Stewardship / Resistance Scan for Jun 05, 2017

News brief

MDR Pseudomonas infections nearly twice as deadly for hospital patients

A review of hospital-onset Pseudomonas aeruginosa infections in the United States found that the mortality from multidrug-resistant P aeruginosa (MDR-PSA) is nearly twice that of non-MDR-PSA infections.

For the study, which was presented at ASM Microbe 2017, which ended today, researchers used an electronic research dataset that includes microbiology/general lab results, pharmacy orders, and financial data to identify PSA isolates from blood, wound, urine, respiratory tract, gastrointestinal tract, and other sources collected at US hospitals from January 2013 to September 2015. Isolates were labeled as hospital-onset if they were collected more than 3 days after admission or through 1 day after discharge. The researchers then compared the mortality and hospital length of stay associated with MDR-PSA versus non-MDR-PSA infections.

Of 4,522 cases, 3,643 (80.6%) were non-MDR and 879 (19.4%) were MDR-PSA. Isolates recovered from respiratory sources accounted for 42.4% of all MDR cases, followed by urine (33.1%), and wound (18.3%). While the overall mortality for all PSA infections was 12.8%, the researchers found that mortality was 19.8% for patients with MDR-PSA infections, compared with 11.1% for patients with non-MDR PSA infections. In addition, patients with MDR-PSA were in the hospital for 14.3 days longer than patients with non-MDR-PSA.

Study co-author Sanjay Merchant, PhD, executive director of the Center for Observational and Real World Evidence at Merck & Co., told Infectious Disease News that the findings highlight the need for effective therapy against MDR PSA infections.

"Additionally, hospitals should consider utilizing various infection management strategies, including hand hygiene, environment cleaning and increasing heterogeneity of antibiotic prescribing, to minimize the emergence and spread of MDR-PSA resistance in hospitals," he said.
Jun 3 ASM 2017 abstract (#5262, pg. 566)
Jun 4 Infectious Disease News article

Study evaluates alternative disinfectants for C difficile

A new study by Dutch researchers in Antimicrobial Resistance & Infection Control indicates that Clostridium difficile spores of PCR ribotypes 014 and 027 strains are harder to eradicate than non-toxigenic PCR ribotype 010.

The researchers were testing four different products commonly used for cleaning and disinfecting in Dutch hospitals for their efficacy against C difficile, the most common source of healthcare-associated diarrhea and a growing threat associated with morbidity, mortality, and extra costs. The four different compounds, potential alternatives to liquid bleach (the main disinfectant used against C difficile), included:

Hydrogen peroxide 1.5%
Glucoprotamin 1.5%
A mixture of ethanol, propane, and N-alkyl amino propyl glycine
A mixture of didecyldimonium chloride, benzalkonium chloride, polyaminopropyl, biguanide and dimenthicone as active ingredients

The products, in wipe and spray form, were tested against ceramic tiles contaminated with an outbreak-related PCR ribotype (027), an endemic PCR ribotype (014), and a non-toxigenic ribotype (010). C difficile 014 is the most prevalent PCR ribotype in the Netherlands. The effectiveness was measured in reduction of colony-forming units (CFUs).

Regardless of the disinfection method, the overall CFU reduction was highest for C difficile PCR 010, followed by 014 and 027. In general, the ready-to-use wipes performed better than the sprays for all compounds, with hydrogen peroxide wipes showing the highest bactericidal activity.

"Ready-to-use wipes eliminate the possibility of human errors that could make the disinfectant less effective or make the wipes unnecessarily toxic," the authors write.

The authors say the findings indicate "the importance of including a variety of clinically relevant ribotypes when evaluating the effects of disinfectants against C difficile."
Jun 3 Antimicrob Resist Infect Control study

News Scan for Jun 05, 2017

News brief

Two suspected Ebola cases confirmed in DRC

The Democratic Republic of the Congo (DRC) on Jun 2 said that two suspected Ebola cases had been confirmed via laboratory testing. According to the World Health Organization (WHO), these cases came from known transmission chains, and the date of the last confirmed case in the DRC remains May 11.

Since Apr 21, there have been 4 confirmed and 3 probable Ebola cases, of which 4 have died (case-fatality rate, 57%). The WHO said scientists are currently investigating unusually high mortality in swine populations from eight villages in northern DRC.

Contact follow-up and tracing were already under way for the two confirmed cases, and the WHO said that the outbreak is controlled.

The current outbreak is the DRC's eighth since Ebola virus was first detected in 1976.
Jun 2 WHO bulletin

Aedes aegypti mosquitoes can transmit both Zika, chikungunya in 1 bite

A new study in PLoS Neglected Tropical Diseases shows that the Aedes aegypti mosquito can transmit both Zika and chikungunya virus in one bite, and co-infection with the viruses does not alter vector competence.

Dutch scientists infected the insects with both viruses to determine transmission rates using an experimental blood meal and found that 73% of the mosquitoes transmitted Zika, 21% spread chikungunya, and 12% transmitted both viruses in one bite. This is the first study to show that, just as in humans, the viruses can commonly co-infect mosquitoes.

"We show that ZIKV and CHIKV can simultaneously disseminate to the saliva of Ae. aegypti mosquitoes, indicating that co-infections do not strongly interfere with virus replication," the authors write.

In other Zika news, a vaccine presented at the American Society of Microbiology (ASM) Microbe 2017 meeting that wrapped up today showed 100% protection from the virus in mouse models. The vaccine is the first to be based on the NS1 protein, and the first to show single-dose protection against Zika.

Also at ASM, scientists described a new reliable clinical test that can diagnose Zika in semen samples. The test could be helpful for couples who are planning a pregnancy after a possible Zika exposure.

The test, called the Aptima assay, was found to have 100% sensitivity and specificity in 100 semen samples.
Jun 1 PLoS Negl Trop Dis study
Jun 4 ASM vaccine press release
Jun 4 ASM Zika test press release

PAHO reports 1,000 new chikungunya cases in the Americas

Following a week in which the chikungunya outbreak in the Americas grew by 80%, on Jun 2 the Pan American Health Organization (PAHO), in its weekly report, noted a return to more modest but still notable numbers, as the agency detailed 1,039 new cases.

The new cases lift the yearly total to 87,472, according to the latest update. Previous weekly reports showed increases of 16,436, 142, and 38,282 cases, respectively. The weeks with five-digit increases are those in which Brazil, which has accounted for 93% of 2017 cases, has reported new infections.

The vast majority of new cases were in Bolivia, which reported 855 new chikungunya illnesses and 2,144 for the year. Peru was second, with 123 new cases and 1,120 total. The number of deaths from the disease remained at 13, all of them in Brazil.

Since the chikungunya outbreak began in late 2013 on the Caribbean island of St. Martin, the virus has sickened at least 2,474,499 people.
Jun 2 PAHO update