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MRSA rates, effectiveness of ICU gowns and gloves, and more.

MRSA rates down from 2005-2011

There were fewer invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in the U.S. in 2011 than in 2005, and the reduction was greatest for health care-associated infections, a recent study found.

Researchers used data from the CDC's Emerging Infections Program-Active Bacterial Core surveillance program to compare MRSA incidence rates from January through December of 2005 and 2011. About 16.5 million people underwent surveillance in 2005 and about 19.4 million underwent surveillance in 2011, in both years from the same 9 metropolitan areas. Cases were defined as hospital-onset if a culture was taken after hospital day 3. Health care-associated community onset (HACO) meant a culture was taken as an outpatient on or before hospital day 3 in a patient with a documented health care risk factor. Community-associated cases were the same as HACO cases except patients lacked a documented health care risk factor. Results were published in the Nov. 25, 2013, JAMA Internal Medicine.

From 2005 to 2011, hospital-onset infections decreased by 54.2%, HACO infections decreased by 27.7%, and community-associated infections decreased by 5.0%. The combined decrease of invasive MRSA infections was 31.2%, with an estimated 80,461 (95% CI, 69,515 to 93,914) infections in 2011 compared to 111,261 in 2005. In 2011, there were an estimated 48,353 HACO infections, 14,156 hospital-onset infections and 16,560 community-associated infections. Of the community-onset (nondialysis) infections in previously hospitalized patients, 64% occurred within 3 months after discharge, and 32% of these were admitted from long-term care facilities.

This is the first time since the CDC started tracking MRSA incidence that hospital-onset infections were fewer than community-associated infections, the authors noted. The reduction of hospital-onset infections could be due in part to greater awareness and implementation of infection-prevention measures, they wrote, adding that MRSA infections with community- or outpatient-onset “remain problematic.”

Gowns and gloves in ICU didn't reduce MRSA/VRE colonization

Employing universal contact precautions in the ICU didn't reduce patients' acquisition of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) compared to usual care.

The trial included 20 medical and surgical ICUs in the U.S. and more than 25,000 patients studied from January to October 2012. The ICUs were randomized to either have all health care workers wear gloves and gowns when entering any patient room or to follow their usual practices. Surveillance cultures for MRSA and VRE were collected on admission and discharge from the ICU. Results were published in the Oct. 16, 2013, Journal of the American Medical Association.

The researchers collected a total of 92,241 swabs. Both intervention and control ICUs decreased patients' acquisition of MRSA or VRE during the study period, and there was no significant difference between the groups (intervention ICUs: from 21.35 acquisitions per 1,000 patient-days to 16.91 per 1,000; control ICUs: from 19.02 acquisitions per 1,000 to 16.29 per 1,000; P=0.57 for difference). When the bacteria types were separated, the researchers did find a significant difference in acquisition of MRSA, although not VRE. Intervention ICUs reduced MRSA acquisitions by 2.98 per 1,000 patient-days more than controls (P=0.046).

The study also found some significant differences in secondary outcomes. Intervention ICUs had reduced health worker room entry (4.28 vs. 5.24 entries per hour; P=0.02) and increased hand hygiene compliance as workers exited patient rooms (78.3% vs. 62.9%; P=0.02) compared to controls. The rate of adverse events did not differ significantly between the groups.

This first cluster randomized trial of universal gowns and gloves in the ICU requires further confirmation, the study authors concluded. It was surprising that MRSA rates were affected, but not VRE rates. This finding could be explained by different bacteria having different methods of transmission or by VRE being more difficult to find on admission. Compliance with the intervention was high, and the intervention costs less than many other methods to decrease transmission of these bacteria. The finding that adverse events were not increased by the precautions conflicts with some previous research but could provide reassurance that this intervention is safe, the authors concluded.

It's possible that patients suffered unmeasured forms of harm, such as feelings of isolation, according to an accompanying editorial, which called for replication of the study's results. The burden of wearing gloves and gowns should also be considered. Still, the universal precaution approach may be worth considering as part of an overall strategy to prevent infections, especially in high-risk settings with high prevalence of MRSA, the editorial concluded.

Tight ICU resources may spur more efficient discharge

When ICU resources are strained, patients may be discharged from the ICU faster and, while they are more likely to be readmitted to the ICU, their overall short-term outcomes are unaffected, a recent study found.

In a retrospective cohort study, researchers reviewed heath records for 200,730 adults discharged from 155 ICUs in the U.S. between 2001 and 2008. They sought to determine how 3 metrics of ICU capacity strain, ICU census, new admissions and average acuity, affected ICU length-of-stay (LOS) and post-ICU discharge outcomes. The 3 metrics were measured on days of patient discharge to hospital floors. The post-ICU discharge outcomes were 72-hour ICU readmissions, subsequent in-hospital death, post-ICU discharge LOS and hospital discharge destination.

