Penetration of isoniazid, rifampicin and pyrazinamide in tuberculous pleural effusion and psoas abscess.

SETTING: Tuberculosis Centre, University Medical Centre, Groningen, The Netherlands. OBJECTIVES: To study intralesional concentrations of isoniazid (INH), rifampicin (RMP) and pyrazinamide (PZA) in tuberculous pleural effusions and psoas abscesses, and to compare these to reference serum values and minimal inhibitory concentration (MIC). DESIGN: Intralesional concentrations were measured 2 h after drug administration (six pleural effusions, 10 psoas abscesses). RESULTS: A wide range of concentrations was found for pleural effusions and psoas abscesses. Concentrations were below MIC values in none of 15 patients for INH, in two of 13 for RMP, and in eight of nine for PZA. The Cmax:MIC ratio was always >4 for INH, in four of 13 for RMP, and in none of nine for PZA. In 5/8 patients receiving all three drugs, both RMP and PZA had Cmax:MIC ratios <4, indicating sub-therapeutic drug levels. CONCLUSION: Penetration of INH was always sufficient, penetration of RMP mostly below the desired ratio, and for PZA on average 10 times too low. Five of eight patients on all three drugs had Cmax:MIC ratios <4. This indicates intralesional sub-therapeutic drug levels for RMP and PZA, and local monotherapy with INH. This could induce drug resistance. Drainage as additional therapy seems indicated.

The specific gallium-67 scan uptake pattern in psoas abscesses.

A psoas abscess is a rare clinical entity that presents diagnostic and therapeutic challenges. In this retrospective study, we reviewed gallium-67 scan findings in cases of psoas abscess to determine the specific uptake pattern and the usefulness of 67Ga scans in diagnosis and management. Fifteen psoas abscess lesions in 13 patients who had undergone a 67Ga scan during an 8-year period were found in the hospital computer. All but two of the patients had been diagnosed as having fever of unknown origin, urinary tract infection or another irrelevant disease prior to the 67Ga scan. Of the 15 psoas abscess lesions, 12 (80%) could be clearly diagnosed on the basis of the specific 67Ga uptake pattern, in which: (1) the oblique direction of the 67Ga-avid lesion correlates with the orientation of the psoas muscle from the lumbar region to the hip joint region; (2) the lesion does not cross the abdominal midline; (3) the lesion goes through the inguinal region; and (4) the lesion involves at least two-thirds of the whole length of the psoas muscle. The specific features may help in the differentiation of psoas abscess from other intra-abdominal lesions or normal bowel distribution, especially with single-photon emission tomographic images. In 7 of 13 patients (53.8%) the 67Ga scan findings contributed to the clinical management of the patients by first detecting the focus of the infection. Multiple concomitant 67Ga-avid lesions were found in ten patients. In conclusion, the specific features as well as the whole-body survey with 67Ga scan are useful and important in the diagnosis of psoas abscesses and the detection of unexpected concomitant multiple infectious foci in clinically suspicious infectious disease patients.

The penetration of drugs into the lesions of spinal tuberculosis.

The concentration of antituberculous drugs in blood and pus from tuberculous spinal lesions was measured initially, and again after 3 to 5 months of treatment in 4 cases. The pre- and post-chemotherapy drug concentrations were almost the same. This indicated that healing does not interfere with the penetration of the drugs into the lesion.