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Maryland collaborative goes after MDR-Ab
A. baumannii widespread in vent patients
In a collaborative effort that may serve as a model for other states, Maryland has linked long-term facilities and hospitals in the fight against multidrug resistant Acinetobacter baumannii (MDR-Ab).
In recent years so-called 'Iraqibacter' has dramatically emerged in many U.S. hospitals and nursing homes after initial cases were linked to soldiers returning from the Mideast wars. However, communication between facilities is typically lacking as these patients move across the health care continuum. Facing recurrent MDR-Ab infections, epidemiologists and infection preventionists at the University of Maryland (UM) had a basic question.
"We wanted to know are we really the only ones that are having this burden with this organism?" said Kerri Thom, MD, MS, a UM assistant professor of epidemiology and public health. "And for those that are seeing acinetobacter, what are they doing to help transmission and spread? These are the questions that really led us to join up with this collaborative that was initially formed in 2009 through the Maryland Department of Health and Mental Hygiene."
The ongoing project began with the initial challenge of assessing MDR-Ab prevalence.
"Clearly we weren't going to go [culture] every patient in every health care facility in the state, so we decided to tackle this by defining what we thought was a high risk populationpatients who are mechanically ventilated," she said recently in Dallas at the annual conference of the Society for Healthcare Epidemiology of America (SHEA). "This was somewhat anecdotal from the experience of the collaborative. We felt that in our facilities and in our state that this was where we were seeing the majority of infections."
A prevalence study was undertaken that involved taking sputum and perianal cultures from all mechanically ventilated patients in the participating facilities. The voluntary effort netted 390 vent patients at 40 facilities, including nine long term care sites.
"There were 57 health care facilities that cared for mechanically ventilated patients, including both acute and long term care, and we were able to recruit 70% to participate," Thom said. " Sixty-four percent of acute care hospitals participated and 83% of long term care facilities that care for mechanically ventilated patients also participated in the survey."
The project achieved geographic representation across the state, in part because assurances of confidentially were in place for both sites and patients. Overall, 34% (121 out of 358) of all mechanically ventilated patients in the state grew A. baumannii from either the sputum or the perianal sample. Among those, 72% (87 out of 121) met the project definition of MDR-Ab: susceptibility to two or fewer classes of antibiotics.
In results by facility type, acute care had a 16% A. baumanni prevalence, with 36 out of 222 patients positive in at least one site. In long term care 85 (63%) out of 136 patients had the organism identified from at least one site. Of those positive in long term care, 79% had MDR-Ab.
"Looking at it [another] way, we can say that 9% of all mechanically ventilated patients in the acute setting were found to have MDR-Ab, compared to 49% of all mechanically ventilated patients in the long term care facilities," she told SHEA attendees.
A. Baumannii was found in 31% of the acute care facilities and at all nine long term care sites. Researchers did molecular typing on the isolates, finding 22 pulse field gel (PFG) groups that involved more than one patient.
"We did see some small clusters of what I will call transmission or isolates that were identical or closely related, both within health care facilities and among different health care facilities within the state," Thom said. One cluster of matching A. baumani strains was found in 13 patients at 7 different health care facilities, including both hospitals and nursing homes.
Thom cautioned against assuming infection control problems in long term care were driving the trend, saying the findings "could just as easily represent the fact that the patients who are at higher risk are the patients who are chronically ill."