• cefotaxime;
  • cephalosporinase;
  • long-term care facilities;
  • antibiotic resistance

OBJECTIVES: To determine the frequency of fecal colonization by cefotaxime-resistant gram-negative bacilli in older patients living in the community and in long-term care facilities (LTCFs) admitted to an acute care hospital.

DESIGN: Case-control, point prevalence study.

SETTING: Hospital.

PARTICIPANTS: One hundred forty-three patients aged 65 and older.

MEASUREMENTS: Rectal swab cultures, antibiotic drug sensitivity, beta lactamase isolation, and clonal identity.

RESULTS: Of the 190 surveillance cultures obtained from 143 patients, 26 cefotaxime-resistant gram-negative isolates from 22 patients were recovered. The prevalence rate of cefotaxime-resistant isolates on admission was 13.3% (19/143). A logistic regression model using cefotaxime colonization as the dependent variable found that multiple comorbidities, admission to a surgical service, and having a diagnosis of infection on presentation and a transfusion history were factors associated with the presence of colonization. These four clinical items accurately classified 74% of patients colonized. Antibiotic use and nursing home residence were not associated with the presence of colonization by cefotaxime-resistant organisms. Twelve of the cefotaxime-resistant isolates (46%) were identified as Pseudomonas aeruginosa, and 14 (54%) were other gram-negative bacilli. In six of the 14 isolates that were not P. aeruginosa (36%), it was possible to demonstrate the presence of an AmpC β-lactamase related to the CMY-2 β-lactamase, a plasmid-borne cephalosporinase.

CONCLUSION: These data raise awareness that there are community- and LTCF-dwelling older patients colonized with gram-negative enteric bacilli resistant to third-generation cephalosporins on admission to the hospital. The “reservoir of resistant bacteria” in older people is no longer confined to LTCFs.