Acinetobacter baumannii outbreak isolates characterized by three typing methods

Forty-two strains ofAcinetobacter baumannii were isolated from 15 patients hospitalized in a French intensive care unit. An epidemiological study based on the typing of these isolates was carried out using biotyping, antibiotyping, and ribotyping to recognize the transmission of multiresistant strains by transfer of a patient from one hospital to another. Fifteen strains from the outbreak (1 strain for each patient), fiveAcinetobacter baumannii strains isolated before the outbreak in Bellevue Hospital (St. Etienne), and five strains isolated in Cochin Hospital (Paris) were included. The three methods gave a good correlation: the epidemic strains had the same antibiotic resistance pattern, the same biotype, and the same ribotypes obtained with three different endonucleases.     

Faecal toxin and severity of antibiotic-associated pseudomembranous colitis.

The relationship between faecal toxin titre, histological evidence of pseudomembrane in the rectum, and severity of antibiotic-associated colitis has been analysed from data on 62 patients whose faeces contained Clostridium difficile toxin. There was a significant correlation between a toxin titre of 6400 or more and the presence of pseudomembrane (p less than 005). There was no correlation between toxin titre, duration of diarrhoea, total white cell count, temperature, serum albumin or serum orosomucoid concentrations. There was, however, a significant correlation between the presence of rectal pseudomembrane and duration of diarrhoea (p less than 0.005). Exposure to clindamycin or lincomycin was also associated with a significantly higher toxin titre than that seen in patients who were given other antibiotics. The duration of diarrhoea of diarrhoea was not longer and rectal pseudomembrane did not occur more often in the patients who had received clindamycin or lincomycin.     

Characterization of a hospital outbreak of imipenem-resistant Acinetobacter baumannii by phenotypic and genotypic typing methods.

During a 13-month period, 31 patients hospitalized primarily in two intensive care units (ICUs) were either colonized or infected by imipenem-resistant Acinetobacter baumannii. Typing of the isolates by three methods (antibiotyping, biotyping, and pulsed-field gel electrophoresis) revealed that two distinct strains were involved in the first 9 cases of the outbreak and that one of these strains, which had acquired a higher level of imipenem resistance as well as resistance to all aminoglycosides, accounted for 21 of 22 cases in the second part of the outbreak. ICU environmental contamination was recognized as an important reservoir of this epidemic strain. The outbreak ceased only after the ICUs were closed for complete cleaning and disinfection.     

Isolation of Clostridium difficile from hospitalized patients without antibiotic-associated diarrhea or colitis.

Stool samples from 100 hospitalized patients and 21 healthy adults, obtained between March and June 1980, were cultured on a special selective medium containing cefoxitin and cycloserine to detect Clostridium difficile. This organism was isolated from 13 of the hospitalized patients and from 1 healthy subject. None of the patients with positive cultures had received antimicrobial therapy in the 3 preceding months. The observed rate of C. difficile isolation from adults not suffering from antibiotic-associated diarrhea or colitis is higher than previously reported. C. difficile culture is not recommended as a substitute for toxin assay in the evaluation of patients with intestinal disorders after antimicrobial chemotherapy.     

一起疑为杯状病毒腹泻暴发的流行病学调查

目的　调查四川省广安市感染性腹泻暴发的流行情况 ,分析发病原因。方法　采用随机抽样的方法对广安市经济技术开发区、广安区机关单位、居委会和农村进行感染性腹泻的流行病学调查。所采粪便标本进行常规检测和肠道致病菌培养 ,用PAGE、ELISA和RT PCR方法进行腹泻病毒病原检测。结果　在调查的 4 5 6 7人中 ,发病 94 2例 ,罹患率为 2 0 .6 3% ,无死亡病例。发病率农村高于城区 (χ2 =2 2 .2 9,P <0 .0 0 5 ) ,5月 10～ 2 5日为发病高峰。 2 6份标本中 ,ELISA方法检出 4份杯状病毒阳性 ,RT PCR方法确认 1例。结论　本次感染性腹泻暴发流行的病原可能为杯状病毒     

Electrophoretic characterization of Clostridium difficile strains isolated from antibiotic-associated colitis and other conditions.

