Difference In Number Of Bacteria Research Articles

Cytoplasmic RNA Sensor Pathways and Nitazoxanide Broadly Inhibit Intracellular Mycobacterium tuberculosis Growth.

SummaryTo establish stable infection, Mycobacterium tuberculosis (MTb) must overcome host innate immune mechanisms, including those that sense pathogen-derived nucleic acids. Here, we show that the host cytosolic RNA sensing molecules RIG-I-like receptor (RLR) signaling proteins RIG-I and MDA5, their common adaptor protein MAVS, and the RNA-dependent kinase PKR each independently inhibit MTb growth in human cells. Furthermore, we show that MTb broadly stimulates RIG-I, MDA5, MAVS, and PKR gene expression and their biological activities. We also show that the oral FDA-approved drug nitazoxanide (NTZ) significantly inhibits intracellular MTb growth and amplifies MTb-stimulated RNA sensor gene expression and activity. This study establishes prototypic cytoplasmic RNA sensors as innate restriction factors for MTb growth in human cells and it shows that targeting this pathway is a potential host-directed approach to treat tuberculosis disease.

Iodine-supported titanium implants have good antimicrobial attachment effects

BackgroundWe have developed iodine-supported titanium implants, which were shown to have good anti-bacterial effects for Methicillin-sensitive Staphylococcus aureus (MSSA) in our past basic research. However, PJI can be caused by various bacteria including MRSA, Pseudomonas aeruginosa, MSSE, and fungus. The purpose of this study was to investigate whether these implants also have good antibacterial attachment effects for MRSA, P. aeruginosa, MSSE, and fungus. MethodsTi–6Al–4V titanium plates were either left untreated (Ti), treated with oxide film on the Ti surface by anodization (Ti–O), or treated with an iodine coating on oxidation film (Ti–I). The antibacterial activity of the TiI was measured by experimental methods according to Japanese Industrial Standard (JIS) protocols. Implants in this study were exposed to MRSA (ATCC43300), P. aeruginosa (ATCC27853), MSSE (ATCC35984), and Candida Albicans (ATCC10231). Colonies were counted immediately after the bacteria attached to the metal surface and again after 24 h incubation. The difference in the number of bacteria on each metal plate was statistically investigated and an antibacterial activity value was calculated. An effective antibacterial active value of more than 2.0 was judged to be effective according to JIS protocol. ResultsNo countable viable bacteria were observed on the Ti–I surface. For all bacteria there was a significant difference in the mean number of viable bacteria between Ti–I and Ti or Ti–O. Antibacterial activity value in Ti–I and Ti–O was more than 5.9 and 3.6 respectively for MRSA, more than 2.8 and zero for P. aeruginosa, more than 4.3 and zero for MSSE, and more than 4.7 and zero for C. Albicans. ConclusionsThis study showed that iodine-supported titanium implants have good antimicrobial attachment effects for MRSA, P. aeruginosa, MSSE, and C. Albicans. Iodine-supported titanium implants could have great potential as innovative antibacterial implants that can prevent early onset periprosthetic joint infection.

Comparison of vaginal microbial community structure of beef cattle between luteal phase and follicular phase

The aim of the current study was to evaluate the vaginal microbial community structure in beef cattle between follicular and luteal phase. Fifteen healthy beef cattle were subjected to an estrus synchronization protocol, and vaginal samples were collected in the follicular and luteal phases. Polymerase chain reaction (PCR) followed by denaturing gradient gel electrophoresis (PCR-DGGE) and real-time PCR were used to determine the vaginal community structure. The results showed that the vaginal microflora of beef cattle mainly comprised of Aerococcus vaginalis, Aerococcus viridans, Haemophilus somnus, Streptococcus pluranimalium, Psychrobacter marincola, Escherichia coli, and Sphingomonas roseiflava. There was no significant difference in the total number of bacteria in the vaginas of beef cattle between the follicular and luteal phase. The quantity of vaginal Streptococcus spp. in the luteal phase was significantly higher than in the follicular phase, while the number of vaginal Lactobacillus spp. in the follicular phase was significantly higher than in the luteal phase. The results indicated that there was moderate significant difference in the structure of the vaginal microbial community in beef cattle between the luteal phase and follicular phase.

