Normal microbiota and endogenous infections · •Normal flora is present in/on –skin –upper...
Transcript of Normal microbiota and endogenous infections · •Normal flora is present in/on –skin –upper...
Normal microbiota and
endogenous infections
Prof. dr hab. n. med. Beata Sobieszczańska University of Medicine
Dept. of Microbiology
• Permanent colonization = resident flora:
• Present invariably in a particular site
• Can be reduced by washing but not eliminated
• Transient colonization = transient flora:
• Present briefly, rest on the body surface but do not persist
• Can be eliminated by washing
Normal microbiota
Outcomes of exposure to a microorganisms:
1. Permanentcolonization
2. Transient colonization
3. Disease
• Normal flora is present
in/on
– skin
– upper respiratory tract
– oral cavity
– intestines, especially large
intestine
– vaginal tract
• Very little normal flora in
eyes & stomach
Normal microbiota
Notably absent in all
internal organsAbsent in:
lower respiratory
tract
muscle tissue
blood & tissue
fluid
cerebrospinal
fluid
peritoneum
pericardium
meninges
Conjunctiva
Skin
Oral cavity
Upper respiratory tract
Urinary tract
Genital tract
Gastrointestinal tract
Normal flora changes continuously through out life and
reflects: age of person, nutrition, genetics, environment, sex
Benefits of the normal flora a. Nutrient production/processing e.g. vitamins
K, B production by E. colib. Competition with pathogenic microbes
(competing for attachment sites and fornutrients; produce toxin that are harmful toother bacteria i.e. non specific fatty acids,peroxides and bacteriocins that inhibit or killother bacteria)
c. Normal development of the immune system (stimulate the production of cross-reactiveantibodies)
d. Stimulate the development of certain tissuese.g. the caecum and certain lymphatic tissues (Peyer's patches) in the GI tract
• ca. 2 m2 of skin
• Lysozyme, NaCl (sweat
glans) low pH, sebum,
fatty acids (oil glans)
• Staphylococci -
S. epidermidis >90%
• Micrococcus,
• Corynebacteria =
diphteroids
• Propionibacterium
Skin flora - GP bacteria
Benefit: inhibits fungal growth
Harm: body odour, acne,
opportunistic infections
Neither profuse sweating nor
washing and bathing can
eliminate or significantly
modify the normal resident
flora
• Low number of bacteria
• Blinking, tear (lysozyme)
Conjunctiva flora
S. epidermidis diphteroids
Neisseria
Haemophilus
Oral cavity flora
Oral and systemic diseases associated with the oral microbiome
• URT (nose, nasopharynx)
assorted Streptococci, Staphylococci,
non-pathogenic Neisseria,
nontypeable Haemophilus influenzae
Anaerobes : Actinomycetes, Fusobacterium
• LRT (trachea, bronchi, and pulmonary tissues) are free
of microorganism – protected by ciliary
epithelium, mucus blanket, alveolar macrophages
• If breached - opportunistic infections
Respiratory tract flora
Gastrointestinal tract flora
Many species
ferment waste
material feces,
generating
vitamins (B12, K,
riboflavin and
thiamine)
Bacterial digestive
enzymes that
convert
disaccharides to
monosaccharides
• Kidney, bladder, urine
in bladder are free of
microorganism
• Urethra:
S.epidermidis
Enterococci
Neisseria
Mycoplasma
Urinary tract flora
Urogenital tract
Male anterior urethra – same as skin (enteric,
enterococci)
Vagina – complex microbiota:
• at birth – same as mother (pH 5)
• neonate – same as skin + enteric, strepto. (pH 7)
• at puberty – Lactobacillus + same as skin +
anaerobes+ streptococci (pH 5)
• at menopause – return to prepuberty flora (pH 7)
Benefit: competition with pathogens and production of
lactic acid
Endogenous infection =
an infection caused by
an infectious agent that
is already present in the
body (normal microflora)
Opportunistic and endogenous infections
Opportunistic infection
an infection caused by
a microorganism that
normally does not
cause disease but can
cause the disease
when the body’s
immune system is
impaired and unable to
fight an infection
Predisposing Factors of
Opportunistic Infections
1. Damage of epithelial
barriers:
burn, trauma, decubitus,
operation and
instrumentation
2. Chronic diseases:
diabetes mellitus,
chronic renal failure,
liver cirrhosis, etc.
Opportunistic and endogenous infections
3. Hematologic disorders and
cancer
Leukaemia, malignant
lymphoma, multiple
myeloma, etc.
4. Iatrogenic - drug induced
Steroids
Cytostatic and
immunosuppressive drugs
Antibiotics
Irradiation
Examples:
• Actinomycosis (A. israeli)
• Endocarditis (oral streptococci,
enterococci)
• Prostheses and catheters
colonization = bacteremia
(coagulase-negative)
staphylococci)
• Plaut-Vincent angina Borrelia +
Fusobacterium)
• Ludwig's angina
• Most UTI, many RTI
Opportunistic and endogenous infections
Candidiasis (C. albicans)
Aspergillosis (Aspergillus
fumigatus)
Pneumocystosis
(Pneumocystis jirovecii)
MOTT-associated infections
& tuberculosis
HSV reactivation (sores,
shingles)
Toxoplasmosis
CMV & EBV infections
Non-fermentative rods