The characterization of Vibrio cholerae isolated in Kenya in 1983

A total of 245 strains of Vibrio cholerae 01 and two strains of V. cholerae non-01 were isolated and collected from diarrhoeal patients in Homa Bay District Hospital and the other medical facilities in Nyanza Province, Kenya in 1983. The majority of V. cholerae 01 tested were Ogawa type (with the exception of nine Inaba type), biotype E1 Tor (except one untypable strain) and Celebes original type (except one cured type). Haemolytic activity to sheep red blood cells was detected in 75.5% of isolates. Out of 245 strains of V. cholerae 01, 184 were resistant to tetracycline, streptomycin and ampicillin. All were sensitive to chloramphenicol and nalidixic acid. Only one strain of V. cholerae 01 was sensitive to all five antimicrobial agents tested. An environmental cholera survey was done after the cholera outbreak subsided. Twenty strains of V. cholerae non-01 were isolated from water samples in Nyanza Province but none of V. cholerae 01 was isolated.     

Susceptibility testing of clinical strains of Legionella spp. isolated in Japan

We determined antimicrobial susceptibilities of 23 strains of Legionella spp. clinically isolated in Japan, between September 1994 through November 1999 by using Etest. The MICs of all isolates against macrorides, fluoroquinolones and rifampicin showed 1 microgram/ml or less. Especially rifampicin showed the most potent activity, of which the MICs of all isolates showed 0.064 microgram/ml or less. Although we could not find resistant strains against any antibiotics tested in this study, we think it is important to follow up the susceptibilities of clinical isolates of Legionella.     

Phenotypic and genotypic characterization of Vibrio cholerae clinically isolated in Surabaya, Indonesia

The phenotypic and genotypic characteristics of 6 clinical strains of Vibrio cholerae isolated in Surabaya, Indonesia in 2009 were examined. The DNA fingerprints obtained suggested that these isolates were not from a single clone. Furthermore, all isolates produced cholera toxin and possessed the classical type of toxin B subunit gene, thus meaning that this is the first report of the occurrence of El Tor variants of V. cholerae in Indonesia. Although all isolates were sensitive to almost all antibiotics tested, including ampicillin, chloramphenicol, ciprofloxacin, gentamicin, levofloxacin, kanamycin, nalidixic acid, norfloxacin, streptomycin, trimethoprim-sulfamethoxazole, and tetracycline, and had no mutation in the gyrA and parC genes, they nevertheless possessed the class 1 integron that is a molecular vehicle for the acquisition of antibiotic resistance genes, suggesting that they have the potential to acquire the genetic element for drug resistance.     

Selection and characteristics of a Vibrio cholerae mutant lacking the A (ADP-ribosylating) portion of the cholera enterotoxin.

After mutagenesis with nitrosoguanidine and selection by immuno-halo techniques, an avirulent mutant, designated Texas Star-SR, which produces no detectable A (active; ADP-ribosylating) region of the cholera enterotoxin (choleragen) but produces the B region (choleragenoid) in amounts similar to the hypertoxinogenic wild-type parent Vibrio cholerae (biotype E1 Tor serotype Ogawa), has been isolated. The mutant retains the colonizing ability, motility, prototrophy, and serologic characteristics of the parent. In relevant intestinal experimental models, it has been shown to be avirulent and to induce protection against challenge with virulent cholera vibrios. The mutant appears to be suitable for further evaluation in volunteers as a candidate living enteric vaccine against cholera and related enterotoxic enteropathies.     

