[Intra-abdominal infection and new quinolones]

Intra-abdominal infection is defined as the presence of an infectious process within the peritoneal cavity. It may be local or have a systemic consequence generating multiple organic disfunction. Most of the studies report a mortality of 30% in severe intra-abdominal infection. Secondary peritonitis is caused by the loss of integrity of the gastrointestinal apparatus, which contaminates with pathogens the peritoneal cavity. Invariably they are polymicrobial infections, mostly due to facultative anaerobic and anaerobic Gram negative bacilli. Prognosis of peritonitis depends on the struggle between two forces: local and systemic immunity of the host and the volume, nature and length of the contamination. Microorganisms and their products estimulate cellular defenses in the host and activate numerous inflammatory mediators responsible for sepsis. Antibiotic treatment of secondary peritonitis must act mainly against Escherichia coli and Bacteroides fragilis. The adequate and early empirical administration of antibiotics against these bacteria is well established. It is necessary to consider if the infection is localized or generalized and if it is accompanied or not by organic disfunction. It also has to be taken into account if peritonitis is community or hospital-acquired when choosing the antibiotic scheme. In community-acquired peritonitis with low to moderate infections a combination of metronidazole-ceftriaxone, metronidazole-gentamycin or a monodrug like ampicillin-sulbactam may be used. In severe hospital-acquired peritonitis imipenem or the combination piperacillin-tazobactam are effective. New quinolones such as trovafloxacin or clinafloxacin, with excellent activity against aerobes and anaerobes producing intra-abdominal infections, may be effective. Future clinical trials are needed to determine their utility. Tertiary peritonitis represent a systemic inflammatory response with multiorganic failure due to the uncontrolled activation of the inflammatory cascade. It is considered a persistent, systemic peritoneal inflammation. Antibiotics and new surgery do not seem to be useful in this situation.