Combined vs. single-drug studies of susceptibilities of Mycobacterium kansasii to isoniazid, streptomycin, and ethambutol.

The effects of combined drugs were compared uith the effects of single drugs in vitro against Mycobacterium kansasii. The single drugs isoniazid 1.0 microgram/ml, streptomycin 2.0 microgram/ml, and ethambutol 5.0 microgram/ml and the combinations of 1.0 microgram/ml isoniazid and 2.0 microgram/ml streptomycin, 1.0 microgram/ml isoniazid and 5.0 ethambutal and 1.0 microgram/ml isoniazid, 2.0 microgram/ml streptomycin and 5.0 microgram/ml ethambutol were evaluated as to their effects on M. kansasii organisms from 22 patients with pulmonary mycobacterial disease. These drugs were incorporated into Middlebrook 7H11 medium. Colonial growth was then observed and assigned numerical values for statistical analysis. The results showed that isoniazid was not significantly better than ethambutol. Streptomycin, however, was significantly better than both isoniazid and ethambutol alone. The double combinations were better than the single drugs, with isoniazid--streptomycin being better than isoniazid--ethambutol. The combination isoniazid--ethambutol was not significantly better than streptomycin alone. However, the triple combination of isoniazid--streptomycin--ethambutol was markedly better than all single drugs, better than isoniazid--ethambutol, but not better than isoniazid--streptomycin. Combined-drug testing thus showed a pattern of susceptibility not demonstrated by single-drug testing.

Pulmonary embolism in respiratory failure.

The occurrence of pulmonary emboli in 617 patients admitted to a respiratory intensive care unit was studied. Pulmonary emboli were found in 18 (27 percent) of 66 autopsies. Half of these pulmonary emboli were not diagnosed before death, despite persistent aggressive attempts to document pulmonary emboli. In this subpopulation of patients with respiratory failure, the usual clinical manifestations of pulmonary emboli (symptoms, signs, chest x-ray film, electrocardiogram, and changes in arterial blood gas levels) frequently are already present, due to the severe underlying pulmonary disease, and any superimposed manifestations of pulmonary emboli are often inapparent. In this group under study, the ventilation/perfusion lung scan correlated poorly with pulmonary angiographic results and with examinations at autopsy; the scan generally was inadequate to rule in or rule out pulmonary emboli. Again, this was due to the distortion of both ventilation and perfusion by the severe underlying pulmonary disease. Currently, pulmonary angiographic studies remain the only reliable technique to confirm or exclude pulmonary emboli in patients with respiratory failure.

The effect of tumor size and location on diagnosis by fiberoptic bronchoscopy.

Evaluation of data from fiberoptic bronchoscopic procedures revealed that for peripheral bronchogenic carcinomas, the diagnostic yield was influenced by the size of the lesion and its distance from the hilum. Failure to diagnose visible carcinomas was related to inability to obtain deep specimens for biopsy. Biopsy, brushing, and washing were complementary procedures in diagnosing bronchogenic carcinomas.

Pneumoperitoneum. A complication of mechanical ventilation.

Pneumoperitoneum occurred in three adults receiving mechanical ventilatory support. Since the presence of a perforated viscus could not be confirmed by combinations of clinical, surgical, or autopsy findings in any of these patients, it appears that the free abdominal air in these patients was a complication of the ventilatory therapy. It is possible that such a complication may be more common than is currently recognized and thus should be added to the differential diagnosis of pneumoperitoneum.

The incidence of urine cultures positive for Mycobacterium tuberculosis in a general tuberculosis patient population.

When urine specimens from a general tuberculosis patient population of 328 were submitted routinely for mycobacterial cultures, 33 patients (10 per cent) a positive turine cultures for Mycobacterium tuberculosis. In 22 patients (7 per cent) a positive urine culture for M. tuberculosis was unanticipated. Review of these 22 patients revealed that all had denied current genitourinary symptoms, 58 per cent had urinalyses within normal limits, and 58 per cent had normal intravenous pyelograms. Thus, lack of symptoms and normal tests do not necessarily exclude the possibility of genitourinary tuberculosis. Only 4.7 per cent of patients with pulmonary tuberculosis but 21 per cent of those with extrapulmonary tuberculosis had unanticipated positive urine cultures for M. tuberculosis. This suggests that routine submission of urine specimens for mycobacterial cultures can be a valuable adjunct to the bacteriologic confirmation of the diagnosis of extrapulmonary tuberculosis.