Clostridium difficile has been recognized as the cause of antibiotic-associated pseudomembranous colitis and of less severe diarrheal diseases associated with the use of antimicrobial agents. However, healthy carriers of this microorganism have been found, particularly healthy neonates and small children. Various typing systems have been used to clarify the epidemiology of C. difficile. We used the electrophoretic patterns of EDTA-extracted proteins to characterize C. difficile strains from various sources. Altogether, 110 strains were studied, including 2 reference strains, and 21 different protein profiles were obtained. However, two patterns were the most common: the group 2 pattern, characterized by a major 35-kilodalton polypeptide band, and the group 5 pattern, identified by principal bands of 37 and 56 kilodaltons. The group 2 pattern was characteristic of strains isolated during hospital outbreaks and from sporadic cases of pseudomembranous colitis and antibiotic-associated diarrhea. The group 5 pattern was obtained only from isolates from healthy neonates and children. A correlation between electrophoretic characteristics and virulence can be hypothesized, namely that group 2 strains are more prone to induce diseases and cause outbreaks. It is noteworthy that strains isolated from children with diarrhea of unknown etiology, not related to antibiotic use, belong to the "virulent" group 2; strains from leukemic patients showed a variety of different patterns, and only two belong to group 2. This characterization can be used to aid studies on the virulence and clinical significance of C. difficile.     

Epidemiologic study by DNA typing of a Candida albicans outbreak in heroin addicts.

The epidemiology of an outbreak of Candida endophthalmitis in heroin addicts was studied by DNA typing. Although one biotype was prevalent, the 13 isolates of Candida albicans from seven of the patients were placed into six separate groups by DNA type. Thus, the outbreak of candidiasis was not, as had been concluded from biotyping, due to a C. albicans strain of common origin.     

Investigation of Candida albicans transmission in a surgical intensive care unit cluster by using genomic DNA typing methods.

An apparent outbreak of serious Candida albicans infections (n = 6) occurred in a surgical intensive care unit over a 4-week period. Four patients developed C. albicans bloodstream infections. An additional patient developed catheter-related C. albicans infection; the sixth patient developed an infection of cerebrospinal fluid. C. albicans was isolated from the hands of five health care workers (17%) and the throat of one health care worker (3%) during the outbreak investigation. Karyotyping and restriction endonuclease analysis of genomic DNA with BssHII of 23 C. albicans isolates from patients and the 6 health care worker isolates revealed 9 and 12 different patterns, respectively. Three of six patients appeared to be infected with the same C. albicans strain (two bloodstream infections and one cerebrospinal fluid infection). The hands of a health care worker were colonized with strain that appeared identical to an isolate from a patient prior to infection of the patient. However, restriction endonuclease analysis with SfiI found differences among the isolates determined to be identical by the other two methods. Karyotyping alone does not appear to be sufficient to differentiate between outbreak and control isolates. Restriction endonuclease analysis typing may be a more sensitive method than karyotyping alone in the investigation of a cluster of C. albicans infections. Furthermore, the use of more than one restriction enzyme may be necessary for optimal strain discrimination in restriction endonuclease analysis of genomic DNA.     

