Little is known about transmission and drug resistance of tuberculosis (TB) in
Bauru, State of São Paulo. The objective of this study was to evaluate risk
factors for transmission of
Mycobacterium tuberculosis
strains
in this area. Strains were collected from patients attended at ambulatory services
in the region and susceptibility towards the main first line antibiotics was determined
and fingerprinting performed. A total of 57 strains were submitted to susceptibility
testing: 23 (42.6%) were resistant to at least one drug while 3 (13%) were resistant
against both rifampicin and isoniazide. Resistant strains had been isolated from
patients that had not (n = 13) or had (n = 9) previously been submitted to anti-TB
treatment, demonstrating a preoccupying high level of primary resistance in the
context of the study. All strains were submitted to IS6110 restriction fragment
length polymorphism (IS6110-RFLP) and double repetitive element PCR (DRE-PCR).
Using IS6110-RFLP, 26.3% of the strains were clustered and one cluster of 3 patients
included 2 HIV-infected individuals that had been hospitalized together during
16 days; clustering of strains of patients from the hospital was however not higher
than that of patients attended at health posts. According to DRE-PCR, 55.3% belonged
to a cluster, confirming the larger discriminatory power of IS6110-RFLP when compared
to DRE-PCR, that should therefore be used as a screening procedure only. No clinical,
epidemiological or microbiological characteristics were associated with clustering
so risk factors for transmission of TB could not be defined in the present study.
