ASP Scan (Weekly) for Dec 14, 2018

Staph bacteria in hog workers
CRP testing in Thailand, Myanmar
Preop screening for silent bacteriuria
Susceptibility testing platforms
De-escalation and patient outcome
Highly concerning ICU sepsis
Resistant Klebsiella in pets, people

Study: Use of face masks by hog workers linked to reduced staph exposure

Consistent use of a face mask was associated with reduced exposure to antibiotic-resistant and livestock-associated strains of Staphylococcus aureus among industrial hog operation (IHO) workers and their household members, according to a study yesterday in Environmental Health Perspectives.

In the observational study, a team led by scientists at Johns Hopkins Bloomberg School of Public Health examined the relationship between IHO work activities and nasal carriage of drug-resistant, livestock-associated S aureus among IHO workers in North Carolina and their household contacts. In particular, the researchers were interested in whether use of personal protective equipment, including gloves, coveralls, and face masks, was related to S aureus nasal carriage patterns and household members' exposure to these bacteria. While previous studies have shown that livestock-associated and drug-resistant S aureus can spread between hogs, IHO workers, and household contacts of IHO workers, the impact of protective equipment in preventing the spread of the pathogen is unclear.

In bi-weekly intervals over a period of 4 months, participants provided nasal swabs and answered questionnaires that assessed demographic information, household-level characteristics, and habitual activities. A total of 101 IHO workers and 79 household members completed 1,456 study visits.

Among the most noteworthy findings was that IHO workers who wore a face mask more than 80% of the time, compared to those who wore a face mask less than 80% of the time, were less likely to carry multidrug-resistant S aureus (odds ratio [OR], 0.31; 95% confidence interval [CI], 0.11 to 0.83), tetracycline-resistant S aureus (OR, 0.32; 95% CI, 0.12 to 0.88), scn-negative (livestock-associated) S aureus (OR, 0.50; 95% CI, 0.23 to 1.10), and S aureus putatively associated with clonal complex (CC) 398 or CC9, the two predominant lineages of livestock-associated S aureus (OR, 0.51; 95% CI, 0.21 to 1.20).

Household contacts of those workers were also less likely carry scn-negative S aureus (OR, 0.12; 95% CI, 0.04 to 0.40)], tetracycline-resistant S aureus (OR, 0.14; 95% CI, 0.04 to 0.53), and S aureus putatively associated with CC398 or CC9 (OR, 0.20; 95% CI, 0.05 to 0.81), compared with the household members of IHO worker who wore face masks less than 80% of the time.

"Findings from this longitudinal study suggest that consistent face mask use may reduce nasal carriage of livestock-associated, antibiotic-resistant S aureus in IHO workers' and their household members," the authors of the study conclude. They suggest future trials to test the preventive efficacy of face masks and other personal protective equipment are needed. 
Dec 13 Environ Health Perspect study


C-reactive protein testing associated with small reduction in prescribing

Researchers in Thailand and Myanmar report in The Lancet Global Health that testing febrile patients for C-reactive protein (CRP) at the point of care was associated with a modest but significant reduction in antibiotic prescribing.

The randomized controlled trial involved 2,410 patients with a documented fever recruited from six primary care clinics in Thailand and three primary care clinics (plus one outpatient department) in Myanmar from June 2016 through August 2017. Patients were randomly assigned in a ratio of 1:1:1 to either a control group or one of two CRP testing groups, which used thresholds of 20 milligrams per liter (mg/L, group A) or 40mg/L (group B) to guide antibiotic prescribing. The primary outcome was the prescription of any antibiotic from day 0 to day 5 and the proportion of patients who were prescribed an antibiotic when CRP concentrations were above and below the 20 mg/L or 40 mg/L thresholds.

During the trial, 318 of 807 patients (39%) in the control group were prescribed an antibiotic by day 5, compared with 290 of 803 patients (36%) in CRP group A and 275 of 800 patients (34%) in CRP group B. While antibiotic use in all three groups was lower than documented in retrospectively collected data on patients with fever in the two countries, the findings indicate that only the higher threshold for CRP was associated with significant reductions in prescribing.

The adjusted odds ratio (aOR) of 0.80 (95% CI, 0.65 to 0.98) and risk difference of −5.0 percentage points (95% CI, −9.7 to −0.3) between group B and the control group were significant, although lower than anticipated, but the reduction in prescribing in group A compared with the control group was not significant (aOR, 0.86 [0.70 to 1.06]; risk difference −3.3 percentage points [–8.0 to 1.4]).

Patients with high CRP concentrations in both intervention groups were more likely to be prescribed an antibiotic than in the control group (group A versus control group, P < 0.0001; group B vs control group, P < 0.0001), and those with low CRP concentrations in both groups were more likely to have an antibiotic withheld (group A vs. control group, P < 0.0001; group B vs control group, P < 0.0001). No differences in the prevalence of clinical recovery were observed between the two groups. Twenty-four serious adverse events were recorded during the trial, consisting of 23 hospital admissions and one death, which occurred in CRP group A.

