Increasing antimicrobial resistance in gram-negative bacilli isolated from patients in intensive care units.

BACKGROUND: We investigated gram-negative bacilli from patients in intensive care units to determine whether antimicrobial resistance was increasing. METHODS: Minimal inhibitory concentrations were determined by broth microdilution on 334 gram-negative bacilli collected in 1990, 1995, and 1998. RESULTS: During the 3 study years, the types of gram-negative bacilli encountered in our intensive care units changed with proportional increases of Pseudomonas sp and decreases of inducible enterics. Dramatic increases in resistance for ceftazidime, cefotaxime, and piperacillin were paralleled between respiratory-tract isolates and inducible enterics. By 1998, ticarcillin was more active than piperacillin against most isolates except Escherichia coli and Klebsiella sp, and most isolates became more resistant to gentamicin and tobramycin. CONCLUSIONS: Continuous changes in the types of gram-negative bacilli and antimicrobial resistance complicate empirical selection of antimicrobials in the intensive care units. These complications will place more emphasis on communication and strategy formations among health care workers (nurses, physicians, laboratorians, and pharmacists) in an effort to treat infections in a timely and effective manner.

Microbiologic survey of long-term care facilities.

BACKGROUND: We undertook a microbiologic survey of long-term care facilities to categorize bacteria found in cultures of residents. Culture and sensitivity data were collected on 566 samples from indwelling bladder catheters, percutaneous gastrostomy tubes, nares, stool, wounds, pressure ulcers, and tracheostomies in 25 Nebraska and Iowa facilities. Information was also collected on resident factors (eg, presence of indwelling urinary catheter, prior antibiotic administration) and institutional variables (eg, number of beds, nosocomial infection rates). RESULTS: There were 478 gram-negative isolates, the leading organisms being Pseudomonas aeruginosa, Proteus mirabilis, Escherichia coli, and Klebsiella pneumoniae. There were 221 gram-positive isolates, the most frequently seen of which were enterococci and Staphylococcus aureus. Of the 442 residents sampled in the study, 168 (38%) were taking, or had within the previous month been taking, a systemic antibiotic. Quinolones were the most frequently prescribed antibiotic class. The institutional prevalence of urinary catheterization averaged 6.7%. CONCLUSIONS: Significant antibiotic pressure exists in long-term care facilities, a fact that is reflected in antibiotic resistance patterns. A variety of gram-positive and gram-negative bacteria were found in nursing home culture specimens.

Antimicrobial resistance rates among aerobic gram-negative bacilli recovered from patients in intensive care units: evaluation of a national postmarketing surveillance program.

We assessed the rates of antimicrobial resistance between 1990 and 1993 in intensive care units in the United States. A standardized microtiter minimal inhibitory concentration panel was used to test approximately 100 consecutive gram-negative aerobic isolates that were recovered primarily from blood, wounds, urine, and pulmonary sites in patients treated in each of 396 intensive care units in 45 states. Amikacin and imipenem were the agents most active against the 33,869 nonduplicate isolates (those recovered only once) tested. Resistance of aerobic gram-negative bacilli to third-generation cephalosporins was found to be an emerging problem. Increases in rates of resistance to ceftazidime among isolates of Klebsiella pneumoniae (from 3.6% to 14.4%; P << .01) and Enterobacter species (from 30.8% to 38.3%; P = .0004) were noted from 1990 to 1993; rates of resistance among Pseudomonas aeruginosa isolates remained stable. Ceftazidime-resistant bacteria were frequently resistant to aminoglycosides and ciprofloxacin. Risk factors for ceftazidime resistance included the number of beds in the hospital, the teaching status of the hospital, and specific body sites from which the isolates were recovered.