Vaginal-rectal colonization with group A streptococci in late pregnancy.

OBJECTIVE: To determine the vaginal-rectal colonization rate with group A streptococci in late pregnancy. METHODS: All patients delivering at a northern New England hospital over a 38 month period had 35-37 week vaginal-rectal swabs cultured for group A and group B streptococci, using selective media and slide agglutination. RESULTS: Six thousand nine hundred forty-four screening cultures were obtained. Among these 1,393 were positive for group B streptococci and 2 for group A streptococci, yielding colonization rates of 20.1% and 0.03%, respectively. CONCLUSIONS: Vaginal-rectal colonization with group A streptococci is rare, arguing against the need for establishing group A streptococcal screening programs in pregnancy. An approach for managing this uncommon finding is presented.

Enterically transmitted hepatitis. Hepatitis A and E viruses.

Enterically-transmitted hepatitis is caused by hepatitis A virus and hepatitis E virus. The most important agent is hepatitis A virus, which is distributed worldwide and infects all age groups. Most infections in children are minimally symptomatic and immunity is long-lasting, so severe disease tends to occur in nonimmune adults. Hepatitis E virus is found in the developing world and has a greater propensity for symptomatic infection of children. Both agents are transmitted via contaminated water, often through food vehicles.

Complicated soft tissue infection with prepatellar bursitis caused by Paecilomyces lilacinus in an immunocompetent host: case report and review.

Documented Paecilomyces lilacinus infections are quite rare. Most reports involve immunocompromised patients or implanted objects. We report the first case of complicated soft tissue infection caused by P. lilacinus in an immunocompetent host. The spectrum of infections involving this fungus is reviewed.

Use of rhesus monkey kidney cells for isolation of varicella-zoster virus.

The authors examined the performance of rhesus monkey kidney cells and human diploid fibroblasts (MRC-5 cells) in primary isolation of varicella-zoster virus from clinical specimens in a diagnostic virology laboratory. Seventy-two varicella-zoster virus isolates were recovered between 1985 and 1993. Twenty-three isolates (32%) grew only in rhesus monkey kidney cells, whereas four isolates (6%) grew only in human diploid fibroblasts (MRC-5)(P = .0001). The time to first detection of cytopathic effect was shorter in rhesus monkey kidney cells than in fibroblasts. The extent of cytopathic effect was greater in monkey kidney cells. In conclusion, the addition of rhesus monkey kidney cells increases the yield of varicella-zoster virus and decreases the time required to make a definitive diagnosis. The optimal yield of isolates and time to specific diagnosis occurs when both monkey kidney cells and human diploid fibroblasts are inoculated.

Legionella and the clinical microbiologist.

Legionella species are important etiologic agents of sporadic and epidemic community-acquired and nosocomial respiratory disease. The list of species continues to expand, and tools for classification and characterization of isolates have become increasingly sophisticated. These organisms are associated with aquatic habitats and are transmitted by aerosol or direct contact. Bacterial culture is the cornerstone of laboratory diagnosis. Careful surveillance of infections is important, because infections potentially can be prevented.

Legionnaires disease: historical perspective.

In the summer of 1976, a mysterious epidemic of fatal respiratory disease in Philadelphia launched an intensive investigation that resulted in the definition of a new family of pathogenic bacteria, the Legionellaceae. In retrospect, members of the family had been isolated from clinical specimens as early as 1943. Unsolved epidemics of acute respiratory disease dating to the 1950s were subsequently attributed to the newly described pathogens. In the intervening years, the Legionellaceae have been firmly established as important causes of sporadic and epidemic respiratory disease. The sources of the infecting bacteria are environmental, and geographic variation in the frequency of infection has been documented. Airborne dissemination of bacteria from cooling towers and evaporative condensers has been responsible for some epidemics, but potable water systems are perhaps more important sources. The mode of transmission from drinking water is unclear. The Legionellaceae are gram-negative, facultative, intracellular pathogens. The resident alveolar macrophage, usually an effective antibacterial defense, is the primary site of growth. Cell-mediated immunity appears to be the most important immunological defense; the role of humoral immunity is less clear. Erythromycin remains the antibiotic of choice for therapy of infected patients, but identification and eradication of environmental sources are also essential for the control of infection.

Legionnaires' disease: respiratory infections caused by Legionella bacteria.

This article provides a review of Legionnaire's Disease, a bacterial pneumonia caused by Legionella species, and of Pontiac Fever, the flu-like illness caused by these microorganisms. The authors draw on their personal experience with major human outbreaks of Legionnaire's Disease and with animal models of Legionella pneumonia. Emphasis is placed on the sources in nature from which legionellosis is acquired, the means of dissemination of bacteria, the epidemiology of human infections, the pathogenetic mechanisms of disease and host defense, the clinical manifestations, and the treatment.

Treatment of alveolar macrophages with cytochalasin D inhibits uptake and subsequent growth of Legionella pneumophila.

Legionella pneumophila multiplied rapidly in guinea pig and rat alveolar macrophages but failed to grow when phagocytic activity was inhibited by pretreatment with 0.5 or 1.0 microgram of cytochalasin D per ml. Attachment was not inhibited by cytochalasin D. No extracellular multiplication occurred when L. pneumophila were in close proximity to viable functional macrophages or even when the bacteria were attached to plasma membranes of the macrophages. Nonopsonized L. pneumophila were avidly phagocytized by alveolar macrophages. When bacteria were centrifuged onto a cell pellet, more than 85% of the phagocytes contained one or more bacteria within 15 min. In contrast, under the same conditions only approximately 15% of the macrophages contained nonopsonized Escherichia coli or Staphylococcus aureus. Phagocytosis of L. pneumophila by untreated guinea pig macrophages occurred by extension of pseudopodia around the bacteria in a classical manner. The failure of the bacteria to actively penetrate the phagocyte suggests that their intracellular survival must not depend on avoidance of a phagosome but rather on an inhibition of or resistance to subsequent microbicidal functions of the macrophage.

Cross-reactive urinary antigens among patients infected with Legionella pneumophila serogroups 1 and 4 and the Leiden 1 strain.

A solid-phase radioimmunoassay was developed to detect antigens of Legionella pneumophila serogroup 4. The assay detected antigen in urine from four of seven patients with pneumonia caused by L. pneumophila serogroup 4, two of two patients with L. pneumophila Leiden 1 strain (proposed new serogroup), and 26 of 55 patients with L. pneumophila serogroup 1 (proven by culture or direct fluorescent-antibody assay). The antigen of two patients with serogroup 4, one with Leiden 1 strain, and 49 with serogroup 1 infections could be detected in a previously described assay for antigens of L. pneumophila serogroup 1. Serogroup specificity of the assays could be demonstrated if serial dilutions of urine were tested. None of 347 urine specimens used as controls were positive in the radioimmunoassay. We conclude that antigens are excreted in the urine of at least some patients with Legionnaires' disease caused by serogroup 4 and Leiden 1 strain. The urinary antigens in patients with serogroup 4 and Leiden 1 strain infections, although different from those in patients with serogroup 1 infections, serologically contain cross-reactive components.

Comparison of media for recovery of clinical isolates of Legionella pneumophila.

Seven media were prepared in house or purchased commercially and were compared for their ability to recover Legionella pneumophila from clinical specimens. Media containing alpha-ketoglutarate from either source detected colonies earlier, more often, and in greater quantities than media without alpha-ketoglutarate. Media without charcoal performed poorly.

Legionella and Legionnaires' disease: a review with emphasis on environmental studies and laboratory diagnosis.

Legionella pneumophila and related species are important causes of epidemic bacterial pneumonia and nosocomial infection. This review will discuss this new family of bacteria and the diseases they produce. The classification, general microbiologic characteristics, and ecology of the bacteria will be reviewed and the epidemiology and clinical aspects of the infection will be discussed. More emphasis will be given to issues that are more directly related to laboratory workers and with which the author has had more direct experience: pathology, laboratory diagnosis of human infection, pathogenesis of the infection, and virulence mechanisms of the bacterium. Therapy and prevention of the infection will be discussed more briefly.

Correlation of subtypes of Legionella pneumophila defined by monoclonal antibodies with epidemiological classification of cases and environmental sources.

Twenty-five clinical isolates of Legionella pneumophila serogroup I were classified as epidemic or sporadic on epidemiological grounds. All were isolated from patients at the Medical Center Hospital of Vermont (MCHV) in Burlington between 1977 and 1983. These coded isolates were examined with a panel of eight monoclonal antibodies to serogroup 1 and an indirect microimmunofluorescent test. Strains from 14 of the 15 MCHV epidemic cases had one staining pattern (A); isolates from eight of nine MCHV sporadic (nosocomial) cases had a different pattern (B). One sporadic strain was of staining pattern A, and in one epidemic case an isolate of each pattern (A and B) was obtained. The only case that was clearly community-acquired displayed a third staining pattern (C). Four isolates from the cooling tower considered the most likely source for the epidemic strains had an antigenic reaction identical to isolates in epidemic cases, whereas three strains from the potable water system displayed an antigenic pattern identical to isolates in sporadic cases.

Onset and duration of urinary antigen excretion in Legionnaires disease.

The purposes of this study were to determine whether antigen is excreted by patients with Legionnaires disease early enough after the onset of symptoms to be useful for making therapeutic decisions and whether antigen excretion ends when successful treatment is concluded. Specific antigen was detected in the urine of 14 (88%) of 16 patients with Legionnaires disease during days 1 to 3 of symptoms, 33 (80%) of 41 patients during days 4 to 7, 25 (89%) of 28 patients during days 8 to 14, and 11 of 11 patients after day 14, by solid-phase immunoassays for serogroup 1 Legionella pneumophila antigen. Antigen excretion persisted for 42 days or longer after the onset of treatment in at least 15 patients. The longest documented duration of excretion was 326 days. We conclude that antigen can be detected approximately as often early after symptoms begin as later, allowing meaningful therapeutic decisions to be made, but that prolonged antigen excretion may negate the diagnostic value of urinary antigen detection for relapsing or recurrent L. pneumophila pneumonia.

Disseminated aspergillosis presenting with endophthalmitis. A case report and a review of the literature.

A patient with idiopathic thrombocytosis developed sudden loss of vision in his left eye secondary to endophthalmitis caused by Aspergillus flavus. He subsequently manifested other symptoms and signs of disseminated infection, and eventually died despite prompt initiation of appropriate parenteral antifungal therapy. A period of profound, iatrogenic neutropenia preceded the development of his terminal infection. Previously reported cases of hematogenously acquired Aspergillus endophthalmitis are reviewed, and approaches to diagnosis and management are discussed. The frequency of eye involvement in cases of disseminated aspergillosis is unknown, but it may be greater than appreciated previously.

The kinetics of early inflammatory events during experimental pneumonia due to Legionella pneumophila in guinea pigs.

An animal model of Legionella pneumophila pneumonia was developed to study aerosol infection, pathogenesis, and pulmonary host defense mechanisms. Guinea pigs were exposed in an inhalation facility that limited the aerosol of L pneumophila to the snout. Bronchoalveolar lavage was used to sample airspace cells, secretions, and bacteria during developing infection in 79 exposed animals and 13 uninfected controls. An influx of polymorphonuclear neutrophils followed exponential bacterial growth during the initial three days of infection and coincided with limitation of the increase in bacteria recovered. A macrophage influx occurred at three to five days. Bacteria were eliminated from the lung by 11 days after exposure. Albumin in lavage fluid peaked at two days. Most viable L pneumophila organisms were associated with alveolar macrophages, whereas most of the bacteria associated with polymorphonuclear neutrophils were nonviable. Recruited, and possibly immune, defenses appear to be required for successful resolution of legionella pneumonia.