Association of HIV with Breast Abscess and Altered Microbial Susceptibility Patterns

Background: Breast abscesses account for 15% of surgical day cases seen in the University Teaching Hospital (UTH) in Lusaka, Zambia. Nearly all of these cases occur in lactating women. Pre-natal HIV prevalence among women seeking care at UTH was estimated at 25% as of 2004. Baseline surveys have shown that up to 60% of soft tissue infections presenting to the UTH are HIV related. Objectives: To determine if HIV infection is a risk factor for the development of breast abscesses in women presenting to the (UTH). Secondary objective was to identify bacteriological aetiologies and drug sensitivity patterns associated with breast abscesses at UTH. Study Design: A case-control study of 110 consecutive breast-feeding mothers diagnosed with breast abscess upon presentation to the UTH surgical service (cases) and 110 representative controls recruited from the UTH postnatal clinic. Main Outcomes: HIV seropositivity and CD4 counts (if HIV positive) among cases and controls. Results: Fifty-four out of 110 (49.1%) lactating women with breast abscess had positive serologic tests for HIV. Only 25 of 110 (23%) control women tested HIV positive. This difference was statistically significant, with an odds ratio of 3.28 (95% CI 1.83–5.87; p = 0.001). Mean CD4 counts in cases were lower than in controls (338 vs. 568, p<0.001). Staphyloccocus aureus was the main causative agent (91.8%) of isolates. Among S. aureus isolates, 70 of 101 (69.3%) were oxacillin susceptible. Forty-three of 50 (86.0%) specimens from HIV positive patients were resistant to SMX-TMP compared with only 61% of specimens from HIV negative patients (p=0.004). Conclusions: HIV infection appears to be a significant risk factor in the development of breast abscess in lactating women in Zambia. Staphylococcus aureus remains the main causative agent, with MRSA accounting for 30.7% of isolates. SMX-TPM resistance likely stems from the wide spread use of the drug for PCP prophylaxis in HIV positive patients. It therefore should not be used for treatment of acute bacterial infections. HIV related breast infections could be considered as a possible entry point to HIV treatment now that the CD4 treatment guidelines have been adjusted to 350cells/cmm, although this requires further studies for validation.