microbio test 3 part b

Hydrogen bond

A hydrogen bond is a weak, noncovalent attraction between a hydrogen atom bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) and another nearby electronegative atom.

a noncovalent electrostatic attraction between a partially positive hydrogen atom (covalently bonded to an electronegative atom like O or N) and another electronegative atom with a lone pair.

ionic bond

A type of chemical bond that involves the electrostatic attraction between oppositely charged ions, transfer of electron(s)

-Forms when electrons are transferred from one atom to another

-Electrostatic force of attraction between oppositely charged ions

-i.e. NaCl

-Easily dissolves in water, free ions are called electrolytes

covalent bond

A type of chemical bond involving the sharing of electron pairs between atoms,

competitive inhibitor

• Inhibitor binds to the active site

• Competes with the substrate

• Can be overcome by ↑ substrate concentration

noncompetitive inhibitor

• Inhibitor binds to site that’s not the active site

• Does not compete with substrate binding

• Cannot be overcome by ↑ substrate

4 steps of aerobic metabolism

1. Glycolysis

2. Intermediate step

3. Krebs cycle

4. Electron transport chain

glycolysis

Anaerobic process that occurs in cytoplasm. Glucose is split into two 3-carbon molecules called pyruvate.

End products:
-Pyruvate - converted to acetyl CoA (intermeidtae step)

-ATP - used up in metabolic reactions

-NADH - transferred to the ETC

Intermediate step

Pyruvate taken from glycolysis and converted to acetyl CoA

End products:
- Acetyl CoA - enters Krebs cycle
- NADH - goes to ETC
- CO2 - given off (decarboxylation)

Krebs cycle

Takes acetyl CoA and incorporates it with oxaloacetate to form citrate.

End products:
NADH - goes to ETC

FADH2 - goes to ETC

ATP - used in metabolic reactions

CO2 - given off as gas

Electron transport chain

Uses NADH and FADH₂ to transfer electrons through membrane proteins, creating a proton gradient that drives ATP production.

End products:

• ATP – used in metabolic reactions

• H₂O – formed when oxygen accepts electrons

• NAD⁺ and FAD – recycled back to earlier steps

aerobic vs anaerobic respiration

???

Growth phases of bacterial cell

Lag, log*, stationary, death

Impetigo

• Cause: Staphylococcus aureus or Streptococcus pyogenes
  
  Superficial pus-filled vesicles

  Itchy vesicles can rupture and ooze

  Highly contagious

  Secondary infections possible

  Transmission: direct contact, fomites

  Treatment: topical antibiotics

  Prevention: good hygiene

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MRSA

• Cause: Antibiotic-resistant strain of Staphylococcus aureus

• What it is (Symptoms):

  • Painful red bumps (look like pimples/spider bites)

  • Swelling, pus, warmth

  • Can become serious if it spreads (blood, lungs)

• Treatment:

  • Drainage of abscess

  • Specific antibiotics (not methicillin-type)

  • Hygiene + wound care
    
    Methicillin-resistant Staphylococcus aureus, a strain of Staph that is resistant to commonly used antibiotics,

Staphylococcal Scalded Skin Syndrome (SSSS)

• Cause: Toxins from Staphylococcus aureus
  
  Staphylococcal Scalded Skin Syndrome

  Affects mostly newborns and babies

  Blistering and sloughing of the skin

  Transmission: toxins may be carried by the bloodstream to the other areas from primary site infection

  Highly contagious

  Treatment: antibiotics
  Virulence: exfoliative toxins

Gas gangrene

• Cause: Clostridium bacteria (often C. perfringens)

• Symptoms:

  • Severe pain, swelling

  • Gas bubbles under skin (crackling sound)

  • Tissue death (necrosis)

• Treatment:

  • Emergency surgery (remove dead tissue)

  • IV antibiotics

  • Sometimes amputation

Usually caused by Clostridium perfringens (gram positive bacilli, anaerobic)

Pain, edema, bloody exudate, blackened necrotic tissue filled with gas bubbles

Transmission: introduction of endospores into wounds, surgical incisions, compound fractures

Virulence: endospores, collagenase, hyaluronidase, DNAse

Treatment: debridement, antibiotics, hybaric oxygen therapy, amputation

Cutaneous anthrax

• