Hospital lab director debunks MRSA rumors
Photo courtesy of CDC
When people leave a hospital, the last thing they want is to go home with an infection they didn't have when they were admitted. And over the last several years, the public's concerns about contracting an infection associated with their health care have been compounded by alarming news reports describing a flesh-eating, drug-resistant "superbug" known as MRSA.
Lena Prisco, Martha's Vineyard Hospital (MVH) laboratory director and director of infection control, said she recognizes and understands that the Island community shares those same concerns. The hospital is required to track MRSA cases and report them to the state.
In a telephone conversation Tuesday, Ms. Prisco spoke to The Times about her concerns that the Island community thinks MRSA is much more prevalent than the numbers show. It began with a casual remark she heard at a recent social gathering.
"Someone made the comment that, 'Oh, wow, the hospital is full of MRSA,'" she recalled. "And it is not. I thought, whoa, there's a perception here that isn't right."
Ms. Prisco, who holds a master's degree and doctorate in pharmacology, said MRSA occurs in the community, but that does not mean it is hospital related. "There is a distinction," she said, between MRSA acquired in the community at large and that acquired in the hospital.
Super bad bug
MRSA is the abbreviation for methicillin-resistant Staphylococcus aureus. It causes a range of illnesses, from skin and wound infections, to pneumonia and bloodstream infections that can cause sepsis and death, according to the Centers for Disease and Control Prevention (CDC) website.
MRSA is a mutated version of Staphylococcus aureus (staph). Staph bacteria, including MRSA, are one of the most common causes of health care-associated infections, the CDC website says.
At any given time, about 25 to 30 percent of healthy people in the U.S. carry staph bacteria on their skin or in their noses, without any signs or symptoms of illness. Two in 100 people carry MRSA.
Although staph bacteria do not usually cause infection, they can bring about disease if they penetrate through a break in the skin or through mucous membranes.
Staph bacteria are one of the most common causes of skin infections, usually minor. Staph can, however, cause more serious illnesses such as surgical wound infections, bloodstream infections, bone infections, and pneumonia.
Staph are spread by direct skin-to-skin contact, and also by contact with items that have been touched by people with staph, for example, shared towels athletic equipment in the gym or on the field. MRSA is spread the same way as other staph. MRSA is categorized by the setting where it is acquired.
Health care-acquired MRSA (HA-MRSA) emerged and was recognized in the 1960s as a more dangerous type of staph infection that was resistant to methicillin, according to the Baylor College of Medicine website. The bacteria is also resistant to the more commonly prescribed penicillin, amoxicillin, and oxacillin, among others.
Most HA-MRSA infections occur in people who've been in hospitals or other health care settings, such as nursing homes and dialysis centers, according to the Mayo Clinic. HA-MRSA infections typically are associated with invasive procedures or devices, such as surgeries, intravenous tubing, or artificial joints.
A second type of MRSA which appeared in the 1990s, known as community-acquired MRSA (CA-MRSA), occurs outside of hospital settings. It usually manifests itself as a skin infection in an otherwise healthy individual.
MRSA by the numbers
"In terms of overall staph cases, infections and wounds, we really don't keep hard numbers on those, because those don't have to be reported anywhere," Ms. Prisco said. "MRSA does have to be reported to the state, so we keep track of those cases."
Keeping track of the cases also includes investigating the source of the infection, she explained.
"So whether or not the patient came through the ER [emergency room] and had it already; whether or not they were in the hospital; and if they came in from the ER, we kind of dig into the notes to see where they may have picked it up," Ms. Prisco said.
Based on her records, kept over the past five years, she said MVH has had no more than two cases per year of HA-MRSA, an extremely low rate. There was no uptick in any particular year. If the hospital cannot rule out any other source of a patient's MRSA infection, it has to be reported as health care-acquired.
Although staph infection numbers do not have to be reported to the state, Ms. Prisco said those have remained fairly flat during the same five-year period.
