US surveillance study finds high incidence of ESBL-E infections
An active laboratory- and population-based surveillance study conducted at five US sites found a high incidence of infections caused by extended-spectrum beta-lactamase–producing Enterobacterales (ESBL-E), researchers reported today in Infection Control & Hospital Epidemiology.
The pilot study, led by researchers with the Centers for Disease Control and Prevention (CDC), identified incident ESBL-E cases at five Emerging Infections Program (EIP) sites in New York, Georgia, Tennessee, Colorado, and New Mexico over a 3-month period (October to December 2017).
An incident ESBL-E case was defined as an Escherichia coli, Klebsiella pneumoniae, or Klebsiella oxytoca isolate resistant to at least one extended-spectrum cephalosporin and non-resistant to carbapenems. Antimicrobial susceptibility testing and whole-genome sequencing was conducted on a convenience sample of case isolates.
The researchers identified 884 ESBL-E incident cases among 815 patients. Of the 884 cases, 790 (89%) were E coli bacteremia, and 94 (11%) were K pneumoniae bacteremia. The estimated annual incidence in the three sites conducting population-based surveillance (New York, New Mexico, and Tennessee) was 199.7 per 100,000 population. Among the cases, 393 (47%) were classified epidemiologically as community-associated, 282 (34%) as healthcare-associated community-onset, and 40 (5%) as hospital-onset.
Among 136 isolates (15%) tested at the CDC, 122 (90%) met the surveillance definition phenotype; 114 (93%) of 122 were shown to be ESBL producers by clavulanate testing. In total, 111 (97%) of confirmed ESBL producers harbored a bla CTX-M gene. Among ESBL-producing E coli isolates, 52 (54%) were sequence type ST131; 44% of these cases were community-associated.
The study authors say the findings are concerning not only because the incidence of ESBL-E infections in the United States appears to be much higher than previously established estimates for other resistant phenotypes, such as carbapenem-resistant Enterobacterales (2.93 infections per 100,000) but also because only 30% occurred in hospitalized patients. The CDC has previously highlighted ESBL-E as a serious antibiotic resistance threat.
"In conclusion, ESBL-E causes a high burden of infections in the community and in healthcare, and additional data are needed to further characterize risk factors and sources of acquisition to focus prevention efforts," they write.
The EIP has implemented ongoing ESBL-E surveillance at six US sites based on the findings.
Feb 14 Infect Control Hosp Epidemiol abstract
VA study highlights inappropriate asymptomatic bacteriuria treatment
An in-depth review of provider documentation at eight Veterans Affairs (VA) sites found that more than a quarter of asymptomatic bacteriuria (ASB) cases were inappropriately treated with antibiotics, researchers reported last week in the American Journal of Infection Control.
In the case-control study, a team led by researchers from Baylor College of Medicine reviewed a random sample of 10 positive urine cultures per month, per facility, classifying them as urinary tract infection or ASB and as treated or untreated. They then reviewed provider-documented text from medical charts that was associated with urine culture ordering to identify symptoms and factors associated with inappropriate ASB treatment.
Out of 960 cultures analyzed from October 2018 through September 2018, 575 were ASB cases. Of these, 158 (27.5%) were inappropriately treated with antibiotics. After controlling for known predictors of ASB treatment, the researchers found that abdominal pain, confusion, decreased urine output, falls, urine characteristics, abnormal vital signs, laboratory values, and voiding issues were all significantly associated with inappropriate ASB treatment. Misleading symptoms with the strongest effect included falls (odds ratio [OR], 3.19), abnormal vital signs (OR, 3.18), and abdominal pain (OR, 2.44).
ASB-treated patients received an average of 1.4 antibiotics, with cephalosporins (41%) and fluoroquinolones (21%) being the most common classes prescribed.
The study authors say the findings suggest a role for diagnostic stewardship to accompany antibiotic stewardship and that future research should examine the factors associated with inappropriate ASB treatment.
"Teasing out these unique cues can help improve our understanding behind improper ASB treatment and should be incorporated into teaching vignettes used in antibiotic stewardship interventions," they wrote.
Feb 11 Am J Infect Control abstract