A laboratory assessment of factors that affect bacterial adhesion to contact lenses.

Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in numbers of bacteria that adhered to hydrogel etafilcon A or silicone hydrogel senofilcon A contact lenses. Pseudomonas aeruginosa adhered in higher numbers compared to Staphylococcus aureus. Within a genera/species, adhesion of different bacterial strains did not differ appreciably. The size of initial inoculum, nutritional content of media, and incubation period played significant roles in bacterial adhesion to lenses. A set of in vitro assay conditions to help standardize adhesion between studies have been recommended.

磷高效转基因大豆对根际微生物群落的影响

Farming is faced with the problems of excessive fertilizer use and the reduction of nutrient use efficiency.Phosphorus is one of the macronutrients necessary for plant growth and development.However,phosphorus is usually immobilized by organic substances or oxidized surfaces of iron-aluminum,and exists in the form of organic or inorganic phosphorus,which makes uptake from most soils difficult.It is well known that acid phosphatase increases the use efficiency of organic phosphorus by releasing inorganic phosphorus from organic phosphorus such as phytate.AtPAP15 encodes a purple acid phosphatase,which has been observed to have phytase activity,in Arabidopsis thaliana.AtPAP15 was over-expressed in transgenic soybean AP15-1 and its expression product was secreted into the rhizosphere because of the presence of a carrot extension gene signal peptide,and thus enhanced use of soil organic phosphorus.Previously,there have not been many reports of research concerning the effects of such nutrient-efficient transgenic plants on soil ecology.In this study,the effects of P-efficient transgenic soybean AP15-1 on soil ecology,especially on the rhizosphere microbial community,were investigated.Transgenic soybean AP15-1 and its receptor YC03-3 were planted in vent-netting greenhouse in 3 m × 5 m experimental plots with three replicates.Soybeans were planted in two successive spring and autumn seasons,and no manure,herbicide or pesticide was used.To ascertain if phytase activity in root exudates of transgenic soybean AP15-1 affects the soil microbe ecosystem,the rhizosphere and non-rhizosphere soil of AP15-1 and its receptor YC03-3 were collected at seedling,florescence and mature developmental stages and analyzed by plate culture count and BIOLOG-EcoPlate.The number of colony forming units(CFU) indicated that the number of culturable bacteria,fungi and actinomyces varied with seasons and development stages.There were no apparent differences in numbers of bacteria,fungi and actinomyces among rhizosphere and non-rhizosphere soil of AP15-1 and YC03-3.The absorbance of BIOLOG-EcoPlate at 590 nm and 750 nm was recorded using microplate spectrophotometer and the average well color development(AWCD) values were calculated.The curves of AWCD versus incubation time showed that the carbon metabolic activity of microbes in rhizosphere soil was higher than that in non-rhizosphere soil from the same season.However,statistical analysis indicated that no significant differences in carbon metabolic activity and carbon source preference were observed among rhizosphere and non-rhizosphere soils of AP15-1 and YC03-3.Statistical analysis of the calculated microbial abundance and diversity index also exhibited no distinct differences among rhizosphere and non-rhizosphere soils of AP15-1 and YC03-3.Principal component and clustering analyses revealed that the difference between the rhizosphere of AP15-1 and YC03-3 was less than that between rhizosphere and non-rhizosphere soil from the same season and at the same plant developmental stage.The effects of season and developmental stage on the community diversity of rhizosphere microbes were greater than that resulting from the genotype differences between AP15-1 and YC03-3.In conclusion,these results demonstrated that the P-efficient transgenic soybean AP15-1 planted in spring and autumn had no significant impact on the soil microbial numbers and community structures.

