In this study, the source of BA in most cases was unknown, and the majority of patients were diagnosed with HIV. A case-control study investigating and quantifying potential risk factors for the BA showed that the odds ratio for HIV was 12.08 (95% CI 6.13–23.7). Based on this study, HIV or immunomodulatory therapies, including cytotoxic agents and biological treatments were important risk factors for the BA .
Another study showed that the BA was more often seen in immunocompromised patients . BA should be considered a severe fatal infection, as increased opportunistic infections can increase the likelihood of BA and death in immunocompromised patients such as HIV-infected patients and transplant recipients.[14, 15]. Because immunodeficiency is an important risk factor for BA; therefore, diagnostic work-ups for HIV in brain abscess patients could be helpful.
In another study, 75 patients were tested over a 5-year period. The main factors that increased mortality from intracranial abscesses were age, delayed hospitalization, focal neurological impairment, patient immunodeficiency, and a Glasgow coma scale (GCS) of less than 12 . Consistent with this study, our study found a link between mortality with immunodeficiency status, and low GCS, while, there was no association between age and other symptoms. In their study and ours, there was no association between mortality and culture results or the number of abscesses.
In another study, patients with good GCS on admission, no underlying disease, positive cultures, or surgical treatment were more likely to have good outcomes. However, patients with acquired immunodeficiency syndrome, hematologic disease, and medical treatment alone exhibited poor outcomes . In agreement with this study, our study showed that the mortality rate was lower in patients who were treated with surgical intervention and there was no association between mortality and result of culture.
Due to the unknown sources of most BA cases, the treatment is a major challenge [4, 13]. A retrospective epidemiological study showed that the majority of BA cases with unknown origins were culture-negative . In our study, a few numbers of BA cases with unknown sources were culture-positive, suggesting that cultures’ results carried low sensitivity for BA diagnosis and were not helpful.
The proportion of positive bacterial cultures in another series was 12% . Administering antibiotics before collecting abscess material could explain sterile cultures. Because BA is a life-threatening condition, empirical treatment is usually initiated before the results of the culture are available .
BA is a fatal disease and initial antibiotic therapy is a necessity based on suspected sources. Anaerobic pathogens should be considered by administrating of the empirical antibiotics, such as a third-generation cephalosporin and metronidazole plus vancomycin. Other antibiotics can be added depending on the predisposition and the outcome of the pus culture [11, 21]. If the culture is negative, broad-spectrum antibiotics should be continued . Ceftriaxone and metronidazole and vancomycin were most commonly used in our study because most patients had negative cultures and the cause of most cases was unknown.
The antibiotics used in BA are based on suspicious sources, and if unknown, empirical antibacterial treatments are based on common sources. In this study, there was no evidence of imaging and physical exam for common source; therefore, routine antibacterial treatment had been modified in some unknown cases.
In our study, the duration of treatment during hospitalization varied among the patients. The duration of BA antibiotic therapy should be personalized based on the size of the BA, response to treatment, and the need for surgical intervention .
In a review, mortality ranged from 5–32% (4). In our study, the mortality rate was about 31%. The high mortality rate may be due to the high prevalence of HIV-infected patients in our study. There were some limitations in our study. Since our study was a retrospective study, it was dependent on physicians’ judgments. There were also no objective measures of health and functional limitations were observed in the follow-up of patients.