Characterization ofListeria strains from a foodborne listeriosis outbreak by rDNA gene restriction patterns compared to four other typing methods

The rDNA gene restriction patterns of 134 isolates ofListeria species were determined with pKK3535 — a pBR322 derived plasmid containing anEscherichia coli rRNA operon — used as a probe following digestion of chromosomal DNA byEcoRI endonuclease. Nineteen reference and type strains representing all species and serotypes ofListeria showed 17 distinct ribotypes. One hundred and fifteen wild strains ofListeria monocytogenes were ribotyped and the results were compared to those of serotyping, phage typing, multilocus enzyme electrophoresis (MEE) and restriction endonuclease analysis (REA). Ninety-sixListeria monocytogenes serotype 4b wild strains displayed six distinct ribotypes (I–VI), 72 % (69/96) of them clustering in two very close rDNA patterns (I and II) of eight and nine bands, respectively. The same 96 strains displayed six REA patterns and eight MEE electrotypes. Among the 96Listeria monocytogenes 4b isolates, the 34 epidemic strains defined by phage typing and by epidemiological data all belonged to one ribotype (ribotype I) representing 56 % of the strains belonging to this ribotype. These same 34 epidemic strains were also grouped by REA and MEE typing in a unique profile (REA-A) and MEE electrotype (ET 1). Twenty-twoListeria monocytogenes strains of serogroup 1/2 analyzed by rDNA typing showed nine distinct ribotypes. For the 96Listeria monocytogenes 4b strains studied, the discriminatory index was highest for phage typing and for any combination including phage typing. Ribotyping appears to be a well reproducible molecular typing method and could be a useful complement to other typing methods for the epidemiological study of listeriosis.     

Evaluation of methods for typing coagulase-negative staphylococci.

One hundred and forty-two coagulase-negative staphylococci (CNS) isolated from dialysate effluent or skin of patients receiving continuous ambulatory peritoneal dialysis (CAPD) were typed by extended antibiogram (16 antibiotics) and biotype (26 reactions). These isolates were then typed by supplementary methods to determine the most suitable typing method for an epidemiological study of antibiotic resistance. These included phage typing, reverse phage typing, plasmid typing, whole-cell protein typing by SDS-PAGE with analysis by densitometry, and immunoblotting. The percentage of isolates typed successfully by the supplementary methods were: phage typing 20%, reverse phage typing 0%, plasmid typing 66%, SDS-PAGE 100%, immunoblotting 100%. The discrimination of each method was: phage typing 20%, plasmid typing 37%, SDS-PAGE 69%, immunoblotting 57%. Reproducibility was 88% for phage typing and 97% for plasmid typing. The reproducibility of the whole-cell protein typing was 83% if the same extracts were used but only 43% when separate protein extracts were analysed on separate occasions. However, strain relatedness was highly reproducible. The determination of an antibiogram-biotype profile was not a sufficiently accurate typing method for an epidemiological study of antibiotic resistance. Whole-cell protein typing by SDS-PAGE or immunoblotting was technically demanding but was the most effective of the supplementary methods for detecting erroneous discrimination and false matching produced by antibiogram-biotype combinations.     

一起小学生群发性腮腺炎癔症调查

目的通过对一起小学生群发性腮腺炎癔症进行调查,总结经验,为预防和处理癔症提供科学依据。方法采用现场流行病学调查方法,结合临床表现进行诊断分析。结果发病23人,罹患率为5.96%。发病的23名学生中有21人45d前接种过腮腺炎疫苗,接种率为91.30%,2名未接种疫苗的学生中有1人确诊为腮腺炎,其余学生无阳性体征。结论对小学生应该加强基础免疫,积极进行查漏补种;同时加强心理健康教育,提高其心理素质和适应能力。     

一起旅行团诺如病毒感染性腹泻暴发疫情调查

目的 对一起感染性腹泻暴发疫情的病原和危险因素进行调查分析.方法 根据病例定义进行主动搜索,利用回顾性队列研究寻找可疑餐次和可疑食物.采集病例和密切接触者粪便、肛拭子等标本进行诺如病毒核酸检测和肠道致病菌分离培养.结果 该旅行团共发现病例28例,流行曲线提示为点源暴露.共采集患者和密切接触者标本分别为12件和7件,经RT-PCR检测11名患者和2名密切接触者GⅡ组诺如病毒核酸检测阳性.对其中1份阳性标本进行测序,该病毒与2014年8月日本提交的GⅡ.17型AB983218和2014年12月中国台湾提交GⅡ.17型KJ156329毒株相似度达到98％.根据诺如病毒的潜伏期和病例的发病时间推测暴露时点为2月6日中餐和晚餐可能性大.应用回顾性队列研究结果显示2月6日晚餐中的深海鱼是危险食物(RR=6.25,95％CI:1.05～37.32).结论 该起疫情是旅行团外出引起的诺如病毒感染性腹泻的暴发,感染来源可能是在旅行期间食用了诺如病毒污染的深海鱼.     

