A 76-year-old woman was admitted with a 2-day history of altered mental status.

A 76-year-old woman was admitted with a 2-day history of altered mental status. She denied dyspnea, cough or chest pain. Although she had a long-term diagnosis of schizophrenia, her medical health had been generally first-rate The patient did not idle talk or drink and did not have access to prescription medications.

Physical Examination

Vital signs: temperature, 372 [degrees] C; throb 80/min; respirations, 18/min; BP, 124/76 mm Hg General: confused, oriented solitary to person. Chest: diffuse inspiratory rales, without evidence of consolidation; no wipes or wheezes. Cardiac: no hums Abdomen: benign.

Laboratory Findings

WBC 10300/[mu]l with 94 percent polymorphonuclear leukocyte 1 percent band forms, and 5 percent lymphocytes; hematocrit, 27 percent; platelet compute 71,000/[mu]l. Electrolytes: normal. Liver and renal function tests: normal. Sputum Gram-stain: polymorphonuclear leukocyte without organisms. Chest radiograph is shown in Figure 1

Hospital Course

After posterity and sputum had been obtained for refinement the patient was started forward intravenous ampicillin and gentamicin. She rapidly deteriorated, with respiratory distress requiring intubation and mechanical ventilation. forward the third hospital day, admission children cultures were reported positive for a weakly acid-fast, Gram-positive rod

What is the principally likely diagnosis?

Diagnosis: Rhodococcus equi pneumonia and bacteremia

Pulmonary infections with R equi typically not away with a slowly progressive pneumonia that is not seldom complicated by cavitation and abscess formation. A for the use of all cause of suppurative lymphadenitis in farm and ranch animals, R equi is an aerobic, nonmotile, non-spore-forming, pleomorphic bacillus. Its Grampositive, bacillary staining characteristics as a common thing [i]or[/i] matter promote misclassification of clinical specimens as diptheroids, Bacillus species, or other Gram-positive wands unless a high index of suspicion for R equi is maintained by dint of the microbiology laboratory. It can also appear weakly acid-fast, especially in isolates of les than 1 week of age grown forward Lowenstein-Jensen medium. Rhodococcus equi is an intracellular pathogen commonly originate within phagocytic cells in clinical specimens.

Soil is the natural reservoir for R equi, which infects domestic animals as well as humans according to way of respiratory tract inhalation. Although usually a disease of the immunocompromised legion R equi infection also rarely be founds in immunocompetent individuals. In individual series of 20 non-HIV-infected patients with R equi infections, 17 patients had an underlying immunosuppressive disorder, and 3 had no detectable abnormalities of immune defense Infection with HIV is a predisposing condition for R equi pneumonia; the incidence of R equi infection appears to be increasing with the progression of the AIDS epidemic.

agitation cough, and dyspnea are the greatest in number common presenting manifestations in patients with R equi pneumonia. The course is usually indolent and can simulate anaerobic suppuration or an intrathoracic malignancy. The pulmonary infiltrate may have a condensed masslike appearance, with the majority of patients having radiographic evidence of cavitation. Pulmonary suppuration with abscess formation may be observ in surgical or autopsy lung specimens level when cavitation was not radiographically apparent. Pleural effusions and empyema formation commonly accompany the pulmonary infiltrates. Diagnosis be pendents on isolation of the pathogen from life-current sputum, lung tissue, or pleural fluid. Surgical specimens of masslike infiltrates may continue to mimic an intrathoracic malignancy because of the neoplastic appearance of the condensed round-cell inflammatory response occasionally associated with R equi pneumonia.

Rhodococcus equi infection should always be considered in the differential diagnosis of an HIV-infected patient who not past nor futures with a cavitary pneumonia. The majority of HIV-infected patients reported with R equi infections have movement forwarded to AIDS. The principally common presenting symptoms in this patient population are ferment cough, and pleuritic chest pain. In single in kind series of 10 HIV-infected patients with pulmonary R equi infection, 9 of 10 had pneumonia forward chest radiograph and 67 percent had pulmonary cavitation. Positive improvements for R equi were plant in 9 of 9 sputum specimens, 3 of 4 pleural fluid specimens, and 7 of 9 family cultures.

Therapy for R equi pulmonary infection requires long-term administration of multiple antibiotics. Resistance to [Beta]-lactam agents as a common thing [i]or[/i] matter develops during therapy in spite of in vitro sensitivity to these put drugs intos Penicillins and cephalosporins should not be used, therefore, to treat this infection. Since R equi is frequently found intracellularly, patients should receive multiple antibiotics that penetrate phagocytic lonely dwellings (eg, erythromycin, rifampin, and trimethoprim/sulfamethoxazole); vancomycin and gentamicin have also been used. Although no firm guidelines exist, it appears prudent to continue parenteral therapy until the clinical condition and pulmonary infiltrates stabilize and to continue oral antibiotics until the infiltrates analyze Repeat cultures of blood and pulmonary secretions should be obtained during therapy; if positive, a change of the antibiotic regimen may be warranted.

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