ICAAC Highlights

BSIs fell 27% of patients with prosthetic devices

Aussie study finds hand rubs halve infections

Staphylococcus aureus bloodstream infections cause a striking level of complications and deaths in patients with prosthetic devices, researchers reported recently at the annual Inter-science Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in Washington, DC.

Despite the extensive use of hospital resources for diagnostic tests and therapeutic interventions, nearly half of patients experienced a major complication, with an overall case-fatality rate of 27%, reported investigators from Duke University Medical Center in Durham, NC.1

Prosthetic devices have revolutionized the management of patients with chronic cardiovascular, orthopedic, and other diseases. While these devices provide life-saving interventions that can improve the quality of life of countless patients, they also paradoxically place these same patients at risk for device-related infections. S. aureus is a major cause of device-related infections and bacteremia, and its frequency is increasing. Yet despite its increasing frequency, little is known about the medical and economic impact of S. aureus bloodstream infections in patients with prosthetic devices.

A total of 298 prospectively identified patients with both S. aureus bloodstream infection and a prosthetic device were included in the study. Devices included long-term indwelling bloodstream catheters, cardiovascular devices (such as pacemakers and prosthetic valves), orthopedic devices (such as prosthetic joints), and other devices (such as hernia mesh).

The mean age of patients was 59. Almost half of the patients (49%) were infected with methicillin-resistant S. aureus (MRSA). Infectious complications were frequent and occurred in 41% of patients. Mortality at 12 weeks was 27%.

Patients with a cardiovascular device had the highest mortality (35%), while patients with an intravascular device had the lowest mortality (17%). Re-hospitalization for recurrent S. aureus infection at 12 weeks occurred in 15% of patients who survived the initial hospitalization.

The median length of stay was 13 days for patients admitted with suspected S. aureus infection and 23 days for patients who acquired S. aureus bloodstream infection in the hospital.

For patients admitted with suspected S. aureus infection, the mean total cost was $39,911 per patient. For patients with hospital-acquired S.aureus bloodstream infection, the mean total cost (starting from the first day of the S.aureus bloodstream infection) was $62,325 per patient. Hospitalization costs differed according to device type, with the highest costs associated with cardiovascular devices (mean $48,390 — admitted with suspected S. aureus infection; mean $82,287 — hospital-acquired S. aureus bloodstream infection).

Given the expanding use of prosthetic devices, the morbidity and cost related to S. aureus bloodstream infection likely will increase. Improvements in prevention and therapeutics are needed for this high-risk population, the Duke researchers noted.  

Good news from the land Down Under 

In other ICAAC news, researchers in Australia report the use of alcohol-based hand rubs was highly effective in reducing nosocomial infections. That’s encouraging news for American ICPs who are switching to the hand-hygiene approach in droves. After a hand-hygiene program using an alcohol chlorhexidine product was put in place, the rate of MRSA bacteremia dropped 53% over three years, researchers at the University of Melbourne reported.2

Presenting data from a 36-month post-intervention period, they found that the total number of clinical MRSA isolates per 100 admissions fell 38%. However, the epidemiologists acknowledged that the program was a more of a quality improvement project than a formal investigation. They were not able to determine exactly which components of the program led to the improvement, but emphasized that the cornerstone was the introduction and promotion of hand-hygiene rubs throughout our institution.

As in many other facilities, MRSA is the most important hospital-acquired infection at Austin Health, an 840-bed university teaching hospital complex. The great majority of patients do not carry MRSA prior to admission, but surveys in selected surgical wards found up to 15% were later colonized in the nose or groin. The most likely reason for that is patient-to-patient transfer of MRSA on the hands of health care workers. Although colonized patients usually remain well, the presence of large numbers of silent carriers was considered a constant threat to other patients undergoing complex surgery, the researchers reported.

Beginning in 2001, the hospital began emphasizing use of hand-hygiene solutions in a program supported by a comprehensive education package to ensure widespread understanding and acceptance of the product. The Australian ICPs also introduced alcohol wipes for shared ward equipment, and nasal antibiotic ointment (mupirocin) for a small subgroup of patients with a known history of past MRSA colonization.

Compliance with hand-hygiene recommendations improved significantly in each of five clinical areas studied. For example, in a spinal injury unit, staff compliance with recommended hand-hygiene practices more than doubled (pre-intervention, 29%; post-intervention 62%).

References

1. Chu VH, Friedman JY, Reed SD. Staphyloccocus aureus bacterimia in patients with prosthetic devices: Costs and outcomes. Abstract K-757. Presented at the 44th Interscience Conference on Antimicrobial Agents and Chemotherapy. Washington, DC; November 2004.

2. Johnson P, Mayall BC, Grabsch EA, et al. Controlling hyperendemic nosocomial MRSA in an Australian teaching hospital. Abstract K-1858. Presented at the 44th Interscience Conference on Antimicrobial Agents and Chemotherapy. Washington, DC; November 2004.