Biocontrol science最新文献

Control of infectious diseases requires switching from usual hygiene such as water wiping and cleaning, to control measures including appropriate and aggressive disinfection using 70% alcohol and/or hypochlorous acid depending on the pathogen. Nevertheless, some nursery schools might not understand or select proper disinfectant methods. A survey was administered by the local government of Ibaraki prefecture, Japan in January 2018 to all 456 nursery schools in Ibaraki prefecture. The surveyed items were the number of nursery teachers, usual manual hygiene among children, usual disinfection for lavatories, diaper changing spaces, tables used by children for meals, and classroom floors when there was no vomiting in the facilities and no outbreak in surrounding area. Moreover, it asked about disinfection procedures if children vomited during a community outbreak of gastroenteritis infection. We defined proper use for usual disinfection of a lavatory or diaper changing space as chlorine-based disinfectant including hypochlorous acid or 70% alcohol according to guidelines. Overall, 403 nursery schools responded to the survey. All nursery schools implemented usual hand hygiene. Association between proper disinfection and the size of nursery schools was not significant. Moreover, association between proper disinfection and nursery schools with nurse presence was not found to be significant.

　Two Bacillus strains were screened and identified using 16S rRNA gene sequencing the phenotypic tests, and then characterized in vitro for the probiotic characteristics. They were able to tolerate pH 2.5 for 2.5 h, following 0.3% bile salts and 0.1% pancreatin treatment for 5 h. They exhibited good ability to attach to intestinal epithelial cells and were susceptible to most of the antibiotics and being killed by several. Further and more important, they showed good proteolytic activity to food protein as gelatin and milk, with even higher activity than the reference strain. Thus, these two Bacillus strains are considered as potential proteolytic probiotic strains to food proteins.

In the present study, we examined whether a commensal gut bacterium Escherichia coli might prevent the formation and development of the biofilm of Staphylococcus epidermidis, a nosocomial extraintestinal pathogen but not a gut microorganism. When co-cultured with S. epidermidis, E. coli strain ATCC 35218, a non-pathogenic strain, was found to be dominant in the biofilm formed on the surface of wells of a microtiter plate. In addition, E. coli significantly incorporated and grew in a niche preoccupied by S. epidermidis biofilm. Two other E. coli strains (strain K-12 and B) also showed to interfere the biofilm formation by S. epidermidis. In contrast, S. epidermidis could not grow in a niche preoccupied by E. coli biofilm. These results suggest that, through inhibition of the formation and development of the biofilm, E. coli may eliminate S. epidermidis from the gastrointestinal tract.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was approved for medical use in 2011, and is currently used as a rapid, accurate and low-cost technique for bacterial identification. Microbiological testing and internal accuracy control in Japan are mainly implemented in accordance with the standards of the Clinical and Laboratory Standards Institute (CLSI). However, few facilities perform internal accuracy control of bacterial identification by MALDI-TOF MS. Therefore, we examined the procedures for internal accuracy control of bacterial identification using MALDI-TOF MS in daily work at clinical laboratories in the seven hospitals.

Microbiological contamination inside rubber ducks floating in the bathtub at a "duck bath" of a bathing facility was analyzed by examining bacterial and amoebic counts. The results of microbial tests, such as standard plate count, heterotrophic plate count and Legionella-LAMP (Loopmediated isothermal amplification) , showed that microbial contamination increased in the rubber ducks over time. When the ducks were washed with sodium hypochlorite, those microbial contaminations were not detected; but when the ducks were washed with an electrolyzed water, the standard plate counts and the heterotrophic plate counts were detected in the amount of 10³ per duck in the wipe samples. Without proper washing of rubber ducks, bacteria and free-living amoeba can grow and colonize biofilms, and can thereby cause infection in humans. Also, microbial contamination inside ducks may reduce chlorination of the entire bathtub and cause bacterial infection such as Legionellosis from the bathtub water.

Antibiotic misuse in the animal sector is the first cause of the emergence and spreading of MDR bacteria. Prevention of infectious diseases and enhancement of animal growth are the main effects of antibiotics that push farmers and veterinarians to use this molecule in animal farms. Thus, the use of alternative solutions such as natural antimicrobial substances as well as probiotic strains is a crucial need in this sector. Enterococcus faecium CMUL1216 was isolated from healthy human baby's feces. This strain was assessed in vitro for probiotic properties including activity against many pathogens isolated from animal, human, and soil samples. CMUL1216 strain exhibits good antimicrobial activity against indicator pathogens in both planktonic and biofilm forms. In addition, CMUL1216 strain showed a strong biofilm formation. Furthermore, CMUL1216 exhibits a good anti-inflammatory effect by inducing the secretion of IL-10 in vitro. Moreover, this strain did not show any pathogenic characteristics such as hemolytic effect, presence of virulence genes as well as susceptibility to the majority of antibiotic families. E. faecium CMUL1216 could be a good candidate to be used a probiotic strain in the animal sector in order to maintain animal health and therefore reduce antibiotic resistance caused by the excessive use in this sector.

