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Item 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 HealthBacillus 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.Item Microbial Spectrum and Antibacterial Susceptibility of Endophthalmitis Cultures in a Tertiary Referral Center in the Midwestern United States: An Analysis From 295 Patients(Sage, 2020-09-22) Gemayel, Michael; Neiweem, Ashley; Aebi, Brent; Bracha, Peter; Ciulla, Thomas; Ophthalmology, School of MedicinePurpose: This work evaluates the microbial spectrum and antibiotic susceptibility pattern of endophthalmitis cases in a large tertiary referral center in the Midwestern United States. Methods: This retrospective case series included patients with clinically diagnosed endophthalmitis between April 14, 2006 and April 14, 2016, in whom ocular samples were submitted to the Microbiology Department at Indiana University. The patients were assessed by 11 vitreoretinal surgeons from 6 different sites in Indianapolis, including Indiana University and private practices, who receive patients from urban, suburban, and rural agricultural areas. Submitted specimens were cultured with the following media: blood agar, chocolate agar, MacConkey agar, and thioglycolate broth. Results: A total of 327 specimens from 295 patients were analyzed, with 96 (32.5%) samples from 90 (30.5%) patients meeting the criteria of confirmed growth. Of these 96 positive specimens, 83 (86.5%) organisms were identified as bacterial, and 13 (13.5%) were identified as fungal. Coagulase-negative Staphylococcus was the most common isolate (37.5%). Fifty gram-positive isolates and 10 gram-negative isolates underwent susceptibility testing. All 40 of the gram-positive isolates tested for vancomycin sensitivity were susceptible, whereas all 7 of the gram-negative isolates tested for ceftazidime sensitivity were susceptible. Conclusions: Empiric treatment with vancomycin and ceftazidime remains appropriate in most cases of endophthalmitis in the Midwestern United States, with 100% susceptibility of bacterial organisms tested with these antibiotics in this series. The high fungal culture rates in this study highlight the utility of obtaining vitreous cultures and potential need for antifungal agents in suspicious cases.