Evaluation of the efficacy of a peroxygen disinfectant-filled footmat for reduction of bacterial load on footwear in a large animal hospital setting

OBJECTIVE-To compare the efficacy of a peroxygenbased disinfectant used in footbaths with the efficacy of the same disinfectant used in footmats for reducing bacterial contamination of footwear in a large animal hospital. DESIGN-Prospective study. SAMPLE POPULATION-Bacteria recovered from the soles of rubber boots after experimental microbial contamination and exposure to disinfectant solutions or water (water-treated control boots) or no treatment (untreated control boots). PROCEDURES-Investigators contaminated boots by walking through soiled animal bedding. Swab samples were collected from the sole of 1 untreated boot (right or left); the other boot was treated as investigators stepped through a disinfectant-filled footbath, a disinfectant-filled footmat, or water-filled footmat. Samples were collected 10 minutes after each treatment. Differences in numbers of bacteria recovered from treated and untreated boots were analyzed. RESULTS-Mean bacterial counts from peroxygentreated boots were 1.3 to 1.4 log(10) lower (95.4% to 99.8%) than the counts from untreated boots. Results were similar for footmat- and footbath-treated boots. In contrast, there were no statistically detectable differences in mean bacterial counts in samples collected from water-treated or untreated boots. CONCLUSIONS AND CLINICAL RELEVANCE-Results suggest that footmats and footbaths containing peroxygenbased disinfectant are effective in reducing bacterial contamination on the soles of boots when used in conditions representative of large animal hospitals. Similar results were achieved with use of either footmats or footbaths. The use of footbaths and footmats containing effective disinfectants may help decrease the risk for spread of nosocomial infection but should not be expected to sterilize footwear.

Evaluation of the effects of footwear hygiene protocols on nonspecific bacterial contamination of floor surfaces in an equine hospital

To evaluate the effects of footwear hygiene protocols on bacterial contamination of floor surfaces in an equine hospital. Field trial. Footwear hygiene protocols evaluated included use of rubber overboots with footbaths and footmats containing a quaternary ammonium disinfectant, rubber overboots with footbaths and footmats containing a peroxygen disinfectant, and no restrictions on footwear type but mandatory use of footbaths and footmats containing a peroxygen disinfectant. Nonspecific aerobic bacterial counts were determined via 2 procedures for sample collection and bacterial enumeration (contact plates vs swabbing combined with use of spread plates), and the effects of each footwear hygiene protocol were compared. There were no consistent findings suggesting that any of the protocols were associated with differences in numbers of bacteria recovered from floor surfaces. Although there were detectable differences in numbers of bacteria recovered in association with different footwear hygiene protocols, differences in least square mean bacterial counts did not appear to be clinically relevant (ie, were < 1 log10). Although cleaning and disinfection of footwear are important aids in reducing the risk of nosocomial transmission of infectious agents in veterinary hospitals, the numbers of aerobic bacteria recovered from floor surfaces were not affected by use of rubber overboots or the types of disinfectant used in this study. Further study is warranted to evaluate the usefulness of footwear hygiene practices relative to their efficacy for reducing transmission of specific pathogens or decreasing nosocomial disease risk.

Variation in Numbers of Bacteria on Paired Chicken Carcass Halves

Bacterial counts from paired broiler carcass halves were examined for relationships between numbers and kinds of bacteria that might indicate fecal contamination. Broiler carcasses removed from a commercial processing plant just before chilling were split aseptically along the midline, and each side was rinsed in 400 mL of phosphate buffered saline for 1 min with either mechanical or hand shaking. Both halves of six carcasses were rinsed on four different days for a total of 24 carcasses sampled with each shaking method. Aerobic bacteria, coliforms, Escherichia coli, and Campylobacter jejuni were enumerated and summed to obtain whole carcass counts. There were no significant (P < 0.05) differences in numbers of bacteria recovered by the two rinse methods. In left-right comparisons, only E. coli was significantly different (P = 0.04), with the right side having higher counts (least-square means of 1.09 vs. 0.97). For aerobic plate count (APC), coliforms, E. coli, and Campylobacter, correlations between paired left and right side counts were between 0.78 and 0.86. The correlation between whole carcass counts and absolute left-right differences was significant for APC (0.43), but was not significant for coliforms, E. coli, and Campylobacter, so higher whole carcass counts were not associated with higher counts on one side of the carcass. Correlations between different bacteria on whole carcasses were significant for E. coli-APC (0.39), E. coli-coliforms (0.67), and APC-coliforms (0.71), but other combinations had non-significant correlations. The correlation was not significant between E. coli and Campylobacter, a relatively fragile organism whose presence can be interpreted to indicate fairly recent fecal contamination. There were no indications that high E. coli counts on inspection-passed, prechill carcasses indicated recent fecal contamination.

