Several classes of antimicrobial agents (e.g., penicillins, cephalosporins, tetracyclines, chloramphenicol, and clindamycin) are useful in treatment … - Sydney M. Finegold

There is an impressive incidence of anaerobes in major infections involving the lung and pleural space, intra-abdominal sites, and the female genital tract. Almost all anaerobic infections are endogenous in origin. Therapy consists of making the environment such that anaerobes find it difficult to proliferate, checking the spread of anaerobes into healthy tissues, and neutralizing the toxins of anaerobes.

Most gastrointestinal infections secondary to the use of antimicrobial agents that have been documented are related to overgrowth of Clostridium difficile which produces a spectrum from severe pseudomembranous colitis to mild diarrhea or asymptomatic carriage. The most common inducers of pseudomembranous colitis or antimicrobial agent-associated diarrhea are ampicillin, clindamycin, and various cephalosporins, but almost all antimicrobials may cause this problem. Symptoms vary from watery to bloody diarrhea; the extent and severity of the diarrhea, fever, and abdominal cramps and the incidence of complications (such as toxic megacolon and perforation of the bowel) and of fatality are variable. Normal carriage of C. difficile in infants and asymptomatic carriage in adults who have received antimicrobial therapy make it impossible to rely on culture for diagnosis. The presence of cytotoxin or enterotoxin produced by C. difficile is much more reliable diagnostically, but there may be false-positives with this as well, particularly in infants.

... (1) What is the clinical relevance of anaerobic bacteriology? (2) How can the microbiologist, with limited and decreasing resources, perform reliable, detailed studies of anaerobic bacteriology? (3) When and how should susceptibility testing be done with anaerobes? If the clinician knows the usual bacteriology of various types of infection and how this may be modified by pathophysiologic processes in the host or by prior therapy, he/she can use a logical empiric approach to treatment of the patient. As to the microbiologist's dilemma, it is not realistic or rational for a microbiologist in a nonteaching hospital to do detailed bacteriologic studies and routine anaerobic susceptibility testing. The resources available should be committed primarily to the patient who is seriously ill. Such allocation of resources, of course, requires repeated and effective communication between microbiologist and clinician.