Subgroups of Legionella pneumophila serogroup 1.
Explore the source record for details and available documents.
Biomedical subjects
Publications and source records attributed to J O Tobin.
Explore the source record for details and available documents.
Swabs and water samples from a hospital water system were cultured for legionellae over an extended period. Legionella pneumophila serogroup 1, including outbreak associated strains, were isolated in small numbers from approximately 5% of these samples despite implementation of the current DHSS/Welsh Office regulations. No cases of nosocomial legionnaires' disease were proven during the study. Physical cleaning and chemical sterilization of taps, and replacement of washers with 'approved' brands did not eradicate the organisms. Eradication of legionellae in hospital water supplies appears to be unnecessary in preventing nosocomial legionnaires' disease provided the current DHSS/Welsh Office recommendations are implemented.
Forty-one clinical isolates of Legionella pneumophila from sporadic cases of legionella pneumonia were collected from laboratories throughout the United Kingdom and were compared with 300 routine environmental isolates using two panels of monoclonal antibodies, covering serogroups 1-10. Eighty-five per cent of the clinical isolates belonged to the subgroup Pontiac of serogroup 1, whilst only 13% of the environmental isolates did. Approximately half of the clinical isolates tested came from patients with a recent history of foreign travel, mainly to southern Europe.
Immunohistology was used for the detection of Legionella pneumophila serogroup I in necropsy tissue. Study of pneumonic lung from the recent Stafford outbreak has shown that this technique has a high sensitivity. A retrospective postmortem examination showed that L pneumophila serogroup 1 was an unusual cause of pneumonia in Oxfordshire during the study period. L pneumophila serogroup 1 can be successfully subgrouped, using a panel of monoclonal antibodies on formalin fixed paraffin embedded sections. Immunohistological methods have a potentially useful role in the diagnosis of Legionellosis at postmortem examination and in the epidemiological investigation of individual cases and outbreaks.
A panel of monoclonal antibodies to Legionella pneumophila serogroup 1 and a subclassification scheme were developed in a collaborative project among three laboratories. The seven most useful monoclonal antibodies were selected from three previously developed panels on the basis of indirect fluorescent antibody patterns with 83 strains of L. pneumophila serogroup 1 that were obtained from widely distributed geographic locations. The isolates were divided into 10 major subgroups on the basis of reactivity patterns that can be readily reproduced in any laboratory and are not subject to major inconsistencies of interpretation of staining intensity. A standard protocol for the indirect fluorescent antibody procedure was also developed.
Multilocus enzyme electrophoresis, monoclonal antibody typing for Legionella pneumophila serogroup 1, and plasmid analysis were used to type 89 L. pneumophila strains isolated from nosocomial cases of Legionnaires disease at the Veterans Administration Wadsworth Medical Center (VAWMC) and from the hospital environment. Twelve L. pneumophila clinical isolates, obtained from patients at non-VAWMC hospitals, were also typed by the same methods to determine typing specificity. Seventy-nine percent of 33 VAWMC L. pneumophila serogroup 1 clinical isolates and 70% of 23 environmental isolates were found in only one of the five monoclonal subgroups. Similar clustering was found for the other two typing methods, with excellent correlation between all methods. Enzyme electrophoretic typing divided the isolates into the greatest number of distinct groups, resulting in the identification of 10 different L. pneumophila types and 5 types not belonging to L. pneumophila, which probably constitute an undescribed Legionella species; 7 clinical and 34 environmental VAWMC isolates and 2 non-VAWMC clinical isolates were found to be members of the new species. Twelve different plasmid patterns were found; 95% of VAWMC clinical isolates contained plasmids. Major VAWMC epidemic-bacterial types were common in the hospital potable-water distribution system and cooling towers. Strains of L. pneumophila which persisted after disinfection of contaminated environmental sites were of a different type from the prechlorination strains. All three typing methods were useful in the epidemiologic analysis of the VAWMC outbreak.
Legionella pneumophila serogroup 1 can be subgrouped by panels of monoclonal antibodies. The Oxford panel divides serogroup 1 strains into three major subgroups, provisionally named Pontiac, Olda and Bellingham. Strains causing outbreaks tend to be in the Pontiac subgroup, with strains from the other subgroups appearing also in sporadic cases. Isolates from sources in the UK unassociated with outbreaks are mainly the Olda and Bellingham strains; only 10% are Pontiac, yet this strain has caused 80 to 90% of the cases of Legionnaires' Disease so far studied. We compared our method with other methods of subgrouping serogroup 1 strains.
