Normal Flora

• Normal flora consists of microorganisms like bacteria and fungi.
• Normal flora are regularly present on the anatomical sites of the human body.
• Commensals, also known as microflora, are normal flora.
• Normal flora can be harmless and even beneficial in healthy humans under normal conditions.
• Normal flora is not present inside sterile vital organs like the brain, kidney, heart, and urinary bladder.

Symbiotic Relationships

• Mutualistic relationships benefit both organisms; E. coli synthesizes vitamin K and B complex vitamins.
• In return, the body provides a warm, moist, nutrient-rich environment for E. coli.
• Commensalistic relationships benefit one organism without affecting the other.
• Opportunistic microbes do not cause disease under normal conditions, but can if conditions become conducive for them.
• E. coli, normally harmless in the digestive tract, can become pathogenic if it enters the urinary tract.

Origin of Normal Flora

• A fetus is sterile at birth.
• Newborns acquire normal flora during passage through the mother's vaginal tract and exposure to the environment.
• Oral and nasopharyngeal flora establishes within hours of birth.
• Resident flora of the lower intestinal tract establishes within one day.

Factors Influencing Normal Flora

• Local environment.
• Diet.
• Age.
• Sex.
• Immune condition.
• Use of antibiotics.

Types of Normal Flora

• Resident normal flora are microorganisms always present on or in a person, residing at specific anatomical sites throughout life.
• Resident flora is relatively fixed, and if disturbed, are able to re-establish itself.
• Over reduction of resident flora can lead to opportunistic microbes causing infection.
• An example is Candida albicans, which can cause candidiasis when resident flora reduces.
• Transient normal flora colonize people for hours to weeks, but do not establish themselves permanently.
• Transient microbes are not able to colonize the body for longer periods, and will move or die off.
• Transient flora can be pathogenic or non-pathogenic.
• Transient flora varies with time and environment.
• Transient flora can inhibit the skin or mucus membrane for hours, days, or weeks.
• Transient flora does not re-establish itself.

Differences Between Resident and Transient Normal Flora

• Resident organisms reside in deeper layers of skin, while transient organisms are in superficial layers.
• Resident flora is permanent, while transient flora is temporary.
• Resident flora reestablishes itself when disturbed; transient flora usually does not.
• Routine hand washing does not remove resident flora, but easily removes transient organisms.
• Resident flora is usually unassociated with transmission of infection; transient flora is usually associated with transmission of infection.

Beneficial Roles of Normal Flora

• Provides a first line of defense against microbial pathogens through "bacterial interference".
• Assists in digestion by producing vitamin B and vitamin K in the intestine.
• Plays a role in toxin degradation.
• Oral flora stimulates immunity by inducing low levels of circulating and secretory antibodies that may cross-react with pathogens.
• Protects the host from colonization by pathogenic microbes.

Prevention of Tumor Formation

• Alters the balance of tumor cell proliferation and death.
• Regulates immune system function.
• Influences metabolism of host-produced factors, foods, and pharmaceuticals.
• Lactobacillus and Bifidobacteria are known to prevent tumor formation.

Harmful Effects of Normal Flora

• Normal flora can become opportunistic pathogens and cause disease when the host immune system is compromised.
• Normal flora may cause diagnostic confusion.
• Penicillinase-producing microorganisms can aggregate and develop antibiotic resistance.

Distribution and Occurrence of Normal Flora

• Skin.
• Eyes.
• Digestive tract.
• Gastrointestinal tract.
• Respiratory tract.
• Urinary tract.
• Genital tract.

Normal Flora of the Skin

• Bacteria and fungi are primary residents of the skin microflora.
• Resident bacteria are present in any layer of the skin.
• Skin can acquire transient bacteria from the environment but it either gets removed or dies off.
• This is because skin is dry, acidic, and produces sweat and oil.
• Resident flora include staphylococcus-epidermis, staphylococcus aureus, streptococcus, diptheroids, propionibacterium acne, and yeast-candida.
• Transient flora include micrococcus and bacteriods.
• Key sites: axilla, groin, and areas between the toes.
• The majority of skin microorganisms are found in the superficial layers of the epidermis and upper hair follicles.

