Stewardship / Resistance Scan for Aug 08, 2016

MCR-1 in Brazil
M genitalium resistance

Brazil reports first detection of MCR-1 in a human

Researchers in Brazil said today they've detected the MCR-1 gene, which confers resistance to the antibiotic colistin, in a hospital patient. It's the first time the plasmid-mediated antibiotic resistance mechanism has been detected in a human in Brazil.

In a study published today in Antimicrobial Agents and Chemotherapy, researchers report the MCR-1 gene was found in a strain of Escherichia coli taken from a diabetic patient who had been hospitalized with an infected foot wound. Whole genome sequencing revealed the presence of the gene on an IncX4 plasmid.

Since MCR-1 was first identified in E coli isolates in China in November 2015, public health officials have warned about its ability to quickly spread resistance to colistin, considered an antibiotic of last resort for multi-drug resistant (MDR) infections. Because plasmids are mobile pieces of DNA, the gene can jump to other types of bacteria, raising the possibility it could latch on to superbugs and create infections that are impossible to treat.

According to a news release from the American Society for Microbiology (the publisher of the journal), earlier research from the same investigators has shown that MCR-1-harboring E coli has been present in food-producing livestock in Brazil since 2012. Brazilian farmers commonly use colistin and other antibiotics to promote animal growth.

The researchers noted that the IncX4 plasmid identified in the study is highly similar to MCR-1-harboring IncX4 plasmids found in E coli isolates on other continents, which suggests the plasmid is contributing to intercontinental spread of the gene. Overall, MCR-1 has now been detected in human, animal, and environmental isolates in more than 30 countries.
Aug 8 Antimicrob Agents Chemother abstract
Aug 8 American Society for Microbiology news release


French study says resistance of M genitalium to two antibiotic classes growing

Resistance of the sexually transmitted bacterium Mycoplasma genitalium to both fluoroquinolones and macrolides is increasing, raising the specter of the infection becoming untreatable, say the authors of a study from France in Emerging Infectious Diseases.

The researchers explored resistance to moxifloxacin, a second-line agent against M genitalium, and to azithromycin, typically the first-line treatment and one to which resistance is well established, by doing a complete analysis of the parC and gyrA genes of Escherichia coli, which are instrumental in DNA replication, as well as looking for mutations in the quinolone-resistance–determining regions (QRDRs) of the genes in urogenital specimens from M genitalium–positive patients at a hospital in Bordeaux in 2013-14.

ParC and GyrA mutations were found in 12 of 200 (6%) patients, none of whom had received fluoroquinolone treatment but about half of whom had received azithromycin. Mutations in macrolide resistance–associated 23S rRNA was identified in 38 of 221 patients (17.20%), which represents an increase over the 2012 rate of 14%. Two of 168 patients (1.2%) had both macrolide- and fluoroquinolone-associated mutations.

M genitalium is associated with urethritis in men and cervicitis and pelvic inflammatory disease in women. The prevalence of the infection at the study hospital was about 4% during the study period.
Aug 5 Emerg Infect Dis letter

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