Drug susceptibility of clinically isolated strains of Neisseria gonorrhoeae

We investigated the drug susceptibilities of Neisseria gonorrhoeae by using 98 strains of clinical isolates at Toho University Omori Hospital from 1994 to 1998. Minimum Inhibitory Concentrations (MICs) of 15 antimicrobial agents were determined with agar dilution methods according to the guidelines of NCCLS. Among these isolates, only 4 strains (4.1%) were found to be penicillinase producing N. gonorrhoeae. Ceftriaxone showed the most potent activity of which MICs of all strains were 0.06 microgram/ml or less. Macroride antimicrobial agents and minocycline also showed strong activities of which MICs of most of the strains were 0.06 microgram/ml or less. With the criteria of NCCLS, 10 strains (10.2%) were found to be resistant to ciprofloxacin and these 10 strains also showed cross resistance to other fluoroquiolones we tested. Our results also revealed that the number of resistant strains against fluoroquiolones abruptly increased from 1996 and indicate the needs of further surveillance of antimicrobial resistance in clinical isolates of N. gonorrhoeae.     

Mutation of penicillin-binding protein genes and antimicrobial susceptibility of Haemophilus influenzae isolated from spinal fluid or blood in children

Between September 1999 and August 2001, we studied serotypes to capsular antigen, beta-lactamase production, mutation of penicillin binding protein (PBP) genes by PCR method, and antimicrobial susceptibilities of 13 strains of Haemophilus influenzae isolated from spinal fluid or blood in children. Diseases of patients were meningitis in 11, pneumonia in 1, and laryngitis in 1. The age range of the patients was from 26 days to 5 years. The serotypes of all strains were b. Four of the 13 strains were beta-lactamase-positive. The mutation of genes of pbp3 was revealed from 4 isolates and 2 of the strains were beta-lactamase-positive. MICs of ampicillin to beta-lactamase-negative strains ranged from 0.125 to 1 microgram/ml and those to beta-lactamase-positive were more than 32 micrograms/ml. MICs of 2 strains of beta-lactamase-negative and mutation-positive were 0.5 and 1 microgram/ml. The excellent active antimicrobials in our study was cefotaxime (MIC90 0.06 microgram/ml), meropenem (MIC90 0.125 microgram/ml), ceftazidime (MIC90 0.25 microgram/ml), and cefepime (MIC90 0.25 microgram/ml).     

Transmission of epidemic Vibrio cholerae O1 in rural western Kenya associated with drinking water from Lake Victoria: an environmental reservoir for cholera?

Sub-Saharan Africa has the highest reported cholera incidence and mortality rates in the world. In 1997, a cholera epidemic occurred in western Kenya. Between June 1997 and March 1998, 14,275 cholera admissions to hospitals in Nyanza Province in western Kenya were reported. There were 547 deaths (case fatality rate = 4%). Of 31 Vibrio cholerae O1 isolates tested, all but one were sensitive to tetracycline. We performed a case-control study among 61 cholera patients and age-, sex-, and clinic-matched controls. Multivariate analysis showed that risk factors for cholera were drinking water from Lake Victoria or from a stream, sharing food with a person with watery diarrhea, and attending funeral feasts. Compared with other diarrheal pathogens, cholera was more common among persons living in a village bordering Lake Victoria. Cholera has become an important public health concern in western Kenya, and may become an endemic pathogen in the region.     

Antimicrobial resistance of bacterial pathogens associated with diarrheal patients in Indonesia