Risk Factors of the Skin Microbiome

• Dandruff caused by Malassezia.
• Acne vulgaris caused by Cutibacterium acnes.
• Atopic dermatitis caused by CONS.
• Bacteremia.
• Osteomyelitis.
• Chronic wounds caused by CONS, Corynebacterium and Malassezia.
• SSTI caused by CONS, Corynebacterium, Cutibacterium acnes, Malassezia, and Roseomonas Mucosa.

Normal Flora of the Eye

• The eye contains a low number of flora due to high moisture.
• Blinking mechanically removes bacteria.
• Lachrymal secretions contain lysozyme.
• The conjunctiva of the eye primarily has S.epidermidis, S.aureus, C. diphtheroid, and S.pneumoniae.
• Neisseriae and gram-negative bacilli resembling haemophili (Moraxella species) are frequently present.

Flora of the Conjunctiva

• Staphylococcus epidermidis.
• Corynebacterium sp.
• Propoinibacterium acnes.
• Staphylococcus aureus.
• Viridans streptococci.
• Neisseria sp.
• Haemophilus influenzae.
• Pathogens of the conjunctiva includes Neisseria gonorrhoeae and Chlamydia trachomatis.

Normal Flora of the Digestive Tract.

• Oral cavity microflora consists of both aerobic and anaerobic bacteria.
• The most common ones are C.diptheroids, S.aureus, and Epidermis.
• Yeast can also reside in the mouth.
• Mouth/Oral cavity includes: lactobacilli, staphylococcus, streptococcus, bacteroides, corynebacterium, etc.
• Teeth: streptococcus mutants, hemolytic streptococci, fusobacterium, etc.

Human Oral Cavity Flora

• Viridans streptococci.
• Lactobacilli.
• Staphylococci (S. aureus and S. epidermidis).
• Corynebacterium sp.
• Bacteroides sp.
• Streptococcus sanguis (dental plaque).
• Streptococcus mutans (dental plaque).
• Actinomyces sp.

Normal Flora of the Gastrointestinal Tract

• Stomach: acid-tolerant streptococci, staphylococci, lactobacilli, candida albican, and helicobacter.
• Gram-positive cocci and rods are more common in the Duodenum.
• Gram-positive, Gram-negative bacterium, Lactobacilli diptheroids, enterococcus, faecalis, yeast- candida, albicans can be seen in the Jejunum.
• Ileum: pH-alkaline, anaerobic gram-positive bacteria are more common entero bacteria, shigellosis.
• Large Intestine: the largest microorganism in the body is anaerobic, gram-positive, and non-sporing bacteria.
• Large Intestine also contains Bacteriods, lactobacillus, E.coli, proteus, yeast, candida, protozoans, entamoeba hystolitica, trichomonas.

Human Gastrointestinal Tract Flora

• In the upper GIT of adult humans is mainly acid-tolerant lactobacilli such as Helicobacter pylori.
• Proximal small intestine contains Lactobacilli, Enterococcus faecalis, Coliforms, Bacteroides.
• The flora of the large intestine (Colon) includes: Enterococci, Clostridia, Lactobacilli, Bacteroides, Bifidobacterium (Bifidobacterium bifidum), Escherichia coli, Methanogenic bacteria, Viridans streptococci, Staphylococcus sp., Proteus sp., Candida albicans (Yeast), and Mycoplama sp.
• In bottle-fed infants Bifidobacteria are not predominant.
• In bottle-fed infants when breast-fed infants are switched to a diet of cow's milk or solid food, bifidobacteria are progressively joined by.
• In bottle-fed infants flora includes Enterics, Bacteroides, Enterococci, Lactobacilli, and Clostridia.

Normal Flora of the Respiratory Tract

• Upper respiratory tract includes Nasal passage and Esophagus.
• The organism which are involved are staphylococcus, streptococcus, diptheriod, bacteroides, micrococci, and haemophilus.
• The Lower respiratory Tract includes trachea, bronchi, and lungs.
• Lower respiratory tract is mostly sterile because the mucous membrane of the lungs remove any microbes.

