Infection control experts at Johns Hopkins are sounding the alarm for vulnerable healthcare workers to be on the lookout for a more aggressive form of methicillin-resistant Staphylococcus aureus (MRSA), called community-acquired MRSA. MRSA infections are resistant to commonly used antibiotics, including oxacillin (Bactocil), penicillin and cephalexin (Keflex).
The warning follows a Hopkins-funded investigation of the infection in two healthcare workers in a very busy outpatient clinic for people with HIV at The Johns Hopkins Hospital in 2004, revealing contamination to be widespread in the clinic and a greater potential risk to staff and patient safety than previously thought. No patients were found to be infected as a result of the outbreak, but afflicted staffers required treatment, and infection control resources were significantly increased to lower the risk of a repeat outbreak.
Health experts fear that the rising trend of MRSA infections in hospitals could render useless many of the most widely available and effective drugs.
“Tighter infection control practices and policies are needed by healthcare workers and hospitals to prevent outbreaks and prevent staff from picking up the community-acquired form of this bacterium from patients,” says Cecilia Johnston, MD, an infectious diseases instructor at Hopkins and leader of the investigation.
“Community-acquired MRSA is an increasing problem in inpatient and outpatient settings, as exposure can occur in the workplace,” says senior hospital epidemiologist Trish Perl, MD, an associate professor of medicine and pathology at the Johns Hopkins University School of Medicine. “Our experience shows that healthcare workers need to be aware of the risk, alert infection control staff immediately after an infection is suspected, and understand that tighter infection control procedures can guard against subsequent exposure.”
High-risk patients in intensive care are monitored regularly for contamination with MRSA, and Johnston says the new Hopkins study calls for increased vigilance in outpatient treatment areas with high patient traffic. “Treatment areas should be cleaned regularly and between each patient visit with strong disinfectants,” she says, adding that healthcare workers should wear gowns and gloves and care for exposed skin and other wounds in designated, confined treatment spaces or separate rooms. Like most bacterial infections, MRSA is usually picked up through direct contact, by touching someone or a surface with it.
The Hopkins team describes the outbreak of community-acquired MRSA (CA-MRSA) and their subsequent investigation, which started in February 2004 and took five weeks to complete, in a report to be published in the journal Infection Control and Hospital Epidemiology online Sept. 18. Their study is believed to be the first to evaluate just how widespread is CA-MRSA during an outbreak in an outpatient setting. Previous research has focused on hospital wards and inpatient settings.
The study showed that the aggressive form of CA-MRSA, which can cause disease in healthy people, including children, was present throughout the clinic, on seven of 36 surfaces tested. The less dangerous, hospital-acquired form of MRSA, or HA-MRSA for short, was not found on any of the surfaces tested.
Though rarely fatal, infections with either form of MRSA can lead to life-threatening complications in patients. CA-MRSA is associated with abscesses, or pimples, on the skin that must be drained to prevent those complications, which include foul-smelling skin infections, muscle swelling (myositis), or lethal necrotizing pneumonia and septic shock. It can also produce more kinds of toxins than its less-virulent form. HA-MRSA, known to colonize the whole body, can lead to dangerous blood stream infections.
Of added concern to infection control specialists is that CA-MRSA infections in hospitals are frequently misdiagnosed as the hospital-acquired kind, which is treated differently. According to researchers, CA-MRSA infections have been effectively treated with oral antibiotics, such as trimethoprim-sulfamethoxazole (Bactrim), minocycline (Minocin) and clindamycin (Cleocin), whereas HA-MRSA infections have been known to be more resistant to these drugs. Another antibiotic, vancomycin, is usually required. And the researchers caution that it is extremely important to identify which bacterium is there, by obtaining cultures, to make sure the right antibiotic is prescribed.
The outbreak was detected soon after it began when two staff members reported MRSA-like lesions to
Once the infection of the two clinic workers was confirmed,
For the investigation, all other clinic staff, approximately 138 nurses, physicians and managers who worked inside the clinic, were tested for MRSA colonization or infection. Researchers swabbed noses, a soft tissue where the bacteria readily colonize. They also dipped hands, another region where bacteria live, into a vat of bacterial growth media to see if the MRSA bacterium would grow. Two additional healthcare workers were found to be colonized with HA-MRSA, but they showed no signs of infection. The two were treated with an antibiotic nasal spray that rid them of the bacterium.
As part of their investigation, the Hopkins team swabbed 36 separate surfaces in the clinic, especially commonly used items, such as phones, door knobs, equipment and furniture, and surveyed each clinic worker to assess possible sources of the MRSA infection and what infection control procedures were in practice. For example, researchers asked the staff about how often they treated patients with signs of CA-MRSA and if open wounds were cleaned and drained in the room, and how often staff washed their hands between patient visits and to what extent the exam room was cleaned between patient visits. It is the routine between patient visits for clinic workers to pull down a fresh sheet of paper over the exam room and wash their hands.
The investigation showed that no other workers had been infected with either form of MRSA. However, cultures of the workplace showed contamination with CA-MRSA to be widespread, with seven surfaces testing positive, including patient exam table surfaces, pulse oximeters (a device for testing blood oxygen levels), countertops, computer keyboards and patient chairs in the triage station, and waiting and exam rooms. Surfaces not found to be contaminated included door knobs, phones, ophthalmoscopes (to check the eyes), otoscopes (to check the ears), blood pressure cuffs, thermometers and sinks.
Researchers were not able to determine why some surfaces were contaminated and others were not.
Staff interviews also revealed that patients with CA-MRSA infections had their abscesses drained and wounds cleaned in whichever room was available, and that some staff wore no protective gowns or masks during the procedure.
After subsequent meetings with clinic staff and hospital cleaning personnel, a number of changes were introduced to the clinic in an attempt to cut back on environmental contamination. Cleaning supplies were checked and switched to make sure all included agents that contain ethyl alcohol and quarternary ammonium, compounds that kill MRSA. Sanitary wipes containing the compound were placed in all exam rooms to encourage cleaning between patients. Cleaning staff practices were also changed to include daily cleaning of all surfaces. To reduce exposure from patients already infected and undergoing wound cleaning, one room was set aside for draining abscesses.
After two weeks of intense efforts to prevent the spread of infection, another round of environmental testing in April 2004 showed no positive cultures of CA-MRSA. The outbreak was deemed to be over.
Researchers say their next step is to work with municipal health officials and to continue to monitor CA-MRSA in the community, evaluate how it spreads among different populations, and assess the risk this poses to healthcare workers and patients in the hospital, as well as what measures will work best to prevent outbreaks.
No firm estimates on the prevalence of MRSA exist, and preliminary numbers vary widely from country to country and between hospitals. In 2006, however, the Joint Commission on Accreditation of Healthcare Organizations released an estimate that 70 percent of the bacteria that cause infections for 2 million hospitalized Americans each year are resistant to at least one of the drugs most commonly used to treat them.
Funding for the study was provided by The Johns Hopkins Hospital. Besides Perl and Johnston, other members of the