Microbial etiology of acute pneumonia in hospitalized patients.

The purpose of this study was to determine the microbial etiology of pneumonia by using strict criteria among a group of hospitalized patients. Patients with acute community-acquired or hospital-acquired pneumonia were studied in a systematic and comprehensive manner for bacterial, viral, chlamydial, mycobacterial, and fungal pathogens. A total of 198 patients with 204 episodes of pneumonia were evaluated. Despite 100 percent follow-up of all surviving patients, a specific etiologic agent could be found in only 103 episodes. Among 154 episodes of community-acquired pneumonia, a diagnosis was made in 79; the most common pathogen was from the genus Legionella, followed by various Gram-negative enteric bacteria, Gram-positive cocci, influenza A virus, and Mycoplasma pneumoniae. The etiologic agent was found in 24 of the 50 patients with hospital-acquired pneumonia; no pathogen predominated. We conclude that even when elaborate diagnostic studies are done, including many invasive procedures, the etiology can be determined in only about half of the patients with acute pneumonia. The pathogens of pneumonia in this study are not markedly different between community-acquired and hospital-acquired infection.

Treatment of varicella-zoster meningoencephalitis with acyclovir--demonstration of virus in cerebrospinal fluid by electron microscopy.

Disseminated varicella-zoster (V-Z) infection developed in three immunocompromised patients, with direct invasion of the central nervous system by virus. For two of these patients, diagnosis was confirmed by electron microscopic examination of cerebrospinal fluid (CSF) and detection of viral particles. Extensive immunologic evaluation demonstrated impairment of cellular immune function. All were treated with acyclovir at a dose of 1,500 mg/m2/day for 5-7 days. Peak and trough plasma levels of this antiviral agent were monitored during the course of therapy and were shown to be well above V-Z virustatic levels. Clinical response was noted by the third day of therapy. Vesicles and CSF were culture negative at termination of treatment. Administration of this high dose of acyclovir was not associated with hematologic, immunologic, hepatic, renal, or gastrointestinal toxicity as judged by frequent laboratory and clinical evaluation.

Influenza type A virus infection of suckling mice pre-exposed to insecticide carrier.

Suckling CD-1 outbred mice exposed topically to insecticide carrier (IC), a mixture of emulsifiers and solvent, were rendered less sensitive to infection with lethal doses of influenza type A/PR8/34 (H0N1) virus than untreated and mock-treated control mice. Decreased sensitivity to influenza type A/PR8/34 virus infection was evidenced by a significant increase in the mean percent survival of the mice. In addition, a 10- to 100-fold reduction in the 50% lethal titer of the stock virus was observed in IC-treated mice relative to untreated mice. Decreased sensitivity was virus dose related and occurred within a dose range of 2 to 8 X LD50. No decrease in mortality rate was observed as a function of exposure to IC.

Determination of nurse adequacy in rural areas.

The examination of the adequacy of nursing resources requires an analysis of a variety of factors. Because registered nurses primarily provide their services as employees of organized health care delivery structures, the number, size and type of these structures in an area are key to the nursing resources required and the nurse supply.

Immune response in mice infected in the genital tract with mouse pneumonitis agent (Chlamydia trachomatis biovar).

Female Swiss-Webster mice were inoculated intravaginally with mouse pneumonitis agent (MoPn), a Chlamydia trachomatis biovar. Inoculation with 3.5 X 10(5) egg lethal doses per mouse resulted in shedding of the agent from the genital tract for as long as 21 days. Immunoglobulin M antibodies to MoPn were detected in plasma by day 7 post-inoculation, and immunoglobulin G antibodies were detected by day 14. Antibodies were detected in genital secretions by day 20, and titers in plasma and secretions were still considerable on day 56. Delayed-type hypersensitivity tests, determined by footpad swelling, were not positive in appreciable numbers of animals until after day 25. Delayed-type hypersensitivity reactions were maximal 24 h after testing and were preceded by an Arthus-like reaction, which appeared within 3 h and declined by 12 h. Convalescent animals were rechallenged by intravaginal inoculation and were found to be solidly immune.

Association of adenovirus type 16 with Reye's-syndrome-like illness and pneumonia.

Thirty-eight antigenically distinct viruses have been described as adenoviruses, though only about one third have been commonly associated with human illnesses. In mid-January 1981, adenovirus 16, one of the more rarely encountered ones, was isolated from three patients in separate hospitals in the Little Rock, Arkansas, area, even though it had not previously been isolated there. We report the details of these cases, which included a Reye's-syndrome-like illness and fatal viral pneumonia. The reports indicate a new and more important clinical role for adenovirus 16 infection.

Response of guinea pigs to intravaginal inoculation with guinea pig cytomegalovirus.

Female guinea pigs were inoculated intravaginally with guinea pig cytomegalovirus (GPCMV) propagated either in guinea pig embryo fibroblast cultures (GPEF) or salivary glands. The incidence of infection was higher with GPEF virus. Rare instances of isolation of GPCMV from cervical swabs 9-48 hr after inoculation was attributed to survival of inoculum in the genital tract. Neither immunofluorescence microscopy nor histopathologic examination showed evidence for active infection of genital tract tissue examined up to day 5 after inoculation. At necropsy on days 30-49, GPCMV was isolated from salivary glands and occasionally from pancreas and lymph nodes. Seroconversion following intravaginal inoculation was demonstrated by an enzyme-linked immunosorbent assay (ELISA) test, and titers were comparable to those after intraperitoneal or subcutaneous inoculation. However, titers of neutralizing antibody, determined by plaque-reduction assay, were significantly lower in the group inoculated intravaginally. These findings are relevant to consideration of cytomegalovirus as a sexually transmitted agent in humans.

A new animal model for the study of Chlamydia trachomatis genital infections: infection of mice with the agent of mouse pneumonitis.

A new animal model for the study of genital infections caused by Chlamydia trachomatis has been developed. Female mice were successfully infected after intravaginal inoculation with the C. trachomatis agent of mouse pneumonitis. Evidence for infection was obtained by detection of chlamydial inclusions in smears of cervical scrapings treated with Giemsa stain. Chlamydiae were observed in sections of cervical tissues examined by light and electron microscopy as well as by immunofluorescence microscopy. An antibody response to the agent of mouse pneumonitis was also demonstrated in sera after infection. The mouse model of genital infection with the agent of mouse pneumonitis offers an opportunity to investigate many questions related to pathogenesis and immunity associated with C. trachomatis genital infections.

Frozen deglycerolyzed blood prevents transfusion-acquired cytomegalovirus infections in neonates.

Frozen deglycerolyzed blood (FDB) was used for routine transfusions to 63 low birth weight newborns (less than or equal to 1500 g) over a 12-month period in an effort to decrease transfusion-acquired cytomegalovirus (CMV) infections. Nine of the 63 infants also received nonfrozen blood products (platelets, liquid blood). Seventy-two percent of the donor blood units were CMV-seropositive. Urine cultures and serum titers for anti-CMV antibody (immunoglobulins G and M) were obtained prior to the initial transfusion and sequentially throughout the study. No infant (0 of 54) who received only FDB acquired CMV, whereas 3 of 9 infants (33%) who received non-frozen blood and FDB acquired CMV, as evidenced by CMV viruria and/or a 4-fold rise in immunoglobulin G anti-CMV antibody titers. These results suggest that transfusions with frozen deglycerolyzed blood decrease the risk in low birth weight infants of acquiring CMV, regardless of the CMV serologic status of the donor.