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PubMed1994

Comparison of four different methods for epidemiologic typing of Acinetobacter baumannii.

A set of 103 epidemiologically well-defined Acinetobacter baumannii isolates obtained from nine hospital outbreaks and 21 unrelated strains were characterized by pulsed-field gel electrophoresis (PFGE) of total genomic DNA digested with ApaI. Among outbreak strains, eight different patterns and five possible variants were identified by PFGE. Results were compared with those from traditional typing methods such as plasmid profile analysis, antimicrobial susceptibility, and biotyping. Plasmid analysis revealed six different and two related patterns; one outbreak strain lacked plasmids. A total of 16 of the 21 unrelated strains harbored plasmids and exhibited unique patterns. Epidemiologically unrelated strains were placed into only two biotypes and had similar antimicrobial susceptibility patterns but were clearly distinguished by PFGE. PFGE of A. baumannii chromosomal DNA yielded reproducible and easily readable results and showed excellent discriminatory power. However, plasmid profile analysis may provide a cost-effective first step in epidemiological typing of A. baumannii isolates obtained from well-defined hospital outbreaks.

Acinetobacter↗

PubMed1998

The public health practitioner as investigator.

The history of public health began with the investigation of communicable diseases. Improved epidemiological methods have subsequently illuminated the causes and management of a wide range of health problems. The day-to-day challenges facing today's public health practitioners must be tackled rapidly and with limited resources, but must still subject to sound epidemiological principles.

Epidemiologic Methods↗

PubMed1985

Results of using the serological method of epidemiological investigation of plague foci in the Muyunkum and Eastern Kyzylkum deserts in 1978-1982.

Results of serological examination of 81,853 mammals from the Muyunkum and 26,303 from the Eastern Kyzylkum deserts were compared with results of a corresponding bacteriological examination for plague. In both foci and in all phases throughout the epizootic of plague, the serological method made it possible to detect infected animals 6-10 times more frequently in comparison with the bacteriological method. The big meriones mice, i.e., the basic carriers of plague in natural foci, were found to be infected considerably more (in percentage) frequently than the meridian meriones. Differences in the reactivity of meriones to the invasion of plague microbe were observed in both foci (the indices of titres in the antigen neutralization reaction were considerably higher in the Eastern Kyzylkums). The serological method of investigation is highly informative in evaluating both the present state of epizootic activity of a plague focus and its activity in the past.

Animal Diseases↗

PubMed1993

Restriction endonuclease analysis of plasmid DNA from methicillin-resistant Staphylococcus aureus: clinical application over a three-year period.

OBJECTIVE: To investigate trends in plasmid types of methicillin-resistant Staphylococcus aureus over a 3-year period and determine the clinical impact of plasmid typing. DESIGN: Restriction endonuclease analysis of plasmid DNA (REAP) was used to type 270 clinical isolates. SETTING: A Veterans Affairs Medical Center. RESULTS: Forty-four different REAP types were identified and, of these, 23 appeared only once. Types designed as V1 and V2 were more commonly found in nosocomial cases than in community-acquired cases (p < .05); whereas the K and D types were more common in isolates from community-acquired cases (p < .05). In 30 (11%) isolates, no plasmid was detected. When combined with epidemiological data, REAP typing revealed 4 small outbreaks that would have been missed using traditional epidemiological methods alone. In large outbreaks involving 10 or more cases, REAP typing data revealed unsuspected patterns of transmission. CONCLUSIONS: Multiple plasmid types were present in this endemic setting. Restriction endonuclease analysis of plasmid DNA was a practical and valuable adjunct to traditional epidemiological methods.

DNA Restriction Enzymes↗

PubMedDate not supplied

Animal rabies in Poland: epidemiological situation and methods of control.

The epidemiological situation and methods of control of animal rabies in Poland are presented. Registered data on rabies cases for the period from 1948 up to 1986 are discussed. Two species of animals, namely dogs and foxes, have played the major role in the epidemics of rabies. The undertaken measures have proved satisfactory to control rabies due to dogs as a vector but were found inadequate to control wild-life rabies. Since 1967 the fox has been the main vector of the epizootics of rabies.

Administration, Oral↗

PubMed2002

Evaluation of a rapid PCR-based epidemiological typing method for routine studies of Mycobacterium tuberculosis.

