The usual treatment of bacterial abscesses, except lung or tubo-ovarian abscesses, includes therapeutic drainage. Increasing evidence suggests that some abscesses respond to antimicrobial therapy without drainage. To study this issue, a MEDLINE search of the literature was performed for cases of bacterial abscess in which treatment without definitive drainage was attempted. Four hundred sixty-five cases were identified. The most commonly involved organs were the liver, brain, and kidney. The success rate of antimicrobial therapy was 85.9%. Factors that predicted a less favorable outcome were abscess diameter of~5 em (odds ratio [OR] = 37.7; P = .0003), involvement of~1 organism (OR = 5.2; P = .014), presence of gram-negative bacilli (OR = 3.4; P = .022), length of therapy of <4 weeks (OR = 49.1; P < .0001), and use of an aminoglycoside as the only active agent (OR = 11.8; P = .008). Many bacterial abscesses can be treated without drainage; abscess size, the organisms involved, and therapy utilized may influence outcome.Bacterial abscesses usually require drainage for cure. Reasons postulated for the ineffectiveness of antibiotics in the treatment of abscesses include the presence of stationary-phase organisms, low pH, high protein content, the large number of bacteria within abscesses, ionic composition, low oxygen tension, sequestration of bacteria within leukocytes, low abscess zinc concentrations, and the presence of antimicrobial agent-deactivating enzymes [1]. Antimicrobial therapy is generally ineffective in experimental models of suppurative infections when initiation of therapy is delayed for ;?:24 hours [2].See the editorial response by Lerner on pages 604-7.It has long been recognized that lung abscesses respond to prolonged courses of antimicrobials without formal surgical drainage. Since many lung abscesses have air-fluid levels that were observed radiographically, suggesting bronchial communication, it is likely that lung abscesses spontaneously drain via the bronchial tree. It has also been well recognized that most abscesses of the tubo-ovarian region-especially those <8 em in diameter-respond to antimicrobial therapy without the need for surgical drainage [3], perhaps again because spontaneous drainage occurs via the fallopian tubes. Since the 1970s there has been an increasing number of reports of other abscesses, especially those involving the brain, liver, and kidney, that have responded to antimicrobial therapy without the need for a drainage procedure. This report reviews the literature regarding medical treatment ofbacterial abscesses in order to determine the extent of the clinical experience documented to date and to define the clinical, microbiological, and therapeutic features of abscesses responding to medical therapy. Since routine initial therapy for lung and tubo-ovarian abscesses no longer includes a drainage procedure, these cases were excluded.
MethodsA MEDLINE search of the literature from 1966 to August 1994 was done to find all English-language reports of bacterial abscesses ...