Stewardship / Resistance Scan for Feb 20, 2019

Nursing home UTI stewardship
;
Triclosan-induced antibiotic tolerance
;
Staph clindamycin resistance

Nursing home stewardship program focuses on undocumented UTIs

An antimicrobial stewardship intervention targeted to rural nursing homes in Alberta, Canada, significantly decreased the level of urine culture testing and antibiotic prescribing without an increase in hospitalization or mortality, Canadian researchers reported today in Infection Control and Hospital Epidemiology.

Given concerns about antimicrobial overprescribing in nursing home residents who don't meet the clinical criteria for urinary tract infections (UTIs), the investigators examined the impact of an intervention focused on urine testing and appropriate treatment.

The study spanned 42 nursing homes from April 2015 through January 2016, with 21 intervention sites receiving staff education, physician small-group academic detailing sessions, and integrated clinical decision-making tools. Patients at control sites received standard care. The researchers collected data on urine culture testing, antibiotic prescribing, and clinical outcomes 6 months before and 12 months after the stewardship intervention.

The team found statistically significant decreases in the rate of urine culture testing and antibiotic prescribing in the intervention group: -2.1 tests per 1,000 resident days (95% confidence interval [CI], -2.5 to -1.7, P < .001) and -0.7 prescriptions per 1,000 resident days (95% CI, -1.0 to -0.4, P < .001). Researchers estimated that over a year at a 40-bed nursing home, the intervention would result in 31 fewer urine cultures and 10 fewer antimicrobial prescriptions.

"Admissions to acute-care facilities or emergency departments or mortality between the groups did not increase, indicating that reducing antimicrobial therapy did not cause harm," the team wrote. They added that the concepts were well accepted by physicians and other staff members, with reassurances that limiting testing and antibiotic prescribing to those with UTI clinical suspicion would not be harmful.
Feb 20 Infect Control Hosp Epidemiol abstract

 

Study: Triclosan lowers antibiotic efficacy in culture, mouse tests

A new study by researchers with Washington University in St. Louis has found that clinically relevant concentrations of triclosan, an antimicrobial used in a wide range of consumer products, significantly increased bacterial tolerance to antibiotics in vitro and reduced antibiotic efficacy in a mouse urinary tract infection model. The findings appeared yesterday in Antimicrobial Agents and Chemotherapy.

To assess whether physiologically relevant levels of triclosan are sufficient to promote tolerance to bactericidal antibiotics, the researchers cultured Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) in amounts of triclosan similar to the concentration found in the urine of individuals who use triclosan-containing products, then exposed the bacteria to high concentrations of antibiotics. The results showed that triclosan had a dramatic protective effect for the microbes, increasing E coli and MRSA tolerance to the antibiotics as much as 10,000-fold.

To determine whether the tolerance observed in vitro was relevant in vivo, the researchers tested the impact of triclosan on mice with E coli urinary tract infections. In mice with levels of triclosan similar to those reported in human urine, the efficacy of ciprofloxacin was reduced up to 100-fold.

The authors of the study note that although the US Food and Drug Administration banned the use of triclosan in household soap in 2017, other countries have not taken similar action, and the compound is still used in a variety of other consumer products. Approximately 75% of US adults have detectable levels of triclosan in their urine, and as many as 10% have concentrations that are equal to or greater than the minimum inhibitory concentration levels for E coli and MRSA.

"These data highlight an unexpected and certainly unintended consequence of adding high concentrations of antimicrobials in consumer products, supporting an urgent need to reevaluate the costs and benefits of the prophylactic use of triclosan and other bacteriostatic compounds," they write.
Feb 19 Antimicrob Agents Chemother abstract

 

Study notes increase in clindamycin resistance in surgical-site infections

In a research brief today, scientists from Johns Hopkins and the Center for Disease Dynamics, Economics and Policy (CDDEP) report a significant increase in clindamycin resistance in Staphylococcus aureus isolates from surgical-site infections (SSIs).

The retrospective study included all S aureus isolates from SSIs in adult patients at Johns Hopkins Hospital from Jan 1, 2012, through Dec 1, 2017. Among the 109 cultures, clindamycin resistance increased from 20% in 2012 to 38% in 2017 (P < .01), while resistance to tetracycline decreased significantly, from 20% to 0%, during the same period. Trimethoprim-sulfamethoxazole resistance remained relatively stable, increasing from 10% in 2012 to 13% in 2017, while erythromycin resistance decreased from 40% to 29%.

Of 68 cases with available SSI prophylaxis and allergy data, 13 (20%) had a reported penicillin allergy. Also, 5 of these patients received clindamycin even though only 1 had a high-severity reaction on record. Of the 5 patients who received clindamycin, 2 developed a clindamycin-resistant S aureus SSI.

The authors conclude, "Increasing clindamycin resistance in SSIs [S aureus] raises concerns about its use as an alternative surgical prophylaxis agent." They add that improving penicillin allergy documentation and considering alternatives to clindamycin could reduce such cases.
Feb 20 Infect Control Hosp Epidemiol extract

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