Normal Microbial Flora

RULES IN THEMICROBIOLOGYLABORATORY

RULES Students who are late for the first hour will notbe accepted for the rest of the laboratory. A clean and proper laboratory coat should beworn. Eating or drinking is not permitted in thelaboratory Personal belongings should not be placedon the benches. Long hair should be tied back in order to preventcontact with flames and infectious materials.

RULES Loops and the other metal stuff should be sterilizedbefore and after use. Liquid media should be kept in tube-holders. If the working area is contaminated it should becleaned with alcohol. Benches, microscopes and other labware used shouldbe cleaned up. Hands should be washed with soap before leaving thelaboratory.

NORMALMICROBIALFLORA

Normal flora ofthe body mainlyinhabits; Skin Oral cavity Upper respiratorytract Intestinal tract Genitourinary tract

Normal flora is beneficial to the bodySome members of normal flora couldbe opportunistic pathogens

Resident FloraMicroorganisms which are regularlyfound in specific sites of body

Transient Flora Microorganisms that inhabit the mucousmembranes for short periods of time Derived from environment Non-pathogenic or potentially pathogenic

Origin of Normal FloraAcquired during birthAcquired from environment

Anatomical LocationSkinConjunctivaPredominant bacteriastaphylococci and corynebacteriasparse, Gram-positive cocci and GramnegativerodsOral cavityteethmucous membranesstreptococci, lactobacillistreptococci and lactic acid bacteriaUpper respiratory tractnares (nasal membranes)pharynx (throat)Lower respiratory tractstaphylococci and corynebacteriastreptococci, neisseria, Gram-negativerods and coccinoneGastrointestinal tractstomach Helicobacter pylori (up to 50%)small intestinecolonlactics, enterics, enterococci,bifidobacteriabacteroides, lactics, enterics,enterococci, clostridia, methanogensUrogenital tractanterior urethravaginasparse, staphylococci, corynebacteria,entericslactic acid bacteria during child-bearingyears; otherwise mixed

Skin Protective Factors:• Dryness• Low pH• Inhibitory substances Staphylococcus epidermidis(90%) Diphteroids

Mouth Mechanical protection bysaliva Aerobes, facultativeanaerobes, obligateanaerobes Streptococcus mutans

Upper RespiratoryTract Protection by:• Ciliated epithelium• Lysozyme in nasal mucus Nose• Staphylococci Nasopharynx• Streptococci• Neisseria• Haemophilus

Lower RespiratoryTractTrachea andbronchi do nothave a normalflora

GastrointestinalTract Stomach, duodenum Jejunum: Enterococci, lactobacilli,diphteroids Ileum: Anaerobic bacteria,Enterobacteriaceae Colon: Anaerobic bacteria

GenitourinaryTract No microorganismsin kidney, ureterand urinary bladder Lower portion ofurethra• Streptococci,diphteroids Vagina• Lactobacilli (low pH)

ON EVERY BENCHStoolsuspensionEMBagarThroatBloodagarNoseBloodagarSkinBloodagar

STREAK PLATE METHOD

On The Front Bench• Nutrient Broth• Nutrient Agar• EMB Agar• Blood Agar• Chocolate Agar

In June 11, you have a quiz about‘normal flora and serological tests’ at theend of serological tests laboratorytraining.