Number Of Intestinal Bacteria Research Articles

Composition and diverse differences of intestinal microbiota in ulcerative colitis patients

ObjectiveTo explore the composition of the intestinal microbiota in ulcerative colitis (UC) patients and to identify differences in the microbiota between patients with active disease and those in remission.MethodsBetween September 2020 and June 2021, we enrolled into our study, and collected stool samples from, patients with active UC or in remission and healthy control subjects. The diagnosis of UC was based on clinical, endoscopic, radiological, and histological findings. The composition of the intestinal microbiota was determined by sequencing of the 16S rRNA V3–V4 region and by bioinformatic methods. The functional composition of the intestinal microbiota was predicted using PICRUSt 2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) software.ResultsWe found that the intestinal flora was significantly less rich and diverse in UC patients than in healthy control subjects. Beta diversity analysis revealed notable differences in the intestinal flora compositions among the three groups, but there was no statistical difference in alpha diversity between UC patients with active disease and those in remission. At the phylum level, the relative abundances of Proteobacteria and Patescibacteria were significantly higher, and the relative abundances of Desulfobacterota and Verrucomicrobiota were lower, in UC patients with active disease than in the healthy control group. Higher levels of potential pathogens and lower levels of butyrate-producing bacteria were also detected in UC patients with active disease. Linear discriminant analysis Effect Size (LefSe) revealed that 71 bacterial taxa could serve as biomarkers, with 26 biomarkers at the genus level. In addition, network analysis showed that there was a positive correlation between Roseburia and Lachnospira. Functional predictions indicated that gene functions involving the metabolism of some substances, such as methane, lipopolysaccharide, geraniol, and ansamycins, were significantly different among the three groups.ConclusionThe richness and diversity of the intestinal microbiota differed significantly among the three groups. Richness describes the state of being rich in number of intestinal bacteria, whereas diversity is the number of different species of intestinal bacteria. Different bacterial taxa could be used as biomarkers, expanding our understanding of the relationship between the intestinal microbiota microenvironment and UC in the future.

Pengaruh Rimpang Kunyit (Curcuma domestica, Val.) terhadap Bakteri Usus secara in vitro

The use of turmeric rhizome to treat diarrhea is written in the original Indonesian medicinal manuscript. Diarrhea disease is still a public health problem in Indonesia, because of its high morbidity and mortality. The morbidity survey conducted by Indonesian Ministry of Health shows an increasing incidence trend. One of the causes of diarrhea is an uncontrolled increase in the number of intestinal bacteria and infection by intestinal pathogenic bacteria. This study aims to determine the effect of the turmeric rhizome preparation process, both traditionally and by extraction method by maceration and soxhletation on antibacterial activity, especially intestinal bacteria, so that it can be applied by the traditional medicine industry as well as traditional herbal medicine sellers (“jamu gendong”). The research method used was to test the antibacterial activity of fresh turmeric juice, pre-dried turmeric juice, turmeric extract by maceration using 95% ethanol, and turmeric extract by soxhletation at 100°C using 95% ethanol. The intestinal bacteria used in this study were Escherichia coli, Yersinia enterolitica, Vibrio nonagglutinable, and Shigella flexneri. The results of this study indicate that the treatment process using the traditional method, both fresh turmeric juice and pre-dried turmeric juice, does not show any antibacterial activity. Turmeric extract by maceration showed antibacterial activity against all bacterias and the greatest against Vibrio nonagglutinable bacteria. Turmeric extract by soxhletation showed antibacterial activity against all bacterias and the greatest against Vibrio nonagglutinable bacteria. The conclusion of this study is that the most appropriate method used to process turmeric rhizome as a medicine for diarrhea caused by bacteria is the extraction method by maceration or soxhletation. The greatest antibacterial effect is against the Vibrio nonagglutinable bacteria.

Influence of the type of housing on the intestinal microflora of layers and broilers

The microbiota of birds of different housing types was studied, namely: cage, outdoor and free-range. The number of bacteria Lactobacillus, Bifidobacterium, Enterococcus, E. coli and lactose-positive, Bacillus in bird faeces was investigated. It has been shown that the composition of the microbiota does not depend on the type of their content but depends on the type of nutrition and on the microbiota that was initially located in a farm or poultry house environment. At the same time, the microbiota of birds can change at a young age, but after puberty, it becomes more stable. The microbiota of free-range birds remained stable while maintaining diet and changed with diet changes depending on the season. It has also been shown that litter and soil are capable of retaining significant numbers of intestinal bacteria. Bacillus can colonize birds’ gut, but it is not a permanent participant in the gut microbiota of birds.

Мікробіота ризосфери Salix sp. за умов використання різних агротехнічних прийомів

The study has established the regularities of distribution of certain physiological groups of microbial cenosis in conditions of growing of fruit and energy plants. In case of willow, the numbers of ammonifiers, micromycetes, actinomycetes, cellulolytic and oligonitrophilic microorganisms were observed to reduce compared to the control. In case of apple-trees, the number of microorganisms was higher but still within the control values. Growing of willows leads to stabilization of soil solution reaction, higher concentration of ammonium nitrogen, and lower concentration of nitrate nitrogen and potassium, compared with the control. We have established decreased concentrations of humus vs. control in both cases – growing of willows and apple-trees, which figure correlates with the number of pedotrophs. Notwithstanding the lowered number of some physiological groups of microorganisms, the soil with willows was characterized by highly intensive mineralization processes, in particular those of transformation of organic matters. An open-field long-term fertilization experiment was set up during 2011 with willow (Salix triandra x Salix viminalis ’Inger’), grown as an energy crop. The brown forest soil was treated during June 2011, May 2013, and May 2016 with municipal biocompost (MBC), municipal sewage sludge compost (MSSC), willow ash (WA) and sulfuric urea (SU) and two times (2011, 2013) with rhyolite tuff (RT). Thus, the most indicative changes in the soil microbiota against the control plot were found in case of the use of municipal sewage sludge compost; rise in the number of intestinal bacteria, ammonifiers, micromycetes and actinomycetes. In case of the use of municipal biocompost rise in the levels of intestinal bacteria, microscopic fungi, actinomycetes, pedotrophs and cellulolytic bacteria were found. While calculating the mineralization/immobilization index, it was shown that the most significant deviation from the control plot was found in rhyolite tuff treated soil – a decrease by 6 times, and in case of willow ash by 2.3 times, which proves the inhibition of mineralization of the organic substances in the soil.

The growth performances and the gut health parameters of Sentul chickens supplemented with various dosage of turmeric powder

Asmara IY, Widjastuti T, Setiawan I, Abun, Partasasmita P. 2018. The growth performances and the gut health parameters of Sentul chickens supplemented with various dosage of turmeric powder. Nusantara Bioscience 10: 121-125. The aim of this study was to investigate the effect of different levels of turmeric powder (0, 1, 2, 3 g/kg) on production performance and the number of Escherichia coli and Staphylococcus aureus bacteria in the intestine of Sentul chickens. The results showed that addition of 3 g/kg of turmeric powder to diet significantly reduced feed intake (FI) and improved feed conversion ratio (FCR) of Sentul Chickens aged 9-16 weeks. The birds fed with control diet had the highest number of S. aureus and E. coli, while the birds fed with the diets added with 2 and 3 g/kg turmeric powder had the lowest number of bacteria. The study reveals that increasing levels of turmeric powder in diets had positive effects on bird’s performance and the number of intestinal bacteria. It can be concluded that a level of 3 g/kg turmeric powder in diets gave the best result due to significantly improved FCR.

Intestinal microecology associated with fluoride resistance capability of the silkworm (Bombyx mori L.).

The silkworm (Bombyx mori L.) is an ideal model of Lepidoptera. However, the diversity and function of the intestinal microbiota in the gut of silkworm remain largely unknown. Changes in the intestinal microecology in fluoride-resistant strain T6 and fluoride-susceptible strain 734 of the silkworm in response to fluoride exposure were investigated. T6 and 734 were treated with 200mg/kg fluoride (designated as T6-T and 734-T groups) and deionized water (designated as T6-C and 734-C groups). Culture-dependent approach revealed that the numbers of intestinal bacteria in the 734-T group significantly decreased compared with that in the 734-C group (4.8 ± 0.6 × 10(7)CFU/mL vs. 7.5 ± 0.7 × 10(7)CFU/mL; P < 0.05). Analyses of the intestinal content pH showed that the pH decreased in the 734-T group only. Additionally, SCFA concentrations significantly decreased in both treatment groups compared with the control groups. High-throughput sequencing indicated that the intestinal microbiota in the 734-T group was significantly more diverse than those in the other groups. The bacterial community was composed of two dominant groups (Firmicutes and Proteobacteria). Principal component analyses revealed a significant difference in the composition of the intestinal microbiota in the 734-T group compared with those in the other groups. Thaumarchaeota and Euryarchaeota were more abundant in the 734-T group, but they were less abundant in the other groups. This study enhances our understanding about the diversity and function of silkworm intestinal microbiota in response to fluoride exposure among silkworm strains with diverse resistance.

The number of intestinal bacteria is not critical for the enhancement of antitumor activity and reduction of intestinal toxicity of irinotecan by the Chinese herbal medicine PHY906 (KD018).

BackgroundThe four-herb Chinese medicine PHY906(KD018) has been shown to both enhance the in vivo antitumor activity of irinotecan (CPT-11) against colon cancer tumor allografts and alleviate intestinal toxicity caused by CPT-11.MethodsSince intestinal bacteria can metabolize CPT-11 and PHY906, we investigated whether intestinal bacteria play a critical role in the in vivo activity of PHY906 in murine Colon-38 tumor-bearing mice. Intestinal bacteria were depleted using streptomycin/neomycin for 10 days before and during treatment with PHY906 and/or CPT-11. qPCR using 16S DNA group-specific primers was used to quantify the levels of the major intestinal bacteria.ResultsBoth PHY906 and antibiotic treatment changed the profile of intestinal bacteria species: Lactobacillus/Enterococcus, Bacteroides, Clostridium leptum, and E. rectale/C. coccoides. Antibiotic treatment did not alter the ability of PHY906 to enhance the antitumor activity of CPT-11. Antibiotic treatment alone partially reduced animal body weight loss in CPT-11-treated mice. However, PHY906 treatment was able to protect against the body weight loss in the CPT-11/antibiotic treatment group. H&E and PCNA staining of intestine showed that antibiotic treatment partially reduced the intestinal damage caused by CPT-11 but not as effectively as PHY906 treatment. Antibiotic treatment plus PHY906 conferred the most effective protection of intestine histological structure against damage by CPT-11. Both PHY906 and antibiotic treatment inhibited CPT-11-associated inflammatory processes, including infiltration of the intestine by neutrophils, MCP1 and TNF-alpha mRNA expression in the intestine, and expression of pro-inflammatory cytokines G-CSF and MCP1 proteins in the plasma. However, whereas antibiotic treatment suppressed the mRNA expression of two important intestinal progenitor/stem cell markers, Olfm4 and Lgr5, PHY906 treatment resulted in enhanced expression of these two stem cell markers.ConclusionsAlterations in the population of intestinal bacteria did not affect the abilities of PHY906 to enhance CPT-11 antitumor activity or reduce the intestinal toxicity associated with CPT-11 treatment. The major species of intestinal bacteria do not appear to play a role in PHY906’s enhancement of the therapeutic index of CPT-11 in tumor-bearing mice. Thus, patients with different intestinal bacterial profiles may still benefit from PHY906 treatment alongside CPT-11.

Rebamipide protects small intestinal mucosal injuries caused by indomethacin by modulating intestinal microbiota and the gene expression in intestinal mucosa in a rat model.

