Findings conflict on C diff rates in acute vs long-term care

Two new studies offer somewhat conflicting signals on the comparative rates of Clostridium difficile infections (CDIs) in hospitals and nursing homes, with one team finding a higher prevalence in nursing homes and the other reporting much higher incidence in acute-care hospitals (ACHs).

And in other C diff findings, a team in Thailand found that about 22% of isolates from patients at a Bangkok hospital were resistant to three or more antibiotics.

C diff causes about a half million infections and 15,000 deaths in the United States each year, according to estimates from the Centers for Disease Control and Prevention.

Detroit study finds more C diff in long-term care

The study reporting more C diff in long-term care facilities (LTCFs) came from researchers at Detroit Medical Center and Wayne State University and was published yesterday in the American Journal of Infection Control.

The team reviewed the results of CDI tests conducted from January 2011 through January 2014 for 8 ACHs, 16 LTCFs, and 45 outpatient clinics in the Detroit area. The tests, conducted in a central laboratory, were on unformed stools only, and diagnoses were based strictly on the test results, without use of clinical criteria.

A total of 24,009 polymerase chain reactions tests for CDI were included in the review. Positive tests were most prevalent among LTCF patients, at 33.3%, followed by ACH patients, with 15%, and outpatients, at 12.8%.

The authors said one LTCF—which was located inside an ACH and run by ACH staff—had a "surprisingly low" rate of CDI, at 12.1%. This facility averaged about 26 CDI tests per month, far more than most other LTCFs in the study.

"We strongly believe that C difficile carriage and unsuspected clinical CDI is increasing in LTCFs. The transmission from these patients to vulnerable hosts is clearly possible and might explain the high CDI prevalence noted in our study," the authors concluded.

VA study points the other way

The contrasting findings came from a 6-year study that aimed to delineate CDI incidence and risk factors in ACHs and LTCFs run by the US Veterans Health Administration. The report was also published yesterday in Clinical Infectious Diseases.

Conducted by a Canadian-American team, the effort was a case-cohort study of people who spent at least 3 days in one of 131 ACHs or 120 LTFCs between 2006 and 2012. The team looked specifically for facility-onset cases—ie, lab-confirmed cases in patients who had had no positive CDI test in the previous 8 weeks.

The researchers found that CDI incidence was five times as high in ACHs as in LTCFs: a median of 15.6 versus 3.2 cases per 10,000 person-days. The level of antibiotic use in the preceding 56 days was higher in acute care than in long-term care facilities, with a median of 739 versus 513 instances per 10,000 person-days, and this explained 72% of the difference in infection incidence, the authors said.

The study also revealed that C diff cases were about three times as likely to be imported from an ACH into an LTCF as the other way around, with a median of 52.3 versus 16.2 imported cases per 1,000 person-days.

"Facility-level antibiotic use was the main factor driving differences in C. difficile infection incidence between acute and long-term care," the researchers concluded. "Importation of acute care C. difficile cases was a greater concern for long-term care as compared to importation of long-term care cases for acute care."

Resistant C diff in Thailand

In the study from Thailand, Thai and Australian researchers sought to remedy a lack of data on the antimicrobial susceptibility of C diff in the country. Writing in Antimicrobial Resistance and Infection Control, they said only three previous studies have focused on this topic, and two dated back to the 1990s.

The team tested 105 C diff isolates for their susceptibility to nine antimicrobials. The isolates came from patients at Bangkok's Siriraj Hospital in 2015. Overall, the researchers found that 21.9% of the isolates (23 of 105) were resistant to three or more antimicrobials.

"All isolates were susceptible to vancomycin, metronidazole, amoxicillin/clavulanate and meropenem," the report says. "Resistance to clindamycin, erythromycin and moxifloxacin was observed in 73.3%, 35.2% and 21.0% of the isolates, respectively."

The team found that rifaximin showed "potent activity" against 85.7% of the isolates and had the lowest minimum inhibitory concentration of the nine drugs tested.

The authors said their findings point up the need for enhanced antimicrobial stewardship and programs to improve awareness of C diff and appropriate use of antimicrobials.

See also:
Jun 8 Am J Infect Control (Detroit) study

Jun 8 Clin Infect Dis (VA) study abstract

Jun 8 Antimicrob Resist Infect Control report

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