Restriction fragment length polymorphism (RFLP) based on the insertion sequence IS6110 is used to investigate episodes of suspected transmission of infection of tuberculosis but usually takes a number of weeks from receipt of request to obtain a result. Often investigations would benefit from a more rapid method, possibly one containing an amplification step. The method employed uses a simple DNA extraction followed by a PCR step involving a single primer. Restriction enzyme analysis was performed when the patterns obtained from the PCR products were indistinguishable, especially when only single similar-size bands were obtained. The isolates used were strains of Mycobacterium tuberculosis submitted for epidemiological investigations as part of (i) possible contact-outbreak (22 episodes involving between 2 and 20 patients), (ii) possible incidents of laboratory cross-contamination (21 episodes), and (iii) possible change in drug resistance pattern or a case of reinfection (1 patient). The PCR products giving similar patterns were then subjected to restriction enzyme analysis. In conclusion it has been shown that this method is rapid, with results within 1 to 2 days of the request being received; is reproducible; and gives the same results as does RFLP. The restriction enzyme analysis stage has improved the efficiency of the technique.

Bacterial Typing Techniques↗

PubMed2001

Value of Mycobacterium tuberculosis fingerprinting as a tool in a rural state surveillance program.

OBJECTIVE: This study demonstrates the value of Mycobacterium tuberculosis fingerprinting used in conjunction with traditional epidemiologic methods to identify smoldering outbreaks of tuberculosis in endemic areas where background rates of tuberculosis are high. METHODS: IS6110 DNA fingerprinting was performed on isolates of M tuberculosis from verified cases of tuberculosis in Alabama from 1994 to 1998. A statewide database groups isolates into "clusters" and tracks them cumulatively over time. A large cluster was identified and was secondarily investigated using traditional epidemiologic methods. RESULTS: Twenty-five isolates were found to be identical by fingerprinting analysis. Patients were living within 10 counties across the state, and 12 cases were localized to a single county. This represented an ongoing, statewide tuberculosis outbreak previously unrecognized by local and state health officials. Secondary investigation of the cases revealed the primary sites of transmission to be a correctional facility and two homeless shelters. CONCLUSIONS: Population surveillance using M tuberculosis fingerprinting was successfully utilized to detect a significant and smoldering tuberculosis outbreak. Measures are currently in place to identify and prevent further transmission in the involved locations.

Adult↗

PubMed2000

A prospective social and molecular investigation of gonococcal transmission.

BACKGROUND: Gonorrhoea is a common infectious disease, poorly controlled despite effective treatments. Tracing chains of transmission is difficult, because sexual partners are commonly difficult or impossible to identify. We assess the use of gonococcal opa-typing in identifying transmission links not revealed through interview. METHODS: Epidemiological data and gonococcal isolates were collected prospectively from patients at two UK clinics in London and Sheffield. Social and epidemiological data were combined with molecular typing of gonococcal isolates by a new methodology based on the polymorphisms of the opa gene. FINDINGS: In London, interview data and opa-typing on samples from 215 cases showed a diverse population with few links. In Sheffield, interview data identified links between 51 (43%) of 120 cases, whereas opa-typing suggested a more connected population: 95 (79%) of cases had shared profiles. There was a highly significant correlation between the two distributions with epidemiological clusters appearing as a subset of the opa clusters. Two large opa clusters, of 18 and 43 cases, accounted for 50% of local cases of gonorrhoea. Discordance between epidemiological and opa-typing data was observed at highly connected points in the sexual network. INTERPRETATION: Opa-typing is a more powerful tool for epidemiological investigation of gonorrhoea transmission than earlier methods. Opa-typing can link infections that would otherwise remain unlinked, and may aid interventions to control endemic disease.

Adolescent↗

PubMed1995

PCR amplification of rRNA intergenic spacer regions as a method for epidemiologic typing of Clostridium difficile.