The effect of rebamipide, a mucosal protective drug, on small intestinal mucosal injury caused by indomethacin was examined using a rat model. Indomethacin administration (10 mg/kg, p.o.) induced intestinal mucosal injury was accompanied by an increase in the numbers of intestinal bacteria particularly Enterobacteriaceae in the jejunum and ileum. Rebamipide (30 and 100 mg/kg, p.o., given 5 times) was shown to inhibit the indomethacin-induced small intestinal mucosal injury and decreased the number of Enterococcaceae and Enterobacteriaceae in the jejunal mucosa to normal levels. It was also shown that the detection rate of segmented filamentous bacteria was increased by rebamipide. PCR array analysis of genes related to inflammation, oxidative stress and wound healing showed that indomethacin induced upregulation and downregulation of 14 and 3 genes, respectively in the rat jejunal mucosa by more than 5-fold compared to that of normal rats. Rebamipide suppressed the upregulated gene expression of TNFα and Duox2 in a dose-dependent manner. In conclusion, our study confirmed that disturbance of intestinal microbiota plays a crucial role in indomethacin-induced small intestinal mucosal injury, and suggests that rebamipide could be used as prophylaxis against non-steroidal anti-inflammatory drugs -induced gastrointestinal mucosal injury, by modulating microbiota and suppressing mucosal inflammation in the small intestine.

양파껍질 추출물 급여가 비만 유도쥐의 소장내 변화에 미치는 영향

본 연구는 양파껍질을 발효주정 에탄올 70%와 95% 농도로 추출하여 항균활성, 항산화활성 및 비만쥐의 소화기관에 미치는 영향에 대하여 알아보고자 실시하였다. 각 주정 추출물 5%는 E. coli와 Listeria monocytogens에서 유의적인 감소를 나타내었다. 각 주정 추출물 내 총 페놀함량은 각각 <TEX>$166.89{\pm}0.03$</TEX> mg/g과 <TEX>$160.89{\pm}0.13$</TEX> mg/g을 나타내었다. 항산화효과를 살펴본 결과 DPPH 라디칼 소거능과 SOD 유사 활성은 100 ug/ml의 농도에서 높은 수준을 나타내었다. 고지방식이를 급여하여 유도한 비만을 유도한 마우스에 70%와 95% 주정으로 추출한 양파껍질 추출물을 1, 3, 5%의 농도로 4주간 급여한 후 체중, 사료섭취량, 사료효율, 소장무게, 길이 장내 융모의 길이, 소장 내 미생물수를 측정하였다. 각 주정으로 추출한 양파 추출물 5%의 농도로 급여하였을 때 대조군에 비해 체중이 유의적으로 낮은 수준을 나타내었으나(p<0.05) 사료섭취량은 증가함을 나타내었다. 실험동물 마우스 소장의 무게와 길이는 양파 껍질추출물 급여에 따른 유의적인 변화는 보이지 않았으나 소장 융모의 길이는 대조군보다 유의적으로 증가함을 나타내었다. 총균수, Cl.perfringenes와 E.coli는 5%의 농도로 양파껍질 주정 추출물을 처리했을 때 유의적으로 감소함을 나타내었으나 젖산균은 증가함을 나타내었다. 이러한 결과는 추후 부가적인 추가 연구가 필요하겠지만 70%와 95%의 주정으로 추출한 양파껍질 추출물을 5% 수준으로 이용하면 체중조절 첨가제로서 그리고 장의 건강을 증진시키기 위한 첨가제로 사용할 수 있는 잠재성이 있는 것으로 기대된다. This study was performed to determine the effect of onion peel extract using 70% ethanol and 95% ethanol on its anti-oxidation activity, small intestine length, and intestinal villi of high-fat fed mice. Five percent of each onion peel extract using 70% and 95% ethanol showed significant decrease of E. coli and Listeria monocytogenes. Total phenolic contents of onion peel extracts using 70% and 95% ethanol were <TEX>$166.89{\pm}0.03$</TEX> mg/g and <TEX>$160.89{\pm}0.13$</TEX> mg/g, respectively. In anti-oxidation activity, DPPH radical scavenging activity and SOD-like activity of onion peel extracts were higher at 100 ug/ml concentration. The obese mice were fed high-fat diets supplemented by 1, 3, and 5% of the onion peel extracts using 70% and 95% ethanol for 4 weeks. Body weight, feed intake, feed efficiency, small intestine weight, length, villi's length, and number of bacteria in intestine were determined. Body weight of mice fed 5% of onion extracts using both 70% and 95% ethanol was significantly lower than that of control (p<0.05). However, feed intake was increased in mice fed 5% of onion extracts at both fermented ethanol levels. Small intestine weight and length of mice showed no significant change with supplementation of the onion peel extracts. However, length of small intestine villi was significantly longer than that of control. Total bacteria counts of Cl. Perfringenes and E. coli in small intestine of the mice were significantly reduced by supplementation of 5% of onion extract using ethanol, while lactic acid bacteria were increased. These results suggest that 5% of onion peel extracts using ethanol at either 70% or 95% concentration have potential to be used as an additive for body weight control and enhanced gut health; however, more research on its effectiveness is needed.

