ABSTRACT
Species that fall into this category are Gram-negative bacilli or coccobacilli that can be divided into those that oxidatively break down carbohydrates and those that are non-oxidizers. The species comprising these groups are ubiquitous in nature and are found in water, soil, soil plants, and decaying vegetation. Many of the species contained herein are major nosocomial pathogens. Among the latter, Pseudomonas aeruginosa, Acinetobacter species, Stenotrophomonas maltophilia, and Burkholderia cepacia are frequent offenders. Favoring nosocomial spread is the ability of these microorganisms to survive under a variety of harsh environmental conditions, including those in humidifiers and in disinfectant solutions. Additionally, these species have a propensity to colonize the human skin and gastrointestinal tract after prolonged hospitalization, especially in intensive care units, and under antibiotic selective pressure.
