Stewardship / Resistance Scan for Feb 22, 2017

MDR Enterobacteriaceae in children
;
MCR-1 in Chinese pets
;
MDR-TB testing, treatment

Study describes incidence, risk factors for MDR Enterobacteriaceae in kids

A study yesterday in BMC Infectious Diseases shows that critically ill children with tracheal Enterobacteriaceae infection are at risk for multidrug-resistant (MDR) infections.

The retrospective, single-center analysis was performed on ventilated patients admitted to the pediatric intensive care unit of the University Children's hospital in Tubingen, Germany, from 2005 to 2014. While mechanically ventilated pediatric patients are known to be at risk for tracheal colonization with MDR Enterobacteriaceae, the underlying risk factors are poorly understood. The investigators were looking to determine the incidence of children with suspected MDR infection and the predisposing risk factors.

During the study period, 167 Enterobacteriaceae isolates were obtained from the lower respiratory tracts of 123 intubated patients. Of those isolates, 116 (69%) were susceptible and 51 (31%) were identified as MDR Enterobacteriaceae. The most prevalent isolates were Enterobacter spp, followed by Escherichia coli and Klebsiella spp. The most prevalent MDR organisms were E coli, Klebsiella, and Enterobacter spp.

Using a classification and regression tree (CRT) analysis to predict risk factors, the investigators determined that antibiotic pre-treatment for more than 7 days increased the risk of infection with an MDR isolate by 62%. In addition, they found that gastrointestinal comorbidity increased the chance of MDR infection from 25% to 40% in patients who received less than 7 days of antibiotic therapy.

"Collectively, our results imply that early identification of patients at risk, rapid microbiological diagnostics and tailored antibiotic therapy are essential to improve management of critically ill children infected with Enterobacteriaceae," the authors write.
Feb 21 BMC Infect Dis study

Researchers report MCR-1 in pets, pet food in China

About 9% of pets and 20% of pet food samples tested in Beijing, China, contained the MCR-1 gene, which confers resistance to the last-resort antibiotic colistin, according to a study yesterday in Emerging Infectious Diseases.

An international team of experts tested 566 Enterobacteriaceae isolates collected from cats and dogs via nasal and rectal swabs in the city from 2012 through 2016. Of the total, 49 (8.7%) of the isolates harbored the MCR-1 gene, which was first reported late last year in a 50-year-old man in China. The gene was found on 47 E coli isolates and 2 Klebsiella pneumonia samples. The overall count of colistin-resistant isolates was 79, mostly E coli.

The researchers also isolated the MCR-1 gene from 1 of 25 Enterobacteriaceae samples collected from 32 nasal swabs from pet owners. The isolate had the same genetic fingerprint as 5 of the pet samples.

In addition, the team tested 35 dog and cat food samples, 7 of which (20%) were positive for MCR-1, signifying a possible source for the animal infections.

The authors noted that colistin is not used to treat companion animals in China, and the pets tested had minimal to no contact with food-producing animals that might have been treated with the drug. They conclude, "Because of frequent and close contact between humans and companion animals, our study proposes that opportunities exist to transmit colistin-resistant Enterobacteriaceae to and from both groups."
Feb 21 Emerg Infect Dis study

 

Study: Xpert TB test not tied to increased rates of second-line treatment

A South African study yesterday concluded that the Xpert MTB/RIF tuberculosis (TB) test was associated with a reduction in treatment delay from a median of 44 days in 2011 to 22 days in 2013 for patients with drug-resistant TB but did not significantly improve the proportion of patients receiving proper antibiotics. The study appeared in PLoS Medicine.

South African and Dutch researchers aimed to assess second-line antibiotic treatment before and after the Xpert MTB/RIF test was implemented in South Africa, so they analyzed data from 2011 and 2013 on more than 5,000 TB cases resistant to the key first-line drug rifampin.

The investigators found that treatment delays were halved after Xpert implementation, from 44 to 22 days. But they found no difference in those who started second-line drug treatment within 6 months of diagnosis by Xpert (62%) and those diagnosed by other methods (64%). They also found substantial variation across the country's nine provinces in both the rate of second-line 6-month treatment initiation and the median time to treat.

Although Xpert appeared to have not improved rates of appropriate treatment, the authors wrote, "given improved case detection, a larger proportion of the total population of individuals with rifampicin-resistant TB will receive treatment." They added, "Further strategies to improve linkage to treatment for all patients diagnosed with rifampicin-resistant TB are required."
Feb 21 PLoS Med study

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