Identification of Legionella pneumophila rcp, a pagP-like gene that confers resistance to cationic antimicrobial peptides and promotes intracellular infection.

In the course of characterizing a locus involved in heme utilization, we identified a Legionella pneumophila gene predicted to encode a protein with homology to the product of the Salmonella enterica serovar Typhimurium pagP gene. In Salmonella, pagP increases resistance to the bactericidal effects of cationic antimicrobial peptides (CAMPs). Mutants with insertions in the L. pneumophila pagP-like gene were generated and showed decreased resistance to different structural classes of CAMPs compared to the wild type; hence, this gene was designated rcp for resistance to cationic antimicrobial peptides. Furthermore, Legionella CAMP resistance was induced by growth in low-magnesium medium. To determine whether rcp had any role in intracellular survival, mutants were tested in the two most relevant host cells for Legionnaires' disease, i.e., amoebae and macrophages. These mutants exhibited a 1,000-fold-decreased recovery during a Hartmannella vermiformis coculture. Complementation of the infectivity defect could be achieved by introduction of a plasmid containing the intact rcp gene. Mutations in rcp consistently reduced both the numbers of bacteria recovered during intracellular infection and their cytopathic capacity for U937 macrophages. The rcp mutant was also more defective for lung colonization of A/J mice. Growth of rcp mutants in buffered yeast extract broth was identical to that of the wild type, indicating that the observed differences in numbers of bacteria recovered from host cells were not due to a generalized growth defect. However, in low-Mg(2+) medium, the rcp mutant was impaired in stationary-phase survival. This is the first demonstration of a pagP-like gene, involved in resistance to CAMPs, being required for intracellular infection and virulence.

Effects of Sediments on Estimates of Bacterial Density

We compared direct epifluorescent microscopic bacterial counts using either acridine orange [AO; 3,6-bis(dimethylamino)acridinium chloride] or DAPI (4',6-diamidino2-phenylindole) in the presence and absence of fine sediments. Differences in a time-series of population estimates obtained using either AO or DAPI direct-count methods were greater in sediment-amended cultures. In the presence of sediments, DAPI yielded significantly lower estimates of bacterial densities than AO. A sediment-addition experiment indicated that DAPI counts may be more sensitive to sediment presence than AO counts, although interaction between treatments (stain, sediment) clouds statistical interpretation. Variation between replicate cultures was greater than between subsamples of preserved combined samples. Mean differences attributable to choice of stain may be as great as differences attributable to potential masking effects of sediments. Despite culture variability, DAPI and AO methods yielded count estimates agreeing within an order of magnitude. Greater correspondence between counts was observed for turbid natural water samples spanning a more limited range of bacterial concentrations. Identifying and interpreting the biotic and abiotic factors responsible for the regulation of bacterial numbers is a major goal of microbial ecology. Bacteria have been enumerated in several ways, with many of the same techniques being applied in a variety of systems. If reported usage is indicative, methods of direct microscopic visualization are increasingly favored over standard platecount techniques which, by necessity, exert a selective effect leading to underestimates of total bacterial numbers. A serious and recognized drawback of plate counts is that no single medium will culture all bacteria (Buck, 1979), yet the presence of large numbers of bacteria (regardless of culturability) may be of great significance. Recently, epifluorescent direct-count techniques have become the methods of choice for enumeration of total bacteria (Fry, 1988). However, clear differences in numbers of bacteria observed depend upon both staining technique and physico-chemical characteristics of the sample. Two fluorochrome stains are most often used in direct-count methods. DAPI (4',6-diamidino-2-phenylindole) is a DNA-specific stain that fluoresces blue or bluish-white when bound to DNA and excited with light at a wavelength of 365 nm. When unbound or bound to non-DNA material, it may fluoresce over a range of yellow colors. As with the other most commonly used strain, AO [3,6-bis(dimethylamino)acridinium chloride or acridine orange], bacteria are identified based not only upon color but also upon size and shape. AO binds to both DNA and RNA, and the excitation maximum for AO is approximately 470 nm. Both DAPI and AO stain bacteria and other fine particulate organic matter (FPOM) differentially. Two experiments were performed to assess differences in bacterial directcount methods. In particular, we were interested in potential differences in counts obtained using DAPI and AO. At the same time, we examined differences TRANS. AM. MICROSC. SOC., 112(4): 316-330. 1993. ? Copyright, 1993, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.163 on Wed, 21 Sep 2016 05:28:09 UTC All use subject to http://about.jstor.org/terms VOL. 112, NO. 4, OCTOBER 1993 in our ability to enumerate bacteria in the presence or absence of fine inorganic sediments (primarily silts and clays) and whether this ability was influenced by choice of stain. Environmental samples also were collected and bacterial counts obtained using the two stains were compared. Particle-attached bacteria pose special problems because of masking effects and the need for dilution of high-turbidity samples. Turbid samples are encountered frequently in many types of studies (e.g., studies examining stormflow, estuarine or saltmarsh water, pore water, sediments, and soil water). The frequent occurrence of sediment-laden samples and common usage of DAPI and AO direct-count (AODC) methods in the enumeration of bacteria have created the need for further methodological comparisons of the type presented here. MATERIALS AND METHODS

