)采用K-B法检测对16种抗菌药物的敏感性,用NotI酶切基因组DNA,经脉冲场凝胶电泳(PFGE)获得电泳图谱,利用BioNumerics软件对图谱进行聚类分析。结果重庆地区O1群霍乱弧菌对复方新诺明耐药、痢特灵和链霉素的耐药严重,耐药率分别为28.81%(17/59)、61.02%(36/59)和30.51%(18/59),人群分离株对丁胺卡那、庆大霉素、妥布霉素、氨苄西林、新霉素和强力霉素敏感,未发现耐药菌株。21株小川型和40株稻叶型O1群霍乱弧菌被分为13种PFGE型18个亚型,从患者分离到的59株O1群霍乱弧菌的相似性值约在88%～100%。结论未发现重庆市O1群霍乱弧菌人群分离株的耐药性有明显改变,小川型和稻叶型的耐药性不同。重庆市O1群霍乱弧菌人群分离株同源性较高,可能为来自同一来源的流行菌株。     

Transferable plasmid-mediated drug resistance among non-O1 Vibrio cholerae and rough strains of Vibrio cholerae from Tamilnadu, India.

A total of 289 non-O1 Vibrio cholerae (NVC) strains and 20 rough V. cholerae (RVC) strains isolated in an endemic area were tested for antibiotic resistance and for transferable R-plasmids. Twenty three per cent of NVC and 40% of the RVC isolates were found to be resistant to one or more drugs. Eight NVC and four RVC strains possessed multiple drug resistance, varying from four to eight drugs. The common spectrum found in NVC isolates were chloramphenicol and streptomycin (CS) or chloramphenicol, streptomycin, tetracycline and ampicillin (CSTA). Resistance to sulphamethoxazole (Su) and to trimethoprim (Tm) was encountered infrequently. In RVC isolates in addition CSTASuTm determinants, resistance markers to aminoglycosides kanamycin, gentamicin and neomycin were also found. Eighteen of the 27 V. cholerae strains with two or more resistance determinants transferred them en bloc to Escherichia coli K12. The level of resistance in the recipient strain was equal to or greater than that of the donor vibrio strains. Most of the strains possessing solitary resistance markers were unable to transfer them. beta-lactamase production could be demonstrated in 92.8% of the ampicillin resistant strains. None of the strains was resistant to nalidixic acid or furazolidone. The results emphasize the importance of antimicrobic susceptibility determination of V. cholerae isolates, regardless of the serotypes, before commencing chemotherapy.