CDC Studies Show Decline in C. difficile and Multidrug-Resistant Bacteria In USA Hospitals

Published April 2, 2020

Declines in C diff

2011 – 2017

The decline in C difficile infections may be another sign of improved infection prevention and antibiotic stewardship in US hospitals

C difficile, a bacterium that causes severe diarrhea, is the primary cause of hospital-associated diarrhea and is linked primarily to broad-spectrum antibiotic use, which can disrupt the balance of bacteria in the gut. Reduction of C difficile prevalence has been among the goals of efforts to improve infection prevention and antibiotic use in US hospitals over the past decade.

To assess progress in reducing C difficile infections, CDC researchers used data from the Emerging Infections Program (EIP), which conducts C difficile surveillance in 35 counties in 10 states.

As with the other study, they classified infections as either healthcare-associated or community-associated. Although primarily considered an infection that affects hospital patients, C difficile infections in people with no recent hospital or nursing home stays have been on the rise.

The researchers also adjusted their findings to account for increased use of nucleic acid amplification testing (NAAT) over the study period. NAAT is more sensitive than other types of
C difficile testing but cannot distinguish between colonization and infection, which has raised concerns about overdiagnosis.

The percentage of cases diagnosed using NAAT at the EIP hospitals increased from 55% in 2011 to 83% in 2017.

The initial estimate showed a small decline in the total national burden of C difficile infection—from 476,000 cases (154.9 cases per 100,000 population) in 2011

to 462,100 cases (143.6 cases per 100,000 population) in 2017.

But after adjusting NAAT use to the 2011 rate of 55%, total
C.  difficile
infections fell by 24% from 2011 through 2017, driven by a 36% decrease in healthcare-associated infections.

Total hospitalizations for C difficile infection fell by 24%.

The adjusted estimate for community-associated C difficile infections—which accounted for 50% of all infections in 2017—saw no change.

The authors of the study say the reductions in healthcare-associated C difficile could be linked to better adherence to recommended infection-prevention practices, as well as to reduced use of fluoroquinolone antibiotics in hospitals.

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In the midst of the COVID-19 pandemic, new data published today in the New England Journal of Medicine (NEJM) provides a glimmer of good news on the infectious disease front.

A study conducted by researchers from the Centers for Disease Control and Prevention (CDC) found that the incidence of infections caused by four multidrug-resistant (MDR) organisms (MDROs) decreased in US hospitals from 2012 through 2017, with the declines ranging from 20% to 39%. While the burden of MDR infections in US hospitals remains substantial, and more work is need to sustain the progress that’s been made, the authors of the study say the findings, which formed the basis for the CDC’s 2019 report on antibiotic resistance, are encouraging.

“For some resistant pathogens, encouraging reductions have been observed in recent years, suggesting that current prevention efforts, particularly infection control interventions focused on healthcare settings, are yielding important benefits,” lead author John Jernigan, MD, of the CDC’s Division of Healthcare Quality Promotion, told CIDRAP News.

In another study today in NEJM, a different team of CDC researchers reported that the national burden of Clostridioides difficile infection and associated hospitalization decreased by nearly a quarter from 2011 through 2017, largely owing to a decline in healthcare-associated C difficile infections.

Declines in 4 MDR pathogens

For the study on MDR infections, Jernigan and his colleagues used electronic health record data from 890 US short-term acute care hospitals to generate a national case count and examine temporal trends for infections caused by the primary MDR pathogens associated with healthcare: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), carbapenem-resistant Enterobacteriaceae (CRE), carbapenem-resistant Acinetobacter species, MDR Pseudomonas aeruginosa, and extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae.

In 2017, these pathogens, which are considered urgent or serious threats by the CDC because they can cause severe, hard-to-treat invasive infections and spread easily in healthcare settings, caused an estimated 622,390 infections among hospitalized patients. Of these cases, 83% (517,818) were community-onset (either obtained in the community or within the first 3 days of hospitalization) and 17% (104,572) were hospital-onset.

