Implanted heart devices prone to silent, dangerous staph infection

August 27, 2001

DALLAS, - Pacemakers and other implanted heart devices prolong the lives of people with heart rhythm problems. However, if an individual with one of these devices develops a staph infection it could pose a potentially life-threatening danger, researchers report in today's Circulation: Journal of the American Heart Association.

This study is believed to be the largest prospective evaluation of individuals with permanent pacemakers or implantable cardioverter-defibrillators (ICDs) who have Staphylococcus aureus bacteremia (staph infection in the blood). A pacemaker is a small, battery-operated device that helps the heart beat in a regular rhythm. An ICD monitors heart rhythm and delivers electric shocks to correct abnormal rhythms.

"If a patient has an implanted cardiac device and develops a Staphylococcus aureus infection, the patient's physicians should be worried that the device is infected," says Anna Lisa Chamis, M.D., a cardiology fellow at Duke University Medical Center in Durham, N.C. "Our data suggest that if the infection occurs within one year of implantation, the device ends up being infected in about three-fourths of the cases. The major new finding is that the majority of the device infections showed no obvious signs."

In this study, most of the staph infections did not originate with the device. The most common cause was a tissue infection originating in another part of the body that then spread to the heart device. However, the heart device was thought to cause the staph infection in 18 percent of cases.

Cardiac device infection carries a high risk of serious illness and death. Previous studies have shown that it occurs in up to 20 percent of permanent pacemakers and up to 1.3 percent of ICDs. According to the American Heart Association Heart and Stroke Statistical Update, in 1998 (the most recent statistics available) there were 26,000 ICD procedures and 170,000 pacemaker procedures.

Chamis and her associates evaluated 33 individuals with cardiac pacemakers or defibrillators who had staph infections. In each case, systemic infection was documented by blood tests. The infection had spread to the device in almost half (15) of the cases.

In some cases, device infection will produce redness, inflammation, abnormal growths or deposits on the device or its lead wire. Some of these can be detected by echocardiography, a procedure that produces images from sound waves bounced off the heart. In the absence of obvious signs of infection, blood tests can confirm a staph infection and help guide the decision to remove an implanted device.

The researchers found that 60 percent of the infected devices showed no obvious signs such as redness or pain in the tissues covering the implanted device. Device infection was confirmed only after it was removed for inspection.

Cardiac device infection can be treated by removing the device or by administering antibiotics. However, patients who did not have the devices removed were more likely to die, says Chamis. Removing the device and implanting a replacement is a major surgical procedure, therefore, accurate documentation of infection is essential to avoid unnecessary surgery, according to the researchers.

The findings also showed that 12 of 33 staph infections occurred within a year of device implantation, defined as early infection. Nine of these early infections involved the device. The remaining 21 cases occurred a year or more after device implantation, termed late infection. In six of these cases a device infection was confirmed, and nine others had suspected device involvement.

The researchers conclude that early staph infection carries a high probability of cardiac device involvement. With late infection the device is unlikely to be the initial source of bacteria in the blood, and few signs of device involvement occur. However, the study showed that the device was involved in at least 28 percent of late infections.

Therefore, the researchers support the removal of cardiac devices among most patients who develop staph infection, whether device infection is confirmed or not. Whether the findings apply to infections other than those caused by Staphylococcus aureus is unclear, says Chamis. However, the results probably do apply to other types of implantable devices.

"Other groups have shown that infections, including this specific type of infection, occur in prosthetic joints at rates similar to what we observed," she says. "Catheters that remain in place in the body and other more permanent types of intravenous devices also have been studied, and similar rates of infection have been reported."
Co-authors of the study include Gail E. Peterson, M.D.; Christopher H. Cabell, M.D.; G. Ralph Corey, M.D.; Robert A. Sorrentino, M.D.; Ruth Ann Greenfield, M.D.; Thomas Ryan, M.D.; L. Barth Reller, M.D.; and Vance G. Fowler, Jr., M.D.

The research was funded by the National Institutes of Health.

CONTACT: For journal copies only, please call: 214-706-1396. For other information, call: Carole Bullock: 214-706-1279 or Bridgette McNeill: 214-706-1135

American Heart Association

Related Infection Articles from Brightsurf:

Halving the risk of infection following surgery
New analysis by the University of Leeds and the University of Bern of more than 14,000 operations has found that using alcoholic chlorhexidine gluconate (CHG) halves the risk of infection in certain types of surgery when compared to the more commonly used povidone-iodine (PVI).

How plants shut the door on infection
A new study by an international team including University of Maryland scientists has discovered the key calcium channel responsible for closing plant pores as an immune response to pathogen exposure.

Sensing infection, suppressing regeneration
UIC researchers describe an enzyme that blocks the ability of blood vessel cells to self-heal.

Boost to lung immunity following infection
The strength of the immune system in response to respiratory infections is constantly changing, depending on the history of previous, unrelated infections, according to new research from the Crick.

Is infection after surgery associated with increased long-term risk of infection, death?
Whether experiencing an infection within the first 30 days after surgery is associated with an increased risk of another infection and death within one year was the focus of this observational study that included about 660,000 veterans who underwent major surgery.

Revealed: How E. coli knows how to cause the worst possible infection
The discovery could one day let doctors prevent the infection by allowing E. coli to pass harmlessly through the body.

UK study shows most patients with suspected urinary tract infection and treated with antibiotics actually lack evidence of this infection
New research presented at this week's European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) in Amsterdam, Netherlands (April 13-16, 2019) shows that only one third of patients that enter the emergency department with suspected urinary tract infection (UTI) actually have evidence of this infection, yet almost all are treated with antibiotics, unnecessarily driving the emergence of antimicrobial resistance.

Bacteria in urine doesn't always indicate infection
Doctors should think carefully before testing patients for a urinary tract infection (UTI) to avoid over-diagnosis and unnecessary antibiotic treatment, according to updated asymptomatic bacteriuria (ASB) guidelines released by the Infectious Diseases Society of America (IDSA) and published in Clinical Infectious Diseases.

Subsidies for infection control to healthcare institutions help reduce infection levels
Researchers compared three types of infection control subsidies and found that under a limited budget, a dollar-for-dollar matching subsidy, in which policymakers match hospital spending for infection control measures, was the most effective at reducing the number of hospital-acquired infections.

Dengue virus infection may cause severe outcomes following Zika virus infection during pregnancy
This study is the first to report a possible mechanism for the enhancement of Zika virus progression during pregnancy in an animal model.

Read More: Infection News and Infection Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to