Impact of intestinal microbiota and gastrointestinal conditions on the in vitro survival and growth of Bacillus cereus

Ingestion of B. cereus can result in diarrhea, if these bacteria survive gastrointestinal passage and achieve growth and enterotoxin production in the small intestine. The gastrointestinal survival of vegetative cells and spores of the diarrheal food poisoning strain B. cereus NVH 1230-88 was investigated during in vitro batch experiments simulating the stomach, duodenum and ileum using simulation media and competing intestinal microbiota. All spores and approx. 30% of the vegetative B. cereus cells survived the 2h incubation in gastric medium with pH 4.0. Sterile intestinal medium induced germination of spores and enabled outgrowth of vegetative cells to approx. 7 log CFU/mL. The behavior of B. cereus in the intestinal environment with competing intestinal bacteria was determined by their relative concentrations. Besides the numbers of intestinal bacteria, the nutrition and composition of the intestinal community were also very important for the growth inhibition of B. cereus.

Bacteriophages and genetic mobilization in sewage and faecally polluted environments

SummaryBacteriophages are one of the most abundant entities on the planet and are present in high concentrations within humans and animals, mostly in the gut. Phages that infect intestinal bacteria are released by defecation and remain free in extra‐intestinal environments, where they usually persist for longer than their bacterial hosts. Recent studies indicate that a large amount of the genetic information in bacterial genomes and in natural environments is of phage origin. In addition, metagenomic analysis reveals that a substantial number of bacterial genes are present in viral DNA in different environments. These facts support the belief that phages can play a significant role in horizontal gene transfer between bacteria. Bacteriophages are known to transfer genes by generalized and specialized transduction and indeed there are some examples of phages found in the environment carrying and transducing genes of bacterial origin. A successful transduction in the environment requires certain conditions, e.g. phage and bacterial numbers need to exceed certain threshold concentrations, the bacteria need to exist in an infection‐competent physiological state, and lastly, the physical conditions in the environment (pH, temperature, etc. of the supporting matrix) have to be suitable for phage infection. All three factors are reviewed here, and the available information suggests: (i) that the number of intestinal bacteria and phages in faecally contaminated environments guarantees bacteria–phage encounters, (ii) that transduction to intestinal bacteria in the environment is probable, and (iii) that transduction is more frequent than previously thought. Therefore, we suggest that phage‐mediated horizontal transfer between intestinal bacteria, or between intestinal and autochthonous bacteria in extra‐intestinal environments, might take place and that its relevance for the emergence of new bacterial strains and potential pathogens should not be ignored.

The Gut Microbiota: A Microbial Arsenal Protecting Us From Infectious and Radiation-Induced Diarrhea

The Gut Microbiota: A Microbial Arsenal Protecting Us From Infectious and Radiation-Induced Diarrhea

Treatment of the primary hyperoxalurias: A new chapter

Despite advances in the enzymology, molecular genetics, and clinical knowledge of the primary hyperoxalurias, few treatments are available. Oxalobacter formigenes is a promising new therapy with potential to induce secretion of oxalate into the intestinal lumen, where it can be degraded by the bacteria.

Bacteriocidal activity of garlic powder against Bacillus anthracis.

