Friday, March 28, 2008

Understanding B. Cepacia

People with cystic fibrosis are prone to a variety of lung infections. Bacteria can easily take hold in the thick, sticky mucus of the airways and begin to grow. Different types of bacteria may only cause occasional flare up for some people with CF, while others may develop chronic infection. In the clinical setting such as hospitalization or office visits, strict anti-infection measures must be implemented in order to prevent the spread of resistant forms of bacteria. The most devastating type of resistant bacteria is a species identified as Burkholderia cepacia (B. cepacia.) This persistent microorganism can occasionally be spread from person to person or object to person. This is of great concern because of the limited number of antibiotics available to fight this bacteria.

History and Epidemics of B. Cepacia

Burkholderia (previously known as Pseudomonas) cepacia, a nutritionally versatile, gram-negative organism, was first described in 1949 by Walter Burkholder of Cornell University, as the phytopathogen responsible for a bacterial rot of onions. Ironically, B. cepacia is now being considered by agricultural microbiologists as an agent to promote crop growth.

The threat of B. cepacia infection led to severe control measures. The popular summer camps like "Camp Pillfeather" were closed once doctors discovered how easily cepacia could spread from person to person. Even transplant centers ceased to accept B. cepacia–infected CF patients as transplant candidates. At first doctors assumed that all species (aka genomovars) of cepacia were equally dangerous, having high morbidity and mortality rates.

In reality transmissibility varies markedly from strain to strain, and that most strains don't cause epidemics, but seem to be relegated to individual cases. Many people with cepacia aren't even sure how they first contracted it. One bit of positive information is that lack of transmission of some strains has also been observed between siblings with CF.

Numerous CF-associated B. cepacia epidemics have now been described, and the epidemic strains have been characterized. One particular highly transmissible strain, epidemically spread within and between CF centers on both sides of the Atlantic, carries the cblA gene. This cblA+ strain has spread across Canada and has now been isolated in 50% of CF centers in the United Kingdom. Another strain of B. cepacia has spread among CF centers in four regions of France.

However, it has become clear that transmissibility varies markedly from strain to strain, and that most strains are not involved in epidemics but appear to be independently acquired and show no evidence of transmission. For example, in 8 years no cases of transmission were detected at the University of North Carolina CF center, despite clinical and social contact between patients and the absence of stringent infection control measures. Independent acquisition of B. cepacia with no evidence of transmission between CF patients was also reported from Denmark.

Shedding Light on B. Cepacia

In the CF community, this exceptionally resistent bacteria is a bone of contention for patients and healthcare professionals alike. Strict adherence to cross-infection avoidance protocols must be a priority. The gravity of the potential probelms for CF patients cannot be denied. However, many patients and their caregivers seem to have almost an irrational fear of being exposed to cepacia.

Because of the different genomovars (i.e. species) of cepacia, it is impossible to predict how an individual's lung function and overall health will be affected once cepacia has been cultured. For some people, decline is rapid and devastating. Others (like myself) may experience some degree of loss of lung function and become more susceptible to other infections.

Most of the anxiety about cepacia stems from the basic reality that cepacia is highly transmissible from patient to patient(1). However, not every species has the same transmissiblity characteristics.

The CFF patient registry tracks approximately 23,000 patients with cystic fibrosis who receive care at CF Centers throughout the country. Overall, only 3-5% of CF patients culture cepacia in any form. This translates to anywhere from 690 to 1150 patients who culture cepacia. In the United States there are 115 care centers. Just from rouhg estimation, this could mean that only 10 patients at each care center have cepacia. Keep in mind that not all of them are present each time the clinic holds appointments, and not all of them continually culture cepacia.

I am not intending to downplay the seriousness of cepacia, nor am I expressing the idea that precautions should be ignored. There are epidemic strains of cepacia. According to an academic paper published in November, 2003 on the study of cepacia in the UK (2)

"Minimising the risk of transmission of this organism from one individual to another requires a multifactorial approach. The polymerase chain reaction [PCR] has allowed for earlier detection of this organism in the clinical progression of the infection, which may allow for earlier and more aggressive intervention with appropriate antibiotics. In addition, such molecular diagnostic approaches may help by giving direction to segregation policies, thus minimising transmission in both the in-patient and the out-patient setting. Most importantly perhaps is vigilance on the part of the CF patient to adhere to infection control practices. Although tedious and socially difficult to maintain properly, these practices do work. " (Emphasis mine)

The more common pathogens of concern in CF clinics are those such as Pseudomonas aerginosa, and various staph infections. I am confident in my doctors' ability to execute proper infection control measures that protect me and others with CF. It's the rest of the world I worry about--I find myself far more likely to catch a nasty bug from the world beyond my health care center's walls. Public places like movie theatres, swimming pools, shopping malls, etc. pose a greater risk to my overall health.

Some Tips on "Germ Etiquette"

  • The best way to prevent infection is good hand washing with soap and water.
    Whenever you interact with someone at a doctor's office or hospital, it's best to wash your hands before and after contact. CF doctors are usually very good about washing their hands. As a CF patient it is your right to insist that your nurses wash their hands as well. Not all medical professionals or caregivers understand just how critical this is for people with CF. Hand washing should be done before and after contact with others, or contact with objects or surfaces that have become contaminated with respiratory secretions. Not only do patients have to wash their hands, but nurses, doctors, therapists and aides do as well.
  • Use common sense and practice good hygiene when in the clinic or hospital.
    Cough into your shoulder or the crook of your elbow. Some CF clinics ask that people who have a cough should wear a mask. Patients with cepacia should also be courteous to wear gloves and maintain a minimal distance of 3 feet away from other patients. CF Clinics recommend that patients with cepacia have either the first or last appointment of the clinic so that they are not posing an exposure risk. Another way to protect yourself from any lingering bacteria on surfaces is to avoid using your hands to touch things. Shut the water faucet off with your elbow. Push the elevator button with your knuckle instead of your fingertip.

For more information be sure to visit the Cystic Fibrosis Foundation's B. Cepacia information page.

Sources and Related Articles:

(1) source: Prevention of Cross Infection in cystic fibrosis. Claus Moser, MD, PhD & Neils Hoiby, MD
(2) source: Burkholderia cepacia and cystic fibrosis. John E. Moor & J. Stuart Elborn. November, 2003. Northern Ireland Public Health Library.

ABC News: Living Dangerously With Cystic Fibrosis

B. Cepacia and Cystic Fibrosis

Agricultural Use of B. Cepacia: A Threat to Human Health?

Infection of B. Cepacia in Cystic Fibrosis Patients

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