4th October 2010

In Today’s Class Define normal flora/biota

Identify sterile and non-sterile sites

Describe the normal flora/biota at non-sterile sites.

Benefits and harm of normal body flora

Definitions Normal Body Flora

Normal Microflora

Normal Microbiota

Describes the various microbial species which inhabit the skin, mucous membranes and other non-sterile sites on the animal without causing disease.

Mixture of organisms regularly found at an anatomical site

Definitions Resident microflora

those organisms that are always present on the body.

Transient microflora

those present temporarily and under certain conditions.

Types of Relationships Commensalism

Mutualism

Parasitism

Sites of Normal BiotaSite Normal Flora Sterile

Liver √

Skin √

Mucous membranes

√

Lungs √

Colon √

Blood √

Middle and inner ear

√

Brain √

CSF √

Sites of Normal BiotaSite Normal Flora Sterile

Bones √

Vagina √

Heart √

Amniotic fluid √

Distal urethra √

Urinary bladder √

Muscle √

External ear √

Factors influencing the composition of normal flora Genetics

Age

Stress

Geographic location

Climate

Nutrition

Diet

Drug therapy

Hormonal changes

Components of normal body flora Mainly bacteria

Eukaryotic fungi

Protists

Methanogenic Archaea

Normal body flora and tissues Show tissue tropism

Specialized ligands or adhesins

Capsules

Fibriae

Cell wall components

Construct biofilms

Sites of normal flora: The skin Bacteria Staphylococcus spp. Staphylococcous epidermidis

Staphylococcous aureus

Propionibacterium acnes

Micrococcus sp.

Yeasts Pityrosporum

Mites Demodex spp.

Sites of normal flora: The conjunctivae Staphylococcus sp.

Staphylococcus epidermidis

Staphylococcus aureus

Propionibacterium acnes

Streptococcus spp.

Haemophilus sp.

Sites of normal flora: Upper respiratory tract of humans Staphylococcus spp.

Staphylococcus epidermidis

Staphylococcus aureus

Corynebacterium spp.

Streptococcus spp.

Streptococcus pneumonaie

Streptococcus pyogenes

Haemophilus influenza

Neisseria meningitides

Sites of normal body flora: Oral cavity Streptococcus spp.

Streptococcus salivarius (until teeth appear)

Streptococcus mutans

Streptococcus sanguis

Staphylococcus spp.

Bacteroides spp.

Diphtheroids (nonpathogenic Corynebacterium spp.)

Lactobacillus spp.

Normal body flora: Upper intestinal tract Upper intestinal tract is usually inhospitable to normal

flora

However

Some Lactobacillus spp.

Half of the American population Helicobacter pylori(pathogenic)

Normal body flora: Lower intestinal tract- small intestine Lactobacillus spp.

Enterococcus spp.

Enterococcus faecalis

Escherichia coli

Bacteriodes spp.

Normal body flora: Large intestine Bacteria present here are qualitatively similar to that

found in faeces

Bacteriodes spp.

Lactobacillus spp.

Bifidobacterium spp.

Clostridium spp.

Clostridium perfringens

Clostridium septicum

Normal body flora: Large intestine (cont’d) Enterobacteriaceae

E. coli

Klebsiella

Enterobacter

Pseudomonas aeruginosa

Proteus mirabilis

Methanogens

Normal body flora: Urogenital tract Sterile

Urinary tract flushes every few hours

Normal body flora: Urethra Staphylococcus spp.

Staphylococcus epidermidis

Staphylococcus aureus

Streptococcus spp.

Enterococcus faecalis

E. coli

Proteus sp.

Corynebacterium sp.

Normal body flora: vagina Corynebacterium spp.

Staphylococcus spp.

Streptococcus spp.

Lactobacillus spp.

E. coli

Yeasts: Candida albicans

Milk Micrococci

Staphylococci

Streptococci

Mycoplasmas

Corynebacterium bovis

Rumen: Ruminants such as cattle, sheep, goats Rumen bacteria classified according to function

Fibre-digesting or Cellulolytic bacteria

Ruminococcus flavefacians

Ruminococcus albus

Bacteriodes succinogenes

Butyrivibrio fibrisolvens (one of the most numerous and versatile bacteria present).

Rumen: cattle, sheep, goats Rumen bacteria classified according to function

Starch and Sugar-Digesting (or Amylolytic) bacteria

Bacteriodes ruminocola

Bacteriodes amylophilus

Selenomonas ruminantium

Streptococcus bovis

Succinomonas amylolytica

Benefits of normal body flora The synthesis and excretion of vitamins

The prevention of colonization by other pathogens

Normal flora can antagonize other bacteria

Normal flora can stimulate the development of certain tissues

The stimulation of the production of natural antibodies

Harmful effects of normal flora Bacterial synergism

Competition for nutrients

Induction of low grade toxaemia

Normal flora may be agents of disease

Transfer to susceptible host

Bacterial Synergism

That is one organism can help the other one grow and survive. Examples of this occur when normal flora supply vitamins and other growth factors for pathogenic bacteria to grow, this is called cross-feeding. Another example of synergism occurs between microbes such as in “staph-protected infections” when a penicillin-resistant staphylococcus (a component of normal flora) shares its drug resistance with other pathogens.

Thank You for your Attention