Predominance of methicillin-resistant Staphylococcus aureus in the residents and environments of long-term care facilities in Taiwan.

BACKGROUND/PURPOSE: This study investigated the distribution and persistence of multidrug resistant organisms (MDROs) including methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Enterobacteriaceae (CRE), carbapenem-resistant Pseudomonas aeruginosa (CRPA), and multidrug-resistant Acinetobacter baumannii (MDRAB) in six long-term care facilities (LTCFs). METHODS: We investigated the distribution of MDROs in residents of six LTCFs and their environments from January to December 2016 (intervention period). Active surveillance of colonization of MDROs was performed by culturing rectal and nasal swab samples from the residents every three months. Multilocus sequence typing (MLST) was conducted, and genes for panton-valentine leukocidin (PVL) from MRSA isolates were determined. RESULTS: A total of 521 samples were positive for MDROs, and MRSA was the most common organism (65.1%), followed by MDRAB (11.3%), carbapenem-resistant Klebsiella pneumoniae (11.1%), carbapenem-resistant Escherichia coli (4.6%), and carbapenem-resistant P. aeruginosa (2.1%, n = 11). By a linear regression model, positive MRSA isolates from the environment were found to be statistically significant and associated with the number of colonized LTCF residents (p = 0.01), while the timing of the surveillance culture was not (p = 0.227). The main MLST types associated with PVL-production were sequence type (ST) 59, (40.0%, 24/60), ST30 (21.4%, 3/14), ST8 (87.5%, 14/16), and ST45 (3.6%, 1/28). The susceptibility rates of tetracycline (96.7%), trimethoprim-sulfamethoxazole (96.7%), and ciprofloxacin (81.7%) were statistically significant and higher in MRSA ST59, compared to the rates in MRSA ST45 isolates. CONCLUSIONS: MRSA was the most commonly colonized MDRO, both in the LTCF residents and in the environment, followed by MDRAB and carbapenem-resistant K. pneumoniae.

Presence of multidrug-resistant organisms in the residents and environments of long-term care facilities in Taiwan.

OBJECTIVES: This study investigated the prevalence of multidrug-resistant organisms (MDROs) in the residents and environments of long-term care facilities (LTCFs) in Taiwan. METHODS: We prospectively investigated the distribution of MDROs in residents of six LTCFs and their environments from January 2015 to December 2015 (intervention period). Active surveillance of colonization of MDROs was performed by culturing rectal and nasal swab samples every 3 months for the residents: 63, 79, and 73 in the first, second, and third surveillance investigations, respectively. If MDROs, including methicillin-resistant Staphylococcus aureus, carbapenem-resistant Enterobacteriaceae, carbapenem-resistant Pseudomonas aeruginosa, and MDR Acinetobacter baumannii were identified, then swab specimens from environmental sources were also collected and cultured. During the study period, several infection control measures were also implemented. RESULTS: The overall infection density decreased significantly from 2.69 per 1000 patient-days in the preintervention (January 2014 to December 2014) to 2.39 per 1000 patient-days during the intervention period (p < 0.001). A total of 154 samples from residents and environmental sources were positive for MDROs. Methicillin-resistant S. aureus (n = 83, 53.9%) was the predominant organism, followed by carbapenem-resistant Enterobacteriaceae (n = 35, 22.7%), MDR A. baumannii (n = 30, 19.5%), and carbapenem-resistant P. aeruginosa (n = 6, 3.9%). The rates of detection of MDROs were 27.9% (60/215) in nasal swabs, 15.8% (34/215) in rectal swabs, and 11.1% (60/542) in the environmental sources. CONCLUSIONS: The distribution and persistence of MDROs varied among the different LTCFs and time periods.

Ethanol production efficiency of an anaerobic hemicellulolytic thermophilic bacterium, strain NTOU1, isolated from a marine shallow hydrothermal vent in Taiwan.

A new extremely thermophilic, anaerobic, gram-negative bacterium, strain NTOU1, was enriched and isolated from acidic marine hydrothermal fluids off Gueishandao island in Taiwan with 0.5% starch and 0.5% maltose as carbon sources. This strain was capable of growth utilizing various sugars found in lignocellulosic biomass as well as xylan and cellulose, and produced ethanol, lactate, acetate, and CO(2) as fermentation products. The results of a 16S rRNA gene sequence analysis (1,520 bp) revealed NTOU1 to belong to the genus Thermoanaerobacterium. When tested for the ability to grow and produce ethanol from xylose or rice straw hemicellulosic hydrolysate at 70°C, the strain showed the highest levels of ethanol production (1.65 mol ethanol mol xylose(-1)) in a medium containing 0.5% xylose plus 0.5% yeast extract. Maximum ethanol production from the rice straw hemicellulose was 0.509 g g(-1), equivalent to 98.8% theoretical conversion efficiency. Low concentrations of inhibitors (derived from dilute acid hydrolysis) in the rice straw hemicellulose hydrolysate did not affect the ethanol yield. Thus, Thermoanaerobacterium strain NTOU1 has the potential to be used for ethanol production from hemicellulose.

Biodegradation of crystal violet by a Shewanella sp. NTOU1.

A bacterial isolate, strain NTOU1, originally isolated from the cooling system in an oil refinery could decolorize and detoxify crystal violet under anaerobic conditions. The strain was characterized and identified as a member of Shewanella decolorationis based on Gram staining, morphology characters, biochemical tests, the 16S rRNA gene and the gyrase subunit beta gene (gyrB). The optimum pH value and temperature for decolorization of crystal violet by this strain under anaerobic conditions were pH 8-9 and 30-40 degrees C, respectively. Formate (20 mM) was the best electron donor. Addition of ferric citrate did not inhibit decolorization of crystal violet, the addition of thiosulfate, ferric oxide, or manganese oxide slightly decreased decolorization, while addition of nitrite (20 mM) inhibited the decolorization of crystal violet. By supplementing the medium with formate and ferric citrate and cultivating it under optimum pH and temperature, this strain could remove crystal violet, at a concentration of 1500 mg l(-1), at the rate of 298 mg l(-1) h(-1) (during decolorization the OD(600) of the cell culture increased from approximately 0.6 to approximately 1.2). GC/MS analysis of the degradation products of crystal violet detected the presence of N,N'-bis(dimethylamino) benzophenone (Michler's Ketone), [N,N-dimethylaminophenyl] [N-methylaminophenyl] benzophenone, N,N-dimethylaminobenzaldehyde, N,N-dimethylaminophenol, and 4-methylaminophenol. These results suggest that crystal violet was biotransformed into N,N-dimethylaminophenol and Michler's Ketone prior to further degradation of these intermediates. This paper proposes a probable pathway for the degradation of crystal violet by this Shewanella sp. Cytotoxicity and antimicrobial tests showed that the process of decolorization also detoxify crystal violet.