A one-year prospective study (1994-1995) for a first evaluation of tuberculosis transmission in French prisons.

SETTING: Ten correctional facilities in Paris, including suburbs. OBJECTIVE: To prospectively determine the incidence of tuberculosis (TB) in prisons during a one-year period and to trace the transmission of tuberculosis by restriction fragment length polymorphism (RFLP) analysis of Mycobacterium tuberculosis strains from inmates. RESULTS: Of 93 cases of tuberculosis observed, 50 were culture-confirmed. The incidence of tuberculosis in correctional facilities was 215 cases per 100,000 inmates. A high turnover of inmates was observed. All patients were male, and a quarter had been homeless. Seventy-two per cent were diagnosed with pulmonary tuberculosis. Several severe cases of TB were observed, including three of tuberculous meningitis. No multidrug-resistant strains were noted. RFLP analysis (n = 24) revealed 22 distinct patterns which made up two clusters. Epidemiological investigation did not show direct tuberculosis transmission, which was, however, probable for one cluster. CONCLUSION: Independently of incarceration, prison inmates run a higher risk of developing active tuberculosis than the general population, which might be the main reason for the high incidence of tuberculosis observed in prisons. However, some cases of transmission may occur inside prisons.

[Enzymatic resistance to imipenem in gram-negative bacilli: NMC-A, an original carbapenemase]. / Résistance enzymatique à l'imipénème chez les bacilles A Gram négatif: NMC-A, une carbapénémase originale.

Carbapenems such as imipenem are beta-lactam antibiotics usually stable to the hydrolytic activity of beta-lactamases. Nevertheless, resistance to imipenem by production of carbapenemases has been described in few species of Gram negative bacilli. This mechanism of resistance remains exceptional in Enterobacteriaceae. These carbapenemases are principally metallo-enzymes that possess a zinc ion in their active site. Enterobacter cloacae strain NOR-1, is resistant to imipenem by production of an inducible chromosomal beta-lactamase which is not a metallo-enzyme but an Ambler class A beta-lactamase. This enzyme displays a strong hydrolytic activity against carbapenems but also against cephamycins which has never been previously observed for beta-lactamases of this class. These properties suggest that NMC-A possesses an original tridimensional structure of its active site allowing hydrolysis of molecules generally protected by the configuration of their lateral chain. Crystallographic study of this enzyme will permit to understand its mechanism of action and serve the development of new beta-lactams stable to b-lactamase hydrolytic activity.