Prophylactic clarithromycin to treat mycobacterium avium in HIV patients receiving zidovudine may significantly increase mortality by suppressing lymphopoiesis and hematopoiesis

Change in T-Lymphocyte Count after Initiation of Highly Active Antiretroviral Therapy in HIV-Infected Patients with History of Mycobacterium Avium Complex Infection

Objective

To compare changes in CD4+, CD8+ and total lymphocyte counts after initiation of highly active anti-retroviral therapy (HAART) between HIV-infected patients with and without a recent history of Mycobacterium avium complex (MAC) infection.

Method

Matched exposed-non-exposed retrospective cohort study.

Results

Fifty-one patients with a recent history of MAC infection (MAC+) started a combination of at least three antiretroviral drugs. They were individually matched to 145 patients without any history of MAC infection (MAC-) according to CD4+ T-cell count (±30 cells/mm3), previous experience of antiretroviral treatment, AIDS clinical stage at the time of HAART initiation (baseline), age (±10 years) and gender. MAC+ and MAC- patients presented comparable median levels of total lymphocytes (488 vs 688/mm3, P=0.09), CD4+ (11 vs 16/mm3, P=0.15), CD8+ count (359 vs 386/mm3, P=0.39) and plasma HIV RNA (5.3 vs 5.1 log10 copies/ml, P=0.22) at baseline. After 6 months on HAART, the median increase of CD4+ T-cell count was 28 cells/mm3 (interquartile range [IQR]: 1–63) in MAC+ and 72 cells/mm3 (IQR: 34–120) in MAC- patients ( P<0.0001), whereas the percentage of CD4+ T cells was not significantly different between the two groups ( P=0.13). Comparable differences were observed for total lymphocytes and CD8+ T cells ( P<0.001). The 6 months decline of plasma HIV RNA was not significantly different according to MAC exposure (-1.6 in MAC+ vs -1.8 log10 copies/ml in MAC- patients, P=0.65). Results were confirmed after adjustment for other characteristics than the matching variables and after taking into account potential informative bias due to unbalanced number of deaths between the two groups.

Conclusion

MAC infection at the time of HAART initiation is an important deleterious factor for immune reconstitution. A better understanding of the underlying mechanism and an evaluation of additional treatment strategies are necessary to help immune restoration in such circumstances.

History of antibiotic use and risk of non-Hodgkin's lymphoma (NHL)

A population-based, incidence case-control study was conducted among women in upstate New York to determine whether histories of certain infections and antibiotic use are associated with risk of non-Hodgkin's lymphoma (NHL). Our study involved 376 cases of NHL identified through the New York State Cancer Registry and 463 controls selected from the Medicare beneficiary files and state driver's license records. Information about use of common medications including antibiotics, history of selected infectious diseases and potential confounding variables was obtained by telephone interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using an unconditional logistic regression model. There was a progressive increase in risk of NHL with increasing frequency and duration of systemic antibiotic use, as assessed over the period of 2-20 years before the interview. The ORs for the highest exposure categories, >/=36 episodes and >/=366 days of use, were 2.56 (95% CI 1.33-4.94) and 2.66 (95% CI 1.35-5.27), respectively. These associations were primarily due to antibiotic use against respiratory infections and dental conditions. Moreover, the association with frequency of antibiotic use for respiratory infections was pronounced for marginal zone B-cell lymphoma and for respiratory tract lymphoma. Analyses by class of antibiotics did not suggest that a general cytotoxic effect of antibiotics was responsible for these increased risks. Although recall bias and selection bias remain potential concerns in our study, the results are generally consistent with the hypothesis that persistent infection/inflammation predisposes individuals to the development of NHL. However, a direct role of antibiotics in NHL induction has not been ruled out.