The authors of the study say that even though the effect size was smaller than anticipated, the modest reduction in prescribing associated with CRP testing could have a significant impact in Southeast Asia, a region where antibiotic prescribing in primary care is widespread and poorly regulated.

"With the majority of human antibiotic consumption occurring in the community and in patients with fevers and respiratory illness in particular, even small reductions in prescription could imply a large alleviation of drug pressure," they write. "Further modelling and cost-effectiveness analyses are required to explore whether these reductions and the cost of achieving them are warranted from an economic and global health perspective."
Dec 14 Lancet Glob Health study


VA study suggests 'no clinical utility' to preoperative urine screening

The results of a retrospective cohort study of Veterans Administration (VA) patients indicate that screening for or treating preoperative asymptomatic bacteriuria (ASB) does not reduce the risk for postoperative infections, researchers reported yesterday in JAMA Surgery.

For the study, researchers from Boston University School of Medicine, Harvard Medical School, and the VA Boston Healthcare System set out to characterize the association between detection and treatment of ASB and postoperative outcomes. While ASB is associated with increases in surgical site infection (SSI) and urinary tract infection (UTI) after nonurologic procedures, there is limited data on whether preoperative screening for ASB, and subsequent antibiotic therapy directed against the colonizing organism, improves clinical outcomes. As a result, clinical practice patterns vary widely, with some hospitals obtaining preoperative urine cultures as part of the standard care.

The study involved 68,265 veterans who underwent cardiac, orthopedic, or vascular surgery at 109 VA health facilities from October 2008 through September 2013.  The researchers reviewed the medical records, looking for preoperative urine culture results, antibiotic prophylaxis, and 30-day SSI and UTI outcomes. The primary outcome was the association between preoperative ASB and postoperative SSI. The secondary outcomes included postoperative UTI and the association between antimicrobial therapy for ASB and postoperative infectious outcomes.

Of the 68,265 patients, 17,611 (25.8%) were eligible for inclusion in the primary analysis. Preoperative urine cultures were performed in 17,749 (26.0%) patients, and the results were positive in 755 (4.3%), of which 617 (81.7%) were classified as ASB. With adjustments for age, American Society of Anesthesiologists class, smoking status, race/ethnicity, sex, and diabetes status, patients with or without ASB had similar odds of SSI (2.4% vs 1.6%; adjusted odds ratio [aOR], 1.58; 95% CI, 0.93 to 2.70; P = .08).

The lack of association between ASB and SSI persisted when the analysis was stratified by surgery type, except for cardiac procedures, in which a 3-fold increase was observed among preoperative patients with ASB. Urinary tract infection occurred in 14 (3.3%) of 423 patients with ASB and 196 (1.5%) of 12,913 patients without ASB (aOR, 1.42; 95% CI, 0.80 to 2.49; P = .22). 

Receipt of antibiotic therapy with activity against the ASB organism was not associated with a reduced SSI risk (aOR, 1.01; 95% CI, 0.28-3.65; P = .99) or with reduced risk of postoperative UTI (aOR 0.68; 95% CI, 0.20 to 2.30; P = .54). In addition, the ASB organisms matched a postoperative wound culture in only two cases, both Staphylococcus aureus. The authors say the data suggest "there is no clinical utility to preoperative screening of urine cultures for cardiac, orthopedic, and vascular procedures." 

An accompanying commentary by a clinician from Baylor College of Medicine adds that the study could have important implications for stewardship. "Interventions that have focused on reducing urine cultures or suppressing their results have reduced the antibiotic treatment of ASB," writes Barbara Trautner, MD, PhD. "Eliminating routine preoperative urine cultures will reduce the number of positive urine culture results in asymptomatic patients, in turn reducing unnecessary antibiotic use."
Dec 12 JAMA Surg study
Dec 12 JAMA Surg commentary


Etest outperforms disc tests for ceftazidime/avibactam susceptibility

Originally published by CIDRAP News Dec 11

US scientists report that the Etest, made by the French company bioMerieux, outperformed disc tests and is a suitable alternative to broth microdilution (BMD) for testing ceftazidime combined with avibactam against ceftazidime- and meropenem-resistant Klebsiella pneumoniae, according to results published yesterday in the Journal of Antimicrobial Chemotherapy.

Researchers from three US universities and Accelerate Diagnostics in Tucson, Ariz., evaluated the Etest, the 30/20-microgram (mcg) disc (Hardy diagnostics), and the 10/4 mcg disc (Mast Group) against the reference BMD method for 102 gram-negative organisms: 69 ceftazidime- and meropenem-resistant K and 33 multidrug-resistant (MDR) non-K pneumoniae isolates.

The team reported that, although none of the three assays met the defined equivalency threshold against all 102 organisms, the Etest performed best, with categorical agreement of 95% and a major error rate of 6.3%. Against the 69 resistant K pneumoniae isolates, only the Etest and the 10/4 mcg disc met the equivalency threshold. None of the three tests met equivalency for the 33 non-K pneumoniae MDR isolates.

