Becker's Clinical Quality & Infection Control

22 ANTIBIOTIC RESISTANCE & STEWARDSHIP Cluster of Uncommon Superbug Strain Found in Houston By Heather Punke S cientists from the Houston Methodist Research Institute using genome sequencing found that more than one-third of Hous- ton Methodist patients studied were infected with a rare Klebsiella pneumo- niae strain. "Finding the otherwise uncommon strain in our city was a surprising dis- covery," said James Musser, MD, PhD, senior author of the study published in mBio. "Because Klebsiella pneumo- niae is a common and important cause of human infections, we urgently need to identify potential vaccine targets or other new treatments, and develop new and rapid diagnostic techniques." Dr. Musser, his team and colleagues at the Argonne National Laboratory and University of Chicago sequenced and analyzed the genomes of 1,777 K. pneu- moniae strains that caused infections in Houston Methodist patients between September 2011 and May 2015. e most dominant strain was clone type 307, which had not previously been identified as an abundant cause of infection in one city. "e faster we can successfully identify which antibiotics this strain is sensitive to, the faster a treating physician can target the appropriate therapy to those ill patients," said S. Wesley Long, MD, PhD, the study's first author. "Our dis- coveries also give us the tools to begin to understand how the germ is spread- ing throughout the Houston area." Dr. Musser said he doesn't know why this particular strain of bacteria is so prevalent in Houston. e good news is the strain is still sus- ceptible to certain antibiotics. n WHO Updates Guidance on 'Last Resort' Antibiotic Use By Heather Punke T he World Health Organization updated its list of essential medicines June 5, including the biggest revision of the antibiotic section since the Essential Medications List was first written 40 years ago. WHO now groups antibiotics into three categories — Access, Watch and Reserve — and offers recommendations as to when each category should be used. The categories include antibiotics used to treat 21 common general infections. "The rise in antibiotic resistance stems from how we are using — and misusing — these medicines," said Suzanne Hill, PhD, director of essential medicines and health products. "The new WHO list should help health system planners and prescribers ensure people who need antibiotics have access to them, and ensure they get the right one, so that the problem of resistance doesn't get worse." Below is information on the three new categories of antibiotics. Access. This group include amoxicillin, ciprofloxacin and other drugs widely used to treat common infections. WHO recommends antibiotics in this group be available at all times. Watch. This category includes antibiotics that have a higher resistance potential, and WHO recommends using them as first- or second-choice treatments for a few specific infections. "These medications should be prioritized as key targets of stewardship programs and monitoring," according to the updated EML. Drugs here include carbapenems, quinolones and fluoroquinolones, among others. Reserve. Antibiotics in this group should be considered a "last resort" and only used in specific patients and settings when other drugs have failed. Examples include fourth and fifth generation cephalosporins, tigecycline and polymyxins. n S. aureus Becoming More Susceptible to Antibiotics, Study Suggests By Brian Zimmerman S taphylococcus aureus' susceptibility to antibiotics appears to increasing, according to a study presented June 4 at the American Society of Microbiol- ogy's ASM Microbe 2017 conference in New Orleans. To assess the antibiotic susceptibility trends of S. aureus in the U.S., researchers tested more than 19,000 clinical isolates obtained from 42 medical centers across the country. Examination revealed S. aureus' resistance to oxacillin decreased from 47.2 percent in 2009 to 42.2 percent in 2016. Additionally, the bacteria's resistance to levofloxacin, clindamycin and erythromycin displayed some decline over the same period. However, susceptibility to ceftaroline, trimethoprim-sul- fanethoxazole and tetracycline remained steady. "The prevalence of the main S. aureus clone causing community-acquired and healthcare-associated infections in many parts of the U.S. seems to be decreasing in some areas," said Helio Sader, MD, PhD, senior director of microbiology and surveillance at JMI Laboratories in North Liberty, Iowa. "A prevalence decrease may change the antimicrobial resistance profiles of S. aureus, emphasizing the importance of monitoring this organism through large resistance surveillance programs." n

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