Factors which affect retention ofSalmonellaby chicken muscle fascia

Retention of Salmonella lyphimurium and Salmonella Singapore by chicken muscle fascia after immersion in bacterial suspensions was directly dependent on the concentration of bacteria in suspension. However, more bacteria were retained by tissue immersed in suspensions for 30 min compared with tissue immersed only transiently (ca 15 s) and no significant difference in retention of either test strain used was noted for suspensions prepared in distilled water or physiological saline. Differences in numbers of bacteria retained were correlated with water induced changes in tissue microtopography. By comparison, addition of sodium or magnesium ions (present as chlorides) in concentrations greater than 0.2mol.l‐1, caused significant reductions in retention. Furthermore, optimal retention of both strains occurred at a pH of ca 7. Cells of the test strains used did not attach to collagen fibres associated with fascia when suspension media other than distilled water were used. Treatment of tissue with cetyl pyridi...

AntibactERial Activity of Four Cephalosporins in an ExpERimental Infection in Relation to In Vitro Effect and Pharmacokinetics

The in vitro activity of four cephalosporins was compared with their effects in an experimental thigh infection (cefuroxime and cefamandole against Escherichia coli and cefamandole, ceftriaxone, and ceftazidime against Klebsiella pneumoniae) in granulocytopenic mice. The effect in vitro (ER) was defined as the difference between the growth rate without antibiotic and the growth rate at the steepest part of a 3-h growth curve in the presence of an antibiotic. The relation between concentration and ER was described with the Hill equation. Using pharmacokinetic parameters of the plasma concentrations in vivo and those of the Hill equation the corresponding time course of ER was calculated and by integration with respect to time (0tERdt), an estimate was obtained of the effect on bacteria. For all four antibiotics this estimate was significantly correlated with the actual values of the effect in vivo (EN), defined as the difference in numbers of bacteria between controls and antibiotic-treated animals at 4 h.

Accelerated restoration of the leukocyte number and augmented resistance against Eschericia coli in cyclophosphamide-treated rats orally administered with a hot water extract of Chlorella vulgaris

The effects of oral administration of a hot water extract of Chlorella vulgaris (CVE) on the restoration of the leukocyte number and on the resistance against Escherichia coli infection were examined in cyclophosphamide (CY)-treated rats. Male Fischer rats (F344/DuCrj) were administered orally 1000 mg/kg of CVE for 14 days and injected intraperitoneally with a single dose of CY (50 mg/kg) (day 0) one day after the 14th CVE administration. CVE was further administered continuously after CY treatment until the rats were sacrificed for analysis. The number of bone marrow cells in the CY + CVE group was significantly higher on day 7 after CY treatment than that in the CY-treated group. The number of spleen cells in the CY + CVE group became significantly higher on day 11 than that in the CY-treated group. In the peripheral blood, the number of PMN recovered efficiently in the CY + CVE group in comparison with the CY-treated group on day 7. When E. coli was injected i.p. into normal, CY-treated, and CY + CVE-treated rats on day 6, the difference in number of bacteria among these three groups was most prominent before 6 h, that is, the number in the CY + CVE group was remarkably lower than those in the CY-treated group, and even in the control group, among all organs so far tested.

