The epidemiology of a leading healthcare-associated infection (HAI) is changing. Clostridium difficile, which kills some 15,000 patients annually, is becoming more of a threat in the community as hard-fought progress is made in hospitals.
According to the Centers for Disease Control and Prevention (CDC), national C. diff infection rates declined 7% from 2015 to 2016.
Yet, while healthcare-associated cases are declining, more C. diff cases are coming in from the community. Some suspect that hospitals are doing more testing on admission to ensure that patients who come in with C. diff are not later counted as hospital-acquired. Although that protects the hospital from financial penalties, a concern is that highly sensitive tests may be picking up mere C. diff colonization, which may then be counted as community-associated cases of actual infections.
Although these factors probably are affecting the shift in numbers, the primary driver of the increase in C. diff in the community likely is antibiotic use beyond the hospital, a leading CDC epidemiologist said recently in Minneapolis at the 2018 Association for Professionals in Infection Control and Epidemiology conference.
“I think it’s real,” Arjun Srinivasan, MD, FSHEA, FAPIC, told Hospital Infection Control & Prevention. “Clearly, there are some people who get tested without clear symptoms — they only have diarrhea — but the concern is that the outpatient cases we are seeing probably reflect antibiotic use. We know that there is a lot of fluoroquinolone use in outpatient settings — an antibiotic that is one of the highest risks for C. diff.”
It is well-known that broad-spectrum antibiotics can disrupt the gut microbiome and set up a C. diff infection. That suggests that these community-onset cases, which have no recent history of hospitalization, received antibiotics after visiting a doctor, dental office, or clinic. Another factor that may be contributing to the trend is that antibiotic stewardship programs are being heavily emphasized in hospitals, but may still be in more rudimentary stages in community care.
In presenting a session on C. diff and other hospital infections, Srinivasan cited data collected by 10 CDC Emerging Infections Program (EIP) sites nationally.
“We are actually seeing decreases in healthcare-associated C. diff, but we are seeing increases in cases of C. diff that have community onset,” he told APIC attendees. “This is a really important distinction that we are seeing.”
Indeed, data from the EIP sites show that the healthcare-associated C. diff rate per 100,000 people fell from 93 cases in 2012 to 83 cases in 2015. Conversely, community-associated C. diff by that same population measure went from 53 cases per 100,000 in 2012 to 66 cases in 2015.
Improved antibiotic use through stewardship is likely the most important issue for both hospital and community-onset cases.
“That is probably the biggest bang for our buck,” he said. “There are studies that suggest that there is only so much we are going to be able to do with improved environmental cleaning. That remains very important, but the biggest yield is likely to come from efforts in improving antibiotic use.”
There also is a need for diagnostic stewardship, not only to prevent unnecessary testing for C. diff, but to improve urine culturing practices, he said.
“More often than not, those cases of asymptomatic bacteriuria that are diagnosed get treated with a quinolone,” Srinivasan said.
With 2015 as the baseline, the CDC and public health partners are trying to reduce C. diff 30% by 2020. The changing epidemiology of the infection may complicate that, and other targeted infections are proving difficult as well.
MRSA and CAUTIs
For example, the 2020 goal is a 30% reduction in catheter-associated urinary tract infections (CAUTIs). Methicillin-resistant Staphylococcus aureus (MRSA) infections — both invasive and facility-onset — are targeted for a 50% reduction.
The MRSA goal is looking unreachable, Srinivasan said.
“We are seeing modest progress in preventing hospital-onset MRSA bacteremia,” he said. “A 6% reduction from 2015 to 2016. It’s not zero, but certainly not enough to make a 50% reduction over five years.”
That has raised the question of alternative strategies, both antibiotic stewardship efforts and considerations of decolonizing patients. “Should we be doing decolonization in select patients at the time of discharge in order to reduce the risks of post-discharge MRSA bacteremias?” he said.
CAUTI reductions are somewhat more encouraging, though surveillance has been complicated by a definition change in 2015. At the suggestion of infection preventionists, the CDC removed yeasts as a cause of CAUTI infections.
“We changed the CAUTI definition because you educated us that we could do a better job with the definitions, so keep that up,” he told APIC attendees. “These are good definitional changes because it helps focus the surveillance on the infections we think can be prevented, and frankly are the ones that are actually infections.”
The CDC is seeing encouraging drops in urinary catheter use, which has been a major emphasis for prevention. “Much of our focus has been to get the catheters out,” Srinivasan said.
Of course, removing catheters is more problematic in the ICU, where little patient mobility is expected. “There was some progress in ICUs, but we saw substantially more progress in ward locations,” he said.
The CDC is trying to expand diagnostic stewardship efforts to eliminate catheter-associated asymptomatic bacteriuria masquerading as CAUTIs, he said.
“If the culture is not sent, then there is not a CAUTI,” Srinivasan said. “We really need to help people understand appropriate sending of urine cultures, especially in nursing home settings.”
The ongoing struggle to reduce C. diff, CAUTIs, and MRSA infection is in sharp contrast to the dramatic reduction in central line-associated bloodstream infections (CLABSIs). With significant reductions in the last few years, and the CDC on target for a 50% reduction by 2020, CLABSIs are “the greatest success story” in the modern infection prevention era, he said.
“I don’t think it’s debatable,” he said. “Success with CLABSIs fundamentally changed the way we talk about HAIs. A decade ago the dogma was that some of these infections might be preventable if you really worked hard at it, but not that many of them.”
However, with the realization that a simple checklist to standardize catheter insertion could prevent many infections, the notion of inevitable infections was finally debunked. The paradigm shifted to many, if not most, HAIs are preventable. “Some people are saying almost all of these infections are preventable,” he said.
In addition, because it was the clinical staff changing practice to prevent CLABSIs, the success reinforced the notion that infection prevention is the broader responsibility of all staff. Infection control is now more frequently seen as the job of frontline providers with support from IPs and healthcare epidemiologists.
“This has obviously not happened everywhere, but we are beginning to see this shift,” he said.
“The CLABSI work was led by clinical teams in ICUs with support from infection prevention. It really shifted that model to it is the job of frontline providers to prevent infections,” he added.
The success in reducing these bloodstream infections emboldened the Centers for Medicare & Medicaid Services to demand reductions in other HAIs, increasing the use of public reporting and pay-for-performance incentives to reduce infections.
“All that we do now, I would argue, was built on the foundation that CLABSI [reductions] established,” Srinivasan said. “We have seen success, but we are not exactly where we want to be.”
There still are individual unit locations — in fact, entire hospitals — followed in CDC surveillance that have CLABSI rates twice the national average, he said.
“What is keeping them from seeing the same success that we see in so many other places?” he said. “We have seen success in so many different types of hospitals. We can no longer say they must have sicker patients or more complex cases.” Some question remains whether the success of preventing CLABSIs in the ICU can be duplicated on hospital wards.
“It is encouraging that in 2015 to 2016 we did see more aggressive prevention in wards,” he said. “Over 50% of CLABSIs now occur in ward locations. That wasn’t always the case.”
Understandably, most of the reductions in CLABSIs have been related to proper central catheter insertion, which has been the focus of the well-known checklist of aseptic technique. “We’ve seen Staph aureus and MRSA drop dramatically,” he said.
“We have not seen as many reductions in infections caused by gram-negatives or Candida — things that wouldn’t necessarily be influenced by putting in the catheter better. Those are likely catheter maintenance issues.”
This corresponds to infection prevention beyond the ICU as well, as catheter maintenance is more of an issue in ward patients, he said.