[Antibiotic resistance--bacteria fight back].

Antibiotic resistance has become one of the leading problems in modern medicine. Resistance to antibiotics emerges in bacteria due to genetic mutations and consecutive selection of resistant mutants through selective pressure of antibiotics present in large amounts in soil, plants, animals and humans. Exchange of genetic material coding for resistance is possible even between unrelated organisms and further promotes the spread of resistance. Constantly evolving resistance mechanisms force experts to redefine breakpoint concentrations and interpretation of in vitro antibiotic sensitivity testing. Developing new antimicrobial agents does not seem to be enough to keep up pace with ever changing bacteria. Using antibiotics prudently and developing new approaches to the treatment of infections is vital for the future. The European Antimicrobial Resistance Surveillance System (EARSS) data clearly show that Scandinavian countries and The Netherlands have the lowest rates of resistance, while Southern and Eastern European countries have the highest prevalence of resistance. This is linked to the European Surveillance of Antimicrobial Consumption (ESAC) data that show very low consumption of antibiotics in Scandinavian countries and The Netherlands. Compliance with strict infection control policies related to multidrug resistant organisms is also high in these countries. Although it is important to be aware of the resistance problems worldwide, rational use of antibiotics should be based on the knowledge of local resistance patterns in common pathogens. Since 1996 there is a continuous surveillance of resistance in Croatia through the Croatian Committee for Antibiotic Resistance Surveillance. There is a particular concern about the rising penicillin and macrolide resistance in pneumococci. In Croatia, data for 2002 suggest that resistance to penicillin in pneumococci was 30% (low level) and 2% (high level). Among invasive isolates, 19% had reduced susceptibility to penicillin (< 1% high level resistance) as compared with 1% in The Netherlands and 53% in France. While methicillin-resistant Staphylococcus aureus (MRSA) has become endemic in many hospitals throughout the world, the most alarming event in 2002 was detection of Staphylococcus aureus fully resistant to vancomycin (VRSA). Of great concern is also reporting of MRSA community outbreaks in some parts of the world. Multiply resistant gram-negative pathogens, especially non-fermentative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumanii, have become dominant in many intensive care settings and some of these strains cannot be treated with any of the currently available systemic antibiotics. Raising awareness about the microbial resistance threat among health care workers and patients is essential if we are to preserve the efficacy of antibiotics for future generations.