Antianaerobic Antibiotic Therapy Promotes Overgrowth of Antibiotic‐Resistant, Gram‐Negative Bacilli and Vancomycin‐Resistant Enterococci in the Stool of Colonized Patients

• Published in: Infection control and hospital epidemiology 2003-09, Vol.24 (9), p.644-649
• Main Authors: Bhalla, Anita, Pultz, Nicole J., Ray, Amy J., Hoyen, Claudia K., Eckstein, Elizabeth C., Donskey, Curtis J.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents - therapeutic use; Antibacterial agents; Antibiotic resistance; Antibiotics; Antibiotics. Antiinfectious agents. Antiparasitic agents; Bacteria, Anaerobic - drug effects; Biological and medical sciences; Blood; Drug Resistance, Bacterial; Enterobacter cloacae; Enterococcus - drug effects; Enterococcus - physiology; Escherichia coli; Feces - microbiology; Female; Gram-Negative Bacteria - drug effects; Gram-Negative Bacteria - pathogenicity; Humans; Male; Medical sciences; Microbial colonization; Microorganisms; Middle Aged; Nursing; Original Articles; Pathogens; Pharmacology. Drug treatments; Population Dynamics; Prospective Studies; Pseudomonas aeruginosa; Sputum; Urine; Vancomycin Resistance
• ISSN: 0899-823X; 1559-6834
• DOI: 10.1086/502267

Antianaerobic antibiotic therapy promotes persistent high-density growth of vancomycin-resistant enterococci (VRE) in the stool of colonized patients. We tested the hypothesis that antibiotic regimens with potent antianaerobic activity promote overgrowth of coexisting antibiotic-resistant, gram-negative bacilli in the stool of VRE-colonized patients. Eight-month prospective study examining the effect of antibiotic therapy on the stool density of gram-negative bacilli resistant to ceftazidime, ciprofloxacin, or piperacillin/tazobactam. A Department of Veterans Affairs medical center including an acute care hospital and nursing home. All VRE-colonized patients with at least 3 stool samples available for analysis. One-hundred forty stool samples were obtained from 37 study patients. Forty-nine (61%) of 80 stool samples obtained during therapy with an antianaerobic regimen were positive for an antibiotic-resistant, gram-negative bacillus, where-as only 14 (23%) of 60 samples obtained 4 or more weeks after completion of such therapy were positive (P < .001). Twenty-four (65%) of the 37 patients had one or more stool cultures positive for a gram-negative bacillus resistant to ciprofloxacin, ceftazidime, or piperacillin/tazobactam. The density of these organisms was higher during therapy with antianaerobic regimens than in the absence of such therapy for at least 2 weeks (mean +/- standard deviation, 5.6 +/- 1.4 and 3.9 +/- 0.71 log10 organisms/g; P < .001). Limiting the use of antianaerobic antibiotics in VRE-colonized patients may reduce the density of colonization with coexisting antibiotic-resistant, gram-negative bacilli.