[Clinical relevance of bacterial resistance: a historical approach (1982-2007)]

Bacterial resistance is currently one of the most important problems of infectious pathology. The relation between in vitro and in vivo bacterial resistance is not always well defined because therapeutic failure is also related to other factors (pharmacokinetics and pharmacodynamics). In addition, there are disagreements between the in vitro and in vivo activity of several antimicrobials (especially ciprofloxacin) due to their low bactericidal activity. In infections due to ciprofloxacin susceptible S. pyogenes, S. aureus, S. epidermidis, E. faecalis, E. coli producing extended spectrum beta-lactamase (ESBL), K. pneumoniae and E. cloacae their clinical use is not associated to cure because of the development of resistances that are induced during the antibiotic treatment. Ceftazidime in infections due to susceptible strains of K. pneumoniae and E. cloacae and ceftriaxone in infections due to methicillin susceptible S. aureus also do not have a good correlation between in vitro and in vivo results due to their low bactericidal activity and to the development of resistances during treatment. The main clinical impact of resistant bacteria is related to the failure of empirical treatments, which is associated to a higher mortality, especially in severe infections with methicillin-resistant S. aureus, Enterobacteriae ESBL and multiresistant P. aeruginosa and A. baumannii. One of the main risk factors for the development of bacterial resistances is the increase of the consumption of several antibiotics. The development of protocols agreed upon by consensus may decrease the impact of bacterial resistances. The knowledge of the previous use of antibiotics is an especially relevant issue to suspect that an infection might be due to resistant bacteria. Resistant pathogens are a severe problem in the clinical setting and the question is of such a complexity that it requires a multidisciplinary effort that involves the different professionals of the Internal Medicine-Infectious Diseases, Microbiology, Pharmacology, Pharmacy and Preventive Medicine Departments and hospital directors and that results in unified and protocolized actions regarding the clinical and therapeutical approach for the management of severely infected patients.