Antibiotic therapy for osteomyelitis

Antibiotic therapy for osteomyelitis has dramatically changed within the past twenty years. The diagnostic criteria for osteomyelitis remain confusing to practicing physicians. Bone biopsy culture is now the standard for determining specific antimicrobial therapy. Many of the newest and most potent antimicrobials are now used to treat the increasingly broad bacterial spectrum of etiologies of osteomyelitis. There are tremendous economic incentives for outpatient and/or oral therapy. The third-generation cephalosporins and the new fluoroquinolones have replaced older, more toxic regimens, especially those containing aminoglycoside used to treat gram-negative osteomyelitis due to susceptible organisms.     

Antibiotic therapy for gram-negative bacteremia.

Although antibiotic therapy is the mainstay of therapy for gram-negative bacillary bacteremia, the amelioration of the underlying conditions, the correction of predisposing factors, the drainage of abscesses, the removal of infected foreign bodies, and adequate supportive care are also of paramount importance for curing the infection and should not be neglected. Beginning in the late 1960s, most of the clinical work on gram-negative infections has focused on the evaluation of new antibiotics. Numerous studies have shown that early, appropriate antibiotic treatment of gram-negative bacteremia significantly improved patients' outcomes and prevented the development of septic shock. Prescribing standard doses of antibiotics does not necessarily mean that therapeutic levels will be reached in all patients, and relapses of infections or breakthrough bacteremias can occur in patients with subinhibitory serum levels of antibiotics. The monitoring of serum concentrations of antibiotic is therefore recommended in critically ill septic patients. Whereas initial studies on the antibiotic treatment of gram-negative bacteremia were carried out in nonneutropenic patients, more recent clinical investigations have been performed almost exclusively in cancer patients with neutropenia. Studies conducted in the 1970s and 1980s among these patients have shown the following: (1) early empirical therapy reduced the mortality of gram-negative bacteremia; (2) therapy with a combination of two antibiotics, be it an extended spectrum penicillin plus an aminoglycoside or a third-generation cephalosporin, has significantly improved patients' outcomes; and (3) triple-drug combinations (i.e., a penicillin plus a cephalosporin plus an aminoglycoside) are not superior to combinations of beta-lactams and aminoglycosides. For the treatment of gram-negative bacteremia, clinicians today have a choice between well-established antibiotic combinations and broad-spectrum single-agent therapy with third-generation cephalosporins or carbapenem antibiotics. Although recent studies suggested that monotherapy could be as effective as combination therapy for the empirical treatment of fever in the neutropenic host, no definitive study has so far unquestionably demonstrated the equivalence of these treatments in patients with gram-negative bacteremias, especially those caused by P. aeruginosa, or in patients with adverse prognostic conditions, such as persistent and profound granulocytopenia. This literature should however be reviewed with great caution. Indeed, only a minority of studies have included a sufficient number of patients to confidently assess the impact of therapy on patients' outcomes. Obviously, small studies can have a significant risk of type II errors, that is, making false-negative conclusions.(ABSTRACT TRUNCATED AT 400 WORDS)     

Antibiotic therapy of septic bursitis

Infected olecranon, prepatellar, and infrapatellar bursae offer a unique opportunity to study the response of a closed-space infection to antibiotic therapy. Using percutaneous needle aspirations, serial bursal fluids were cultured. The length of time necessary to achieve culture sterility with antibiotic therapy (an average of 4 days in 25 patients) was correlated with the duration of symptoms prior to diagnosis (r = 0.68, P < 0.001). In patients treated within 2 weeks from onset of symptoms, bursal fluid sterility was achieved within 1 week of therapy, while longer duration of symptoms was associated with delayed response. When antibiotic therapy was continued for 5 additional days after documented culture sterility, all 19 patients in the prospective trial were cured (average followup period of 6.8 months). In septic bursitis, the effects of delay in treatment are deleterious by prolonging culture-positivity despite adequate antibiotic therapy. By analogy, delay in treatment of septic arthritis may result in the persistence of an adverse environment which can lead to further articular damage. After accurate diagnosis of septic búrsitis, a therapeutic approach consisting of prompt and appropriate antibiotic usage, frequent needle drainage, and treatment duration based on the culture results of serial aspirations is effective and may be applicable in the management of certain nongonococcal bacterial joint infections.     

Antibiotic therapy for Crohn's disease: a review.

Increasing evidence suggests that gut bacteria play a pathogenic role in Crohn's disease (CD), providing a rationale for the use of antibiotics in the primary treatment of the disease. While there are data to suggest that antibiotics may be effective in treating active luminal, particularly colonic, and/or perianal CD, evidence for their use in these settings is hampered by the lack of well-designed, adequately powered, placebo-controlled trials. Furthermore, although nitroimidazole antibiotics have been shown to reduce postoperative recurrence following ileocolonic resection, their use is limited by side effects. There is a current need for rigorous multicentre studies looking into the role of antibiotics in treating perianal and luminal CD, as well as a need for the large-scale assessment of novel antibiotics, with low systemic absorption, which may improve patient tolerance.     

Antibiotic therapy of pleural empyema.

Most empyemas occur as a complication of pneumonia or lung abscess, but 15% to 30% occur after thoracic surgery and 10% occur in association with an intraabdominal infection. The bacteriology of empyemas that occur in association with lung infections is often polymicrobial and mixed, containing multiple species of both aerobic and anaerobic bacteria, the latter found in up to 75% of cases. In contrast, empyema following thoracic surgery is more likely to be monomicrobial and caused by common nosocomial pathogens such as Staphylococcus aureus and aerobic gram-negative bacilli. Diffusion of antibiotics into both infected and uninfected pleural fluid is good, but certain agents (aminoglycosides and some beta-lactams) may be inactivated in the presence of pus, low pH, and beta-lactamase enzymes. Single antibiotic agents that are likely to be active against the wide spectrum of potential pathogens include imipenem-cilastatin and ticarcillin-clavulanic acid. Combinations of antibiotics should include an effective agent against anaerobic bacteria (clindamycin, metronidazole) coupled with an agent active against aerobic gram-positive cocci and gram-negative bacilli.