From January to March 1993, a suspected outbreak of antibiotic-associated diarrhea occurred on a pediatric oncology ward of the Clinical Center Hospital at the National Institutes of Health. Isolates of Clostridium difficile obtained from six patients implicated in this outbreak were typed by both PCR amplification of rRNA intergenic spacer regions (PCR ribotyping) and restriction endonuclease analysis of genomic DNA. Comparable results were obtained with both methods; five of the six patients were infected with the same strain of C. difficile. Subsequent analysis of 102 C. difficile isolates obtained from symptomatic patients throughout the Clinical Center revealed the existence of 41 distinct and reproducible PCR ribotypes. These data suggest that PCR ribotyping provides a discriminatory, reproducible, and simple alternative to conventional molecular approaches for typing strains of C. difficile.

Bacterial Typing Techniques↗

PubMed1990

[A dietary method for epidemiological study of cancer].

A semiquantitative frequency questionnaire was developed to estimate the average intake of foods and nutrients of individuals with the aim of utilization in cancer epidemiology. Validity of the questionnaire was evaluated in comparison with four 7-day dietary records carried on 25 spouses over one year. Absolute mean intakes estimated by the questionnaire and by the records were roughly comparable at the group level. However, the individual's estimated intakes generally showed poor agreements between the two methods in terms of rank correlation, except for a few foods such as fish and milk and for alcoholic beverages. Further efforts should be exercised to develop a more accurate dietary method.

Age Factors↗

PubMed2002

Predictors of clustering of tuberculosis in Greater Vancouver: a molecular epidemiologic study.

BACKGROUND: The understanding of how tuberculosis is transmitted can be improved by combining DNA fingerprinting of Mycobacterium tuberculosis with conventional epidemiologic methods. We used such techniques to determine the predictors of clustering of identical isolates from tuberculosis patients in Vancouver. METHODS: We used the restriction fragment length polymorphism (RFLP) technique and, if necessary, spoligotyping to determine DNA patterns of M. tuberculosis isolates from all patients with newly diagnosed tuberculosis in Greater Vancouver reported to the Division of Tuberculosis Control from January 1995 to March 1999. Isolates were considered to be part of a cluster if they had an identical DNA pattern. We also collected demographic and epidemiologic data. Predictors associated with being in a cluster were analyzed in a multivariate logistic regression model. RESULTS: Isolates from 793 patients (430 men) were identified; 137 (17.3%) were considered to be in clusters. After adjustment for multiple potential predictors, we found that the following patients were more likely to be part of a cluster: Canadian-born Aboriginals (v. foreign-born patients) (adjusted odds ratio [OR] 6.0, 95% confidence interval [CI] 3.0-11.7), Canadian-born non-Aboriginals (v. foreign-born patients) (adjusted OR 3.6, 95% CI 2.1-6.3), and injection drug users (v. patients who did not inject drugs) (adjusted OR 3.9, 95% CI 1.9-8.1). Patients with a prior history of tuberculosis were less likely to be part of a cluster than were patients with no history of tuberculosis (adjusted OR 0.3, 95% CI 0.1-0.8). INTERPRETATION: Our findings indicate the need to target groups at high risk of tuberculosis more aggressively to prevent transmission and to treat latent infection. DNA fingerprinting may be a useful adjunct to conventional epidemiologic methods to monitor the transmission of tuberculosis in an inner-city setting.

Adult↗

PubMed1982

Subdivision of Mycobacterium tuberculosis into five variants for epidemiological purposes: methods and nomenclature.

Virulent strains of Mycobacterium tuberculosis isolated from humans are divisible into five variants by using four tests: oxygen requirement (aerobic or microaerophilic), nitrate reductase activity, susceptibility to pyrazinamide (60 micrograms/ml) and susceptibility to thiophene-2-carboxylic acid hydrazide (5 micrograms/ml). The five variants are referred to as Classical human, Asian human, bovine, African I and African II. The relation of these variants to previously described types is discussed. This simple division has been shown to be useful in epidemiological studies.

Humans↗

PubMed1989

[Study on the effect of micronucleus with drinking water in the high risk area of stomach cancer].

Mutagenicity/Carcinogenicity of samples of drinking water supplies in the high risk area of stomach cancer was studied with micronucleus test and the epidemiologic method in Zanhuang county, Hebei. The results showed that the micronucleus cell rates in NIH mice induced by concentrated drinking water samples from the high risk area of stomach cancer were higher than those from low risk area and there was close correlation between degree of water concentration and micronucleus cell rates. This corresponded with the results obtained by the epidemiological method showed that the drinking water was obviously mutagenic and that it was closely correlated with the production of stomach cancer.