The antimicrobial susceptibility patterns for 2,812 bacterial pathogens isolated from diarrheal patients admitted to hospitals in several provinces in the cities of Jakarta, Padang, Medan, Denpasar, Pontianak, Makassar, and Batam, Indonesia were analyzed from 1995 to 2001 to determine their changing trends in response to eight antibiotics: ampicillin, trimethoprim-sulfamethoxazole, chloramphenicol, tetracycline, cephalothin, ceftriaxone, norfloxacin, and ciprofloxacin. Vibrio cholerae O1 (37.1%) was the pathogen most frequently detected, followed by Shigella spp. (27.3%), Salmonella spp. (17.7%), V. parahaemolyticus (7.3%), Salmonella typhi (3.9%), Campylobacter jejuni (3.6%), V. cholerae non-O1 (2.4%), and Salmonella paratyphi A (0.7%). Of the 767 Shigella spp. isolated, 82.8% were S. flexneri, 15.0% were S. sonnei, and 2.2% were S. dysenteriae (2.2%). The re-emergence of Shigella dysenteriae was noted in 1998, after an absence of 15 years. Shigella spp. were resistant to ampicillin, trimethoprim-sulfamethoxazole, chloramphenicol, and tetracycline. Salmonella typhi and Salmonella paratyphi A were susceptible to all antibiotics tested, while Salmonella spp. showed various resistance patterns according to species grouping. A small number of V. cholerae O1 were resistant to ampicillin, trimethoprim-sulfamethoxazole, chloramphenicol, and tetracycline; however, they were still sensitive to ceftriaxon, norfloxacin, and ciprofloxacin. Similar results were shown for V. cholerae non-O1. Campylobacter jejuni showed an increased frequency of resistance to ceftriaxone, norfloxacin, and ciprofloxacin, but was susceptible to erythromycin. This study shows that except for C. jejuni and V. parahaemolyticus, which appeared to be resistant to ciprofloxacin, the majority of the enteric pathogens tested were still susceptible to fluoroquinolones.     

Salmonella enteritidis diarrhoea in Harare, Zimbabwe

The study was conducted to determine the prevalence of Salmonella enteritidis diarrhoea in an urban area in Zimbabwe. Stool specimens from people of all ages presenting at primary level health centres in Harare were investigated for S. enteritidis and other bacterial and parasitic enteric pathogens. The first 46 S. enteritidis isolates were phage-typed, and all isolates were tested for susceptibility to ampicillin (10 microg), chloramphenicol (30 microg), cotrimoxazole (25 microg), tetracycline (30 microg), gentamicin (10 microg), nalidixic acid (30 microg), ciprofloxacin (5 microg) and ceftriaxone (30 microg). S. enteritidis was isolated in 74 (1.8%) of 4155 stool specimens which represented 30.7% of all Salmonella species isolated. The most common S. enteritidis phage type was 4 (78.3%) followed by 7, 9 and 23 (8.7%, 2.2%, 2.2%, respectively) All S. enteritidis isolates were sensitive to gentamicin, ciprofloxacin and ceftriaxone. Less than 10% of the isolates were resistant to the other antimicrobials except ampicillin, to which 13.5% were resistant. One isolate was resistant to ampicillin, chloramphenicol, cotrimoxazole and nalidixic acid.     

Susceptibility testing and molecular epidemiology of clinical strains of Bordetella pertussis isolated in Japan from 2001 to 2002

We determined antimicrobial susceptibilities and analyzed molecular epidemiology of 26 strains of Bordetella pertussis clinically isolated and then performed pulsed-field gel electrophoresis (PFGE) in Japan (Japanese Pertussis Surveillance Group Participants), from 2001 to 2002. The MICs of erythromycin, clindamycin, tetracyclines, fluoroquinorones, trimethoprim-sulfamethoxazole and rifampicin of all isolates against these showed 1 microgram/ml or less. Sparfloxacin is the most potent agent, of which the MICs showed 0.008-0.016 microgram/ml. Results of DNA fingerprinting by pulsed-field gel electrophoresis (PFGE) differentiated three types (Type I; 11 strains (42%), type II; 14 strains (54%) and type III; 1 strains (4%)). However, no relation between regions and identical PFGE patterns was found in this study. Further, surveillance of the antimicrobial susceptibilities and molecular epidemiology of B. pertussis will be required.     