A panel of 10 monoclonal antibodies was used to subgroup 326 strains of Legionella pneumophila serogroup 1. All but two strains could be classified into three major subgroups named after their representative strains Pontiac 1, Olda and Bellingham 1. Of the 50 isolates from patients, 44 representing 32 separate incidents were of the Pontiac subgroup. This subgroup was also found in 16 of 18 buildings epidemiologically associated with Legionnaires' Disease. In contrast, strains of the Olda subgroup predominated in buildings where no infections had occurred. In 9 of the 11 incidents where isolates were available from at least one patient as well as from the suspected environmental source, the monoclonal antibody reaction patterns of strains from patients were identical to those of one or more of their environmental counterparts.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Antibody to cytomegalovirus (CMV) was sought in sera from Malta using immunofluorescence. Seven per cent of the infants, 36% of the school children, increasing to 100% of the adults aged over 40 years were found to have antibody. Most infection occurred in pre-school children and adults over 25 years of age. This pattern of antibody acquisition appears different from that described for other countries.
Between December, 1979, and July, 1980, 12 cases of legionnaires' disease were recognised in a district general hospital. 11 of the patients probably acquired their infection within the hospital. Epidemiological and environmental studies indicated that the plumbing system and possibly also the air-conditioning cooling-tower exhaust in the new building of the hospital were the sources of infection. Chlorination of the cold-water supply and raising the hot-water temperature appeared to terminate the outbreak.
A preliminary survey of water systems in hospitals and hotels showed that Legionella pneumophila may be found in water storage and distribution systems as well as in the recirculating cooling water of air-conditioning plants. Altogether 42 isolates of L pneumophila were made from 31 establishments, six of which were associated with cases of legionnaires' disease but in 25 of which there was no known association with disease. In the six establishments implicated epidemiologically as the source of legionnaires' disease, these organisms were found in each of their water-distribution systems and also in the cooling water from each of the three with cooling towers. In establishments not associated with cases, water from three out of nine cooling towers, four out of 24 taps or showers, and one out of 15 storage tanks was found to contain legionellae. The organisms were isolated by guinea-pig inoculation and subsequent culture of their peritoneal fluid, liver, and spleen. Finding L pneumophila in water systems in the absence of cases of legionnaires' disease should not at present be an indication for attempts at eradication.
Explore the source record for details and available documents.
Early antenatal serum specimens were collected from 25 women who subsequently gave birth to infants with anencephaly or spina bifida. Fluorescent-antibody test for influenza-specific IgA and IgM antibodies, although shown to be reliable for the detection of recent influenzal infection, failed to demonstrate such infection in any of these women. Early infection was detected in one of 50 control women who gave birth to a healthy infant. The results indicate that influenzal infection in pregnancy was not a major cause of neural-tubal defects in Oxford during 1972--76, if a cause at all.
Legionnaires' disease was diagnosed in two patients in a transplant unit, both patients having occupied the same postoperative cubicle shortly before onset of their illnesses. Legionella pneumophila was found in water taken from the cubicle shower bath and from other showers in the unit. To eradicate the legionellae, the water supply was treated with chlorine, but this had only a temporary effect.
A prospective study of viral infections occurring after 188 renal transplants in 167 patients showed active cytomegalovirus (CMV) infection after 52 per cent of transplantations. All 37 CMV seronegative cases who received grafts from seronegative donors remained free of infection, while 24 (70.6 per cent) of 34 seronegative recipients whose donors were seropositive developed primary CMV infection (p less than 0.001). The diagnosis of 92 per cent of these primary infections was made between one and two months after grafting. Secondary CMV infection was found in 71 (62 per cent) of 114 seropositive cases, and the frequency of infection was not affected by the CMV status of the renal donor. Neither acute rejection episodes nor total graft rejections were associated with primary or secondary infections. CMV was isolated from a colonic abscess and the relationship of the virus to the intestinal disease is discussed. Herpes simplex virus was isolated from 47 per cent of cases and 32 per cent had an increase in antibody titre. Zoster was seen in nine patients, representing an incidence of 3.4 per cent per year. Other viral or mycoplasmal infections diagnosed included 71 due to respiratory tract pathogens, and a single case of hepatitis B. None of these infections was particularly severe or frequent and no association with graft rejection was detected.
Explore the source record for details and available documents.