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1. Dysbiosis, causes. Ways and mean
for dysbiosis correction.
Microbiocenosis of the
gastrointestinal tract, main causes
of its disorders, laboratory
diagnostics of gastrointestinal
dysbiosis. Antibiotic-associated
pseudomembranous enterocolitis.
Laboratory diagnostics.

2. Normal microbiota
Normal microbiota (normal flora) is microbial
populations associated with skin and mucous
membranes of every human being from shortly
after birth until death.
The community of microorganisms colonising certain
biotope of human body (host) is also known as
microbiocenosis (microbiome)
The human body is inhabited by about 1014
microorganisms.

3. • Normal flora is divided into constant and transient
flora.
• Constant (obligate, resident, indigenous,
autochthonous) microflora is the native flora.
• Transient (temporary, facultative, allochthonous)
microflora is acquired flora, which is accidentally
taken from environment.
Most members of the normal flora are bacteria,
but fungi and protozoa inhabit the body as well.

4. Normal flora inhabits the next areas and systems of
the host:
• Skin and nails
• Eyes (conjunctiva)
• External acoustic duct
• Mucous membranes of the
–Upper respiratory tract (nose, oropharinx)
–Gastrointestinal tract (from mouth to rectum
– Genitourinary tract

5. According to their significance in
human pathology normal flora can
be categorized is
• helpful (mutualutic symbionts)
• harmless (commensals)
• potential harmful (opportunists)

6. Beneficial role of normal flora
1. Normal flora provides colonization resistance of
the skin and mucous membranes by:
• Competition with “foreigners” for nutrients
• Binding with specific receptors required for adhesion
of pathogens
• Releasing harmful for pathogens metabolic products
or bacteriocins production
2. Synthesis of vitamins (group B and K) by
intestinal microbiota

7. Beneficial role of normal flora
3. Intestinal mirobiota takes part in bile acids
metabolism and capable of secreting digestive
enzymes
4. Neutralization a small amount of natural toxic
substances, binding of heavy metal salts,
phenolics and aldehydes by intestinal microbiota
5. Stimulation of the host's immune system and non-
specific immune response

8. Harmful effect of normal flora
1. Some normal flora organisms can be
opportunistic pathogens, which cause infectious
if tissue injury occurs at specific body sites, or if
the resistant of the body to infection is
decreased.
2. Disoders in vaginal and intestinal microbiota due
to antibiotic therapy may lead to disbiosis with
clinical appearence

9. Harmful effect of normal flora
• Usage of broad spectrum antibiotics may inhibit
sensitive members and thereby select resistant
bacteria
• Normal flora may produce enzymes splitting or
inactivating antibiotics
• Some metabolic products of normal flora act as
cocarcinogenes (protein putrefaction products,
nitrites, nitrates,etc.)

10. Harmful effect of normal flora
• Normal germs may cause confusion in
diagnosis due to their presence in clinical
samples and their resemblance to pathogens
• Some pathogens may belong to normal
microbiota of carriers and be transmitted to
healthy persons

11. EYES
• The bacteria of the mucous membranes
of the eyes include Staphylococcus
epidermidis, Corynebacterium xerosis.

12. Normal flora of the skin

13. Normal flora of the axilla, perineum and toe
webs:
1. Gram(-) bacilli
2. S.epidermidis
3. Propionbacterium spp.
4. Anaerobic and lipophilic diphtheroids
5. Peptococci
6. S.viridans
7. S. aureus

14. Normal flora of the axilla, perineum and toe
webs:
1. Gram(-) bacilli
2. S.epidermidis
3. Propionbacterium spp.
4. Anaerobic and lipophilic diphtheroids
5. Peptococci
6. S.viridans
7. S. aureus

15. Normal flora of the upper respiratory tract
Nose and nasopharynx harbors:
1. Streptococci spp.
2. Staphylococci spp.
3. Diphtheroids
4. Haemophillus influensa
5. In rare cases: E.coli, pseudomonads, Proteus spp.

16. Normal flora of the upper respiratory tract
The pharynx and trachea contain:
1. α- and β-hemolytic streptococci
2. S.aureus and S.hominis
3. Neisseria spp.
4. Diphtheroids
5. Hemophillus influenzae
6. Pneumococcus
7. Mycoplasma pneumonia
8. Klebsiella spp.

17. Microflora of the urinary tract.
• In men in the anterior part
of the urethra there are
Staphylococcus
epidermidis, diphtheroids
and Gram-negative non-
pathogenic bacteria.
• Mycobacterium smegmatis
and mycoplasmas are
found on the external parts
of the genitalia, and also in
the urine of men and
women.

