Impact of climate zones and seasons on indoor airborne microbial communities: Insights from a comprehensive analysis.

Bacteria and fungi are ubiquitous throughout built environments and are suspended in the air, potentially affecting human health. However, the impacts of climate zones on the diversity, structure, and stochastic assembly of indoor airborne microbes remain unknown. This study comprehensively analyzed indoor airborne microbes across five climate zones in China during the summer and winter using high-throughput sequencing. The diversity and structure of indoor airborne communities vary across climatic zones. A random forest model was used to identify biomarkers in different climate zones. The results showed no relationship between the biomarkers and their rankings in mean relative abundance. The Sloan neutral model fitting results indicated that the impact of climate zones on the stochastic process in the assembly of indoor airborne microbes was considerably more important than that of seasons. Additionally, the influence of seasons on the diversity, structure, and stochastic assembly process of indoor airborne microbes differed among different climate zones. The diversity, structure, and stochastic assembly processes of bacteria present distinctive outcomes in climate zones and seasons compared with those of fungi. Overall, these findings indicate that customized strategies are necessary to manage indoor airborne microbial communities in each climate zone, season, and for specific microbial species.

Giant duplication of the transverse colon in an adult: A case report and literature review.

Intestinal duplication is a rare congenital malformation that can occur in any segment of the digestive tract. It is most commonly found in the ileum of infants and is rarely reported in adults, especially in the colon. Diagnosing intestinal duplication can be extremely challenging due to its diverse clinical manifestations and complex anatomical structure. Surgical intervention is currently considered the mainstay of treatment. In this report, we presented a case of giant duplication of the transverse colon in an adult.

Boron Exposure Assessment of Desalinated Seawater on an Island in China.

This study aimed to investigate the boron level in drinking water and daily boron intake of island residents, and to have a health risk assessment of the boron exposure. One-year water boron surveillance was made through the 18 selected sampling sites (5 finished water and 13 tap water) covered by 5 water treatment plants with different water sources. We recruited 220 healthy volunteers (half men and half women) from 89 families covering all age groups living in Shengshan to provide basic information and living habits. One-third of the families attended the daily food boron intake evaluation through the double meal method for three days. In each family, only one family member provided the food samples. Urine samples were collected from all subjects to get the urine boron level. Furthermore, we used the EPA model and TDI for health risk assessments. The boron level in finished water and tap water with different sources were 0.68-1.46 mg/L and 0.62-1.26 mg/L for desalinated water, 0.30-0.39 mg/L and 0.20-0.50 mg/L for reservoir water, and 0.32-0.43 mg/L and 0.20-0.79 mg/L for mixture water. The average level of water boron intake, diet boron intake, and total boron intake was 0.113 ± 0.127 mg/d, 1.562 ± 0.927 mg/d, 1.674 ± 0.939mg/d, respectively, for the select sampling subjects. There were no significant differences in total boron intake for different age groups (1.685 ± 1.216 mg/d vs. 1.669 ± 0.793 mg/d for <45 yrs vs. ≥45 yrs, p = 0.968) and gender groups (1.754 ± 1.009 mg/d vs. 1.633 ± 0.923 mg/d for male vs. female, p = 0.735). Urine boron concentrations were similar in the two age groups (1.938 mg/g creatinine vs. 1.762 mg/g creatinine for <45 yrs vs. ≥45 yrs, p = 0.635). There were significant differences in urinary boron between males and females (1.569 mg/g creatinine vs. 2.148 mg/g creatinine, p = 0.018). The largest hazard quotient (HQ) of drinking water was 0.31, and the total boron exposures in this population were 0.03 mg/kg bw per day. The study showed that there was no possible non-carcinogenic risk of water boron exposure and lower health risk of total boron exposure to humans in this region, but its toxicity should not be ignored. The subsequent studies should strengthen the analysis of the subgroup populations.

Comparison of airborne bacteria and fungi in different built environments in selected cities in five climate zones of China.