Amphotericin B-resistant yeast infection in severely immunocompromised patients

Systemic yeast infections are a major cause of morbidity and mortality in severely immunocompromised patients. The in vitro susceptibility to amphotericin B of 29 yeasts causing fungemia was examined in 26 patients undergoing allogeneic or autologous bone marrow transplantation and/or myelosuppressive chemotherapy. The minimal inhibitory concentrations (MICs) of amphotericin B observed with blood isolates from these patients were significantly higher than those observed with blood, sputum, or skin isolates from non-immunocompromised patients (p less than 0.01). All episodes (10 of 10) of bloodstream infection in immunocompromised patients caused by isolates with MICs greater than 0.8 micrograms/ml were fatal, versus eight of 17 episodes of bloodstream infection caused by yeasts with MICs of 0.8 micrograms/ml or less (p = 0.04). Although 15 of 26 patients received empiric treatment with amphotericin B before laboratory evidence of fungemia developed, the amphotericin B susceptibilities of their isolates were not significantly different from those of patients who had not received empiric amphotericin B treatment. It is concluded that yeast fungemia in severely immunocompromised patients is often caused by organisms resistant to the usual concentrations of amphotericin B obtainable in vivo, and that this finding is clinically significant.     

Emergence of Vibrio cholerae O1 biotype El Tor serotype Inaba causing outbreaks of cholera in Orissa, India

A total of 431 rectal swabs, collected from acute diarrheal cases at a surveillance site and at different diarrheal outbreak areas of Orissa from May to October 2005, were bacteriologically analyzed. Out of 265 culture-positive samples, Vibrio cholerae O1 was isolated in 56 samples (20.8%), of which 37 were the Inaba serotype and 19 were the Ogawa. The antibiogram profile revealed that all the V. cholerae O1 Ogawa and Inaba serotypes were uniformly sensitive to ampicillin, chloramphenicol, gentamicin, ciprofloxacin, norfloxacin and tetracycline. The V. cholerae O1 Inaba serotypes were resistant to furazolidone and nalidixic acid, while the Ogawa strains were resistant to furazolidone, nalidixic acid and neomycin. The multiplex polymerase chain reaction (PCR) assay on some selected strains of both serotypes revealed that all the strains were positive for ctxA and tcpA genes showing biotype El Tor. The present study revealed the emergence of V. cholerae O1 biotype El Tor serotype Inaba, which caused sporadic outbreaks of cholera in 2005. The outbreaks of diarrheal disorders in one geographical area of the state (in the Pattamundai area, Kendrapara district) in 2005 were due to V. cholerae O1 Ogawa, whereas the other outbreaks in other areas (Puri, Khurda and Dhenkanal districts) from August to October 2005 were due to V. cholerae O1 serotype Inaba. This is the first report that an emergence of V. cholerae O1 serotype Inaba caused sporadic outbreaks of cholera in different parts of Orissa. Switching over of V. cholerae O1 Ogawa strains to Inaba, causing diarrheal outbreaks in Orissa, needs close monitoring.     

结核分枝杆菌对利福喷汀与利福平交叉耐药的实验研究

目的 观察利福喷汀对结核分枝杆菌的杀菌效力及其与利福平的交叉耐药性，探讨利福喷汀对结核分枝杆菌的实验室耐药界限，为临床应用利福喷汀治疗结核病，包括治疗对利福平耐药的结核病提供依据。方法 用7H9液体培养基、苏通液体培养基、改良罗氏固体培养基测定利福喷汀和利福平对结核分枝杆菌标准株(H37Rv)及临床分离的利福平敏感株、利福平耐药株的最低抑菌浓度(MIC)。结果 在7H9液体培养基上对临床分离的19株利福平敏感株分别测定利福平和利福喷汀的MIC，有80％利福平敏感株利福平的MIC≥0．32μg／ml，而利福喷汀的MIC多分布在0．02～0．32μg／ml之间(占84％)；无论标准株H37Rv、利福平敏感株(19株)或是利福平耐药株(45株)，利福喷汀对结核分枝杆菌的MIC普遍比利福平低2～4倍；利福喷汀敏感株和耐药株的MIC差别较大，在MIC为5～10μg／ml处能最大限度地区分敏感菌和耐药菌。结论 利福喷汀与利福平存在着交叉耐药，但利福喷汀比利福平有更强的杀菌效力，部分结核分枝杆菌对利福平达到临床耐药时，仍未达到利福喷汀临床耐药，对利福平耐药的部分结核分枝杆菌对利福喷汀仍具有一定程度的敏感性，提示临床上对利福平耐药的结核病患者使用利福喷汀可能有一定效果；实验结果对利福喷汀临界耐药界限进行了初步筛查，为利福喷汀常规药敏试验的开展提供了基本试验数据。     