Nosocomial infection by Staphylococcus haemolyticus and typing methods for epidemiological study.

A patient with chronic myelogenous leukemia became colonized with a Staphylococcus haemolyticus strain and experienced a septic episode caused by this strain during a cytostatic course. The strain was multiply resistant to antibiotics; the MIC and MBC of vancomycin were 2 and 4 mg/liter, and the MIC and MBC of teicoplanin were 4 and 16 mg/liter, respectively. We performed a surveillance study on the carriage of S. haemolyticus in medical and nursing staff of the hospital ward where the patient was treated. S. haemolyticus was isolated from 18 sites on 12 of the 39 people tested. A number of typing methods were performed in order to investigate the possible relationships among the isolates. Methods used were immunoblotting of staphylococcal peptides, plasmid analysis, restriction fragment length polymorphism of chromosomal DNA, and pulsed-field gel electrophoresis of total DNA. Compared with the immunoblotting technique, the molecular methods were more discriminative. The strain colonizing the patient showed a consistent pattern by all typing methods during isolation. When the immunoblot technique was used, similar patterns were found with isolates from hospital staff and isolates from unrelated sources. With the molecular techniques, no evidence of a local spread of the patient's strain was found. However, plasmid profiles and restriction fragment length polymorphism and pulsed-field gel electrophoresis patterns showed that S. haemolyticus isolates collected from hospital ward personnel were related, which was not the case with isolates collected from unrelated sources. Restriction fragment length polymorphism analysis was more discriminative when IS431 was used as a DNA probe instead of a probe based on the 16S rRNA gene. S. haemolyticus, as in this case, may develop resistance to vancomycin and teicoplanin. These antibiotics are considered the last-resort drugs for the therapy of nosocomial gram-positive infections. Thus, local spread of staphylococci resistant to these drugs is an important problem, which should be prevented by strict hygienic measures and antibiotic policy.     

Epidemiology and molecular typing of an outbreak of tuberculosis in a hostel for homeless men

AIM: To investigate a possible outbreak of tuberculosis in a hostel for homeless men using IS6110 profiling, a polymerase chain reaction (PCR) based fingerprinting technique. METHODS: Eight cases of tuberculosis were diagnosed in residents of the hostel over a period of 28 months. To provide epidemiological data, a heminested inverse PCR (HIP) assay targeting the insertion sequence IS6110 together with its upstream flanking region was used to fingerprint the eight isolates of M tuberculosis under investigation. RESULTS: The HIP technique gave IS6110 profiles which showed that while three isolates were clearly distinct, the remaining five strains were indistinguishable, suggesting the latter were representatives of a single outbreak strain. CONCLUSIONS: The HIP assay proved discriminatory and facilitated repeated testing for the direct comparison of strains as more patients presented over the protracted course of this outbreak.     

Comparison of epidemiological marker methods for identification of Salmonella typhimurium isolates from an outbreak caused by contaminated chocolate.

