BackgroundThe bactericidal effect of disinfectants against biofilms is essential to reduce potential endoscopy-related infections caused by contamination. Here, we investigated the bactericidal effect of a high-level disinfectant, peracetic acid (PAA), against Staphylococcus aureus and Pseudomonas aeruginosa biofilm models in vitro.Methods S. aureus and P. aeruginosa biofilms were cultured at 35 °C for 7 days with catheter tubes. The following high-level disinfectants (HLDs) were tested: 0.3% PAA, 0.55% ortho-phthalaldehyde (OPA), and 2.0% alkaline-buffered glutaraldehyde (GA). Biofilms were exposed to these agents for 1–60 min and observed after 5 min and 30 min by transmission and scanning electron microscopy. A Student’s t test was performed to compare the exposure time required for bactericidal effectiveness of the disinfectants.ResultsPAA and GA were active within 1 min and 5 min, respectively, against S. aureus and P. aeruginosa biofilms. OPA took longer than 10 min and 30 min to act against S. aureus and P. aeruginosa biofilms, respectively (p < 0.01). Treatment with PAA elicited changes in cell shape after 5 min and structural damage after 30 min.ConclusionsAmongst the HLDs investigated, PAA elicited the most rapid bactericidal effects against both biofilms. Additionally, treatment with PAA induced morphological alterations in the in vitro biofilm models, suggesting that PAA exerts fast-acting bactericidal effects against biofilms associated with endoscopy-related infections. These findings indicate that the exposure time for bactericidal effectiveness of HLDs for endoscope reprocessing in healthcare settings should be reconsidered.

BackgroundHelicobacter cinaedi is an important pathogen that causes bloodstream infections. Owing to the challenges in its culture and identification, its clinical and bacterial characteristics remain unknown. Our study aimed to investigate the molecular epidemiology and antimicrobial susceptibility of H cinaedi.Materials and MethodsFrom 2003 to 2016, we analyzed 16 non‐repetitive H cinaedi strains, isolated from blood, at the medical hospital of Tokyo Medical and Dental University. Multilocus sequence typing was performed to analyze the genetic relationship across the different isolates. The minimum inhibitory concentrations (MIC) of antibiotics were determined by the agar dilution method.ResultsThe median age of subjects in this study was 61 years (range, 18‐84 years). The most common risk factors included the use of steroids (75.0%) and immunosuppressant drugs (37.5%). In addition, the most common symptoms of H cinaedi bacteremia included colitis (37.5%) and cellulitis (31.3%). The infection recurred in three of seven cases (42.8%) that underwent antibiotic therapy for <10 days. The strains were classified into five sequence types (ST), of which, ST 10 (43.8%) and ST 4 (31.3%) were predominant. The MIC90 values of amoxicillin, gentamycin, imipenem, ciprofloxacin, and clarithromycin were 4, 0.5, 0.25, 64, and 128 mg/L, respectively.ConclusionsSince there is no recommended guideline yet for the choice or duration of antibiotic therapy and antimicrobial break points, our results suggested, for the first time, that prolonged antibiotic therapy, except with ciprofloxacin and clarithromycin, would be required to ensure resolution of symptoms and prevention of recurrence.

No abstract