Antimicrobial susceptibilities of Haemophilus species in Hong Kong

Altogether 403 Haemophilus spp. were isolated in seven hospital laboratories in Hong Kong during June 1986, mostly from sputum. Of these 73% were Haemophilus influenzae and 27% Haemophilus parainfluenzae. All the isolates of H. influenzae were non-capsulated; Haemophilus spp. were not isolated from blood or cerebrospinal fluid (CSF) during the period of the study. Antimicrobial resistance, including multiple resistance, was common. Of all the strains of H. influenzae, 20% were resistant to 1 mg/l ampicillin, (all except one by production of TEM-1 beta-lactamase), 65% were resistant to 0.5 mg/l erythromycin, 25% to 1 mg/l tetracycline, 14% to 1 mg/l chloramphenicol (mediated by the production of a chloramphenicol-destroying enzyme) and less than 1% to 8 mg/l cefaclor and 0.5 mg/l trimethoprim. All isolates were susceptible to cephamandole and cefuroxime. Haemophilus parainfluenzae showed similar susceptibilities, except that a greater proportion of strains was sensitive to erythromycin and chloramphenicol. Only 50% of the ampicillin-resistant strains of H. influenzae and H. parainfluenzae contained detectable plasmids of 2-55 Mdal arranged in six to nine different plasmid profiles. Resistance to ampicillin and chloramphenicol has increased markedly in isolates of H. influenzae in Hong Kong over the last 5 years. This resistance may be associated with transposable genes.     

Antifungal susceptibilities of clinical and environmental isolates of Cryptococcus neoformans in Goiânia city, Goiás, Brazil

We evaluated the antifungal activities of amphotericin B, fluconazole, itraconazole and voriconazole in 70 Cryptococcus neoformans strains obtained from cerebrospinal fluid from AIDS patients and 40 C. neoformans strains isolated from the environment. Four clinical isolates were identified as C. neoformans var. gattii. The susceptibility test was done using a broth microdilution method according to NCCLS M27-A2. Range minimal inhibitory concentrations (MICs) for C. neoformans clinical isolates were 0.06-1.0 microg/mL for amphotericin B, 0.125-8 microg/mL for fluconazole, 0.03-0.5 microg/mL for itraconazole and 0.03-0.25 microg/mL for voriconazole. C. neoformans environmental isolates showed range MICs 0.015-0.125 microg/mL, 0.25-2.0 microg/mL, 0.007-0.125 microg/mL and 0.03-0.25 microg/mL for amphotericin B, fluconazole, itraconazole and voriconazole respectively. The MICs results obtained from clinical and environmental isolates showed similar pattern of susceptibility and no resistance has been found in our isolates.     