Normal Flora of the Respiratory Tract includes

• Staphylococcus epidermidis.
• Corynebacteria.
• Staphylococcus aureus.
• Neisseria sp.
• Haemophilus sp.
• Streptococcus pneumoniae.
• The upper respiratory tract (nasopharynx) includes Non-hemolytic streptococci, Alpha-hemolytic streptococci, Neisseria sp., Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, and Neisseria meningitidis.

Normal Flora of the Genitourinary Tract

• Urethra and urinary bladder are sterile.
• Non-pathogenic gram-positive cocci and gram-negative enterobacteriaceae may be extremely in normal flora.
• Mycobacterium smegmatis is commonly present in both male and female genital tracts.
• Male Genital tract includes: Lactobacillus bacteroids, staphylococci, and corynebacterium.
• Female Genital tract has complex normal flora from puberty to menopause.
• The pH is acidic between 4.2-4.6, acidophilic colonizing bacteria i.e. Lactobacilli acts as known as doderline bacilli, staphylococcus epidermis, streptococci, peptostreptococci, clostridium species, diptheriods, candida.
• Anteriour urethral flora: Staphylococcus epidermidis, Enterococcus faecalis, Alpha-hemolytic streptococci,Some enteric bacteria (e.g. E coli, Proteus sp.), Corynebacteria sp., Acinetobacter sp., Mycoplasma sp., Candida sp., and Mycobacterium smegmatis.
• Vaginal bacteria: Corynebacterium sp., Staphylococci, Nonpyogenic streptococci, Escherichia coli, Lactobacillus acidoph, Flavobacterium sp., Clostridium sp., Viridans streptococci and Other Enterobacteria

Nosocomial Infections

• Nosocomial is also known as a hospital-acquired infection.
• Nosocomial is an infection acquired in the hospital by a patient admitted for a reason other than the infection.
• Infection in health care facility which was not present or incubating at the time of their admission.
• This includes infections acquired in the hospital but appearing post discharge and also the occupational infections among the staff of the facility.
• Approximately 9% of all hospital patients develop hospital infection.
• Common Nosocomial infection include urinary tract infections (UTI), Surgical wound infections (SWI), Lower respiratory infections, Traumatic wounds and burns infections, Primary bacteremia and Gastrointestinal tract.
• The mode of transmission is Contact/hand borne (most common), Aerial route or airborne, Oral route, Parenteral route and Vector borne.
• Sources of Nosocomial infection includes lower defenses, antibiotic treatment and contaminated hospital Environment (fluid, blood, food, air), Patients flora (cutaneous, GIT flora, Respiratory flora), Medical or surgical procedures (catheters and medical equipment), and Medical personals.
• Measures to prevent and control includes treat all patients as a potential biohazard,Isolation, and Sterilization.

Standard Precautions include

• Hand hygiene.
• Use of personal protective equipment (e.g., gloves, gowns, masks).
• Safe handling of potentially contaminated equipment/surfaces/sharp disposal.
• Respiratory hygiene.
• Safe injection practices.
• The use of masks.

Universal Precautions include

• Hand washing.
• Personal protective equipment [PPE].
• Preventing/managing sharps injuries.
• Aseptic technique.
• Isolation.
• Staff health.
• Linen handling and disposal.
• Waste disposal.
• Spillages of body fluids.
• Environmental cleaning.
• Risk management/assessment.
• Personal protective Equipment should be anticipated when contamination or splashing with blood or body fluids.
• Consists of: Disposable gloves Plastic aprons Face masks Safety glasses, goggles, Fluid repellent gowns.
• Everything You Touch Has Been Touched By Someone Else.
• Hand hygiene iis the simplest, most effective measure for preventing hospital-acquired infections.

Normal flora are microorganisms that live on another living organism (human or animal) or inanimate object without causing disease. Resident organisms typically found on skin, mucous membranes, and in the gut, while transient organisms are temporary.