18. Urogenital microbiota
Frequent residents of the urethra (distal part):
1. S.epidermidis
2. Enterococci
3. Diptheroids
Occasional members (10-30%):
1. E.coli
2. Proteus spp.
3. Opportunistic Neisseria
4. Mycoplasma and Ureaplasma

19. Microflora of the vagina.
• The vaginal contents of the healthy woman have a
relatively high concentration of sugar and glycogen,
and a low content of the diastatic enzyme and
proteins.
• The pH is 4.7 during which all other microbes, except
for Doderlein's lactic acid bacilli, cannot develop.

20. Normal flora of vagina
The flora before puberty and after
menopause:
1. Micrococci
2. Streptococci, enterococci
3. Diphtheroids
4. S.epidermidis, coli-forms
The flora of adults:
1. Lactobacillus spp.
2. Streptococci, staphylococci
3. C.albicans
4. Corynebacteria

21. Microbiota of mouth cavity
• The oral cavity is colonize by microorganisms from the
surrounding environment within hours after a human is
born.
• Initially the microbiota consists mostly of the genera
(aerobes and anaerobes)
• Streptococcus (α-hemolytic and viridans group)
• Neisseria
• Actinomyces
• Veillonella
• Lactobacillus
• Candida

22. Microbiota of mouth cavity
• As the first teeth erupt, the anaerobes
(Porphyromonas, Prevotella, Fusobacterium) become
dominant due to the anaerobic nature of the
gingival groove.
• As teeth grow, S.parasanguis and S.mutans attach
to their enamel surfaces.
• S.salivarius attaches to the buccal and gingival
epithelial surfaces and colonizes the saliva.

23. Bacterial biofilms

24. Intestinal microbiota
The intestinal microflora is a complex
ecosystem containing over 400 bacterial
species.
Anaerobes outnumber facultative anaerobes.
The flora is sparse in the stomach and
upper intestine, but luxuriant in the lower
bowel.
Bacteria occur both in the lumen and attached
to the mucosa, but do not normally
penetrate the bowel wall .

25. Esophagus and stomach
The total amount is about 102-103 cells per ml in
the stomach
Representatives are:
1. Lactobacilli
2. Micrococci
3. Candida
4. Sarcina
5. Bacilli
6. Helicobacter pylori (in 30% of healthy
individuals)

26. Duodenum and jejunum
• The bacterial count in duodenum is 103-105
per gram, in the jejunum and proximal ileum
105-107 per gram
• Enterococci, fungi, lactobacilli, coliforms and
various other microbes are predominant in
the duodenum and small intestine.

27. In the large intestine there are large amounts
of microorganisms (about 107-109 per gram in
the caecum and 1010-1012 in the rectum).
Almost one-third of the dry weight of the
faeces is made up of microbes.
The faecal flora consists generally from
anaerobic microorganisms (96-99%)

28. There are 300 times as many anaerobic
bacteria as facultatively anaerobic
bacteria in the large intestine.

29. The anaerobic Gram-negative bacteria include
species of Bacteroides and Fusobacterium.

30. The Gram-positive anaerobic flora belongs to genera
Bifidobacterium, Lactobacillus, Clostridium.

31. The intestinal facultative anaerobs belong to genera
Escherichia, Proteus, Klebsiella, Candida (yaest-like
fungi). Anaerobic Streptococcus are also present.

32. Dysbacteriosis
• is disbalance in the species
composition and the number of
bacteria in definite microbiome
• The disorders of intestinal microflora
appear a whole series of complications:
intestinal dyspepsia, intoxication,
diarrhoea etc.
• At intestinal dysbacteriosis the
number of lactic acid bacteria is
diminished, the number of other
anaerobes increased, especially

33. The factors causing dysbacteriosis:
Exogenous:
1. Environmental pollution
(ionizing radiation, salts of heavy
metals, industrial poisons,
pesticides and other chemical
compounds);
2. Climate and geographical
changes;
3. Adverse sanitary and hygienic
living conditions;
4. Professional activity, which is
associated with the action of
harmful factors;
5. Any kind of physical or
chemical actions on the body.
Endogenous:
1. Primary disorders of biocenosis
formation in the neonatal period
(perinatal infections, pathological
duration of pregnancy, complications
in labor, artificial feeding, congenital
malformations, etc.);
2. Stress;
3. Age;
4. Irrational nutrition;
5. Drug therapy (antibiotics,
cytostatic, immunosuppressants,
radiotherapy and chemotherapy,
hormones, etc.).