"So the majority of MRSA cases that we do see at the hospital are community-acquired MRSA," she said. "Over the past five years, on average about 120 people a year walk into the hospital with CA-MRSA. Now, they've all been treatable; vancomycin is the standard treatment."
The Times asked Ms. Prisco what she thought the Island community's misconception about MRSA's prevalence at the hospital stems from.
"I think what happens is somebody has a procedure at the hospital and then comes in with a MRSA infection and maybe gets mixed up when it actually happened," she said. "They're not told they have it until they're in the hospital for something else, and they make the leap that they got it here, when they really haven't."
CA versus HA
Ms. Prisco said that most CA-MRSA cases seen at MVH were in patients previously treated in off-Island institutions. "A lot of people go off Island for procedures, whether it be for a catheter placement, or epidurals or whatever else, and they get exposed and then they come back here, and they've got an infected wound," she said.
Ms. Prisco said the hospital's low number of HA-MRSA cases is an incentive for Islanders to have minor procedures done at MVH, rather than risking exposure elsewhere. MVH also offers the advantage of single-patient rooms, which help prevent the spread of infection in general," she added.
"We do a lot of mandatory hand washing and hand washing surveillance, and we make sure people are really being as cognizant as possible about the spread of anything," Ms. Prisco said.
Another source of CA-MRSA is environmental exposure. "It can be commonly found in dirt, like in the case of a girl who was playing on a swingset, and got flesh-eating bacteria," Ms. Prisco said. "It's out there in the environment. You see it a lot in patients that are immuno-compromised. That could be people who are elderly, who are taking a lot of drugs."
Insect bites, particularly spider bites, are another common source of origin for MRSA infections, Ms. Prisco noted. "Somebody will come in and they think they got bit by something, and boom, it's infected and it's MRSA."
The number of CA-MRSA cases seen at MVH has gone up over five years.
"We see it more in the summer, when people are outside more," Ms. Prisco said. "And we also are seeing it more because we have an aging population here with people with compromised immune systems.
Also, antibiotic use is still pretty rampant, which encourages bacteria species to mutate and become drug-resistant, which is why other strains are developing," she added. "It all goes hand in hand."
Proactive measures at MVH
Although MRSA screening is not mandatory for hospitals, Ms. Prisco said a lot of larger hospitals that do a lot of surgery and have a lot of outpatients, including Massachusetts General Hospital and Cape Cod Hospital, prescreen all patients. MVH screens patients that will be undergoing orthopedic surgery.
In addition, Ms. Prisco said MVH recently instituted increased surveillance and follow-up procedures for the community, to better serve patients on the Island.
"Recognizing that we do have a decent amount of MRSA walking through the door, we need to follow these people and make sure they're treated appropriately," she said.
People who have been diagnosed with MRSA in the past may continue to be "colonized," which means they still carry the bacteria.
"Imagine you're now going in for hip surgery, for example, and you're colonized and we don't know it, and then you come up with a MRSA infection, because you're infecting yourself," Ms. Prisco said. "Before, we would track the cases and report them, but we never flagged those people so we could get them extra treatment in the hospital."
Now, Ms. Prisco said MRSA cases are documented in patients' registration information, so hospital personnel can find out if they followed up with their physicians for another MRSA screen, should they return to the hospital for another procedure.
MVH is also working on a system to notify a patients' attending physician that he or she had a positive MRSA screen and should return for follow-up. "If you can find people before they actually have an infection and get it wiped out of their nose by treating them, then they don't spread if anywhere else," she said.
With the increased surveillance and tracking, and a limited amount of prescreening, Ms. Prisco said she believes the hospital will be able to keep MRSA numbers low and probably even decrease them.
When asked what message about MRSA she would like to leave with the Island community, Ms. Prisco said, "People should be diligent, but also know that their hospital is aware of it, we're tracking it, and we're proactively doing something about it."
The good news is that MRSA infections are on the decline. Between 2005 and 2011, overall rates of invasive MRSA dropped 31 percent. The largest declines, 54 percent, were observed among infections occurring during hospitalization, according to the CDC.