All 3 metrics of ICU strain were associated with shorter ICU LOS (all P<0.001) and greater odds of ICU readmission (all P<0.050). Specifically, the difference between the 5th and 95th percentiles of strain was a 6.3-hour reduction in ICU LOS (95% CI, 5.3 to 7.3 hours) and a 1.0% increase in the odds of ICU readmission (95% CI, 0.6% to 1.5%). None of the strain metrics was significantly associated with risk of subsequent in-hospital death, being discharged home from the hospital, or longer total hospital LOS. Results appeared in the Oct. 1, 2013, Annals of Internal Medicine.

When ICU resources are strained, physicians may be more apt to efficiently discharge patients without negative repercussions on outcomes, the authors concluded.

Nosocomial C. difficile sources may be more community-based than previously thought′

Genetically diverse, community-based sources of Clostridium difficile may play a larger role in nosocomial transmission than previously thought, a study found.

Researchers performed whole-genome sequencing on isolates obtained from patients with C. difficile infection identified through health care or community settings in Oxfordshire, U.K., from September 2007 through March 2011. The researchers looked at single-nucleotide variants (SNVs) between the isolates. Genetic relationship was defined as ≤2 SNVs between the 2 isolates.

Results appeared in the Sept. 26, 2013, New England Journal of Medicine.

Of 957 sequenced isolates from patients with C. difficile infection, 333 (35%) were genetically related to at least 1 isolate from a previous case, and 428 (45%) had more than 10 SNVs. Of the 333 patients with genetically related isolates, 126 (38%) had ward contact with a previous genetically related case, 5 (2%) were linked only by possible ward-based contamination after the discharge or recovery of an infectious patient, 29 (9%) shared time in the same hospital but were never on the same ward, and 21 (6%) had both ward contamination and hospital-wide contact.

However, the remaining 152 patients (46%) had no hospital-based contact. Of these patients, 15 (10%) were patients at the same general medical practice, and 17 (11%) lived in the same postal-code district. Overall, 120 patients (36%) had no hospital or community contact with a previous genetically related case, and when researchers looked back at unlimited infectious, incubation, and ward-contamination periods, 68 patients (20%) still had no hospital or community contact.

The researchers noted that since 45% of cases had sufficient genetic diversity to represent transmission originating from sources other than the cases that were included in the study, and since distinct subtypes of infection continued to be identified throughout the study, there may be a considerable reservoir of C. difficile in the community.

The authors noted several changes to antibiotic prescribing habits across the U.K. during the study period, including the reduction in use of fluoroquinolones and cephalosporins.

“The incidence of genetically distinct C. difficile cases was similar to that of genetically related cases,” the authors wrote. “This finding suggests that interventions to reduce susceptibility to disease in exposed patients (e.g., changes in the use of antibiotics or specific types of antibiotics), rather than just to reduce transmission of C. difficile from symptomatic patients, might have played a major role in reductions in the incidence of C. difficile infection in the region during the past 5 years.”

An accompanying editorial noted that the study challenges the idea that symptomatic patients in hospitals account for most C. difficile transmission and infection: “The major implication of the study is that control of C. difficile will require that we move beyond the usual suspects (symptomatic patients in hospitals).”

CDC: C. diff, CRE top list of bacterial threats to U.S. health

Clostridium difficile, carbapenem-resistant Enterobacteriaceae (CRE), and drug-resistant Neisseria gonorrhoeae are the most urgent bacterial threats to health in the U.S., the CDC said in a recent report.

The report, “Antibiotic Resistance Threats in the United States, 2013,” categorizes 18 organisms as “urgent,” “serious” or “concerning.” The serious threats include: multidrug-resistant Acinetobacter and Pseudomonas aeruginosa; drug-resistant Campylobacter, non-typhoidal Salmonella, Salmonella typhi, Shigella, Streptococcus pneumoniae and tuberculosis; fluconazole-resistant Candida; extended-spectrum ≤-lactamase-producing Enterobacteriaceae; vancomycin-resistant Enterococcus; and methicillin-resistant Staphylococcus aureus. The concerning threats are vancomycin-resistant Staphylococcus aureus, erythromycin- resistant group A Streptococcus and clindamycin-resistant group B Streptococcus, the report said.

For each of the bacterial threats, the report includes an overview of the organism and associated health conditions, what the CDC is doing to combat the threat, recommendations for the health care community and for patients, and links to more resources. Generally, to fight the spread of resistance, the CDC is supporting 4 core actions:

  • Preventing infections from occurring and resistant bacteria from spreading
  • Tracking resistant bacteria
  • Improving antibiotic use
  • Promoting development of new antibiotics and new diagnostic tests for resistant bacteria

Antibiotic-resistant infections kill at least 23,000 people each year and make at least 2 million people ill, the report said. The CDC's Antibiotic Stewardship Drivers and Change Package includes interventions to help combat resistance, the report said.