nonEnterobacteriaceae

NonEnterobacteriaceae are bacteria that are not part of the Enterobacteriaceae family. In clinical microbiology, the term describes Gram-negative bacteria outside Enterobacterales that may be recovered from similar specimens and cause comparable infections, but require different identification and antimicrobial testing strategies. The group is taxonomically diverse, spanning multiple families within the Proteobacteria as well as other phyla. Examples include Pseudomonas, Acinetobacter, Stenotrophomonas, Burkholderia, Legionella, and Vibrio species. These organisms are frequently environmental and can be opportunistic pathogens, especially in hospitalized or immunocompromised patients; some species, however, cause distinct enteric or extraintestinal diseases in otherwise healthy individuals.

Infections caused by nonEnterobacteriaceae range from pneumonia, bacteremia, and wound infections to gastrointestinal illness and urinary tract infections, depending on the species. Notable pathogens include Pseudomonas aeruginosa, a common cause of hospital-acquired pneumonia and septicemia; Acinetobacter baumannii, associated with ventilator-associated pneumonia and wounds; Stenotrophomonas maltophilia, which can cause pneumonia and bloodstream infection; and Burkholderia cepacia complex, important in cystic fibrosis and chronic lung disease. Legionella pneumophila causes Legionnaires’ disease, while Vibrio species can cause gastroenteritis or wound infections after exposure to seawater.

Diagnosis relies on Gram staining, culture on selective and nonselective media, and biochemical or molecular methods such as MALDI-TOF. Many nonEnterobacteriaceae exhibit intrinsic or acquired antibiotic resistance, necessitating tailored susceptibility testing and infection-control measures to limit transmission in healthcare settings.