Stewardship / Resistance Scan for Jan 11, 2018

MCR-4 in humans
Antibiotics in early pregnancy
Nasal screen for MRSA pneumonia

Italian scientists report first MCR-4 isolates from human samples

Scientists from Italy today reported detecting the worrisome colistin-resistance gene MCR-4 in two isolates of Salmonella from people, only the second time the gene has been reported and the first time in humans, according to their report in Eurosurveillance.

Chinese researchers first reported the MCR-1 gene in Escherichia coli from pigs, pork products, and humans in 2015. Since then, the gene has been detected in bacteria from animals and humans in more than 30 countries, and MCR-2 and MCR-3 have been identified, as well. The MCR-4 gene was first identified last August in the same journal by a mostly different group of Italian researchers.

The genes are of particular concern because they are located on plasmids, which are small, highly mobile pieces of DNA that can spread resistance within and between different species of bacteria. They confer resistance to colistin, a last-resort antibiotic used to treat multidrug-resistant infections.

In today's report, the investigators said the MCR-4 genes were identified in two Salmonella Typhimurium isolates collected in October and November 2016 from separate Italian patients.

They conclude, "To our knowledge, this is the first report of mcr-4-positive bacterial isolates of human origin. The two Salmonella species belonged to the same serovar as the first mcr-4-positive Salmonella strain reported in a pig slaughtered in Italy."
Jan 11 Eurosurveill report
Aug 3, 2017, CIDRAP News story on first identification


CDC notes inappropriate UTI antibiotic prescribing in early pregnancy

Because of concern over birth defects, sulfonamides and nitrofurantoin are not recommended for treating urinary tract infections (UTIs) in the first trimester of pregnancy unless other options are deemed inappropriate. But more than 40% of pregnant women with UTIs receive those antibiotics early in pregnancy, experts with the Centers for Disease Control and Prevention reported today in Morbidity and Mortality Weekly Report (MMWR).

The researchers analyzed insurance data for pregnant women in 2014. Of 14,286 women diagnosed as having a UTI in the first trimester, 9,846 (68.9%) received antibiotics. The most-prescribed antibiotics were nitrofurantoin (34.7%), ciprofloxacin (10.5%), cephalexin (10.3%), and trimethoprim-sulfamethoxazole (7.6%).

Which means that, in spite of American College of Obstetricians and Gynecologists guidelines recommending against sulfonamides and nitrofurantoin unless absolutely necessary, 42.3% of women in their first trimester of pregnancy received them to treat UTIs.

The authors conclude, "Given the recommendations to avoid nitrofurantoin and trimethoprim-sulfamethoxazole in early pregnancy if possible, it is important that health care providers of various specialties be familiar with these recommendations and that they consider that they might be 'treating for two' when prescribing antibiotic treatments for urinary tract infections to pregnant women and women who might become pregnant in the near future."
Jan 12 MMWR study


Review highlights utility of nasal screening for MRSA pneumonia

A meta-analysis of 22 studies has found that nasal screening for methicillin-resistant Staphylococcus aureus (MRSA) had a high specificity and negative predictive value (NPV) for ruling out MRSA pneumonia and may be an important antibiotic stewardship tool, according to a study today in Clinical Infectious Diseases.

US researchers pooled the data from the studies, which covered 5,163 patients. Overall sensitivity and specificity for nasal screening for all MRSA pneumonia types was 70.9% and 90.3%, respectively. Positive predictive value (PPV) was 44.8%, while NPV was 96.5%. Sensitivity and specificity for community-acquired and healthcare-associated MRSA pneumonia was 85.0% and 92.1%, respectively, while PPV and NPV increased to 56.8% and 98.1%, respectively.

The authors conclude, "Utilization of MRSA nares screening is a valuable tool for [stewardship programs] to streamline empiric antibiotic therapy."
Jan 11 Clin Infect Dis study

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