Drug-resistant bacteria in clinical situations

There are two major categories of drug-resistant bacteria that can cause severe and intractable infections. The first includes multi drug-resistant Mycobacterium tuberculosis(MDRMT), penicillin-resistant Streptococcus pneumoniae(PRSP), and beta-lactamase positive or negative ampicillin-resistant Haemophilus influenzae, which used to be isolated from the patients with community-acquired infection. However, these pathogens have been often isolated in recent years from patients with hospital/chronic care facilities/nursing-home mass infection. The second major category includes methicillin-resistant Staphylococcus aureus(MRSA), vancomycin-resistant Enterococcus species(VRE), Pseudomonas aeruginosa, and Enterobacteriaceae including extended-spectrum beta-lactamases(ESBLs) producing strain, which are mainly isolated from compromised patients with nosocomial infections. The pathogenicity of these pathogens, almost all of which are found in the normal flora of humans, is weak, but often cause nosocomial infections in compromised patients. We need, therefore, surveillance system for these pathogens, and carefully determine whether these pathogens, if isolated, are causative pathogens.