The antibacterial activity of garlic powder was examined against Bacillus anthracis using agar plate cultivation and test tube methods. On the agar plate test, 1-5% garlic powder inhibited the growth of B. anthracis and Escherichia coli O157 used as references. A 1% water solution of garlic powder in the test tube method killed B. anthracis at 10(7) cfu/mL within 3 h of treatment at room temperature. A number of intestinal bacteria in a BALB/c mouse decreased after the oral administration of 1 mL of 1%, garlic powder solution once a day for 3 d. These results suggest that the oral administration of garlic powder is effective against pathogenic bacteria invasion into the intestine as an infection.

ВЛИЯНИЕ НА АЕРОЙОНИЗАЦИЯТА ВЪРХУ МИКРОФЛОРАТА НА ВЪЗДУХА В ЖИВОТНОВЪДНИ СГРАДИ, РАЗПОЛОЖЕНИ В ЗАМЪРСЕНИ С ТЕЖКИ МЕТАЛИ РАЙОНИ, И ЗАБОЛЕВАЕМОСТТА ПРИ ТЕЛЕТА

Click to increase image sizeClick to decrease image sizeРЕЗЮМЕВ результате проведеиного зксперимента установлено, что общее количество микрооргани змов в 1 m 3 воздуха в опытном ионизированном помещении уменьшается в среднем на 67.92%, достигая максимума 76.74% по сравнению с контрольным неионизированным помещением. Количество кишечных бактерий снижается примерно на 59.72% при максимуме 89.47%, а плесени-на 30.82% при максимуме 52.17%.SUMMARYThe total number of microorganisms per 1 m3 air in the experimental ionized premise is reduced by 67.92% on the average and reaches a maximum of 76.74%, as compared with the control one, without application of any air ionization. The number of intestinal bacteria is reduced by 59.72% on the average and the maximum reaches 89.47%, while the quantity of moulds is reduced by 30.82% on the average and reaches a maximum of 52.17%.

Metabolism of sennosides by human intestinal bacteria.

Species and numbers of intestinal bacteria have recently been investigated and the biochemical interaction between a host and its intestinal flora has become the object of research. It has been suggested that the purgative activities of Rhei rhizoma and Sennae folium are related to the intestinal bacterial action. The present study was undertaken to reveal the process of the metabolism of sennosides, the main effective components of these crude drugs, by human intestinal bacteria, to account for the relation between their defaecation effect and intestinal flora. Through a qualitative study of the ability of 20 species of anaerobes to metabolize sennoside A (A), species were classified into four types: Type I possessing ß-glucosidase activity to produce sennidin, Type II isomerizing A to sennoside B (B), Type III producing unknown glucosides, and Type IV possessing no metabolic activity. Quantitative analyses of intermediates and products clarified the process of the metabolism of A. Type I bacterium, using Clostridium sphenoides as a typical example, reductively cleaved A to produce 8-glucosylrheinanthrone (8GRA), which was then hydrolyzed by ß-glucosidase to produce rheinanthrone (RA), which was rapidly oxidized to sennidin. Type II bacterium, using Eubacte-rium rectale, reduced both A and B to 8GRA in the same way as Type I bacteria, followed by oxidation to the isomers B and A, because of deficiency of ß-glucosidase activity. The active principle is probably RA, which can be formed by Type I bacteria through the reduction and subsequent hydrolysis of sennosides. The individual differences of Type I bacteria in the purgative effect of sennosides may be due to the difference of Type I bacteria in the intestinal flora.

L'activité uréasique de la flore du tractus digestif de la pondeuse, effet de la Bacitracine et de la Flavomycine

Counting of bacteria, detection of urease-positive bacteria and estimation of bacterial ureolysis influenced by Bacitracin and Flavomycin was done on intestinal contents from different segments of the digestive tract of laying hens. It was concluded that: - the intestinal flora was numerically most important in the caecum and was composed principally of lactobacilli in the crop, gizzard, duodenum, jejunum and ileum, and of lactobacilli and anaerobes in the caecum and colon. - 17% of the total number of intestinal bacteria were urease-positive. - the ureolytic activity was most important in the caecum: 24 mg of urea hydrolysed/g of contents during 4 hours of incubation. The range is between 2 and 4 mg in the other segments. - until the level of 500 ppm, Bacitracin and Flavomycin did not influence the in vitro ureolytic activity of fecal and cecal material.