The scientists also pooled the data with those from a previous study of 74 carbapenem-resistant Enterobacteriaceae and from the ceftazidime/avibactam new drug application to bolster the findings.

The authors concluded, "Our data indicate that the Etest is a suitable alternative to BMD for testing ceftazidime/avibactam against ceftazidime- and meropenem-resistant K. pneumoniae. The 30/20 [mcg] discs overestimate resistance and may lead to the use of treatment regimens that are more toxic and less effective."
Dec 10 J Antimicrob Chemother abstract


Study shows no clinical detriment to antibiotic de-escalation for bacteremia

Originally published by CIDRAP News Dec 11

A Spanish team that assessed de-escalation as an antimicrobial stewardship approach in patients with single-pathogen bacteremia caused by Enterobacteriaceae (BSI-E) have determined it was not associated with a poorer clinical outcome, according to their data presented in Clinical Infectious Diseases.

The investigators conducted a post-hoc multicenter analysis involving 516 patients, 241 (47%) of whom had early antibiotic de-escalation, 98 (19%) had late de-escalation, and 180 (35%) had none.

De-escalation refers to reducing the spectrum of antibiotics through discontinuation or switching to a narrower-spectrum antibiotic.

After controlling for confounders, the researchers found that neither early nor late de-escalation was linked to increased death. In addition, de-escalation of any length was not associated with clinical failure or a longer hospital stay.
Dec 8 Clin Infect Dis study


Data show 'alarming' antimicrobial resistance levels in ICU sepsis in India

Originally published by CIDRAP News Dec 11

A single-center case-control study in India has found alarming levels of antimicrobial resistance among sepsis patients admitted to the intensive care unit (ICU), according to results published in Antimicrobial Resistance & Infection Control.

The research team analyzed 77 Escherichia coli isolates from the blood of patients diagnosed as having sepsis and 71 from the stool cultures of patients admitted to the ICU who were not diagnosed as having sepsis. The scientists used polymerase chain reaction to characterize the isolates genetically.

They found that 46% of blood isolates and 22% of fecal isolates were enterotoxigenic E coli (ETEC). They also found that 16% of blood isolates and 28.5% of fecal isolates were enteroaggregative E coli(EAEC). Both ETEC and EAEC are common causes of diarrhea.

In their susceptibility analysis, the investigators found that more than 90% of the blood and more than 70% of the fecal isolates were resistant to cephalosporins. In addition, 68% of blood and 44% of the fecal isolates were found to be producers of extended-spectrum beta-lactamase, which conveys resistance to third-generation cephalosporins.

The researchers conclude, "The antimicrobial resistant profile found in this study is alarming and poses a great threat to public health. Apparently, an increased antimicrobial resistance to the extensively used cephalosporins is affecting an optimal drug therapy for patients. In addition, the presence of catheters, prolonged duration of stay in the hospital and poor hygienic conditions due to infrequent urination of the patient can lead to an additional vulnerability."
Dec 7 Antimicrob Resist Infect Control study


Pets, humans can be infected with same resistant Klebsiella lineage

Originally published by CIDRAP News Dec 11

Researchers from Portugal who examined antimicrobial resistance and virulence genes of K pneumoniae strains that cause urinary tract infections (UTIs) in dogs and cats and humans found that pets with UTI can be infected with high-risk clonal lineages similar to the ones in humans. The group reported its findings yesterday in the Journal of Antimicrobial Chemotherapy.

For the study, the investigators tested K pneumoniae and K oxytoca isolates from the University of Lisbon that were collected from 24 dogs and cats with UTI from the Lisbon area. They also tested K pneumoniae and K oxytoca isolates from humans with UTI that they obtained from a clinical lab and a hospital lab in the Lisbon area. The specimens from the animals were isolated from 2002 to 2015, and the human ones from the clinical lab were isolated in 2014. The hospital lab samples were isolated randomly from 2006 to 2015.

Disc diffusion testing on 27 animal and 77 human specimens identified resistant isolates, which were then tested by polymerase chain reaction testing for 16 resistance genes and 7 virulence genes. The researchers used multilocus sequence typing on all pet samples and third-generation-cephalosporin (3GC)-resistant isolates from humans.

The blaCTX-M-15 resistance mechanism was detected in more than 80% of 3GC-resistant strains, and the K pneumoniae high-risk ST15 clonal lineage predominated in dog and cat isolates (60%, 15/25). Most of the pet ST15 lineage belonged to two pulsed-field gel electrophoresis clusters (C4 and C5) that also included human strains. Pet and human isolates from the lineage shared a virulence marker, with four also harboring yersiniabactin siderophore-encoding genes. A hospital-adapted lineage was found in a cat and a human, and both of the isolates were MDR.

The team concluded that animal caretakers should take precautions to prevent the spread of antimicrobial-resistant K pneumoniae.
Dec 10 J Antimicrob Chemother abstract

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