Bioaerosols in different built environments and climate zones have unique effects on occupant health, which demands comparisons of their characteristics to make targeted control measures. This study investigated bioaerosol distribution in five different climate zones across China with four building types (n = 686 rooms). The results showed significant disparities in bioaerosol concentrations among various buildings and climate zones. The bacterial concentrations in residences (536 ± 647 CFU/m3) were significantly higher than in schools, offices, and hospitals owing to different built environments and human activities. The highest mean value of fungal concentration was found in schools (826 ± 955 CFU/m3) due to their greater landscaping area. The bacterial concentrations in the cold zone (307 ± 506 CFU/m3) and the hot summer and cold winter zone (214 ± 180 CFU/m3) were significantly lower than in the other three climate zones. The fungal concentrations in the severe cold zone (709 ± 900 CFU/m3) and the hot summer and warm winter zone (1094 ± 832 CFU/m3) were significantly higher than in the other three climate zones; the lower the indoor temperature (T) and the higher the air exchange rate, the lower the indoor airborne bacterial concentration; the lower the relative humidity (RH), the lower the indoor airborne fungi. In addition, a higher air exchange rate could also reduce the effect of occupant density on indoor bacterial concentration. The results of this study provide valuable data on bioaerosol profiles in various built environments and climate zones and highlight the significance of T, RH, and air exchange rate on indoor bioaerosol concentrations.

Levels, distributions and influential factors of residential airborne culturable bacteria in 12 Chinese cities: Multicenter on-site survey among dwellings.

Residential airborne culturable bacteria (RAB) are commonly used to assess indoor microbial loads, which is a very effective and recognized indicator of public concern about residential air quality. Many countries and organizations have set exposure limits for residential bacteria. Nevertheless, few studies have been conducted in multicenter cities about the distribution and influencing factors of RAB. It is a challenge to investigate the distribution of RAB and identify the association between indoor influencing variables and RAB in China. The current finding implied the comparative results from a one-year on-site survey of 12 cities in China. The concentration of RAB ranged from 0 CFU/m3 to 18,078 CFU/m3, with an arithmetic median of 350 CFU/m3. RAB concentrations were more in the warm season than those in the cold season, and were more in the bedrooms than those in the living rooms. Indoor environmental indicators (including PM2.5 and PM10) showed the mediating role in the process of temperature and relative humidity effects on RAB. . Influential factors including family-related information (income), architectural characteristics (house type, building history, living floor, the layers of window glass, and decoration) and lifestyle behaviors (heating, new furniture, incense-burned, insecticides-used, air condition-used, and plants-growed) were related with the concentration of RAB. This study presents essential data on the distribution of RAB in some Chinese cities, and reveals the residential influential factors that might minimize health risk from RAB.

Characteristics of airborne bacterial communities in indoor and outdoor environments during continuous haze events in Beijing: Implications for health care.

There is solid evidence that haze pollution threatens human health owing to the abiotic pollutants it contains. However, the characteristics of airborne bacterial communities in indoor and outdoor environments exhibiting haze occurrence are still unknown. Thus, we examined variations in both indoor and outdoor airborne bacterial communities in Beijing from December 9-27, 2016, a period which included three haze events. The outdoor airborne bacterial communities were clustered into two main groups (Groups I and II), and they shifted between two typical bacterial communities regardless of the haze event. The Chao1, Shannon, and phylogenetic diversity indexes and abundance of dominant classes changed significantly, as did airborne bacterial community type. The indoor airborne bacterial community closely tracked the outdoor bacterial community type, forming two obvious groups supported by Adonis analysis, changes in dominant classes, and bacterial diversity compared to the outdoor group. Furthermore, we found that the airborne bacterial community type could affect the morbidity of respiratory diseases. Daily pneumonia cases were significantly higher in Group I (p = 0.035), whereas daily amygdalitis cases were significantly higher in Group II (p = 0.025). Interestingly, the enriched classes in the indoor environment were quite different from those in the typical airborne bacterial community environment, except for Clostridia, which had significantly higher abundance in both indoor environments. In conclusion, we found that the two indoor and outdoor airborne bacterial community types changed independently of haze events, and the special airborne bacterial community type was closely related to the incidence of pneumonia in the heavy haze season.

