Identification of imipenem resistance among selected gram-negative bacilli, especially Pseudomonas aeruginosa and Enterobacter species.

We analyzed 1986-1990 National Nosocomial Infection Surveillance (NNIS) data from 3,316 P aeruginosa isolates and 1,825 Enterobacter species isolates for which susceptibility results to imipenem were reported.

For P aeruginosa, 11.1% of the isolates were resistant to imipenem; 16.1% were either intermediate-susceptible or resistant to the drug. A logistic regression model found that resistance was more common among P aeruginosa isolated from the respiratory tract, patients in intensive care units, and in teaching hospitals. Additionally, resistance to imipenem increased by 25% in teaching hospitals from 1986-1988 to 1989-1990. For Enterobacter species, 1.3% of the isolates were resistant to imipenem; 2.3% were either intermediate-susceptible or resistant to the drug. However, imipenem resistance for these isolates did not differ between the two periods and was not more common in patients in an intensive care unit or infections at any specific site.

The frequency of resistance to imipenem is greater among P aeruginosa than among Enterobacter species. Resistance to imipenem among the P aeruginosa isolates is more common from strains isolated from patients with nosocomial infections in an intensive care unit, from the respiratory tract, and from teaching hospitals. Resistance appears to be increasing among nosocomial P aeruginosa isolated in teaching hospitals.

To describe the characteristics and the problems arising from the use of vascular catheterization in a general hospital and to identify avoidable risk factors associated with catheter-related infections.

Cross-sectional, including the entire hospitalized population.

A university-affiliated hospital.

Three-hundred fifty-three intravascular catheters were implanted in 315 of a total of 1,838 hospitalized patients (17.1%, confidence interval [CI] = 15.7-18.5). Of the 353 intravascular catheters, 26 (7.3%) were intraarterial, 273 (77.3%) were peripheral, and 54 (15.3%) were central. The median (range) duration of the catheterization was 3 (1-1 1) days for arterial catheters, 1 (1-24) for peripheral catheters, and 5 (1- 130) for central catheters. Fifty-three (15%, CI = 11.5-19.5) showed signs of infection. Independent risk factors associated with infection were the presence of infection located elsewhere (odds ratio [OR]=8.7, CI=4.13-18.3, p<.0001), inappropriate catheter care (OR= 5.3, CI = 2.5-11.2, p<.0001), inappropriate length of catheter use (OR= 3.5, CI = 1.4-9.02, p<.01), and duration of hospitalization exceeding 14 days (OR=2.6, CI=O.9-7.83,p=.07).

The risk factors associated with catheter-related infections suggest that many are preventable by improved protocols for management. This hypothesis can easily be tested.

Current efforts to contain antimicrobial costs in hospitals are based on restricting drugs. We explored the effects of unsolicited case-specific recommendations to physicians to discontinue parenteral antimicrobial therapy in medically stable patients with pneumonia, in order to shorten hospital length of stay

A nurse-interventionist, working as an emissary of an appropriate committee in 3 nonteaching community hospitals, presented randomly assigned physicians with nonconfrontational suggestions to substitute comparable oral antimicrobials for parenteral antimicrobials. Blinded observers evaluated in-hospital and 30-day postdischarge courses of patients of physicians who had been contacted by the nurse (cases) and those who had not (controls).

Eighty-two patient episodes (47 physicians) met study criteria. There were 53 cases and 29 controls. In 42 of 53 (79%) case episodes, physicians discontinued parenteral antimicrobials; patients' mean length of stay was 2.4 days less than for 29 control episodes (estimated cost savings was $884/patient). In 11 (21%) episodes, case physicians continued parenteral therapy; patients' mean length of stay was 1.9 days longer than for controls (estimated cost excess was $704/patient). Education, training and practice characteristics were comparable in physician groups. Severity of illness indicators and postdischarge outcomes were comparable in patient groups.

The major cost-saving potential for shifting from par-enter-al to oral antimicrobial therapy is shortened length of stay. Timely information about alternative drug therapies, offered on a patient-specific basis, appears to modify the treating behavior of physicians. The program as currently conducted is cost-effective, with an estimated net savings of $50,000 per 100 interventions.

To evaluate plasmid and chromosomal typing methods for differentiation of methicillin-resistant Staphylococcus aureus (MRSA).

Comparison of relatedness of strains using epidemiologic features, phage typing, and antimicrobial susceptibility with blinded assessment by molecular typing methods. Molecular typing methods included AccI and Clal restriction endonuclease fingerprinting of chromosomal DNA and plasmid typing.

Tertiary-care teaching hospital.

Convenience sample of 10 MRSA strains, including 4 outbreak-associated and 6 sporadic strains of diverse epidemiologic origins without evidence of nosocomial transmission.

Only 2 strains were phage typeable. The epidemic strain was distinguishable by its susceptibility pattern. The other strains were not consistently separable by phenotyping or plasmid typing methods but were distinct by chromosome typing.

These observations document the diversity of origins of MRSA strains introduced into an acute-care institution. Chromosomal typing may be the preferred method for the determination of clonal origin of MRSA.