Symposium on infectious complications of neoplastic disease (Part II). Legionnaires' disease. Aspects of nosocomial infection

Molecular epidemiology of Legionella pneumophila serogroup 1 by ribotyping with a non-radioactive probe and PCR fingerprinting

Hybridization with acetylaminofluorene-labelled 16 + 23 S rRNA from Escherichia coli was used to detect DNA polymorphism among Legionella pneumophila serogroup 1 isolates. Isolates from unrelated patients showed at least four different rRNA restriction patterns, whereas those from related patients showed a single pattern. Amplification of genomic regions with an arbitrary primer by polymerase chain reaction was used to further analyze the isolates. Related isolates showed closely related patterns while unrelated isolates displayed six distinct patterns. We could differentiate the majority of unrelated isolates with the combination of the patterns obtained with the ribotyping and the PCR fingerprinting, while strains from the same outbreak remained highly related. The ribotyping and the PCR fingerprinting are proposed as useful and easy to perform epidemiological markers of L. pneumophila serogroup 1 infection.

Comparative study of Legionella pneumophila and other nosocomial-acquired pneumonias

We studied, in a prospective way, the characteristics of definitively diagnosed nosocomially acquired pneumonias in our hospital over 36 months. Out of 55 cases, 27 were due to Legionella pneumophila and 28 to other, non-Legionella bacteria. The cases of legionellosis concentrated in July, August, and December. The only risk factors that showed significant differences (p less than 0.05) were general anesthesia and surgery and immunosuppressive disease, which were more frequent in the non-Legionella group, as were chronic liver disease and lowering of consciousness level. The absence of severe underlying disease, chronic or not, was uncommon in both groups, but more frequent in the Legionella group. We observed no differences in the clinical features of the two groups. Mean values of gamma-glutamyltranspeptidase and total bilirubin were higher (p less than 0.05) in the non-Legionella group. The only x-ray data that showed significant difference were pleural effusion, more frequent in the non-Legionella group (p less than 0.02). The mortality rate of legionellosis was 14.6 percent compared to 35.7 percent for the non-Legionella group (p less than 0.05). We conclude that a sure differential diagnosis based on clinical, roentgenographic and analytical features of both groups is not possible. The relatively low mortality rate of the Legionella group, when compared to other series of nosocomial legionellosis, could be due to the standard use of erythromycin in the therapeutic approach to nosocomial-acquired pneumonia in our hospital.

Legionellosis in heart transplant recipients

We report on 20 cases of Legionnaires' Disease (LD) in heart transplant recipients during a two-year study. The overall frequency in this setting amounts thus to 17% (20/115). In contrast, the frequency of legionellosis in postoperative cardiac patients without immunosuppression was only 4.7% (4/84). Legionellosis was diagnosed by culture and/or antibody detection in ten (20) as well as by the detection of urinary antigens in all 20 patients. Only nine (20) patients developed pneumonia, whereas five patients presented with nodular infiltrates. The remaining six patients had moderate fever with no signs of lung infection. In contrast to the majority of patients with other underlying diseases, antigen shedding lasted for long periods in most transplant patients. In high risk patients the application of conventional diagnostic methods together with regular urinary antigen testings (i.e. twice a week) may be advantageous for the early diagnosis of Legionella infection.

Legionella pneumophila associada a insuficiência respiratória aguda: primeiro isolamento no Brasil

Relatam os autores isolamento de Legionella pneumophila sorogrupo 1, acompanhado de evidências sorológicas de infecção atual, em homem de 40 anos com infecção respiratória grave que evoluiu para insuficiência respiratória aguda. Esta foi caracterizada por hipoxemia severa refratária a altas concentrações de oxigênio e radiograficamente por infiltrados difusos em ambos pulmões. Com introdução de clindamicina, amicacina, ceftriaxone e ventilação à volume com Pressão Expiratória Positiva Final (PEEP) de 14 cm de H(2)0, houve estabilização do quadro e gradual recuperação. Suspeitando-se de legionelose, foi colhido sangue e secreção traqueal para exames específicos. A secreção traqueal foi semeada em meio BCYE com isolamento de bacilo gram-negativo, identificado como Legionella pneumophila sorogrupo 1 por características culturais, bioquímicas e reações de imunofluorescência direta e de aglutinação em lâmina. O estudo sorológico revelou títulos de anticorpos 128, 1024, 4096 e 8192 para amostras coletadas na 1ª, 3ª, 4ª e 6ª semanas após o início do quadro. Os resultados definitivos foram obtidos com o paciente em recuperação. É realçada a comprovação da presença de Legionella sp. como agente patológico em nosso meio; a importância das medidas de suporte na evolução do paciente; a necessidade de se pensar neste agente no diagnóstico diferencial de pneumonias e de se pesquisar mais esta etiologia com metodologia laboratorial específica.

Are health care workers at risk for infection during an outbreak of nosocomial Legionnaires' disease?

We studied data from 500 health care workers to answer the question: Are health care workers at risk for infection during an outbreak of nosocomial Legionnaires' disease? These workers were employed at a hospital where eight cases of nosocomial Legionella pneumophila serogroup 1 pneumonia occurred over a 4-week period. The source was potable water. Acute-phase blood samples were collected on the day the water supply was decontaminated, convalescent samples were collected 4 to 6 weeks later from 373 subjects, and a single serum sample was obtained from an additional 127 subjects. Antibody titers to L. pneumophila were determined by an indirect immunofluorescent antibody (IFA) technique and by a microagglutination assay with the epidemic strain as the test antigen. Subjects who had an IFA titer of greater than or equal to 1:256 were retested with an anti-human IgM conjugate. None of the 373 health care workers had a fourfold rise in antibody titer. The geometric mean antibody titer of 73.8 for the 500 health care workers was significantly higher than that of 68.1 for 976 blood donors (p less than 0.01). Only 2.4% had recent infection as evidenced by a microagglutination test, despite the fact that 84% were susceptible. We conclude that in the setting of a short-term outbreak of Legionnaires' disease caused by contaminated potable water the risk of infection among health care workers is low: 2.4% or less.

Infectious complications of neoplastic disease

Progress has been made in the diagnosis and treatment of infection in patients with neoplastic disease. Among the advances is the appreciation that certain opportunistic infections occur in association with particular host immune defects and epidemiologic factors. Such immune defects are seen secondary to or as a consequence of treatment for the patient's basic disease. Improved methods such as serology, open lung biopsy, and fiberoptic bronchoscopy have allowed for earlier diagnosis and treatment of opportunistic infections. The development of empiric antibiotic regimens, particularly aminoglycosides and the antipseudomonal penicillins, have improved the outcome in the febrile neutropenic patient. The benefits of protective environments have been challenged; prophylactic antibiotics and various forms of immunotherapy are of interest but remain investigational.