Identification of Nosocomial Pathogens and Antimicrobials Using Phenotypic Techniques

Nosocomial infections caused by multidrug-resistant strains increase morbidity and mortality in hospitalized patients, prolong hospitalization, and they have significant negative economic impact. Currently, nosocomial infections are included in a broader concept as healthcare-associated infections. These are caused by a wide variety of pathogens, typically Staphylococci, Enterococci, Pseudomonas aeruginosa, Klebsiella spp., Escherichia coli, etc. Certain fungal agents, e.g., yeasts of Candida genus and aspergilla, are also associated with these infections. The situation is further complicated by the development of resistance in the gram-positive cocci such as staphylococci or enterococci to second-line antibiotics used for the treatment of gramnegative bacteria and resistant gram-positive bacteria. Pathogenesis of mentioned infections plays a key role in forming biofilms on artificial surfaces.

Rapid detection and identification of etiological agents of nosocomial infections and determination of antibiotic susceptibility of pathogens are required for the optimal therapeutic scheme. Chromatographic methods such as high performance liquid chromatography or liquid chromatography-mass spectrometry are universal techniques widely applied to this purpose. However, only capillary electrophoretic techniques are able to determine both, antibiotics and microorganisms, during a single analysis. Differences in the chemotaxonomic fingerprints of the microorganisms can be utilized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. In this chapter, we would like to outline an overview of available analytical techniques capable of rapidly identifying and estimating levels of antibiotics as well as microorganisms in real samples with a focus on nosocomial infections.

Keywords: Antibiotics and antifungals, capillary electrophoretic techniques, liquid chromatography, MALDI-TOF mass spectrometry, microorganisms, Nosocomial infections.