Objective Bacterial biofilms cause serious problems, such as antibiotic resistance and medical device-related infections. Recent reports indicate that Bacillus species potentially form biofilms and cause nosocomial bacteremia via catheter infection. Our objective was to investigate the relationship between nosocomial bacteremia caused by Bacillus species and biofilm formations. Methods Between 2001 and 2006, Bacillus cereus and Bacillus thuringiensis were isolated from blood samples of 21 patients with nosocomial bacteremia in two hospitals. The patients had underlying diseases such as cerebrovascular damage, malignant disease, or chronic obstructive lung disease and had high fever at the onset of bacteremia. After investigation, B. cereus and B. thuringiensis were isolated from patient's catheter tip, gauze, and hospital environment. Pulsed-field gel electrophoresis (PFGE) on 32 B. cereus and 7 B. thuringiensis isolates, microtiter biofilm assay and scanning electron microscopy (SEM) on 22 B. cereus isolates from patient's blood were performed. Results Molecular analysis by PFGE showed that 32 B. cereus strains had 21 patterns and 7 B. thuringiensis strains had 3 patterns. The PFGE patterns of B. thuringiensis and B. cereus in blood samples from 2 patients blood were similar to those from the same patient's catheter tip. The PFGE pattern of B. cereus from a hospital environment was similar to that from 2 patients' blood samples, and the PFGE pattern of B. thuringiensis from 2 hospital environments was similar to that from 2 patients' blood. The biofilm formations by 22 B. cereus isolates from patients' blood were confirmed by microtiter biofilm assay and SEM even at 24 hours. Conclusion Our data indicate that various types of Bacillus species exist in hospital environments and the biofilm-forming strains potentially cause nosocomial bacteremia by catheter infection.

Corynebacterium is a genus consisting of Gram-positive, rod-shaped bacteria, that is wildly distributed in nature. We report the epidemiological characterization of Corynebacterium spp. isolated from blood specimens at the Kurume University Hospital, between June 2008 and November 2011. Twenty-two strains that were likely Corynebacterium spp. were isolated from 22 hospitalized patients, of which 12 (54.5%) were identified as Corynebacterium striatum. Minimum inhibitory concentration tests were performed after biochemical and genotypic identifications. Biofilm production was detected using a 96-well microplate assay. The dissemination of C. striatum was investigated using pulsed-field gel electrophoresis (PFGE). All strains showed the tendency to be resistant to multiple drugs except vancomycin. Fourteen (82.4%) strains, including 9 C. striatum strains were capable of producing biofilms. Four distinct PFGE patterns were detected among C. striatum strains; 6 of which were identified as dominant pattern A (defined in this study) and had high biofilm production ability. During the 3-year monitoring period, these strains might have repeatedly infected the patients or could have readily colonized the hospital environments. C. striatum appeared to be a potential risk factor for bloodstream infections in hospitalized patients. More surveillance and enhanced control strategies are necessary to decrease Corynebacterium spp. infections in hospitals.

Ocular candidiasis is a critical and challenging complication of candidemia. The purpose of this study was to investigate the appropriate timing for ophthalmologic examinations, risk factors for complications of ocular lesions, and their association with mortality. This retrospective cohort study applied, using multiple logistic regression analysis and Cox regression models, to cases of candidemia (age ≥ 18 years) for patients who underwent ophthalmologic consultation. Of the 108 candidemia patients who underwent ophthalmologic examination, 27 (25%) contracted patients had ocular candidiasis, and 7 experienced the more severe condition of endophthalmitis, which included subjective ocular symptoms. In most cases, the initial ophthalmologic examination was performed within one week of the onset of candidiasis with a diagnosis of ocular candidiasis, but in three cases, the findings became apparent only after a second examination within 7–14 days after onset of candidiasis. The independent risk factor extracted for the development of ocular candidiasis was the isolation of C. albicans (OR, 4.85; 95% CI, 1.58–14.90), unremoved CVC (OR, 10.40; 95% CI, 1.74–62.16), and a high βDG value (>108.2 pg/mL) (HR, 2.83; 95% CI = 1.24–6.27). Continuous ophthalmologic examination is recommended in cases of candidemia with the above risk factors with an initial examination within 7 days of onset and a second examination 7–14 days after onset.

Bloodstream infection (BSI) due to carbapenem-resistant Enterobacteriaceae (CRE) has a high mortality rate and is a serious threat worldwide. Ten CRE strains (eight Enterobacter cloacae, one Klebsiella pneumoniae and one Citrobacter freundii) were isolated from the blood of nine patients, a percentage of whom had been treated with indwelling devices. The steps taken to establish cause included minimum inhibitory concentration (MIC) tests, a pulsed-field gel electrophoresis (PFGE), biofilm study, a multiplex PCR for resistant genes of carbapenemases and extended-spectrum beta-lactamases (ESBLs), and plasmid incompatibility typing. All strains showed a tendency toward resistance to multiple antibiotics, including carbapenems. Frequently isolated genes of ESBLs and carbapenemases include bla_TEM-1 (four strains), bla_SHV-12 (four strains) and bla_IMP-1 (six strains). A molecular analysis by PFGE was used to divide the XbaI-digested genomic DNAs of 10 CRE strains into eight patterns, and the analysis showed that three E. cloacae strains detected from two patients were either identical or closely related. The biofilm production of all CRE strains was examined using a microtiter biofilm assay, and biofilm growth in continuous flow chambers was observed via the use of a confocal laser scanning microscope. Our study indicates that biofilm formation on indwelling devices may pose a risk of BSI due to CRE.

Background: We dealt with the occurrence of an outbreak of Candida parapsilosis in a neonatal intensive care unit (NICU) in September 2020. There have been several reports of C. parapsilosis outbreaks in NICUs. In this study we describe our investigation into both the transmission route and the biofilm of C. parapsilosis. Methods: C. parapsilosis strains were detected in three inpatients and in two environmental cultures in our NICU. One environmental culture was isolated from the incubator used by a fungemia patient, and another was isolated from the humidifier of an incubator that had been used by a nonfungemia patient. To prove their identities, we tested them by micro satellite analysis. We used two methods, dry weight measurements and observation by electron microscopy, to confirm biofilm. Results: Microsatellite analysis showed the five C. parapsilosis cultures were of the same strain. Dry weight measurements and electron microscopy showed C. parapsilosis formed biofilms that amounted to clumps of fungal cells. Conclusions: We concluded that the outbreak happened due to horizontal transfer through the humidifier of the incubator and that the C. parapsilosis had produced biofilm, which promoted an invasive and infectious outbreak. Additionally, biofilm is closely associated with pathogenicity.