Biomedical subjects
Publications and source records attributed to H Hallander.
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To clarify whether a nosocomial outbreak of legionnaires' disease in the Värnamo hospital in Sweden was part of a wider outbreak in the Värnamo community a number of investigations were performed. First, the proportion of cases of legionnaires' disease in a group with nosocomially acquired pneumonia (11%) was compared to the proportion within a group with community-acquired pneumonia (14%) and the difference was found not to be significant (p > 0.05). Second, the proportion of the nursing staff at the Värnamo hospital with an elevated antibody titre (> or = 16) to Legionella pneumophila serogroup (sg) 1 (33%, 84/258) was compared to the proportion in a group of local residents of Värnamo community (26%, 25/96) and found not to be significant; in contrast, comparison with the proportion in a group from the assistant nursing staff at another hospital 60 km away (5%, 4/80) was highly significant (p < 0.001). Furthermore, Legionella species were cultured from samples drawn from the hospital water supply as well from the water supply from municipal buildings. In 1996 a follow-up study was conducted, which showed that < 1% of the assistant nurses and local residents had an elevated titre to L. pneumophila sg 1. These results indicate that there was a temporary spread of L. pneumophila sg 1 in the Värnamo community at the beginning of 1991, both in the local hospital and the surrounding community. This implies that physicians should be aware of community-acquired cases of legionnaires' disease when a nosocomial outbreak is detected.
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Pertussis is re-emerging in vaccinated populations, and to gain insight into the reasons for this development population-based studies are necessary. Unfortunately, various techniques are used to study Bordetella pertussis populations, hampering comparison between studies. A standard methodology for epidemiological typing of Bordetella pertussis isolates is proposed which is based on serotyping, pulsed-field gel electrophoresis and gene typing. Such a standard approach will allow comparisons between studies performed in different laboratories. Comparisons may reveal whether the epidemiological differences observed between countries are due for instance to different Bordetella pertussis populations or different vaccines used.
Using the comparison method, we have evaluated the technical performance of Uricult Trio by culturing on Uricult Trio and agar plates. Urine samples (477) from patients in primary healthcare were cultured in parallel in a microbiology laboratory. The result for Uricult Trio evaluated using the comparison method was incorrect in 32% of the cultures. We also studied the performance of Uricult Trio when used in primary healthcare by using external control panels. External control panels consisting of Uricult Trio, inoculated with known concentrations of certain bacterial strains, were used to assess the performance of Uricult Trio in primary healthcare during the period 1993-7. Aberrations in reports of concentration have ranged from 10% to 33%, failure in reporting of mixed culture from 0% to 91% and reporting of E. coli from 15% to 86%. There has been no sign of improvement over the years. The results indicate that Uricult Trio is unsuitable for indications other than exclusion of urinary tract infection or diagnosis of urinary tract infection caused by E. coli. Further, there is need for quality assurance and training activities at primary healthcare laboratories, probably best carried out in collaboration with local clinical microbiology laboratories.
This study evaluates the effect of training on the results from Uricult Trio and an established urine culture when used at primary healthcare laboratories in two Swedish counties, Uppsala and Värmland. Urine cultures and dipslides, Uricult Trio, performed at these laboratories were interpreted a second time at central laboratories. Interpretation errors at the primary healthcare laboratories were calculated. Primary healthcare laboratories also received external control panels with urine cultures and dipslides. There was one study period each year for 3 years in Uppsala and for 2 years in Värmland. A training programme was completed between study periods in Värmland. In Uppsala, primary healthcare laboratory results could be reviewed, as interpretations by the central laboratory were returned to them. The main outcome measures were the percentage of interpretation errors which, in the first study period, was 33-39%. This dropped to 15-19% in the second study period. In the results from the external control panels there were no striking differences between the studied areas and Sweden as a whole, except that Uppsala showed a better result in reporting E. coli and failed in 10% compared to Sweden 46%. A method for both quality assessment and education is to ask the primary healthcare laboratories to send cultures to the central laboratory for interpretation requesting their return to the primary healthcare laboratory with the interpretation from the central laboratory attached.
An evaluation of the delayed fluorescence immunoassay (Delfia) against an ELISA method for determination of diphtheria antitoxin levels in serum was performed. The Delfia was also validated in the in vivo toxin neutralisation test (Txn) in rabbits. Two variants of the Delfia were studied, a single-antigen Delfia (sDelfia) with only the diphtheria toxin included and a dual-antigen Delfia (dDelfia) with tetanus toxoid included for simultaneous detection of antibodies against two antigens. The diphtheria antitoxin cut-off levels in the sDelfia and the dDelfia were 0.004 and 0.002 AU/ml, respectively, which is lower than the internationally accepted level showing any protection against diphtheria (0.01 IU/ml). Both Delfia variants showed good correlation with the ELISA procedure above the ELISA cut-off level of 0.02 AU/ml. Results from samples assayed in the in vivo Txn assay indicated that the low antitoxin levels detected by the Delfia were valid. These results show that the Delfia could be considered as an in vitro reference method for detection of diphtheria antitoxin in seroepidemiological surveys and vaccine studies.
