Over
the past 2 years, researchers have reported a growing number of cases of multidrug-resistant
(MDR) and extensively drug-resistant (XDR) tuberculosis (TB) in people with HIV/AIDS.
The
first large outbreak of rapidly fatal XDR-TB, in rural KwaZulu-Natal province
in South Africa, was reported at the XVI International AIDS Conference in Toronto
in August 2006.
More recently, at the at the 15th
Conference on Retroviruses and Opportunistic Infections this month in Boston,
investigators with the Tugela Ferry Care and Research Collaboration provided further
information from a case-control study of patients at Church of Scotland Hospital
in KwaZulu-Natal. Overall, more than 530 cases of MDR or XDR TB were seen at the
hospital between June 2005 and August 2007, more than 300 of them extensively
drug-resistant.
The present analysis looked at patients who had recurrent
TB with increasing drug resistance (susceptible to MDR or XDR, or MDR to XDR).
Among 170 patients in the retrospective case-control study, 43 had baseline and
follow-up sputum cultures obtained at least 1 month after the initial culture.
A polymerase chain reaction method known as spoligotyping was used to determine
TB genotypes.
Results
•
Of the patients with paired sputum cultures,
23 developed recurrent MDR or XDR tuberculosis, and paired spoligotypes were available
for 17.
•
Among these 17 patients (11 men, 6 women),
15 tested HIV positive and the median CD4 cell count was about 90 cells/mm3.
•
Adherence to anti-TB therapy was reportedly
good in all cases.
•
All had differing spoligotypes between the
initial and follow-up TB isolates, suggesting re-infection with a new strain.
•
Many of the secondary strains were related,
suggesting a few common sources of transmission.
•
15 of the 17 patients died within 2 weeks
after collection of the second sputum sample and before MDR or XDR TB had been
confirmed.
Conclusion
"Exogenous
re-infection with drug-resistant strains was responsible for all new drug resistance
among patients in the first year after TB diagnosis," the researchers concluded
-- rather than emergence of drug resistance due to failed treatment related to
insufficiently potent drugs or poor adherence.
The investigators expressed
concern over these repeat infections, recommending that, "In addition to
supporting medication adherence, TB control programs must urgently address infection
control to reduce transmission of resistant TB and curtail the rise of MDR and
XDR TB in HIV-infected patients."
Speaking at a press briefing at
the conference, investigator Neel Gandhi said that the hospital had instituted
several such measures, including better isolation of patients with coughs, more
rapid diagnosis and treatment, and steps to reduce the time HIV positive people
spend in the hospital, where drug-resistant TB is prone to spread.
Yale
Univ Sch of Med, New Haven, CT; Albert Einstein Coll of Med, Bronx, NY; Nelson
R Mandela Sch of Med, Durban, South Africa; Philanjalo and Church of Scotland
Hosp, Tugela Ferry, South Africa.
2/26/08
Reference
J Andrews, Neel Gandhi, P Moodley, and others (Tugela Ferry Care and Research
Collaboration). Exogenous Re-infection with Multidrug- and Extensively Drug-resistant
TB among TB/HIV Co-infected Patients in Rural South Africa. 15th Conference on
Retroviruses and Opportunistic Infections (CROI 2008). Boston, MA. February 3-6,
2008. Abstract 143.
Re-emergence
of Drug-resistant Tuberculosis in HIV Positive People Is Due to Re-infection,
Not Treatment Failure
Over
the past 2 years, researchers have reported a growing number of cases of multidrug-resistant
(MDR) and extensively drug-resistant (XDR) tuberculosis (TB) in people with HIV/AIDS.
Results