34. Other endogenous factors
Drinking too much alcohol (two or more alcoholic beverages per day)
Eating too much protein, sugar, or consuming high amount of food additives
High-fat and high sugar diets, and diets that are low in fermentable fiber also lead
to dysbiosis
Accidental consumption of chemicals, such as lingering pesticides on unwashed fruit
Poor dental hygiene, which allows bad bacteria to grow out of balance in your mouth
High levels of anxiety or stress, which can weaken your immune system
Cancer and chemotherapy, The use of antiviral drugs and radioactive isotopes
Hormone therapy and New medications, especially antibiotics, that affect your gut
flora
Chronic and acute infections (HIV, Hepatitis C and B)
Diabetes mellitus, Diseases of liver and pancreas
Unprotected sex, which can also expose you to harmful bacteria
Presence of intestinal parasites (helminths) Inflammatory processes in the intestines
Uncontrolled rectal cleansing with enemas
Dysbiosis on your skin can be caused by exposure to harmful bacteria or an
overgrowth of a single type of bacteria.

36. The stage of development of
dysbacteriosis of the intestinal:
1 stage – a latent phase;
2 stage – a start phase;
3 stage – the phase of an aggression
of anaerobic bacteria;
4 stage – an associated dysbiosis.

37. Microbiological characteristics of normal state of
intestinal microbiome and its disorder
Microbiome Normal flora (lg CFU/g) Opportunists (lg
CFU/g)
lactobacilli bifidobacteria E.coli
Normal biocenosis >7 >9 >8 <3
Dysbiosis 1st degree. <6 <9 >або <8 >3
Dysbiosis 2nd degree <6 <8 <8 >4
Dysbiosis 3rd degree <5 <7 <6, appearance of wealkly
lactose (+) or/and EPEC >104
>6

38. https://www.researchgate.net/figure/An-overview-of-the-possible-mechanisms-for-gut-microbiota-
dysbiosis-in-causing_fig1_311707051

39. Dysbiosis-associated diseases
1. Inflammatory Bowel Diseases (IBD) (Crohn`s
disease and ulcerative colitis, diarrheal syndrome
in childhood)
2. Antibiotic-associated pseudomembranous
enterocolitis
State and diseases at which human microbiome
changes
1. Obesity
2. Diabetes mellitus
3. Colon cancer
4. Autoimmune states

40. FIGURE 1 | Conceptual diagram of
autoimmune responses induced by
dysbiosis and LGS. Several bacterial
products reinforce epithelial barrier
and regulate the mucosal immune
response to maintain symbiotic
relationship in the intestine.
Environmental factors such as a
westernized diet and drugs cause
dysbiosis, which impairs epithelial
barrier function and elicits
proinflammatory response. Microbial
adhesion to epithelial cells and the
induction of proinflammatory cytokines
further damage TJ integrity, leading to
LGS. LGS enhances bacterial
translocation to the systemic
circulation. Some of the translocated
bacteria provide mimotopes or serve
as adjuvants to initiate or worsen
autoimmune responses, respectively.

41. Antibiotic-associated diarrhea
(AAD)

42. AAD

43. The supplements for treatment of
dysbacteriosis
Probiotics – the supplements consist of alive
microorganisms (Bacilli, enterococcus, E.coli,
lactobacteria, bifidobacteria).
Prebiotics - the supplements consist of non-microbial
substances stimulating the growth of the normal
flora.
Synbiotics - the supplements consist of the
probiotics and the prebiotics.
Metabolic preparations – supplements containing
physiologically active metabolites of normal flora

44. Main probiotics
Containing bifidobacteria (Bifidumbacterin with
B.breve; Bifidin з B.adolescentis).
Containing lactobacilli (Acilac, Biobacton with
Lactobacillus acidophilus; Lactobacterin with
Lactobacillus fermentum).
Containing non-pathogenic Bacilli (Sporobacterin).
Containing Е. coli (Colibacterin)
Policomponent: Bifilong, Bifilak, Bificol, Bifiform,
Acipol, Biosporin, Linex

45. Sources, used at complying lecture
material
1. https://biospecnutritionals.com/health-topics/gut-health-and-
gastrointestinal-gi-imbalances/
2. Partners in Leaky Gut Syndrome: Intestinal Dysbiosis and Autoimmunity/
Yusuke Kinashi and Koji Hase//Front. Immunol., 22 April 2021
|https://doi.org/10.3389/fimmu.2021.673708
3. Antibiotic-associated diarrhea: epidemiology, trends and treatment/Lynne
V McFarland//Future Microbiology (2008). Vol.3, No5.
https://doi.org/10.2217/17460913.3.5.563
4. P.R.Murrey, K.S.Rosental, M.A.Pfaller. Medical Microbiology, 8th edition,
Elseiver, 2017.- 836 p.
5. Mandell, Douglas and Bennett`s Infectious Diseases Essentials, [edited by ]
J.E.Bennett, R.Dolin, M.J.Blaser. -Elseiver, 2017. – 520 p.