Comparison of culturable antibiotic-resistant bacteria in polluted and non-polluted air in Beijing, China.

BACKGROUND: Air pollution has been a serious health issue in Beijing for years. Airborne antibiotic-resistant bacteria could be a potential health crisis as reserve of antibiotic resistance transmission in environment. The composition and antibiotic resistance pattern of culturable bacterial community and how these are affected by air pollution remain unclear. OBJECTIVES: This study aimed to compare the compositions and antibiotic resistance patterns of culturable bacteria in polluted and non-polluted weather conditions in Beijing. METHODS: Air samples were collected indoors and outdoors during polluted and non-polluted weather using six-stage Andersen Samplers. For each isolated bacterium, the 16S ribosomal RNA gene was amplified, sequenced, and blasted against the National Center for Biotechnology Information database Antibiotic resistance was conducted by antimicrobial susceptibility testing. RESULTS: Bacterial concentration in polluted weather was significantly higher than in non-polluted weather, both indoors and outdoors (P < 0.05). Gram-positive bacteria (GPB) were dominant in both weathers but gram-negative bacteria (GNB) were more abundant in polluted weather than non-polluted weather both indoors and outdoors. Multidrug-resistant (MDR) bacteria occupied 23.7% of all bacterial isolates, 22.4% of isolates from polluted weather and 27.8% of isolates from non-polluted weather. Penicillins were resisted by 72.4% and 83.3% of isolates from polluted and non-polluted weather, respectively. CONCLUSIONS: The bacterial concentration was significantly higher in polluted weather, compared to non-polluted weather. Polluted weather is correlated with changes in the bacterial composition in the air, with a greater abundance of GNB. Penicillins was resisted by over 70% of bacterial isolates. The abundance of MDR bacteria suggested potential risks for human health.

[Equivalence test between trial method and reference method of the total coliforms and E. Coli in water].

OBJECTIVE: To compare the equivalence on detection total coliforms and E. Coli between a new technique with portable sterile culture system and enzyme substrate technique by 51 holes in water. METHODS: Collected drinking water and source water, then detected total coliforms and E. Coli using the twomethod in three laboratories respectively. Analyzed the experimentalresult according to the ISO 17994∶ 2014 which was dedicated to analyze the equivance of water quality between different microbial detection method. RESULTS: The confidence upper limit of the expanded uncertainty of the mean of total coliforms from three laboratories were within the range from 0. 0494 to 0. 0903, andthe range of confidence lower limit were from minus 0. 0713 to minus 0. 0490. The confidence upper limit of the expanded uncertainty of the mean of E. Coli from three laboratories were within the range from 0. 0307 to 0. 0882, while the range of confidence lower limit were from minus 0. 0928 to minus 0. 0381. They were all within the acceptable range which the confidence upper limit was from 0 to 0. 10000, and the confidence lower limit was from minus 0. 10000 to 0. CONCLUSION: The aforementioned method in detecting total coliforms and E. Coli possess the equivalence compared with the classical method, so the portable sterile culture system can be an alternative of method detecting total coliforms and E. Coli in water.

[Preliminary study on preservation and preparation of Giardia standard body by ~(60)Co irradiation].

OBJECTIVE: Preliminary study on preparation methods of Giardia standard body by~(60)Co devitalized and the preservation conditions. METHODS: Giardia irradiated by different doses of~(60)Co 0-1200 Gy and assessed by immunofluorescence assay. In the same time, the inactivated Giardia were preserved in 2. 5% K2Cr2O7 at 4℃. Then the Giardia by immunofluorescence assay was observed over the next 5 months. RESULTS: After treatment with 900 Gy of~(60)Co radiation, 91. 44% ± 1. 64% of the cysts were inactivated. Moreover, indicators of cysts meet the requirements. After stored at 4 ℃ for 4 months, the number of total cysts, inactivation ratio and the morphology of cysts were meet the requirement. CONCLUSION: It is an effective method to inactivate Giardia cysts with 900 Gy irradiation of~(60)Co. And Giardia cysts can be preserved in 2. 5% K2Cr2O7 at 4 ℃ for 4months.

