An outbreak of multidrug-resistant tuberculosis involving HIV-infected patients of two hospitals in Milan, Italy. Italian Multidrug-Resistant Tuberculosis Outbreak Study Group

AIDS. 1998 Jun 18;12(9):1095-102.


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 and molecular typing.

Methods: All cases identified by intensive case-finding were described in terms of clinical characteristics, previous nosocomial exposure to an infectious MDR-TB patient, previous stays in other institutional settings where exposure to MDR-TB could have occurred, and restriction fragment length polymorphism (RFLP) pattern.

Results: Between October 1991 and July 1995, 116 cases of MDR-TB were identified (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 identical pattern; 10 strains had unique RFLP patterns. Nosocomial exposure to an infectious MDR-TB patient was ascertained for 39 of the 56 patients 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 exposure was 32 days at hospital A and 40 days at hospital B. For eight patients with the outbreak strain, exposure was determined to have probably occurred in other hospitals, in the community or in prison.

Conclusions: This is the largest nosocomial outbreak of MDR-TB reported in Europe. Exposure to MDR-TB cases in other institutions caring for HIV-infected patients probably contributed to the spread of this epidemic. Strict control measures should be immediately adopted in order to prevent the spread of TB amongst HIV-infected patients in institutional settings in Europe.

MeSH terms

  • AIDS-Related Opportunistic Infections / epidemiology*
  • AIDS-Related Opportunistic Infections / microbiology
  • AIDS-Related Opportunistic Infections / transmission
  • Adult
  • Cross Infection / epidemiology*
  • Cross Infection / microbiology
  • Cross Infection / transmission
  • Female
  • Hospitals, Urban
  • Humans
  • Italy / epidemiology
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis* / drug effects
  • Mycobacterium tuberculosis* / genetics
  • Polymorphism, Restriction Fragment Length
  • Tuberculosis, Multidrug-Resistant / epidemiology*
  • Tuberculosis, Multidrug-Resistant / microbiology
  • Tuberculosis, Multidrug-Resistant / transmission