Analytical quality specifications for ordinal scale measurements have not been presented so far. Criteria are suggested for multiproperty (multiple) urine test strips based on upper limits of healthy reference intervals, analytical performance and statistical tests applicable to ordinal scales. Trueness (accuracy) can be evaluated against an acceptable comparison method by applying sensitivity and specificity concepts, and defining a grey zone with a lower detection limit and an upper confirmation limit. Concordance (agreement) of two or more ordinal scale categories should be evaluated by subtracting random agreement, using Kappa statistics. Repeatability (precision) can be calculated for categorized results using binomial statistics.
AIMS: Cross-sectional serological studies have suggested an association between ischaemic heart disease and infections from Chlamydia pneumoniae and Helicobacter pylori. We therefore sought to find out if patients with ischaemic heart disease had an increased prevalence of C. pneumoniae in the pharynx. As the course of the C. pneumoniae infection remains unclear, both acute and follow-up samples were taken and compared with antibody levels. METHODS AND RESULTS: We studied 282 patients with ischaemic heart disease. One hundred and two subjects without history or symptoms of ischaemic heart disease served as controls. Pharyngeal specimens for polymerase chain reaction detection of C. pneumoniae, and blood samples for C. pneumoniae and H. pylori antibody detection, were collected. In patients with positive polymerase chain reaction or C. pneumoniae IgA titres > or = 32, indicating current infection, convalescent samples were taken at least 6 weeks later. An immunofluorescent antigen detection test was used to confirm the presence of C. pneumoniae elementary bodies in specimens found to be polymerase chain reaction positive. The prevalence of positive polymerase chain reaction tests was 36% among patients and 22% among controls (P<0.05). Forty-seven percent of patients with positive polymerase chain reaction remained positive in the convalescent test. Elevated C. pneumoniae IgG titres > or = 512 were found in 39% of patients and 26% of the controls (P<0.05). IgA titres > or = 32 were found in 46% of the patients and 44% of the controls (ns). Antibody titres remained largely unchanged at convalescent testing. Two patients and none of the controls had IgM titres > 16. There was no link between positive H. pylori serology and positive C. pneumoniae polymerase chain reaction tests. CONCLUSIONS: The high prevalence and persistence of positive pharyngeal C. pneumoniae polymerase chain reaction and elevated antibody titres in patients with ischaemic heart disease indicate a chronic infection. The pharyngeal presence of C. pneumoniae might contribute to a low grade inflammatory activation or be a source for further spread of the bacteria to atherosclerotic vessels.
We analyzed the prevalence of rotavirus in 296 children age between 3 and 36 months who were hospitalized in 1994 with severe gastro-enteritis at two health centres for diarrhoea treatment in León, Nicaragua. Enteric viruses were detected in 96 (32.4%) of the children and rotaviruses were the most common pathogens detected in 84 (28%). The majority of rotavirus infections occurred in children less than 1 year old and all strains isolated belonged to subgroup II and had 'long' RNA patterns. Molecular epidemiology of 55 rotavirus strains revealed that all had the same RNA migration pattern and serotyping of 37 strains by PCR technology revealed that all isolates belonged to serotype 3. A significant observation was that only one electropherotype of rotavirus circulated. No non-group A rotaviruses were found by RNA gel electrophoresis. Adenoviruses were found by ELISA in 14 of 265 (5%) children and were most frequently detected during the 1st year of life. Of 103 faecal samples analyzed by electron microscopy, four contained small round structured viruses.
