Clinical failures: the tip of the iceberg?

In pneumococcal meningitis, it is well accepted that resistance in Streptoc occus pneumoniae compromises clinical outcome. However, the clinical impact of increasing resistance on community-acquired respiratory tract infection s (RTIs) is less clear. Bacteriological eradication should be the aim of an timicrobial therapy. The pharmacodynamics (potency and pharmacokinetics) of an antimicrobial agent against the infecting pathogen can be used to predi ct the potential for bacterial eradication. Surveillance of clinical isolat es from community-acquired RTIs shows that, in many countries, there is a t rend towards an increasing prevalence of drug-resistant S. pneumoniae. Resu lts from a number of published clinical trials suggest that resistance has not compromised the clinical efficacy of aminopenicillins when used at the correct dose. However, emerging data indicate that resistance is compromisi ng the efficacy of some other routinely used antimicrobials. There are repo rts of clinical and bacteriological failure with macrolides and fluoroquino lones in patients with community-acquired pneumonia. Recent retrospective a nalyses and increasing sporadic reports of clinical failure with these agen ts may be more representative of the true situation. These reports suggest a need to reassess current empirical therapeutic recommendations for the tr eatment of community-acquired RTIs.