Browsing by Author "Ho, Yenling"

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    The dangers of sublethal carvacrol exposure: increases in virulence of Bacillus cereus during endophthalmitis
    (E-Century Publishing, 2018-10-08) Rajabli, Niloofar; Williamson, Lauren; Nimmer, Pierre S.; Kelly-Worden, Marie; Bange, Jill S.; Ho, Yenling; McKillip, John L.; Epidemiology, School of Public Health
    Bacillus cereus can cause endophthalmitis through secretion of virulence factors, including hemolysin BL (Hbl) and nonhemolytic entertoxin (Nhe). Carvacrol is an extract from oregano oil, with potential for curtailing B. cereus endophthalmitis, due to antimicrobial and anti-inflammatory qualities. However, sublethal levels of carvacrol increases B. cereus virulence. The goal of this study was to investigate the increase in B. cereus virulence potential in response stress induced by a subinhibitory concentration (SIC) of carvacrol. Enterotoxin production and tissue damage were examined during ocular infections in vitro and in vivo. We hypothesized that the SIC of carvacrol would significantly increase toxin production in B. cereus without progressing systemically. RT-PCR determined SIC carvacrol-treated B. cereus had significantly higher hblC and nheA mRNA expression levels than controls in vitro. ELISA and RPLA analysis revealed a 46.8% and 50% increase in NheA and HblC toxin levels, respectively, in SIC-treated cultures. Caenorhabditis elegans-fed SIC carvacrol-treated B. cereus had a significantly higher mean mortality rate than nematodes fed untreated B. cereus. Significantly higher TNF-α levels were observed in SIC carvacrol-treated B. cereus mice compared to other treatment groups except for mice infected with B. cereus alone. Significantly higher IL-6 levels were also found in SIC-B. cereus mice. Histological analysis using Rose-Bengal and DAPI determined that the eyes of mice infected with SIC carvacrol-treated B. cereus had significantly more damage than eyes treated with B. cereus alone. The SIC of carvacrol increased B. cereus virulence in vitro and in vivo, with a mild systemic infection noted.
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    Reliability of administrative data to identify sexually transmitted infections for population health: a systematic review.
    (BMJ, 2019-08) Dixon, Brian E.; Rahurkar, Saurabh; Ho, Yenling; Arno, Janet N.; Epidemiology, School of Public Health
    INTRODUCTION: International Classification of Diseases (ICD) codes in administrative health data are used to identify cases of disease, including sexually transmitted infections (STIs), for population health research. The purpose of this review is to examine the extant literature on the reliability of ICD codes to correctly identify STIs. METHODS: We conducted a systematic review of empirical articles in which ICD codes were validated with respect to their ability to identify cases of chlamydia, gonorrhoea, syphilis or pelvic inflammatory disease (PID). Articles that included sensitivity, specificity and positive predictive value of ICD codes were the target. In addition to keyword searches in PubMed and Scopus databases, we further examined bibliographies of articles selected for full review to maximise yield. RESULTS: From a total of 1779 articles identified, only two studies measured the reliability of ICD codes to identify cases of STIs. Both articles targeted PID, a serious complication of chlamydia and gonorrhoea. Neither article directly assessed the validity of ICD codes to identify cases of chlamydia, gonorrhoea or syphilis independent of PID. Using ICD codes alone, the positive predictive value for PID was mixed (range: 18%-79%). DISCUSSION AND CONCLUSION: While existing studies have used ICD codes to identify STI cases, their reliability is unclear. Further, available evidence from studies of PID suggests potentially large variation in the accuracy of ICD codes indicating the need for primary studies to evaluate ICD codes for use in STI-related public health research.