Avian Flu Diary: Persistent Pathogens

# 6757

While exotic emerging viruses tend to garner the greatest headlines, old school bacterial nemeses like C. diff, S. aureus, and A. baumannii exact an impressive toll each year, killing tens of thousands of hospitalized patients and adding billions of dollars in health care costs.

This oft quoted assessment from the CDC on the burden of Hospital Acquired Infections in the United States is from 2010.

A new report from CDC updates previous estimates of healthcare-associated infections. In American hospitals alone, healthcare-associated infections account for an estimated 1.7 million infections and 99,000 associated deaths each year. Of these infections:

32 percent of all healthcare-associated infection are urinary tract infections

22 percent are surgical site infections

15 percent are pneumonia (lung infections)

14 percent are bloodstream infections

Hospitals are engaged in a perpetual warfare against the spread of infection - and while progress is being made - many pathogens continue to slip past the infection control safeguards.

The American Journal of Infection Control - the official publication of APIC – provides a sobering overview of this daily battle, and while infection control techniques are improving, bacteria can be masters at evading even the most stringent measures.

One of the toughest bacteria that hospitals must deal with is multidrug-resistant (MDR) Acinetobacter baumannii, which in recent years has made headlines as the cause of difficult to treat wound infections among our troops serving in the Middle East.

Acinetobacter (of which there are many varieties, but A. baumannii is most often linked to human infection ) are ubiquitous in nature, and can be found in soil, water, animals and humans. A very hardy species, they can survive for extended period of time on inanimate surfaces, making them difficult to control in a health care setting.

Yesterday the AJIC carried an article on just how tough eradicating this bacteria really is.

The effect of terminal cleaning on environmental contamination rates of multidrug-resistant Acinetobacter baumannii

Paula Strassle, BS, Kerri A. Thom, MD, J. Kristie Johnsonm, PhD(ABMM), Surbhi Leekha, MBBS, MPH, Matthew Lissauer, MD, FACS, Jingkun Zhu, MS, Anthony D. Harris, MD, MPH

We evaluated the prevalence of multidrug-resistant Acinetobacter baumannii environmental contamination before and after discharge cleaning in rooms of infected/colonized patients. 46.9% of rooms and 15.3% of sites were found contaminated precleaning, and 25% of rooms and 5.5% of sites were found contaminated postcleaning. Cleaning significantly decreased environmental contamination of A baumannii; however, persistent contamination represents a significant risk factor for transmission. Further studies on this and more effective cleaning methods are needed.

The full text to this study are available on the AJIC website, but we’ve also a brief summary via a press release.

Hospital cleaning protocol ineffective against A. baumannii

Washington, November 30, 2012 -- Current hospital cleaning protocol may be inadequate to rid patient rooms of multidrug-resistant (MDR) Acinetobacter baumannii, according to a study in the December issue of the American Journal of Infection Control, the official publication of the Association for Professionals in Infection Control and Epidemiology (APIC).

A team of researchers from the University of Maryland collected 487 cultures from 32 hospital rooms occupied by just-discharged patients with a known history of MDR A. baumannii both before and after terminal cleaning of the rooms. Over half of the rooms positive for the A. baumannii bacteria prior to cleaning remained contaminated after terminal cleaning had occurred.

Fifteen rooms (46.9 percent) and 41 sites (n=268, 15.3 percent) tested positive for MDR A. baumannii before cleaning. Post-cleaning, eight rooms (25 percent) and 12 sites (n=219, 5.5 percent) still tested positive for the pathogen. Sites with post-cleaning contamination included the floor (12.5 percent), call button (10 percent), door handle (9.4 percent) bedside table (7.4 percent), and supply cart (3.8 percent).

"Persistent room contamination serves as a potential reservoir for transmission and colonization of future room occupants," state the authors in the article. "Current cleaning techniques in terms of products used or thoroughness of cleaning may not be adequate in the decontamination of this pathogen."

Acinetobacter baumannii is a type of bacteria that has become increasingly prevalent in healthcare facilities and is resistant to most antibiotics. Infections from this pathogen primarily occur in very ill, wounded, or immunocompromised patients. The germ can remain on wet or dry surfaces for longer than most other organisms, making it harder to eradicate.

"This study shows how difficult it is to ensure removal of particularly resistant organisms from the environment even upon thorough discharge cleaning," said Anthony D. Harris, MD, MPH, lead study author and professor of epidemiology and public health at the University of Maryland School of Medicine. "With new, innovative means of monitoring cleaning processes that we have incorporated since the study was done, coupled with other infection control efforts, we are seeing lower rates of A. baumannii at our hospital."

The good news is that while difficult, control of these organisms is possible with the right measures. We’ve looked at the problem of controlling HAIs frequently in the past. A few examples include:

Last month in The Flight Of The Bacterial Intruder at how bacteria, including C. diff and MRSA, can ride air currents and contaminate surfaces more than 3 meters from a patient.

In 2010, we saw a study published in the AJIC: American Journal of Infection Control that found that the more roommates you have during a hospital stay, the greater chance you will have of contracting an HAIs (Hospital Acquired Infections) like MRSA or C. Diff.
- Exposure to hospital roommates as a risk factor for health care–associated infection
- Meghan Hamel, MSc, Dick Zoutman, MD, FRCPC, Chris O'Callaghan, DVM, MSc, PhD

That said, the subjects of HAIs and resistant bacteria are most consistently (and frankly, better) addressed by Maryn McKenna on her excellent Superbug Blog, and was a major focus of her book SUPERBUG: The Fatal Menace Of MRSA.

Both of which are highly recommended.