AN OUTBREAK OF MULTIDRUG-RESISTANT TUBERCULOSIS INVOLVING HIV-INFECTED PATIENTS OF 2 HOSPITALS IN MILAN, ITALY

Objective: To describe an outbreak of multidrug-resistant tuberculosis (MDR-TB), amongst HIV-infected patients, spread from one hospital in Milan to another. Design: Descriptive epidemiological investigation an d molecular typing. Methods: All cases identified by intensive case-fi nding were described in terms of clinical characteristics, previous no socomial exposure to an infectious MDR-TB patient, previous stays in o ther institutional settings where exposure to MDR-TB could have occurr ed, and restriction fragment length polymorphism (RFLP) pattern. Resul ts: Between October 1991 and July 1995, 116 cases of MDR-TB were ident ified (85 at hospital A and 31 at hospital B). A single case patient, infected at hospital A, introduced the strain into hospital B. Eighty- two of the 92 strains available for fingerprinting revealed an identic al pattern; 10 strains had unique RFLP patterns. Nosocomial exposure t o an infectious MDR-TB patient was ascertained for 39 of the 56 patien ts with the 'outbreak' RFLP strain at hospital A (69.6%) and for 24 of the 26 patients at hospital B (92.3%). The median duration of exposur e was 32 days at hospital A and 40 days at hospital B. For eight patie nts with the outbreak strain, exposure was determined to have probably occurred in other hospitals, in the community or in prison. Conclusio ns: This is the largest nosocomial outbreak of MDR-TB reported in Euro pe. Exposure to MDR-TB cases in other institutions caring for HIV-infe cted patients probably contributed to the spread of this epidemic. Str ict control measures should be immediately adopted in order to prevent the spread of TB amongst HIV-infected patients in institutional setti ngs in Europe. (C) 1998 Lippincott-Raven Publishers.