Pseudomonas aeruginosa is a major cause of nosocomial infections. This organism shows a remarkable capacity to resist antibiotics, either intrinsically (because of constitutive expression of beta-lactamases and efflux pumps, combined with low permeability of the outer-membrane) or following acquisition of resistance genes (e.g., genes for beta-lactamases, or enzymes inactivating aminoglycosides or modifying their target), over-expression of efflux pumps, decreased expression of porins, or mutations in quinolone targets. Worryingly, these mechanisms are often present simultaneously, thereby conferring multiresistant phenotypes. Susceptibility testing is therefore crucial in clinical practice. Empirical treatment usually involves combination therapy, selected on the basis of known local epidemiology (usually a beta-lactam plus an aminoglycoside or a fluoroquinolone). However, therapy should be simplified as soon as possible, based on susceptibility data and the patient's clinical evolution. Alternative drugs (e.g., colistin) have proven useful against multiresistant strains, but innovative therapeutic options for the future remain scarce, while attempts to develop vaccines have been unsuccessful to date. Among broad-spectrum antibiotics in development, ceftobiprole, sitafloxacin and doripenem show interesting in-vitro activity, although the first two molecules have been evaluated in clinics only against Gram-positive organisms. Doripenem has received a fast track designation from the US Food and Drug Administration for the treatment of nosocomial pneumonia. Pump inhibitors are undergoing phase I trials in cystic fibrosis patients. Therefore, selecting appropriate antibiotics and optimising their use on the basis of pharmacodynamic concepts currently remains the best way of coping with pseudomonal infections.

The in vitro activities of numerous antimicrobials against clinical isolates of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis from patients with bloodstream and respiratory tract infections in the United States, Canada, Europe, Latin America, and the Asia-Pacific region were studied in the SENTRY Antimicrobial Surveillance Program. Penicillin resistance (minimum inhibitory concentration, > or =2 microg/mL) was noted in all 5 geographic regions, and a high and increasing rate of macrolide resistance among S. pneumoniae isolates was observed. Elevated rates of resistance to clindamycin, trimethoprim-sulfamethoxazole, chloramphenicol, and tetracycline were seen. beta-Lactamase-mediated resistance in H. influenzae to amoxicillin and variable trimethoprim-sulfamethoxazole resistance by region were documented. Resistance to several drugs continues to emerge among pneumococci worldwide, but more stable resistance patterns have been noted for H. influenzae and M. catarrhalis. Continued surveillance of this pathogen group appears to be prudent.

Gingival and dental plaque antiseptic decontamination significantly decreased the oropharyngeal colonization by aerobic pathogens in ventilated patients. However, its efficacy was insufficient to reduce the incidence of respiratory infections due to multiresistant bacteria.