[Clinicopathological study of methicillin-resistant Staphylococcus aureus detected by pulmonary microbial culture in autopsied cases]

Microbial culture of lung specimens from 569 autopsied cases from 1986 to 1989 revealed methicillin-resistant Staphylococcus aureus (MRSA) in 28 cases, which were subsequently analyzed clinicopathologically. The number of MRSA positive cases has markedly increased in recent years (2 cases in 1986, 2 in 1987, 6 in 1988, 18 in 1989). The most frequent underlying disease was neoplasm, which was seen in 17 cases. Of non-neoplastic diseases, liver cirrhosis and diffuse panbronchiolitis were prevalent. Twenty-four cases had received a course of antibiotic therapy. Antibiotics frequently administered were third-generation Cephem and Imipenem/cilastatin sodium (used in 20 cases). Antibiotics o which MRSA was sensitive were administered in only one case (minocycline). Sputum culture was performed in only 10 cases, 5 of which were MRSA positive. MRSA had acquired resistance to fosfomycin and ofloxacin. Histological examination revealed complication by pneumonia in 19 cases. In 7 of these 19 cases, MRSA was the only pathogen detected. Pulmonary MRSA infection detected at autopsy is frequently seen in patients with terminal stage cancer, but it is frequently not diagnosed and is undertreated. This may be a factor responsible for the recent marked increase in the proportion of MRSA in pathogens causing infection within medical institutions.

[Cavitated pneumonia and toxic shock syndrome: presentation of a case]

Toxic shock syndrome (TSS) is a potentially fatal acute disease preferentially affecting menstruating women and is related to the use of vaginal tampons seems to be due to an specific exotoxin produced by some Staphylococcus aureus strains. We present here the case of a male patients suffering cavitated pneumonia who developed a systemic clinical picture comparable to TSS. This unusual form of presentation is discussed as well as the diagnostic criteria which define this entity.

Miliary pattern in neonatal pneumonia

We have seen 10 newborn babies who developed respiratory distress and whose chest radiographs showed a miliary nodular pattern of disease. Of these infants only 3 had blood cultures that were positive for staphylococcus aureus. Of the remaining 7, 2 had conjunctivitis from which Staphylococcus aureus was cultured, 4 had negative cultures and 1 did not have a blood culture done. All patients were diagnosed as having bacterial pneumonia and appeared to respond favourably to antibiotic therapy. The pulmonary abnormalities resolved. The children were clinically well in less than 3 weeks. The author suggests that the miliary pattern is one of the radiological patterns of neonatal pneumonia possibly produced by hematogenous bacterial dissemination.

Inflammatory responses to Pseudomonas aeruginosa and Staphylococcus aureus in the murine lung

The changes in pulmonary cell population in response to aerosols containing either Pseudomonas aeruginosa or Staphylococcus aureus were studied in a murine model. The lungs of inbred DBA/2J mice received an inoculum of 2 X 10(5) colony-forming units of the microorganism and lung lavages were performed at various time intervals thereafter. P. aeruginosa aerosols produced an immediate decrease in the number of resident alveolar macrophages (AM), followed by a two-waved recruitment of cells into the respiratory tract; the first wave was composed of polymorphonuclear leukocytes (PMN) and the second of monocyte-like peroxidase-positive AM. The change in cell populations was transient and returned to baseline values within a week after aerosolization. In contrast, aerosolized S. aureus initially induced a slight increase in mononuclear cells, and by 60 min after aerosol exposure, the cell population was not different from that of control animals.

Multiple staphylococcal pneumatoceles in an adult

A 33-year-old male with staphylococcal pneumonia who presented radiographically with multiple thin-walled pulmonary cavities (pneumatoceles) is reported. The cavities rapidly altered following treatment with antibiotics and the patient clinically improved.

Hematogenous staphylococcal pneumonia secondary to soft tissue infection

Staphylococcal pneumonia is rare, has a high mortality and morbidity rate, and occurs commonly during influenza epidemics (airborne) or during the course of right sided bacterial endocarditis in drug addicts (blood borne). In recent years, much emphasis has been given to the staphylococcal infections in intravenous drug abusers. This report describes ten patients with staphylococcal pneumonia resulting from soft tissue infection who were previously healthy and had no history of drug abuse. They were 12 to 45 years old. Eight were male patients. Soft tissue infection was community-acquired in nine and was most commonly located in the lower extremities. Three patients had diabetes. All presented with a clinical picture of acute pneumonia. Hemoptysis occurred in three. Chest roentgenogram showed multiple large or small round discrete densities in most of the patients. Lobar involvement was notably absent. Eight developed cavitary lesions in their lungs. The average length of hospital stay was 40 days. One patient died and six developed complications. Staphylococcal etiology should be suspected in patients with acute pneumonia who have soft tissue infection or have characteristic chest roentgenogram findings; antistaphylococcal agents should be included in the therapeutic regimens of such patients until the results of the cultures are known.

Infectious mononucleosis. Death due to agranulocytosis and pneumonia

Infectious mononucleosis (IM) is usually considered a benign disease. Agranulocytosis developed in a young college student 14 days after the onset of IM. Fulminant staphylococcal pneumonia and bilateral pulmonary infarcts resulted, and the patient died 4 1/2 hours after admission to a hospital. Agranulocytosis secondary to IM may be more prevalent than previously thought. A review of the literature indicated that infection developed in 57.9% of the patients with IM and extreme neutropenia and 45.4% of the infected patients died.

Pulmonary bacterial susceptibility in the burned rat

An in vivo model system, using the burned rat as a model of altered host resistance, was developed and studied to investigate the lung's ability to handle an aerosolized bacterial insult of either P. aeruginosa or S. aureus. Rates of lung bacterial clearance were correlated with mortality, bacteriologic and histologic results. Susceptibility of the lung to sepsis was shown to be directly related to host resistance and was significantly increased following cutaneous thermal injury. Exposure of burned, non-seeded rats to a bacterial aerosol on day one post burn resulted in a mortality of 50% (P. aeruginosa) and 11.1% (S. aureus). This mortality clearly demonstrates an increased susceptibility at day one post burn. In contrast, this susceptibility gradually decreased with time; no mortality in the burned rat when exposed on day six post burn or in the normal, unburned rat. Histologic findings correlate well with the mortality results showing a gradually decreasing severity of pneumonitis if aerosol exposure was further delayed. Lung bacterial clearance studies revealed that the initial good response of the pulmonary defense mechanisms immediately following aerosol challenge are short-lived and that a marked increase in pulmonary bacterial susceptibility occurs as early as 24 hours following thermal injury.

Pathology of the lung in fatally burned patints

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