ADHESIVE PROPERTIES AND ANTIBIOTIC-RESISTANCE OF KLEBSIELLA, ENTEROBACTER, AND SERRATIA CLINICAL ISOLATES INVOLVED IN NOSOCOMIAL INFECTIONS

Intestinal colonization by Klebsiella, Enterobacter, and Serratia (KES ) strains is a crucial step in the development of nosocomial infection s. We studied the adhesive properties, antibiotic resistance, and invo lvement in colonization or infection of 103 KES clinical isolates: 30 Klebsiella pneumoniae (29%), 16 Klebsiella oxytoca (15%), 30 Enterobac ter aerogenes (29%), 14 Enterobacter cloacae (14%), and 13 Serratia sp . (13%) isolates. Half of them were resistant to several antimicrobial agents, including aminoglycosides and beta-lactam antibiotics. A tota l of 27 of 30 K. pneumoniae isolates (90%) adhered to the human cell l ine Intestine-407 (Int-407), while none of the K. oxytoca or E. aeroge nes isolates and only 2 of the E, cloacae isolates adhered, Three adhe sive patterns were observed for K. pnenmoniae: an aggregative adhesion in 57% of the isolates, a diffuse adhesion in only one isolate, and a new pattern, localized adhesion, in 30% of the isolates, While most o f the sensitive strains adhered with the aggregative phenotype, the lo calized pattern was associated with resistant K. pneumoniae isolates p roducing the CAZ-5 beta-lactamase. Furthermore, 45% of such localized- adhesion isolates were involved in severe infections, The distribution s of type 1 and type 3 fimbriae, enteroaggregative E. coli, and cf29, pap, and afa/Dr adhesin-encoding genes were determined by using specif ic DNA probes, No relationship was found between the adhesive pattern and the production of specific fimbriae, suggesting that several unrec ognized adhesive factors are involved. Our study indicates that specia l adhesive properties associated with resistance to antimicrobial agen ts could account for the pathogenicity of certain nosocomial strains.