Infection of Mycobacterium leprae and Mycobacterium lepraemurium into a cloned macrophage like cell line

Intracellular killing of Mycobacterium leprae and M. lepraemurium by cloned macropha- ge cell line was observed by direct staining with FDA/EB or in the spread subcutaneous tissue preparation with Ziehl-Neelsen stain. Clone 16, derived from J774, can produce superoxide anion (O2-) and H2O2 upon appropriate stimulation, while clone C3C, a variant in oxidative metabolism, defects in production of reactive oxygen intermediates. After both clones of the cells were infected with M. leprae or M. lepraemurium for three hours, and further incubat-ed in 5% CO2-air at 37°C, most of the bacteria of both species were stained green with FDA/EB staining. Under the microscopic observation of the spread subcutaneous tissue preparation, there was no difference in number of bacteria between clone 16 and C3C cells, but decreased number of bacteria was assessed in the cells of further incubation in 5% CO2-air at 37°C after one hour-infection than in the cells immediately after the one hour-infection periods. These results indicated that M. lepraemurium, and may be M. leprae, was partially killed or growth-inhibited by oxygen-independent killing mechanisms of macrophage cell line, rather than by reactive oxygen intermediates.

Epiphytic bacteria: development of a method for determining respiring bacteria on leaves

A method was developed for studying the total numbers and the proportion of active bacteria on leaf surfaces. It involves staining gelatin impressions of leaves treated with an electron transport system indicator, 2‐(p‐iodophenyl)‐3‐(p‐nitrophenyl)‐5‐phenyl tetrazolium chloride (INT). The method is rapid, inexpensive and allows simultaneous observation of numbers, ecology and respiratory activity of epiphytic bacteria. The total numbers of epiphytic bacteria for four species of aquatic plants varied between 0.6 to 10.2 times 106/cm2. The proportion of active bacteria on leaves of aquatic plants ranged from 2.2 to 42.9%. The method was also applied to a comparison of surface fouling of glass slides and aquatic leaf surfaces, indicating significant differences in numbers of bacteria but little difference in the proportion active on the two surfaces.

Microbiological Survey of Adirondack Lakes with Various pH Values

Nine high-altitude oligotrophic Adirondack lakes in upstate New York having water of pH 4.3 to 7.0 were surveyed for total bacterial numbers and possible adaptation of the microbial communities to environmental pH. The number of heterotrophic bacteria from water samples recoverable on standard plate count agar were low (10 to 10 per ml) for most of the lakes. Acridine orange direct counts were approximately two orders of magnitude higher than plate counts for each lake. Sediment aerobic heterotrophs recovered on standard plate count agar ranged from 1.4 x 10 to 1.3 x 10 per g of sediment. Direct epifluorescence counts of bacteria in sediment samples ranged from 3.0 x 10 to 1.4 x 10 per g. Low density values were consistent with the oligotrophic nature of all the lakes surveyed. There were no apparent differences in numbers of bacteria originally isolated at pH 5.0 and pH 7.0 between circumneutral lakes (pH > 6.0) and acidic lakes (pH < 5.0). Approximately 1,200 isolates were recultured over a range of pH from 3.0 to 7.0. Regardless of the original isolation pH (pH 5.0 or pH 7.0), less than 10% of the isolates grew at pH < 5.0. Those originally isolated at pH 5.0 also grew at pH 6.0 and 7.0. Those originally isolated at pH 7.0 preferred pH 7.0, with 98% able to grow at pH 6.0 and 44% able to grow at pH 5.0. A chi-square contingency test clearly showed (P < 0.005) that two distinct heterotrophic populations had been originally isolated at pH 5.0 and pH 7.0, although there is undoubtedly some overlap between the two populations.

Extensive small gut resection in the rat. Microbiological studies with a strict anaerobic technique.

The small intestinal microflora of the rat was examined 6 w after resection of the proximal half of the ileum. A comparison was made with animals where the ileum had only been transected and re-sutured. The study included a strict anaerobic culturing and an investigation of bacterial metabolites with a gas chromatography technique. In both groups the flora was found to be mainly facultative and there was no difference in the total number of bacteria. There was no difference between the groups or between the single animals in the proportional of aerobes-anaerobes. In spite of numerous adhesions between the ileal loops causing impaired intestinal motility and intraluminal stasis, there was no colonization of the small intestinal flora and the concentration of bacteria was too low to give a positive response for gas chromatography. It is stated that the low amount of intestinal bacterial flora is not likely to be a significant factor causing adaptive mucosal hyperplasia after gut resection.

