A brief insight into Citrobacter species - a growing threat to public health

spp. are Gram-negative, non-spore forming, rod-shaped, facultative anaerobic bacteria from the family often found in soil, sewage, sludge, water, food, and the intestinal tracts of animals and humans. Several members of spp. especially , , are frequently detected in newborn illnesses, urinary tract infections, and patients with severe underlying conditions, including hypertension, diabetes, cancer, and respiratory infections, or those who are immunocompromised. Strains of spp. can spread vertically or horizontally from carriers or other hospital sources and thus cause nosocomial infections in hospital settings. A total of 19 genomospecies have been recognized based on genomics. It has been noted that the genus acquired antimicrobial resistance and virulence, including invasion, colonization, biofilm formation, and toxin production. The recent emergence and spread of antimicrobial resistance to β-lactams, carbapenems, fluoroquinolones, aminoglycosides, and colistin in spp. through chromosomal and plasmid-mediated resistance limits the empiric treatment options. Therefore, combination therapy involving costly and potentially hazardous antibiotics poses significant challenges in treating infections. Here we summarized the nomenclature of spp., clinical manifestations, epidemiology, pathogenesis, antibiotic resistance mechanisms, and treatments from various clinical samples. This review will expand our knowledge of the genomics and epidemiology of spp., enabling improved control of infections and the spread of these organisms.