From 2012 through 2017, the researchers found that the incidence decreased for infections caused by MRSA (from 114.18 to 93.68 cases per 10,000 hospitalizations), VRE (24.15 to 15.76 cases per 10,000 hospitalizations), carbapenem-resistant Acinetobacter species (3.33 to 2.47 cases per 10,000 hospitalizations), and MDR P aeruginosa (13.10 to 9.43 cases per 10,000 hospitalizations). There was no significant change on the incidence of CRE infections (3.36 to 3.79 cases per 10,000 hospitalizations).

Although the study did not determines the reasons for these declines, Jernigan says it’s likely that improved infection prevention and control efforts in hospitals have contributed to reducing the spread of these pathogens, particularly MRSA and VRE, which tend to be prevalent in patients who’ve had a lot of healthcare exposure. The incidence of hospital-onset MRSA and VRE declined nearly twice as fast as in community-onset cases.

“During the past decade, healthcare decision makers have placed increased emphasis on infection control in healthcare, including efforts to improve implementation of strategies for preventing device- and procedure-related infections and general infection control measures such as hand hygiene,” he said. “In addition, there has been widespread implementation of MDRO-specific measures designed to prevent healthcare transmission of the pathogens we studied, and many healthcare systems have increased emphasis on antimicrobial stewardship as well.”

Neil Clancy, MD, an associate professor of medicine and infectious disease specialist at the University of Pittsburgh who was not involved in the study, says the data are a welcome bright spot as the nation grapples with the COVID-19 pandemic.

“Taken together, these data suggest that national efforts over the past decade in antimicrobial stewardship and infection prevention, many led by CDC, are making a positive impact on AMR [antimicrobial resistance] in this country,” Clancy said. He’s particularly encouraged by the declines in two of the most worrisome MDR gram-negative (GN) pathogens—carbapenem-resistant Acinetobacter and MDR Pseudomonas.

“Although infections by these pathogens are less common than those caused by MRSA, there are fewer antibiotics active against MDR-GNs,” he said. “Moreover, these bacteria are often acquired by very sick patients in the hospital, so their impact on death and poor outcomes in general is high.”

Notes of caution

But there’s some bad new with the good news. The study also found a 53% rise in incidence of infections caused by ESBL-producing Enterobacteriaceae, largely driven by an increase in community-onset infections. The authors hypothesize that this increase could be linked to Escherichia coli sequence type (ST)131—an epidemic MDR E coli strain that has become a primary cause of antibiotic-resistant infections worldwide and is the most common cause of urinary tract infections.

“More widespread emergence of ESBL bacteria, particularly among otherwise healthy people who are not in the hospital or nursing homes, but rather living in the community, is a potential public health nightmare,” said Clancy, noting that infections caused by ESBL bacteria are also problematic because there are currently no active oral antibiotics for treating them.

Clancy also pointed out that, with 83% of the MDR infections found to be originating in the community, it’s not only the sick people in hospitals who need to worry about those infections.

“The study serves as a reminder that antimicrobial resistance, over the long-term, is as big a public health threat as emerging viral pandemics,” he said.

In an editorial that accompanies the study, infectious disease experts from the University of Washington and the University of California, San Diego, say the results of the study suggest that when it comes to antibiotic resistance, the glass is half full. While the observed reductions indicate that progress is being made, the rise in community-onset MDR infections, and the dwindling pipeline of new antibiotics, underscore the challenges that remain and the need for innovative approaches.

“We cannot afford to be complacent about recent progress in the health care setting, because resistant pathogens are still too common in most institutions, and favorable trends can be readily reversed,” they write. “Moreover, the continued presence of MDR organisms and the rapid emergence of antimicrobial resistance to recently introduced agents mean that new strategies for the treatment of infections by MDR organisms must continue to be a high priority.”

Jernigan agrees.

“Innovative interventions and strategies, tailored for the spectrum of healthcare and community settings, will be needed to sustain progress in combating antibiotic resistance,” he said.

 

Source: https://www.cidrap.umn.edu/news-perspective/2020/04/cdc-studies-show-drop-mdr-bacteria-c-diff-us-hospitals