pncA mutations in pyrazinamide-resistant Mycobacterium tuberculosis clinical isolates from the southeast region of Brazil.

OBJECTIVES: To investigate the presence of mutations in the pncA gene in 31 pyrazinamide-resistant Mycobacterium tuberculosis and 5 susceptible strains. MICs and pyrazinamidase (PZase) activity were also determined. METHODS: All 36 M. tuberculosis clinical isolates were genotyped by mycobacterial interspersed repetitive units (MIRUs) and most were also typed by spoligotyping. The MIC value necessary to inhibit 99% of the resistant mycobacterial isolates was determined by microplate Alamar Blue assay (MABA) and by Löwenstein-Jensen assay (LJA). The PZase activity was measured by pyrazinamide deamination to pyrazinoic acid and ammonia, and the entire pncA sequence including the 410 bp upstream from the start codon was determined by DNA sequencing of purified PCR products. RESULTS: Of the 31 isolates resistant to pyrazinamide, 26 (83.9%) showed at least one mutation in the pncA gene or in its putative regulatory region. Among the 22 different mutations detected in the pncA gene and in its regulatory region, 9 (40.9%) mutations (consisting of six substitutions, two insertions and one deletion) have not been described in previous studies. Three pyrazinamide-resistant isolates, confirmed by MIC varying from 800 to 1600 mg/L, carried the wild-type pncA sequence and retained PZase activity. CONCLUSIONS: These results contribute to the knowledge of the molecular mechanism of pyrazinamide resistance in Brazil and also expand the profile of pncA mutations worldwide. The MABA was successfully used to determine the MICs of pyrazinamide.

[Are early unforseen rehospitalizations inevitable?]. / Les réhospitalisations précoces imprévues sont-elles évitables?

We randomly selected 198 readmissions to an acute-care hospital within the 3 months following the last discharge during the year 1993 to describe the reasons for planned readmissions and to assess whether unplanned readmissions were appropriate and/or avoidable. 49.5% of readmissions were planned: for medical investigations (45%), surgery (30%), or medical treatments (such as chemotherapy) (18%). Among the 100 unplanned readmissions, 13% were assessed as inappropriate, and 37% as potentially avoidable. Given this high rate of potentially avoidable readmissions, there is a need to identify preventive interventions.

Endocarditis due to six entrapped pacemaker leads and concomitant recurrent coronary arteriosclerosis.

A case of endocarditis associated with six entrapped endocardial pacer leads is presented. Because of many failed attempts at removing them by conservative measures, cardiopulmonary bypass was needed; concomitant redo coronary bypass grafts were done. To our knowledge, this represents a unique case, the like of which has not been reported previously. Salient features of management are discussed.