In-vitro antibiotic resistance phenotypes of respiratory and enteric bacterial isolates from weaned dairy heifers in California

Antimicrobial drug (AMD) use for bovine respiratory disease (BRD) continues to be concerning for development of antimicrobial resistance (AMR) in respiratory and enteric bacteria of cattle. This study aimed to provide data regarding AMR in respiratory isolates, and identify relationships between respiratory and enteric AMD susceptibility, in weaned dairy heifers. A cross-sectional study was performed between June of 2019 and February 2020, on 6 calf rearing facilities in California. Deep nasopharyngeal and rectal swabs were collected from 341 weaned heifers and submitted for selective bacterial culture and AMR testing. Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni were selectively isolated from respiratory samples; Escherichia coli and Enterococcus spp. were selectively isolated from rectal swabs. Minimum inhibitory concentrations (MIC) were determined for selected isolates against 19 AMD. The proportion of resistant isolates was calculated using Clinical Laboratory Standards Institute (respiratory) or USDA NARMS (enteric) breakpoints; when no applicable breakpoint was available, the distribution of MIC was described and compared. Association between AMR in a calf’s respiratory isolate and a higher or lower MIC of the matched enteric isolates was determined. More than 50% of P. multocida isolates were resistant to each of 7 AMD commonly used to treat BRD (florfenicol, gamithromycin, tildipirosin, tilmicosin, danofloxacin, enrofloxacin and tetracycline). Resistance in respiratory isolates was only associated with higher matched enteric MIC for gamithromycin and tulathromycin. Multidrug resistance was reported in >70% of P. multocida and M. haemolytica isolates. Antimicrobial resistance, including multidrug resistance, in respiratory isolates appears to be widespread in weaned dairy heifers; this finding has not previously been reported and raises concern for the future efficacy of AMD used to treat respiratory diseases in weaned dairy heifers. Enteric bacterial MIC appear to have limited direct association with respiratory isolate AMR classification.

1382. Acid-Fast Bacilli Testing Trends at 43 In- and Outpatient Facilities and Nontuberculous Mycobacterial Pulmonary Isolation Rate, United States, 2009–2015

Background The prevalence of nontuberculous mycobacterial pulmonary disease (NTM PD) is increasing in the United States and globally. The reasons for this increase are not clear but could be related to both gained awareness leading to increased mycobacterial testing, or to a true NTM PD increase. To further examine the role of testing rates in the observed increase, we studied trends in Acid-Fast Bacteria (AFB) testing and NTM isolation positivity using a large Electronic Health Record (EHR) dataset in the United States. Methods Using the Cerner Health Facts EHR dataset, we extracted microbiologic, demographic, and clinical data for patient encounters (inpatient or outpatient), with ≥1 orders for AFB respiratory cultures. The analysis was limited to the 43 facilities reporting continuously for the period 2009–2015. A patient with at least one AFB test was considered tested (AFB) and a patient with at least one pathogenic NTM respiratory isolate was considered positive. Trends in AFB testing and NTM positivity were estimated using log-linked Poisson regression (P < 0.05). Results From 2009 through 2015, of 14.8 million patients, 65,010 had 142,315 AFB tests, averaging 2.2 AFB tests/patient, for an overall testing prevalence of 0.43%; the annual testing prevalence remained unchanged during the study period (P = 0.44) (Figure 1). Of the 65,010 patients with AFB tests, 3,942 (6.1%) had ≥1 pathogenic NTM species, for an overall pulmonary NTM isolation prevalence of 2.7/10,000 patients represented in Cerner Health Facts dataset. Of the patients that had at least one pathogenic NTM, 3,094 (78%) had M. avium complex, and 265 (7%) had M. abscessus/chelonae, (Figure 2). Among patients with at least 1 NTM-positive culture, 138 patients had concomitant growth of M. tuberculosis. Conclusion Increases in NTM PD are not explained by increases in AFB testing, which remained constant in the population represented here. This study was funded in part by the Division of Intramural Research, NIAID, NIH. Disclosures All authors: No reported disclosures.

Epidemiologic Review of Veterans Health Administration Patients with Isolation of Nontuberculous Mycobacteria after Cardiopulmonary Bypass Procedures

We evaluated the isolation of postoperative nontuberculous mycobacteria (NTM) associated with heater-cooler devices (HCDs) used during cardiopulmonary bypass (CPB) surgery in the Veterans Health Administration from January 1, 2010, to December 31, 2016. In more than 38,000 CPB procedures, NTM was isolated in 111 patients; 1 Mycobacterium chimaera mediastinitis case and 1 respiratory isolate were found.Infect Control Hosp Epidemiol 2017;38:1103–1106

First identification of class A carbapenemase-producing Klebsiella pneumoniae in the Republic of Ireland

The Klebsiella pneumoniae carbapenemase (KPC) was detected in a carbapenem-resistant respiratory isolate of Klebsiella pneumoniae in an Irish hospital. This is the first report of a KPC-producing isolate in the Republic of Ireland. The isolate was resistant to all β-lactams. Furthermore, it had reduced susceptibility to three other classes of non-β-lactam antibiotics. The isolate was not associated with travel abroad. Detection of KPC-producing bacteria has important infection control and public health implications.

Isolation of Chlamydia pneumoniae Clonal Variants by a Focus-Forming Assay

ABSTRACT Chlamydia pneumoniae is an obligate intracellular prokaryotic human pathogen that causes community-acquired respiratory infection and has been associated with atherosclerosis and cardiovascular disease. Unexpected results from genomic sequencing indicate that significant intrastrain polymorphism exists for some C. pneumoniae isolates. These polymorphisms could reflect genotypes with differing disease-causing characteristics. A definitive means to test this hypothesis is to obtain genetically homogeneous clonal populations of the pathogen and test them in models of infection and disease. To date, methods for cloning C. pneumoniae have not been reported. In this study, we describe the isolation of clonal variants with genetic differences in the tyrP locus from a polymorphic respiratory isolate, using a novel focus-forming assay. These results now allow investigations on the biology and pathogenesis of C. pneumoniae clonal genovars that could lead to new insights into the pathogenesis of this important human pathogen.