Surveillance of Mycobacterium tuberculosis susceptibility to second-line drugs in Hong Kong, 1995-2002, after the implementation of DOTS-plus.
OBJECTIVE
To determine the trend in changes in susceptibility of Mycobacterium tuberculosis strains, including to second-line drugs, from patients with a history of previous anti-tuberculosis (TB) treatment in a 'DOTS-Plus' programme.


METHODS
A retrospective survey of centralised M. tuberculosis laboratory records of all culture-positive cases over an 8-year period. The drug susceptibility of the isolates was determined using the absolute concentration method. Isolates obtained from patients with a history of previous treatment were further analysed for trends of changes in susceptibility to first- and second-line drugs.


RESULTS
Of 1921 patients with a previous history of treatment and positive cultures, 1425 (74.2%) had isolates susceptible to all four first-line drugs, while 176 (9.2%) were multidrug-resistant (MDR-TB). For the MDR-TB group, 101 (57.4%) isolates were sensitive to all second-line drugs, while 30 (17.0%) were resistant to three or more second-line drugs.


CONCLUSIONS
In a DOTS-Plus programme environment where there is strict control on use of second-line drugs, the prevalence of MDR-TB is low amongst retreatment cases and the prudent use of second-line drugs in a population with well functioning DOTS-Plus programme does not generate super-resistant strains. In circumstances where most retreatment strains are still susceptible and good laboratory support for detection of MDR cases is available, retreatment using first-line drugs is feasible.
Kam
K M
KM
Public Health Laboratory Centre, Department of Health, Tuberculosis Reference Laboratory, Kowloon, Hong Kong SAR, China. kmkam@dh.gov.hk
Yip
C W
CW
D000583:Amikacin / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D000995:Antitubercular Agents / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D003140:Communicable Disease Control / Q000379:methods; D003523:Cycloserine / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D023801:Directly Observed Therapy; D004338:Drug Combinations; D005000:Ethionamide / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000302:isolation & purification; D015242:Ofloxacin / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use; D011159:Population Surveillance; D015397:Program Evaluation; D012008:Recurrence; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy* / Q000453:epidemiology; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000473:pathology
D000900:Anti-Bacterial Agents; D000995:Antitubercular Agents; D004338:Drug Combinations; D000583:Amikacin; D003523:Cycloserine; D015242:Ofloxacin; D005000:Ethionamide