Our weekly wrap-up of antimicrobial stewardship & antimicrobial resistance scans

Drug-resistant leprosy reported in West Africa

An international team of researchers is reporting transmission of antibiotic-resistant leprosy in Guinea.

Using molecular methods, the team tested skin biopsy samples from 24 patients—one relapse case and 23 new cases—collected in the country from 2012 to 2015. Whole-genome sequencing revealed mutations in four of the samples. In one of them the researchers found a mutation previously associated with high-level rifampicin-resistant leprosy. In the three other samples, they found a mutation associated with dapsone-resistant leprosy that has not been identified anywhere else. All four drug-resistant cases occurred by transmission.

The authors say this is the first time that cases of primary rifampicin- and dapsone-resistant leprosy have been identified in West Africa, and that's a concern because rifampicin and dapsone are two of the first-line drugs used in multidrug treatment of leprosy. While dapsone-resistant strains have been around since the 1970s (and prompted the introduction of multidrug therapy), the authors warn that the emergence of these strains could have a serious effect on leprosy control programs, because of the lack of effective alternative drugs.

An accompanying commentary says the findings indicate the need to increase monitoring for antibiotic-resistant leprosy in countries with low, middle, and high levels of the disease. Guinea, which reported 313 cases of leprosy in 2014, has a moderate leprosy burden.

The study was published Aug 23 in Clinical Infectious Diseases.
Aug 23 Clin Infect Dis abstract
Aug 23 Clin Infect Dis commentary (subscription or fee required)

Most adults with bronchitis receive unnecessary antibiotics

Originally published Aug 25.

A new study from the Centers for Disease Control and Prevention (CDC) has found that more than three quarters of adults diagnosed as having bronchitis receive an antibiotic, despite the fact that antibiotics are not indicated for the condition.

The study, published in the American Journal of Managed Care, analyzed three measures related to antibiotic prescribing from the Healthcare Effectiveness Data and Information Set (HEDIS), a tool used by more than 90% of the nation's health plans to evaluate performance on important dimensions of care. Two of the measures focused on the pediatric population (appropriate testing for pharyngitis and appropriate treatment for upper respiratory infections), and the third measured avoidance of antibiotics in adults with acute bronchitis.

The researchers examined data for the years 2008 to 2012, and the data set included only commercial health plans. For each measure, a higher percentage indicated a better performance.

The results indicated that health plans generally performed well on the first two measures, with an average of 77% performing appropriate testing for pharyngitis and 84% treating upper respiratory infections in children appropriately (without antibiotics).

But only 24% avoided antibiotic treatment for adults with bronchitis. And that number grew worse over time. In 2008, 26.6% of health plans avoided prescribing antibiotics for bronchitis; in 2012 antibiotic avoidance for adults with bronchitis was 22.7%. The authors concluded that interventions to improve antibiotic use should target providers who treat adults.

Geographic variations in health plan performance were observed as well, with health plans in southern states generally having lower scores than other parts of the country on all three measures. But health plans in New England had the lowest score (21.9%) when it came to avoiding antibiotic treatment for adults with bronchitis.

"Though drastic improvement is needed in the South, the data suggests that there are opportunities to improve antibiotic prescribing across the United States," Lauri Hicks, DO, co-author of the study and director of the CDC's Office of Antibiotic Stewardship, said in a statement.
Aug 17 Am J Manag Care study

Prevalence of MRSA in diabetic foot infections low, but antibiotic use high

Originally published Aug 25.

A study yesterday suggests that antibiotic therapy targeted against methicillin-resistantStaphylococcus aureus (MRSA) may be overused in patients with diabetic foot infections (DFIs).

The study, published in PLoS One, included 318 patients treated at a Texas hospital from 2010 to 2014 for diagnosed DFIs, the leading cause of non-traumatic lower extremity amputations in the United States.

Because limited data exist to support the recommendation that DFI patients with associated risk factors be treated with antimicrobials active against MRSA, the researchers wanted to determine prevalence of MRSA DFIs at the institution and compare that with the proportion of patients who received MRSA antibiotic coverage. They also wanted to identify risk factors for MRSA DFI.

What the researchers found was that while S aureus was present in 46% of culture-positive DFIs, MRSA was present in only 15% of the infections. Yet 86% (273) of the DFI patients received MRSA antibiotic coverage, resulting in 71% unnecessary use. In a multivariable analysis, male gender and bone involvement were found to be independent risk factors for MRSA in DFIs.

The authors said knowledge of MRSA prevalence in DFI patients, as well as the factors that might make certain patients more likely to be infected by MRSA, could help guide clinician decision-making and aid in antimicrobial stewardship efforts. They also called for larger epidemiologic investigations.
Aug 24 PLoS One study

Researchers report antibiotic resistant E coli in French drinking water

Originally published Aug 22.

A team of French researchers today reported the detection of antibiotic resistant Escherichia coli in French drinking water supplies.

In a study published in Antimicrobial Agents and Chemotherapy, the researchers described finding a single E coli isolate containing an extended-spectrum beta lactamase (ESBL) gene similar to those previously found in humans and animals. The isolate was found among drinking water samples from 28 water supply systems located throughout France, taken from where water enters the distribution system. The locations were chosen because of multiple water quality failures.

E coli was found in all the samples, but six isolates from six different water supplies were found to be resistant to at least one antimicrobial. Sequencing indicated that the isolate that was resistant to several antimicrobials harbored an ESBL-carrying plasmid. ESBLs are resistant to many penicillin and cephalosporin antibiotics.

While resistance-carrying genes have been detected in drinking water in low-income nations with poor sanitation and unregulated antibiotic use, the researchers said their study is likely the first report of an ESBL-producing bacterium in drinking water in a high-income country. Although the water supply where the isolate was found has been repaired, and the isolate would probably not have been pathogenic to humans, the concern is that the reservoir for antibiotic resistance is expanding.

"All potential reservoirs—human, animal, and environmental—are now contaminated by extended spectrum beta-lactamases," said Marisa Haenni, PhD, senior scientist with the Agency for Food, Environmental, and Occupational Health & Safety in Lyon, France, in a news release from the American Society for Microbiology (ASM), which publishes the journal.

"Though this contamination strongly varies, depending on the studied reservoir and country, no one is protected from the sporadic presence of ESBLs in places that should be free of this resistant bacterium."
Aug 22 Antimicrob Agents Chemother abstract
Aug 22 ASM news release