Study: Prior antibiotic use may raise risk of resistant urinary tract infections

Receiving two or more antibiotic regimens is associated with an increased risk of gram-negative pathogens in patients with hospital-onset urinary tract infections (UTIs), according to a study yesterday in BMC Infectious Diseases.

The retrospective, observational study examined discharge data on hospital patients who had a positive urine culture for gram-negative bacteria and received an antibiotic against gram-negative bacteria from January 2012 through March 2013. The researchers were looking to determine if prior antibiotic exposure in these UTI patients affected the distribution and non-susceptibility patterns of key gram-negative pathogens.

The gram-negative organisms of interest were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and other members of the Enterobacteriaceae family. Organisms were assessed for susceptibility to fluoroquinolones, carbapenems, and piperacillin/tazobactam.

A total of 5,574 unique UTI episodes were included in the analysis (2,027 in patients with prior antibiotic exposure, 3,547 in patients with no prior antibiotic exposure) and 6,093 pathogens were isolated from urine cultures. The most commonly isolated pathogens were E coli (49.5%), K pneumoniae (17.1%), and P aeruginosa (8.2%). P aeruginosa was isolated significantly more often from patients who had at least two prior antibiotic exposures (12.6%) than in patients with no prior antibiotic exposure (8.2%) or with one prior exposure (7.9%). Distribution trends for other pathogens were not affected by the presence or absence of antibiotics.

In addition, the results showed that among all the pathogens of interest, two or more prior antibiotic exposures were associated with slightly higher incidences of fluoroquinolone nonsusceptibility, multidrug resistance, and extended-spectrum beta lactamase phenotypes than were one or no previous antibiotic exposures. This trend, the researchers note, was largely driven by susceptibility pattern changes observed in K pneumoniae isolates.

Although the findings could not substantiate prior antibiotic exposure as an independent risk factor for drug-resistant UTIs, the authors argue that it is an easily identifiable variable that can be used to guide empirical therapy.
Feb 28 BMC Infect Dis study

Poll shows most Americans know little about superbugs

A new poll shows that more than two thirds of Americans are in the dark about the threat of antibiotic-resistant "superbugs," and more than half think antibiotics are effective against viral infections.

The poll, conducted online Feb 6 through 8 by HealthDay News and The Harris Poll, included 2,202 adults. In the poll, 69% of respondents said they know little or nothing about the superbug problem, while 53% said antibiotics work against viral infections, 40% said they work against the common cold, and 48% said that antibiotics can be used against the flu. The numbers were even higher for younger respondents.

"This poll shows that public ignorance is a huge part of the problem," Humphrey Taylor, chairman emeritus of the Harris Poll, told HealthDay News. "Millions of patients continue to believe that antibiotics will help them recover from colds, flu, and other viral infections."

On a positive note, HealthDay News reports that when asked to pick from a list of possible causes of antibiotic resistance, roughly two thirds of respondents selected inappropriate antibiotic prescriptions. And 90% said the public "bears some responsibility" in fighting antibiotic resistance.

Research by the US Centers for Disease Control and Prevention and the Pew Charitable Trusts shows that at least 30% of outpatient antibiotic prescriptions in the United States are inappropriate. The data show that most unnecessary antibiotics are prescribed for respiratory conditions caused by viruses, including common colds, bronchitis, and sinus and ear infections.
Feb 27 HealthDay News article

Report: Sharp rise seen in colistin prescriptions in English hospitals

Prescriptions for the last-resort antibiotic colistin rose by 40% from 2014 to 2015 in English hospitals, according to a story by the Bureau of Investigative Journalism.

Data from Public Health England obtained by the bureau showed that defined daily doses of colistin rose from 346,143 in 2014 to 485,024 in 2015, and have been on the rise every year since 2010.

Medical experts tell the bureau that the rise in colistin prescriptions is an indication that multidrug-resistant infections—such as carbapenem-resistant Enterobacteriaceae—are becoming more common. Colistin, which was introduced in the early 1970s and then withdrawn because it can cause damage to the kidneys, is considered a last option for treatment of infections that don't respond to other antibiotics.

Concerns about emerging colistin resistance have been growing since late 2015, when researchers discovered a highly mobile gene (known as MCR-1) that confers resistance to colistin in Escherichia coli samples from humans, pigs, and pork products. Since then, the MCR-1 gene has been identified in various human and animal bacteria in more than 30 countries, including the United Kingdom.

Michael Weinbren, MD, an infectious disease expert with the Chesterfield Royal Hospital NHS Foundation Trust, told the bureau that growing use of colistin in human medicine will aid the spread of MCR-1. "The one thing you can be sure of is that the organisms will develop resistance," he said.

The bureau also reports that the UK's Veterinary Medicines Directorate last year licensed three new products containing colistin for use on British farms. The emergence and spread of the MCR-1 gene in China, which had widely used colistin in food-animal production, prompted Chinese officials to ban the drug as an animal feed additive in 2016.
Feb 24 Bureau of Investigative Journalism story