Microbiology Ayşın hoca

• pathogenic microorganisms (only few)

• non-path. mo (essential)

• opportunistic path. (potentially pathogenic under certain conditions f.e. immunosuppression)

the ability of a microorganism to harm the host/cause disease

measured by degee of virulence severity

disease severity; ability and the degree to cause damage to a host

ability to spread

• infectious dose 50 (ID50) -> number of mo that will infect 50% of hosts within a specified time (5 out of 10 infected people get disease)

• lethal dose 50 (LD50) -> number of mo that will kill 50% of hosts within a specified time (5 out of 10 infected people die)

life originates from nonliving things spontaneously -> no science

• Commensalism

  • 1 benefits, 1 doesn't benefit (no harm)

    f.e. microbiota

• Mutualism

  • both benefit

    f.e. Vit. B & K2: human can’t synth. -> gut bacteria assists

• Parasitism

  • 1 benefits, 1 harmed

    f.e. parasite lives inside/on host

• Endogenously acquired

  • agents on/in us

    • from internal microbiota (alterations due to f.e. antibiotics)

    • injuries introduce skin bacteria (staphylococcus)

  • colonizes in patient

• Exogenously aqcuired

  • from outside source (environment)

1. Diphtheria toxin consists of 2 subunits -> toxin-binding subunit (B) attaches to cell membrane (glycopr./-lipid)

2. Toxin as whole molecule in vesicle -> other subunit (A) dissociates & free in cell

3. A catalyzes inhibition of elongation factor 2 of ADP-ribosylates (EF2 ADPR)

   • essential for ribosomal reactions

4. EF2 inh. -> no protein synthesis -> host damage

• Molecular level

  • inactivate essential genes/promote oncogenesis

• Cellular level

  • apoptosis

  • necrosis

  • malignant transformation

  • disruption of pump dysfunction

• Organ & tissue level

  • cellular/metabolic/immune dysfunction

  • obstruction of ducts (f.e. worms)

• Organism level

  • behavioural changes in the host f.e. loss of a fear of cats by rats

cell death and the replacement of viable cells and parenchyma with fibrosis

Chronic inflammation - amyloid production (TBC)

• immune response to a microorganism/microbial antigens

• Chemokine & cytokine mediated response

• Antigen-antibody complexes deposit & trigger inflammation, organ damage and dysfunction

• Antigenic mimicry -> cross recognition of microbial & self epitopes -> destroy cells and tissue (f.e. acute rheumatic fever)

1. Microorganism enters

2. Incubation period

3. Prodromal period

4. Symptoms (disease)

5. Convalescence period

6. Recovery

• acute -> disease after short time & lifelong prevention

  • acute pharyngitis, influenza, measles

• Latent infection -> disease after short time but reactivation

  • herpes simplex virus HSV, varicella zoster virus VZV

• Chronic infection -> disease after short time & end stage

  • hepatitis B virus HBV, syphilis

  • human immunodeficiency virus HIV (symptoms small in beginning)

• Slow infection-> late disease after years & death

  • measles, rubella, prions

• abortive infection (infected cell but no progeny virus)

• lytic infection (cytocidal, acute)

• persistent infection

  • chronic (nonlytic, productive)

  • latent (restricted virus synthesis, virus Ø)

  • recurrence

  • transformative

• Entry

  • Mucous membranes (Respiratory, GI, Genitourinary system)

  • Blood (+ placenta)

  • Skin

• Exit

  • Blood

  • Excretions

  • Secretions

  • Skin

• can be primary or secondary reservoir

• Anthroponosis

  • human to human/animal

• Zoonosis

  • animal to human

• Mucous membranes

  • Respiratory -> COVID-19, Influenza, Tuberculosis, Measles, mo causing CNs inf. …

  • GI -> Hepatitis A virus, Poliovirus, Cholera, mo causing diarrhea…

  • Genital -> Hepatitis B virus, HIV, Gonorrhea, Syphillis…

• Blood

  • contact with inf. blood: Hepatitis B or C virus, HIV

  • Blood sucking arthropods: Crimean Congo hemorrhagic fever, yellow fever

  • at birth: HIV, Hep. B virus, Syphilis

  • wound: Tetanus

• Skin

  • Malaria, dengue fever, Japonese encephalitis, African sleeping sickness, Kala-azar, schistosomiasis, typhus

• Rabies (animals)

• Malaria (mosquito)

• Salmonella (raw meats, eggs, and dairy)

• Lyme disease (ticks)

• Crimean-Congo haemorrhagic fever (ticks)

• Direct

  • direct contact (touch, droplets, kiss, sexual intercourse)

  • direct spread (transplacental)

  • no multiplication of mo needed

• Indirect

  • Airborne (aerosols, droplets; < 5 micron) -> no multiplication of mo needed

  • Vehicle borne (surface, water, biol. products) -> no multiplication of mo needed

  • Vector borne (more complicated)

    • mech. -> insect carries but no multiplication of mo needed

    • biol. -> multiplication/cyclic development required before arthropod can transmit infected form of mo

• Aerosols

  • normal breathing talking

  • far distance bc light

  • suspensions of particles in the air with partial/whole mo

• Droplets

  • loud talking, sneezing, coughing

  • short distance bc heavier

  • large particles resulting in direct transmission

• Vertical

  • one generation to another

  • Hereditary

  • Congenital (Germinal, Placental, birth)

• Horizontal

  • one individual to another (population)

  • Direct (droplets, mucosa, skin)

  • Indirect (vector, reservoir, latrogenic)

• other than GI

• via blood, body fluids

Infection acquired during hospitalization (not during admission) or appearing ~2 weeks after discharge

Staphylococcus aureus

e.coli, enterococci, candida (from GI)

• Urinary tract inf. due to urinary catheter

• Bloodstream inf. due to venous catheter

• Surgical site inf. due to surgical procedures

• Resp. tr. inf. due to mechanical ventilation

Measles 18 hours

Tuberculosis 6 hours

• vaccinations -> when exposed to pathogens body already has antibodies

• prophylactic drug -> only in high-risk patients; prevent spread of disease

• herd immunity -> high enough resistant people in population; susceptible people automatically also protected bc not enough reservoirs

ALL microorganisms, prions & bacterial spores killed/deactivated (1 mo in 10^6 left)

REDUCE microorganisms so don’t cause disease

by heat & chemical agents

happens after every patient so medical device/environmental surface can be stored in a state safe to handle

destruction or inhibition of microorganisms on living tissues (f.e. wash hands); limit/prevent infection

70% Alcohol (skin)

Quarterner amonium (Antisepsis, Environment surface disinfectant)

Phenol (Environment surface disinfectant)

• Chlorine (Environmental, corrosive)

• Iodine (skin antisepsis, surgical hand washing)

• Heavy metals (antiseptic)

• Hydrogen peroxide (sterilization of gas plasma, damaged tissue antiseptic)

• Aldehydes

• Not with high level disinfection

• decontamination, clean with water + detergent & dry

• bacteria adheres at surfaces (tooth decay, surface of catheters…) -> mo colonization & film formation

• antimicrobial tolerance -> bacteremia -> sepsis