Animals↗

PubMed2004

Adapting smoking cessation interventions for developing countries: a model for the Middle East.

OBJECTIVE: To describe the rationale and methods for the development of culturally-sensitive smoking cessation interventions for primary care settings in developing countries. RATIONALE: Smokers in the Middle East have great difficulty quitting. Effective smoking cessation programs are currently lacking in the Middle East, and the development of culturally sensitive programs is hindered by the dearth of standardized information regarding tobacco use and dependence in this region. METHODS: Epidemiological and clinical laboratory methods are needed to determine the prevalence and patterns of tobacco use and nicotine dependence. One strategy is to adapt smoking cessation methods widely used in industrialized countries to the Syrian and Middle Eastern environment. In a recently initiated project, the Syrian Center for Tobacco Studies has been established to address these issues. Initial work is focusing on collecting formative data including key informant interviews, focus groups, and epidemiological surveys to assess smokers' use patterns, needs, and resources. Clinical laboratory techniques are also being applied to assess the physiological, behavioral, and subjective effects of local tobacco use methods, such as narghile (water pipe) smoking. These data will be used to help adapt existing smoking cessation interventions from industrialized countries to be evaluated in a randomized controlled trial. CONCLUSION: There is a great need to develop and disseminate effective cessation interventions in low-income countries. Successful interventions will contribute to a culturally sensitive and sustainable regional tobacco control infrastructure. This paper describes one approach to the development of such an infrastructure that is currently underway in the Middle East.

Developing Countries↗

PubMed1994

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.

Base Sequence↗

PubMed1991

[Clostridium difficile: a typing method for epidemiological studies].

One hundred and twenty two strains of Clostridium difficile were studied: 33 strains were isolated from stools of neonates or children, 89 cases of antibiotic associated diarrhea. The strains were identified by biochemical tests and gaz liquid chromatography of the fermentation products. A typing scheme for Clostridium difficile were proposed by using a polyacrylamide gel electrophoresis of whole cell proteins. We studied the correlation between this typing and the serogrouping scheme based on slide agglutination with a rabbit antisera and previously described by Delmée. The serogrouping defines 10 groups, PAGE allows the differentiation of 12 profiles, with a good correlation between the two methods for some serogroups except for the heterogenous serogroup A.

Bacterial Proteins↗

PubMed1989

[Detection of ischemic heart disease in a survey of a male population 40-59 years of age (data of cooperative studies performed in Moscow, Kaunas, Kiev and Kharkov)].

The authors analyzed the prevalence of coronary heart disease (CHD) and its various types detected by routine epidemiological methods among the examinees in four cities (Moscow, Kaunas, Kiev, and Kharkov). The results were obtained in the collaboration study, adhering to the rigid standardization of all the procedures applied. Examination of 17, 168 males aged 40-59 years revealed signs of CHD in 13.8%; 3.3% had a history of myocardial infarction; 5.3% suffered from exertional angina without prior myocardial infarction; 5.2% showed a painless course of CHD. The analysis demonstrated that simultaneous use of the standard epidemiological methods is the only way of ensuring a more complete detection of CHD. In different cities, from 36.4 to 60.8% were not aware of the presence of the disease. Secondary preventive measures should involve methods for identifying the major risk factors and eliminating the latter.

Adult↗

PubMed1990

Infectious disease control in a long-term refugee camp: the role of epidemiologic surveillance and investigation.

This report demonstrates the role of epidemiologic surveillance and investigation in the control of infectious diseases in a long-term refugee camp. The applications of simple epidemiologic methods in a refugee camp on the Thai-Cambodian border are described for a one-year period. The development of a Health Information Office facilitated the collection of demographic and vital statistics data, administration of a disease surveillance system, regular monitoring of hospital and outpatient discharge diagnoses, and investigation of disease outbreaks. This office also organized community health education campaigns and disease control efforts. Examples of specific disease investigations are provided to demonstrate the utility of epidemiologic surveillance in the control of infectious disease. We conclude that simple epidemiologic methods play an important role in health planning in long-term refugee camps.

Adolescent↗