Journal Reviews

Asian salmonella strain emerging in the U.S.

Olsen SJ, DeBess EE, McGivern TE, et al. A nosocomial outbreak of fluoroquinolone-resistant salmonella infection. N Engl J Med 2001; 344:1,572-1,579.

The first recognized outbreak of fluoroquino-lone-resistant salmonella infection in the United States can be traced back to an emerging strain in the Philippines, the authors reported. Similar outbreaks are likely in the U.S. institutional settings as the resistant strain emergences, which is more likely to occur where is heavy use of antimicrobial agents, they warn.

"Those involved in infection control in hospitals, as well as public health authorities, should be aware that fluoroquinolone-resistant salmonella has arrived in the United States," they stated. "Clini-cians should consider drug-resistant salmonella in the differential diagnosis of nosocomial infections."

The outbreak strain was Salmonella enterica serotype Schwarzengrund. Between February 1996 and April 2000, 11 patients with laboratory-confirmed infection with fluoroquinolone-resistant S. enterica serotype Schwarzengrund were identified in Portland, OR. Transmission occurred in two nursing homes and one hospital in the Portland area. Transmission was likely due to cross-transmission from patient-to-patient or through contact with contaminated surfaces. Treatment with fluoroquinolones during the six months before a culture was obtained was associated with a significant risk of salmonella infection.

"The outbreak was notable for two reasons: The salmonella infections were acquired nosocomially, and the outbreak was difficult to control and continued for several years," the authors found.

The index patient apparently acquired the infection while hospitalized in the Philippines in 1994 and was subsequently transferred to one of the Portland nursing homes. The isolates from the outbreak also were similar to the only previous isolate of fluoroquinolone-resistant salmonella in the United States, which came from a patient in New York who had been transferred from a hospital in the Philippines. The isolates from the outbreak in Oregon and the isolate from the patient in New York had similar patterns on pulsed-field gel electrophoresis, suggesting that the infections arose from a common source. Further investigation revealed that the two patients had been hospitalized in the same facility in Manila. Several factors contribute to increasing fluoroquinolone resistance in the Philippines, including over-the-counter availability of antibiotics and the use of drugs in food animals.

"Because fluoroquinolones are the drug of choice for the treatment of severe salmonella infections in adults, the potential continued emergence and dissemination of fluoroquinolone-resistant salmonella are of great concern," the authors concluded.

Pediatric infection control approaches vary widely

Girouard S, Levine G, Goodrich K, et al. Infection control programs at children’s hospitals: A description of structures and processes. Am J Infect Control 2001; 29:145-151.

Children’s hospitals vary widely in how they design and implement their infection control approaches, and more standardization is needed if nosocomial infection rates are to be meaningfully compared between pediatric facilities, the authors reported.

The variations influence adverse event detection and nosocomial infection rate calculations. If medical errors, including nosocomial infections, are to be detected and hospital rates compared, standardized methods to collect, analyze, and report data are needed, they emphasized. For example, more standardization is needed in surveillance practices and approaches to combat antibiotic resistance.

"If benchmarking and interhospital comparisons are to be valid similar detection methods must be used. . . . Without standardized, consistent performance measures, it will be impossible to determine the most effective structures and processes for reducing the incidence of nosocomial infections and antimicrobial resistance," the authors

A survey was sent to 56 children’s hospitals collaborating in the Pediatric Prevention Network. Completed surveys were returned from 48 hospitals.

As reported by respondents, responsibility for the infection control program resided with the medical director (21%); vice president for patient care (18%); quality improvement director (17%); other senior hospital administrator (15%); or other hospital personnel (18%).

Forty-two hospitals had an infection control committee; 32 had antimicrobial restriction/
control policies; and 21 had an antimicrobial restriction/control task force or committee.

Components of antimicrobial restriction programs included infectious disease specialist approval, restricted formularies, selective susceptibility test reporting, and staff education programs.

Many methods were used to detect infections, including microbiology laboratory reports (100%); record reviews (98%); informal reports from providers (90%); and readmission reviews (77%).

Subset savings: IV set duration extended

Raad I, Hanna HA, Awad A, et al. Optimal frequency of changing intravenous administration sets: Is it safe to prolong use beyond 72 hours? Infect Control Hosp Epidemiol 2001; 22:136-139.

In patients at low risk for infection from infusion- or catheter-related infection who are not receiving total parental nutrition, blood transfusions, or interleukin-2, delaying the replacement of IV administration sets up to seven days may be safe, the authors reported. "By extending the duration
of placement of the IV administration sets beyond
72 hours in this group of patients, at least a 35% reduction in the number of sets used would occur. This would result in a $700,000 annual cost savings at our institution."

In the study, cancer patients requiring IV infusion therapy were randomized to have the IV tubing sets replaced within three days (280 patients) or within four to seven days of placement (232 patients). Demographic, microbiological, and infusion-related data were collected for all participants. The main outcome measures were infusion- or catheter-related contamination or colonization of IV tubing, determined by quantitative cultures of the infusate, and infusion- or catheter-related bloodstream infection (BSI), determined by quantitative culture of the infusate in association with blood cultures in febrile patients.

The two were comparable in terms of patient
and catheter characteristics and the agents given through the IV tubing. Intent-to-treat analysis demonstrated a higher level of tubing colonization in the four- to seven-day group vs. the three-day group. In addition, there were three episodes of possible infusion-related BSIs, which all occurred in the four- to seven-day group. When the 84 patients who received total parenteral nutrition (TPN), blood transfusions, or interleukin-2 through the IV tubing were excluded, the two groups had a comparable rate of colonization (0.4% vs. 0.5%), with no catheter- or infusion-related BSIs in either group

"The results of this study suggest that the incidence of colonization and infection associated with IV administration set replacement at four- to seven-day intervals is similar to that of IV administration set replacement at three days, except in patients receiving interleukin-2, TPN, or blood products through the tubing," the authors said. "Strong consideration should be given to extending the duration of IV administration set placement up to seven days. This would have a major cost-saving impact on the health care of hospitalized patients worldwide."