Normal Microbial Flora Eric Stanbridge PhD September 11th Lecture Medical Microbiology Tel

Sites of normal microbial colonization

TABLE 7-2. Microorganisms Found on the Skin Staphylococcus epidermidis (albus) (coagulase negative) Staphylococcus aureus (coagulase positive) 5-25 Streptococcus pyogenes (Group A)0-4 Propionibacterium acnes (anaerobic corynebacteria) Aerobic corynebacteria (diphtheroids)55 Candida albicansUncommon Other Candida species, particularly C. parapsilosis 1-15 Gram negative bacteria, e.g., Enterobacteriaceae or Pseudomonas species Uncommon MicroorganismRange of Incidence (Per Cent)

STAPHYLOCOCCUS

STREPTOCOCCUS

Mixed Flora, including YEAST (Candida)

TABLE 7-3. Microorganisms Found in the Nose and Nasopharynx Staphylococcus aureus20-85 Staphylococcus epidermidis90 Aerobic corynebacteria (diphtheroids)5-80 Streptococcus pneumoniae0-17 Streptococcus pyogenes (Group A)0.1-5 Alpha-and nonhemolytic streptococciUncommon Neisseria catarrhalis12 Haemophilus influenzae12 Haemophilus parainfluenzae20-35 Gram negative bacteria (Enterobacteriaceae)Uncommon MicroorganismRange of Incidence (Per Cent)

Neisseria meningitidis

HEMOPHILUS

COLIFORMS (Escherichia coli)

TABLE 7-4. Microorganisms Found in the Oropharynx Staphylococcus aureus35-40 Staphylococcus epidermidis30-70 Aerobic corynebacteria (diphtheroids)50-90 Streptococcus pyogenes (Group A)0-9 Streptococcus pneumoniae0-50 Alpha-and nonhemolytic steptococci25-99 Neisseria catarrhalis10-97 Neisseria meningitidis0-15 Haemophilus influenzae5-20 Haemophilus parainfluenzae20-35 Gram negative bacteria, e.g., Klebsiella pneumoniaeUncommon MicroorganismRange of Incidence (Per Cent)

TABLE 7-5. Microorganisms Found in the Mouth (Saliva-Tooth Surfaces) Staphylococcus epidermidis Staphylococcus aureusCommon Streptococcus mitis and other alpha-hemolytic steptococci100 Streptococcus salivarius100 Peptostreptococci (anaerobic)Prominent Veillonella alcalescens (anaerobic)100 Lactobacilli95 Actinomyees israeliCommon Enterobacteriaceae65 Haemophilus influenzae Bacteroides fragilis (anaerobic)Common Bacteroides melaninogenicus (anaerobic)Common Bacteroides oralis (anaerobic)Common Fusobacterium nucleatum (anaerobic)15-90 Candida albicans6-50 Treponema dentium and Borellia refringensCommon MicroorganismRange of Incidence (Per Cent) Viridans Group

Gillies & Dodds, Bacteriology Illustrated, R.R. Gillies, 5 th Edtion, p125 ACTINOMYCES

Treponema

TABLE 7-6 Microorganisms Found in the Stomach and Small Intestine Microorganism Stomach - Usually sterile or transient small numbers, owing to gastric pH of 2-3, and rapid transit time of food (but remember Helicobacter pylori). Jejunum - Small numbers of Gram positive facultative bacteria (Enterococci, lactobacilli, diphtheroids) Candida albicans Ileum - Distal portion may show small numbers of Enterobacteriacae and anaerobic gram negative bacteria

H. pylori survives in the submucosal layer

Mixed Flora- Fecal Material

Mixed Flora- Abscess

TABLE 7-9. Microorganisms Found in the Genitourinary Tract Kidneys and urinary bladder normally sterile, Female and male urethra usually sterile except for short anterior segment Microorganism Vagina and Uterine Cervix Lactobacilli50-70 Bacteroides species60-80 Clostridium species15-30 Peptostreptococcus30-40 Bifidobacterium10 Eubacterium5 Aerobic corynebacteria (diphtheroids)45-75 Staphyloccus aureus5-15 Staphyloccus epidermidis35-80 Enterococci (Group D Streptococcus)30-80 Streptococcus species (usually Group B)5-20 Enterobacteriaceae18-40 Candida albicans30-50 Trichomonas vaginalis10-25 Range of Incidence (Per Cent)

Dynamics of Lifetime VAGINAL COLONIZATION micrococci enterococci diphtheroids lactobacilli (D Ö derlein’s bacillus) No Doderlein’s bacillus micrococci  - plus non hemolytic streptococci coliforms (E. coli) diphtheroids Includes D Ö derlein’s bacillus + yeast + bacteroides (anaerobes) No D Ö derlein’s bacillus Birth STERILE 24 hours Mixed Flora: Several weeks Mixed Flora: Puberty  Mixed Flora: Menopause  Mixed Flora persists Acidic pH Maternal glycogen deposited Glycogen decreased Alkaline pH Glycogen redeposited Acidic pH Glycogen decreased Alkaline pH

Lactobacillus species