MCR-1 E coli found in cluster of New York City liver transplant patients
A study yesterday in Antimicrobial Agents and Chemotherapy describes the detection of MCR-1-carrying Escherichia coli in three liver transplant patients at a New York City hospital.
The three patients at Columbia University Irving Medical Center were found to be colonized with MCR-1–carrying E coli in 2015 after undergoing liver transplants. MCR-1, which confers resistance to the last-resort antibiotic colistin, was first discovered in China in 2015 and has since spread to more than 30 countries. To date, 53 US cases have been reported, but this report represents the earliest documented healthcare-related cluster of MCR-1 in the country.
Two of the liver transplant patients (patients 2 and 4) were epidemiologically linked, potentially through same-day endoscopic procedures, to an index patient (patient 1) who had been infected with MCR-1 E coli and successfully treated. Patient 2 underwent endoscopic retrograde cholangiopancreatography (ECRT) on the same day as patient 1 in March 2015, and then underwent ECRT again in September 2015, on the same day that patient 4 underwent gastroduodenoscopy. Patient 3 had no epidemiologic links to the other cases. The three colonized patients did not experience infections in more than 2 years of follow-up.
Multi-locus sequence typing indicated that all the MCR-1 E coli isolates belonged to sequence type (ST)117 and were related, and whole-genome sequencing revealed that, in addition to carrying MCR-1 on identical plasmids, the isolates also harbored resistance genes for beta-lactams, aminoglycosides, sulphonamides, trimethoprim, macrolides, chloramphenicol, and tetracyclines. Retrospective molecular screening of more than 500 samples (cephalosporin-resistant E coli isolates and discarded surveillance rectal swabs) found no other MCR-1–carrying isolates.
"The detection of this cluster demonstrates the potential for silent dissemination of mcr-1 in the hospital setting through asymptomatic colonization and suggests a possible role for same-day endoscopy-related transmission, independent of using the same endoscope," the authors of the study write. "While infective episodes have the greatest impact on patient outcomes, detection of silent colonization may play an important role in stemming the spread of mcr-1."
Apr 8 Antimicrob Agents Chemother abstract
Analysis finds declining outpatient antibiotic use in Massachusetts
Researchers from the Massachusetts Department of Public Health and Harvard reported yesterday in Open Forum Infectious Diseases that outpatient antibiotic prescribing in Massachusetts fell by nearly 17% from 2011 to 2015. Their analysis also found a wide variation in antibiotic use by census tract.
Using outpatient prescription claims from the Massachusetts All-Payers Claims Database from 2011 through 2015, the researchers measured claims for antibiotic prescriptions and calculated rates per 1,000 people by calendar year, sex, and age-group. Population-wide antibiotic use was measured for major antibiotic classes and the most frequently prescribed individual antibiotics. To describe in-state geographic patterns, the investigators measured prescribing rates for the four most frequently prescribed antibiotics—penicillins, quinolones, cephalosporins, and macrolides—stratified by the US census tract of residence documented in the claim.
The study population had 17.1 million antibiotic claims prescribed for 4.9 million members over the study period. The overall annual rate of outpatient antibiotic use for individuals 64 years old and younger was 696 prescriptions per 1,000 people, falling from 759 to 652 prescriptions per 1,000 people from 2011 through 2015, a decline of 16.7%. The highest rate of prescribing was among infants, and the lowest was among children and young adults aged 10 to 19 years. In 2015, 68% of people had no antibiotic prescription, and 17% had only one.
The researchers noted dramatic variability in antibiotic use by census tract within the state, with penicillin use ranging from 31 to 265 prescriptions per 1,000 people, macrolide use ranging from 28 to 333, cephalosporin use ranging from 8 to 89, and quinolone use ranging from 13 to 118. In general, urban areas had lower antibiotic use among the four major antibiotic classes.
The authors of the study believe that the detailed characteristics of populations and providers with higher prescribing rates can be used to focus education and monitoring. They say they plan to share these results with providers and the community through online reports.
"Combining these data with clinical indications for antibiotic prescriptions, particularly in areas with higher prescribing rates, will aid in shaping stewardship interventions," they write.
Apr 8 Open Forum Infect Dis abstract