Culturable bacteria were isolated from tomato seeds using media selective for the canker pathogen Clavibacter michiganensis subsp. michiganensis. Clustering analysis (>99% identity) revealed the presence of 16 operational taxonomic units (OTUs) among isolates detected on semi-selective media. Three OTUs belonged to the phylum Actinobacteria, including those of Micrococcus and Dermacoccus, and 13 OTUs belonged to the phylum Firmicutes, including Bacillus and related genera. These Gram-positive endophytic bacteria have the potential to provide false-positive results in seed health tests using media considered semi-selective for the cancer pathogen.

We examined the hospital-wide incidence of methicillin-resistant Staphylococcus contamination in a hospital environment to predict the risk of the nosocomial spread of infection. Samples were also taken different surfaces and medical equipment in a general hospital ward and a staff station. The isolates were identified bacterial strains and analyzed by PCR for detection of the mecA gene and staphylococcal cassette chromosome mec (SCCmec) types (I-V). Overall, out of 146 isolates that were screened, 15.7% of the samples in the hospital wards were contaminated with Staphylococcus aureus and 74.7% were isolated with coagulase-negative Staphylococci (CNS). The methicillin-resistant mecA gene was detected in all oxacillin-resistant S. aureus, and 89% of oxacillin-resistant CNS was identified as methicillin-resistant S. aureus (MRSA) and MRCNS respectively. All S. aureus and CNS from the hospital wards with MRSA patients were detected as MRSA and MRCNS. A widespread distribution of MRSA and MRCNS was detected in the Cuff. The majority of the MRSA and MRCNS isolates in this study were SCCmec type V, which are a community-acquired infection type. The increased incidence and prevalence of community-acquired MRSA and MRCNS, as well as hospital-acquired MRSA, should be recognized as serious healthcare problems.

In this study, spore heat resistance and growth ability at refrigeration temperatures of Bacillus spp. and Paenibacillus spp. were determined. The spore D_90°C of 67.6% (23 of 34 strains) of Bacillus and 73.9% (17 of 23 strains) of Paenibacillus was less than 15 min. The growth abilities of both genera were equivalent at 10°C. However, 71.1% (32 of 45 strains) of Paenibacillus and only 6.3% (3 of 48 strains) of Bacillus cereus group could grow at 4°C. Eight B. cereus strains formed spores with higher heat resistance compared to the other Bacillus strains assessed; however, they did not grow at tempreratures below 10°C. Conversely, four Paenibacillus strains formed spores with heat resistance equivalent to that of the eight B. cereus strains and grew at 6°C or lower. In particular, Paenibacillus sp. JCM13343 formed the highest heat-resistant spores (D_90°C = 136.1 min) and grew well at 4°C. These results indicate that Paenibacillus can grow in processed foods during refrigerated storage and has the potential to cause spoilage as well as Bacillus. Therefore, Paenibacillus should be considered as one of the targets for microbiological control in refrigerated processed foods.

Aeromonas hydrophila is a major waterborne pathogen, which induces various diseases in freshwater fish with the capability for zoonotic potential. This study was applied to investigate the prevalence of A. hydrophila in diseased Nile tilapia fish, genetic characterization of the virulence encoding genes (act, aerA, alt, and ast genes), and antibiotic susceptibility. Out of the 500 diseased Nile tilapia fish samples, 70% (350/500) Aeromonas species were isolated. From which 53.4% (187/350) of Aeromonas hydrophila strains were identified. A. hydrophila was detected in kidneys, followed by liver, spleen, intestine, and gills. The results of virulotyping displayed the presence of act, and aerA genes in a high percentage of 40%, followed by alt gene (30%), but ast gene was not detected (0%) in A. hydrophila strains. Based on DNA sequence analysis of three virulence associated-genes (act, aerA, and alt genes), the phylogenetic tree showed the genetic relationship with related species. Finally, the antibiotic susceptibility tests revealed high resistance toward chloramphenicol (67.4%), followed by amikacin (51.9%) and gentamicin (47.1%), whereas a high sensitivity was exhibited toward meropenem (90.9%), followed by ciprofloxacin (84.2%), amoxicillin-clavulanic acid (73.3%) and trimethoprim-sulfamethoxazole (64.2%). The multidrug-resistant A. hydrophila strains were observed in 69.0% of strains with six resistance patterns.