Bacterial flora of hospital carpets

An experiment was set up in Christchurch Hospital to attempt to identify and quantify the bacterial flora of carpet and sheet vinyl floor coverings in a ward and laboratory area, and the bacterial flora in the air of the same area noting any bacteria/fibre relationships, as well as determining the effect of ambient temperature, humidity and people on the bacterial counts. The test areas were a blind ward corridor and a first floor laboratory corridor. Both areas had rooms with windows opening to the outside leading off each side of the corridor. Analytical samples were collected from predetermined sites using settle plates, a Casella slit sampler and a vacuum sampler. Studies were carried out before, during and after a 12 ft length of carpet was laid over the complete width of each corridor. Analysis of the results showed: (1) The difference in numbers of bacteria on the settle plates, number and types of bacteria on the floor and in the air, from the vinyl and carpeted floor areas was generally not significant. (2) There was no evidence that carpet harbours any more pathogenic bacteria than a sheet vinyl floor covering. (3) There was no statistical relationship between the fibre count and the bacterial count of the settle plates from the carpeted floor areas. (4) The bacterial counts were significantly lower 18 ft from the entrance of each corridor no matter which floor covering was in situ , but these counts were significantly lower when the corridor entrance was carpeted. (5) There was no statistical correlation between the bacteria counted and the recorded humidity or temperature.

実験動物施設における空中細菌について

Some investigations were carried out on airborne bacteria in different parts of laboratories. The results are summarized as follows:1) The numbers of air-borne bacteria were much different among animal rooms under different conditions. (Fig. 2) .2) Bacterial number in the experimental room attained its maximum at daytime and its minimum at night (Fig. 5) . The mean number of air-borne bacteria in animal room however, was larger at night than at daytimes (Fig. 4) . The daily changes of bacterial number in the vestibule were similar to those in the experimental room (Fig.3) .3) The numbers of bacteria in animal rooms before and after introduction of animals was considerably different. (Fig.6 & 7) .4) The numbers of air-borne bacteria in the animal rooms differs with the species of animals. The highest contamination was observed in the rabbit room.5) The difference in number of bacteria between the levels of 170 cm and 20 cm distant from the floor was obserbed (Fig. 6 & 7) .6) Over 90 per cent of the contaminated bacteria were of underf fined micrococci, and the rests were of diphtheroids, coliforms and fungi (Table. 2) .

Hygienical Studies on Suf ace Water in the Agricultural Zones

The author made hygienical and bacteriological studies on superficial water (3 places of river water, 1 place of swamp water and 1 place of rain water) in the agricultural zones.1. As for river water, coli bacilli and enterococci were proved even in the upper streams of the rivers in the mountains. However, considerable difference in number of bacteria, coli bacilli and enterococci between the upper and lower streams was observed. Naturally, the water in the lower streams was much dirtier than that in the upper streams. By the same token, river water in the plain showed more dirtiness than that in the mountains after various examinations.2. The swamp water of the Inbanuma showed high degree of dirtiness. It was as dirty as river water in the plain, or even dirtier, although number of enterococci was smaller.3. Coli bacilli were proved in all the tested materials of the reserved rain water (in Toshima of Tokyo Metropolitan District) but the dirtiness was somewhat lighter than that in river water.4. Correlations between each examined values were stndied. Definite correlation between coli bacilli and enterococci was noted especially in river water of the upper steams, although the correlation in swamp water was different from that in river water. No constant correlation was observed between number of bacteria and coli bacilli or between number of Leiriaa nd enterococci.5. M.P.N. values on coli bacilli and enterococci were studied using fermentation tube methods, and comparison was done between 3 tube method (M.P.N. per 100 ml. of sample using 3 tubes) and 5 tube method (M.P.N. per 100 ml. of sample using 5 tubes) using swamp water. The ratio of the values obtained from these two methods revealed that values by 3 tube method were apt to be higher than those by 5 tube method. The same material which showed positive reaction on enterococci by 5 tube met hod, reacted negatively by 3 tube method. This result meant that the material with comparatively less dirtiness should have been examined by 5 tube method.