新型隐球菌及念珠菌临床分离株对5种抗真菌药物的体外敏感性

目的 了解临床分离的新型隐球和念珠菌对氟康唑、两性霉素B、伊曲康唑、氟胞嘧啶和酮康唑的体外敏感性及临床治疗效果的相关性。方法 采用标准微量稀释法测定了上述5种抗真菌药物对临床分离株的35株新型隐球菌和56株念株菌量的最低抑菌浓度（MIC）。结果 56株念珠菌对5种药物的敏感性（MIC）分别为氟康唑0.125～64ug/ml,94.6%的菌株对氟康唑敏感,1.8%为剂量依赖性敏感,3.6%耐药;伊曲康唑0.03～1ug/ml,57.1%敏感,37.5%剂量依赖性敏感,5.4%耐药;氟咆嘧啶 0.125～32ug/ml,92.8%敏感,3.6%中度敏感,3.6%耐药;两性霉素B0.06～2ug/ml;酮康唑0.03～0.5ug/ml。35株新型隐球菌对5种药物的MIC范围分别为氟康唑2～64ug/ml,伊曲康唑0.25～1ug/ml,两性霉素B0.3～1ug/ml,氟胞嘧啶0.25～64ug/ml,酮康唑0.125～1ug/ml。结论 标准微量稀释法测定酵母菌对抗真菌药物的敏感性其结果具有可重复性和一致性的特点。     

杭州市首例外环境水体中检出稻叶型霍乱弧菌及病原学分析

目的监测杭州市外环境水体中霍乱弧菌并对分离菌株进行病原学分析。方法2006年5月-2006年9月采集杭州市运河水系水样75份,按国标方法进行霍乱弧菌分离与鉴定。采用PCR检测霍乱弧菌分离菌株ctxA和tcpA毒力基因携带情况。采用KB纸片法检测霍乱弧菌分离菌株对14种临床常用抗生素的敏感性。结果从75份运河水标本中检出O1群霍乱弧菌稻叶血清型1(编号06-19)。O1群霍乱弧菌06-19株噬菌体分型6K,属于霍乱弧菌非流行株;ctxA和tcpA毒力基因PCR结果均为阴性。该菌株对11种抗生素均显示不同程度敏感性,但对四环素、氯霉素、链霉素耐药。结论本次分离的O1群霍乱弧菌06-19株属于不产生霍乱肠毒素和菌毛的非流行菌株。由于霍乱弧菌非流行株可引起散发性腹泻以及运河水系与杭州市市民日常生活的密切关系,故仍有必要加强对运河水系霍乱弧菌监测及污染源管理。     

Isolation of enterotoxin structural gene deletion mutations in Vibrio cholerae induced by two mutagenic vibriophages.

Phenotypically nontoxinogenic mutants of Vibrio cholerae were isolated after infection with either of two mutagenic vibriophages, VcAI and VcA2ctsl. DNA isolated from these mutants was analyzed for toxin gene sequences by the Southern blotting method with 32P-labeled probes derived from the cloned A and B subunit genes for the heat-labile enterotoxin of Escherichia coli, designated LT. Several of the mutant isolates were shown by this method to have lost all sequences hybridizing to the LT probes, indicating that these clones contain deletion mutations that removed the structural gene(s) for cholera toxin. The mutants were prototrophic and grew normally, in vitro, demonstrating that the toxin is not essential for the growth and viability of V. cholerae. Moreover, the toxin gene deletion mutants multiplied well in vivo in ligated rabbit intestine. Because of these growth properties and the stability of deletion mutations, these strains are promising candidates for testing as live oral vaccine strains for protection against cholera.     

Seroepidemiological studies of El Tor cholera in Bangladesh: association of serum antibody levels with protection

In rural Bangladesh, family contacts of patients with cholera were studied prospectively to examine whether protection against colonization and disease due to Vibrio cholerae O1 was associated with circulating antibodies to V. cholerae. Family contacts (1,071) of 370 patients with cholera were visited daily for 10 days, cultured for V. cholerae, and queried about diarrhea. Sera collected on days 1 and 21 were assayed for vibriocidal antibodies, IgG and IgA antibodies to cholera toxin, and IgG antibodies to lipopolysaccharide (LPS). Vibriocidal titers of greater than or equal to 20 present in 50% of contacts by 20 years of age were associated with protection against both colonization and disease. An elevated level of IgG antitoxin was not associated with protection against colonization or disease but was the most sensitive indicator of recent symptomatic cholera and of immune response to the oral immunogen B subunit. IgG antibody to LPS and IgA antitoxin were of little value in predicting colonization or disease.