The Number and Varieties of Bacteria carried by the Common House-fly in Sanitary and Insanitary City Areas

1. Over 450 naturally infected or wild flies (Musca domestica) were caught in Liverpool during September and the first part of October 1911 from different parts of the city. The number and kinds of bacteria carried and contained by them have been investigated.2. The number of bacteria coming from house-flies whilst struggling in liquid may be very large, varying from 2000, the lowest figure in 5 minutes, to 350,000, the highest figure in 30 minutes. This number may be taken as a measure of their capacity to pollute liquid with their vomit or excrement, or by wallowing in it. The number of bacteria carried inside the fly is very much greater.3. Flies caught either in insanitary or congested areas of the city carry and contain far more bacteria than those from the more sanitary, less congested or suburban areas. The number of aerobic bacteria from the former varied from 800,000 to 500,000,000 per fly, and from the latter from 21,000 to 100,000.4. The number of intestinal bacteria as indicated by glucose bile salt fermenters is also greater in the insanitary or congested areas, the numbers varying from 10,000 to 333,000,000, than in the more sanitary areas where they carried from 100 to 10,000.5. Pathogenic bacteria and those allied to the food poisoning group were only obtained from the congested or moderately congested areas and never from the suburban areas.6. We have examined the morphological characters and cultural reactions of 123 strains. Among those identified were twoStreptococci, and severalStaphylococciandSarcinae. 106 were small Gram negative non-spore bearing bacilli, and have been grouped as follows:Chromogenicgroup. Two strains ofB. pyocyaneuswere isolated from a knacker's yard; for the first time, we believe, from wild flies.Colon group. 41 colonies of this group were picked off haphazard and classified according to McConkey as follows:B. acidi lacticitype 19·5%B. coli communistype 12·2 %B. neapolitanustype 19·5 %B. lactis aerogenestype 46·4 %Salmonella group. One bacillus gave identical reactions toB. enteritidisof Gaertner except that serological tests were negative.Morgan's infantile diarrhoea group. One identical to Morgan's No. 1, and many others closely resembling it and Morgan's Nos. 2 and 3 were obtained.Others fall into Proteolytic, Acid lactose-sucrose (saccharose), and Miscellaneous groups.7. Flies caught in milk shops apparently carry and contain more bacteria than those from other shops with exposed food in a similar neighbourhood. The reason of this is probably because milk when accessible, especially in the summer months, is suitable culture medium for bacteria, and the flies first inoculate the milk and later reinoculate themselves, and then more of the milk, so establishing a vicious circle.8. On one occasion we compared the number of bacteria carried by house-flies caught in an eating house opposite the slaughter houses with the number carried by blue-bottles; the latter, as might be expected, was far larger.9. In cities where food is plentiful flies rarely migrate from the localities in which they are bred, and consequently the number of bacteria they carry depends upon the general standard of cleanliness in that locality. This is well indicated by the fact that flies caught in a street of modern fairly high class workmens' dwellings forming a sanitary oasis (Hornby Street) in the midst of a slum area, carried far less bacteria than those caught in the adjacent neighbourhood.10. It is clear that flies from the suburbs where infantile diarrhoea is rare carry far less bacteria than those in the city where it is common. It was, nevertheless, impossible in the time at our disposal to correlate exactly the number or varieties of bacteria carried by flies in the city with the number of cases and deaths from infantile diarrhoea in individual streets.11. As the amount of dirt carried by flies in any particular locality, measured in terms of bacteria, bears a definite relation to the habits of the people and the state of the streets, it demonstrates the necessity of efficient municipal and domestic cleanliness, if the food of the inhabitants is to escape pollution, not only with harmless but also with occasional pathogenic bacteria.