BACKGROUND: Rotavirus is an important cause of dehydrating diarrhea in young children throughout the world. Knowledge about frequency of reinfections, development of immunity to the virus and the possible protective effect of breast milk is important, in particular in relation to possible strategies for immunization. METHODS: A prospective study of rotavirus infections in a cohort of 235 infants followed from birth until 2 years of age was performed in León, Nicaragua. Fecal and serum specimens were collected at specified times, and stools were also obtained during episodes of diarrhea. Fecal specimens were screened by rotavirus antigen detection and serum and colostral specimens were analyzed by isotype-specific rotavirus antibody enzyme-linked immunosorbent assay. RESULTS: As judged by anti-rotavirus IgA antibody seroconversion and/or demonstration of rotavirus antigen in fecal specimens, > 50% of the babies had evidence of past rotavirus infection by the age of 2 months. The total incidence of rotavirus infections, including many reinfections, was 0.7 infection/child-year, of which only 17% were associated with diarrhea. The time from birth to the first demonstration of rotavirus in stool samples correlated significantly with the concentration of anti-rotavirus IgA antibodies in colostrum. There was also a tendency toward a relationship between long duration of breast-feeding and asymptomatic infection. CONCLUSIONS: Rotavirus infections are acquired very early in infants in León, Nicaragua, and reinfections are common. Most infections are asymptomatic. Breast milk appears to confer partial protection against rotavirus infection, probably mediated by specific IgA antibodies. To be effective rotavirus vaccination would probably have to be given at a very early age to infants in developing countries.
Diarrheal episodes with enterotoxigenic Escherichia coli (ETEC) were prospectively monitored during the first 2 years of life in a cohort of 235 infants from Leon, Nicaragua. ETEC was an etiological finding in 38% (310 of 808) of diarrheal episodes and in 19% (277 of 1,472) of samples taken as asymptomatic controls at defined age intervals (P = <0.0001). The majority of diarrheal episodes (80%) occurred before 12 months of age. The major ETEC type was characterized by colonization factor CFA I and elaboration of both heat-labile enterotoxin and heat-stable enterotoxin (ST). The proportion of E. coli strains with CFA I was significantly higher in cases with diarrhea (P = 0.002). The second most prevalent type showed putative colonization factor PCFO166 and production of ST. The prevalence of PCFO166 was approximately 20%, higher than reported before. Children with a first CFA I episode contracted a second ETEC CFA I infection 24% of the time, compared with 46% for ETEC strains of any subtype. Most of the ETEC episodes were of moderate severity, and only 5% (15 of 310) were characterized as severe. In conclusion, our results give valuable information for the planning of intervention studies using ETEC vaccines.
Sera from 20 male patients with a diagnosis suggestive of myocarditis, perimyocarditis or pericarditis were found significantly more often to have specific IgA antibodies to Chlamydia pneumoniae than sera from healthy blood donors of the same age and from the same time period. A less pronounced difference in IgG titres was found between patients and blood donors, and IgM antibodies were found only in one patient. A striking variation over time in the prevalence of specific antibodies to C. pneumoniae was seen in consecutive male blood donors over a 5-year observation period. The findings were discussed and it was concluded that C. pneumoniae may be associated with inflammatory heart disease.
During the years 1970 to 1995, the serotypes of collected clinical isolates from the different regions of Sweden were examined. Vaccination using whole-cell pertussis vaccine decreased during the year preceding cessation of general vaccination of children in 1979. Although the total number of clinical isolates examined was limited up to 1978 compared to later years, serotype 1, 2, 3 clinical isolates generally predominated. During periodical pertussis outbreaks, serotype 1, 3 strains were isolated, the proportion of which was about equal to that of serotype 1, 2, 3 isolates. Following cessation of general vaccination in 1979, the proportion of both serotypes 1, 2, 3 and 1, 3 isolates gradually diminished, together contributing about 20 percent of the total number of isolates in 1995. Clinical isolates of serotype 1, 2 were identified in the year 1977, just before cessation of general vaccination in Sweden using whole-cell vaccine. Since then, this serotype has gradually increased to over 80 percent of total isolates in 1995, possibly indicating that the use of whole-cell pertussis vaccine was effective against this serotype or that the vaccine influenced serotype expression. Vaccine efficacy studies conducted in Sweden during 1986-87 using one and two-component vaccines (BIKEN) and in 1994-95 using two-component (SmithKline Beecham Pharmaceuticals) and five-component (Connaught Laboratories, Ltd.) vaccines are examined with the object of studying whether the vaccines showed any influence on the different serotypes of B. pertussis causing disease.
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We report a nosocomial outbreak of Legionella pneumophila serogroup (sg) 1 infection at the general hospital, Värnamo, Sweden. From December 1990 to February 1991, 28 patients and 3 staff fell ill with pneumonia and 3 died. L. pneumophila sg 1 together with several other Legionellae were isolated from the hot water supply to 17 of 20 hospital wards, probably being spread by aerosolization via shower nozzles. Raising the hospital's hot water temperature from 45 degrees C to 65 degrees C, together with heat disinfection of the shower equipment, arrested the outbreak within a week. Keeping the hot water temperature > or = 60 degrees C without chlorination eliminated L. pneumophila from > 75% of the wards. During a period of 2 years after the outbreak we have diagnosed only 1 case of nosocomial legionellosis at the hospital despite an active surveillance program.
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