Plasmid profile analysis, restriction endonuclease analysis, and multilocus enzyme electrophoresis were used in conjunction with serotyping, bacteriophage typing, and biochemical fingerprinting to trace epidemiologically related isolates of Salmonella typhimurium from an outbreak caused by contaminated chocolate products in Norway and Finland. To evaluate the efficiency of the epidemiological marker methods, isolates from the outbreak were compared with five groups of control isolates not known to be associated with the outbreak. Both plasmid profile analysis and phage typing provided further discrimination over that produced by serotyping and biochemical fingerprinting. Plasmid profile analysis and phage typing were equally reliable in differentiating the outbreak isolates from the epidemiologically unrelated controls and were significantly more effective than multilocus enzyme electrophoresis and restriction enzyme analysis of total DNA. The greatest differentiation was achieved when plasmid profile analysis and phage typing were combined to complement serotyping and biochemical fingerprinting. However, none of the methods employed, including restriction enzyme analysis of plasmid DNA, were able to distinguish the outbreak isolates from five isolates recovered in Norway and Finland over a period of years from dead passerine birds and a calf.     

Comparison of molecular typing methods for Candida albicans.

Four molecular approaches to determining the types of Candida albicans strains were compared. The strains used were those whose repeated DNA (ribosomal and mitochondrial) EcoRI restriction fragment length polymorphisms (RFLP) were determined by Stevens et al. (D. A. Stevens, F. C. Odds, and S. Scherer, Rev. Infect. Dis. 12:258-266, 1990). Scherer and Stevens (S. Scherer and D. A. Stevens, Proc. Natl. Acad. Sci. USA 85:1452-1456, 1988) used the same strains to examine the Southern blots of genomic EcoRI digests probed with the repeated sequence 27A. The results of these investigators were compared with determinations of RFLPs generated from repeated DNA by the enzyme HinfI and examination of the karyotypes of strains under two sets of conditions, one for the smaller chromosomes and one for the larger ones. Analysis of RFLPs of repeated DNA is most convenient but shows the lowest degree of resolution. Use of the repeated sequence and use of karyotype have very high resolution, but the former method is more convenient than the latter. HinfI digestion is more sensitive than EcoRI digestion but equally convenient. By using all four methods, separate types were identified for 18 of the 20 strains examined.     

Comparison of six typing methods for Actinobacillus actinomycetemcomitans.

Actinobacillus actinomycetemcomitans is an important pathogen in the etiology of severe periodontitis. For epidemiological studies on the prevalence of certain pathogenic clones and transmission of this bacterium, adequate typing methods are necessary. The purpose of this study was to compare six different typing methods for A. actinomycetemcomitans. Five reference strains and 27 fresh clinical isolates from periodontitis patients were used. Serotyping showed 12 serotype a strains, 13 type b strains, 6 type c strains, and 1 nontypeable strain. Biotyping on the basis of the fermentation of mannose, mannitol, and xylose resulted in six biotypes. Antibiogram typing was evaluated by measuring the inhibition zones of seven antibiotics in agar diffusion tests. With this method eight main types which could be further differentiated into 15 subtypes were found. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of outer membrane proteins were similar among all isolates tested. Restriction endonuclease analysis (REA) of whole chromosomal DNA resulted in five main types. These five main types were further differentiated into 24 subtypes on the basis of DNA fragment differences in the high-molecular-weight region. Hybridization of DNA fragments with ribosomal DNA (ribotyping) resulted in 22 to 24 different types, depending on the restriction endonuclease used. Ribotype patterns were easy to interpret and provided an univocal distinction between different strains compared with REA results. When applied to epidemiologically related isolates, all methods were able to discriminate two clonal types among five isolates from five children from one family. We conclude that serotyping, biotyping, and outer membrane patterns were reproducible but had a low discriminatory potential. REA and ribotyping were reproducible and gave the highest number of distinct types. When the DNA typing methodis were compared, all strains tested could be distinguished. These findings confirm the heterogeneity found within the species A. actinomycetemcomitans.     

Comparison of typing methods for Clostridium difficile isolates.

A simple discriminative typing method for Clostridium difficile has been developed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell proteins and restriction enzyme analysis are relatively simple techniques but are difficult to evaluate, especially the restriction enzyme analysis. Immunoblotting and restriction fragment length polymorphism typing facilitate simple discrimination of patterns.