[Rapid method study of methicillin-resistant Staphylococcus aureus identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry].

OBJECTIVE: To establish the method on rapid identification of Staphylococcus aureus and the performance of methicillin-resistance. METHODS: 40 isolation strains of staphylococcal were analyzed by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF-MS) and API Staph Ident system, and the performance of methicillin-resistance was tested by Disk Diffusion Susceptibility Testing. RESULTS: 34 isolation strains were identified by MALDI-TOF-MS as Staphylococcus aureus, and the result was uniform to the API Staph Ident system. 11 isolation strains were identified as methicillin-resistant Staphylococcus aureus (MRSA) and 23 isolation strains were methicillin-susceptible to Staphylococcus aureus (MSSA). All the 34 isolation strains were clustered to 2 species identified by MALDI-TOF-MS. The result was uniform to the Disk Diffusion Susceptibility Testing. CONCLUSION: These results demonstrated that MALDI-TOF-MS could be a rapid technique for identification and discrimination of MRSA.

[Detection of Salmonella in water by using MUCAP test].

OBJECTIVE: To study the sensitivity, specification, detection limit and the practical use of MUCAP method for the detection of Salmonella in water. METHODS: A comprehensive method of pre-enrichment + selective cultivation + initial screening with MUCAP + oxidase test + serological test was applied to check Salmonella in water samples spiked with bacteria and environmental water samples. RESULTS: the sensitivity of MUCAP method was 100%, the specification was 80.8%, and the detection limit was 1 cfu/100 ml. CONCLUSION: MUCAP method can effectively identify Salmonella in water and the testing time was shortening from 72h to 48h.

[Viable but nonculturable state of bacteria and its hygiene significance].

Viable but nonculturable state of bacteria means the state of bacteria cannot be cultured in routine media, but is alive and metabolic active. Many bacteria including some pathogens can enter this state and maintain virulence or pathogenicity. In this paper, the information including character, induction factors, resuscitation, detection and hygiene significance about bacteria's viable but nonculturable state was reviewed.

[Primary research on detecting bacteria drug resistance by matrix-assisted laxer desorption ionization time-of-flight mass spectrometry].

OBJECTIVE: To study the feasibility of bacteria drug resistance determinated by matrix-assisted laxer desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). METHODS: 11 strains of 8 genera in drug resistant-bacteria separated from clinical specimens and the corresponding standard strains were detected by MALDI-TOF-MS, and the differences of the mass spectrums were analyzed. At the same time, 30 strains of Staphylococcus aureus separated from clinical specimens were detected by MALDI-TOF-MS and their antimicrobial susceptibility were tested. All bacteria were cultured under the same conditions. RESULTS: When drug-resistant bacteria determinated by MALDI-TOF-MS, it was efficient for Staphylococcus, especially the methicillin-resistant Staphylococcus aureus, but it was not efficient for other genera. CONCLUSION: MALDI-TOF-MS can be used to detect drug resistance of some bacteria.

[Comparison between rapid detection method of enzyme substrate technique and multiple-tube fermentation technique in water coliform bacteria detection].

OBJECTIVE: To compare between rapid detection method of enzyme substrate technique and multiple-tube fermentation technique in water coliform bacteria detection. METHODS: Using inoculated and real water samples to compare the equivalence and false positive rate between two methods. RESULTS: Results demonstrate that enzyme substrate technique shows equivalence with multiple-tube fermentation technique (P = 0.059), false positive rate between the two methods has no statistical difference. CONCLUSION: It is suggested that enzyme substrate technique can be used as a standard method for water microbiological safety evaluation.

[Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry used to bacteria detection].

To investigate the influence variations, three culture media and different culture time were evaluated using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry for the rapid identification of eight strains of bacteria. These culture media are Colombia Blood Agar, Eosin Ethylene Blue Agar and Nutrition Agar. Results demonstrate that different culture media and culture time can influence the reproducibility of the bacteria fingerprint. It is suggested that appropriate culture media and culture time can enhance the accuracy of the bacteria detection using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry.