Washington C. Winn

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.

Mucoid Pseudomonas in Cystic Fibrosis

Pseudomonas aeruginosa is a frequent and virulent pulmonary pathogen in patients with cystic fibrosis. If colonization is not prevented, P aeruginosa becomes permanently established and nearly always mutates into a mucoid strain. The alginate-containing matrix of the mucoid strain is thought to allow the formation of protected microcolonies and provide increased resistance to opsonization, phagocytosis, and destruction by antibiotics. As a result, conversion to the mucoid phenotype is associated with a significant increase in morbidity and mortality. In the microbiology laboratory, mucoid P aeruginosa has a distinct Gram stain and culture appearance that can expedite its identification and facilitate appropriate patient management. Important aspects of the mucoid phenotype are reviewed.

Pyelonephritis Associated with Legionella pneumophila, Serogroup 4

A patient with bladder carcinoma metastatic to lung and brain died of pneumonia. Autopsy examination showed a confluent bronchopneumonia with several small abscesses and acute pyelonephritis with abscess formation. Legionella pneumophila, serogroup 4, was isolated in pure culture from lung tissue postmortem and was also shown by direct immunofluorescence in the kidney and spleen. In the kidney, the organism was noted in areas of acute pyelonephritis. This represents the first case of an extrathoracic inflammatory lesion associated with L. pneumophila.

Laboratory Diagnosis of Bone, Joint, Soft-Tissue, and Skin Infections

The diagnosis of infections of bones, joints, skin, and soft-tissues requires the combined use of a number of laboratory and pathology tests. The diagnosis of most infections requires microbiological cultures, both for isolation and for identification of causative organisms, as well as for antimicrobial susceptibility testing. Chemical analysis of joint fluids and histopathologic examination of infected tissues are often necessary to distinguish infections from other causes of inflammation, as well as to provide information as to the type of infection before the results of cultures are available. At this time, the use of molecular amplification tests is of limited value in the diagnosis of these infections, their value primarily being as adjunct tests for the diagnosis of rare or unusual infections.

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.

Neuropathologic evaluation of 40 confirmed cases of Legionella pneumonia

Autopsy examination of the brain was performed in 40 cases of Legionella pneumonia. Thirty-nine of 40 patients had underlying chronic or acute medical problems. Sixteen patients (40%) had neurologic signs or symptoms that were not explained by preexisting disease. CSF was normal in six of seven patients examined; CSF protein content was 66 mg/100 ml in one patient. Neuropathologic examination in all 40 patients demonstrated no lesions attributable to disseminated Legionella pneumophila. Mechanisms other than direct cerebral invasion by the causative organism must be sought to explain the neurologic manifestations of Legionella pneumonia.

Performance of microtrak direct test for Chlamydia trachomatis in a prevalence study.

Three hundred thirty-two women, aged 18-30 yr. attending two clinics in Burlington Vermont were screened for infection with Chlamydia trachomatis by two methods. Microtrak Direct Test (SYVA) and cell culture. The overall sensitivity for Microtrak compared with culture was 75% (18 of 24), the specificity was 99.7% (307 of 308), the positive predictive value was 94.7% (18 of 19), and the negative predictive value was 98.1% (307 of 313). Prevalence of Chlamydia trachomatis in this population was estimated to be 7.2% (95% confidence intervals 4.4-10.0). The results from this study suggest that Microtrak is less sensitive when used in unselected patient groups from populations of lower prevalence, in contrast to higher sensitivities previously reported.

Macroscopic Mimics of Helminths in Stool Specimen Examination

Much has been written concerning diagnostic pitfalls in microscopic examination of stool for ova and parasites but very little pertaining to macroscopic mimics of parasites in stool samples. Though much more common in some locations than others, parasitic infections are found in nearly all populations; consequently, familiarity with the gross appearance of parasites and common distractors is important to ensure quality patient care. This review of the literature on macroscopic mimics, along with photographs of mimics and true parasites for comparison, will facilitate accurate and timely recognition of a parasitic mimic. In the current age of frequent and easy travel, both the likelihood and suspicion of patients contracting an “exotic” illness have increased, making a sound understanding of parasitology all the more important.

Proteins and Antibody in Lavage Fluid of Guinea Pigs with Legionella pneumophila Pneumonia

Guinea pigs were infected in an inhalation facility that limited an aerosol of L. pneumophila to the snout, as previously reported in detail (Davis et al., 1982). Individual animals were sacrificed for study either immediately after exposure, at 16 hours, at days one through seven, or at 11 days. Bronchoalveolar lavage was carried out to obtain fluid to study the following: total protein, albumin and immunoglobulin G (IgG) concentrations, and the titer of antibody to L. pneumophila. Antibody also was measured in serum obtained at the time of sacrifice. Concentrations of total protein, albumin, and IgG in lavage fluids peaked 2 days after exposure and correlated with the appearance of maximal numbers of polymorphonuclear cells in the lungs. Presumably, this increased protein resulted from exudation of serum across the alveolar-capillary membrane, which loses its integrity secondary to pneumonia. However, the ratio of IgG/albumin was elevated in animals studied 11 days after exposure even though the concentration of albumin was normal by this time. One possible explanation for this observation is that IgG was being produced in the lung. Antibody in lavage fluid was detected 7, and 11 days post-exposure, and might be important in the recovery of guinea pigs from this infection.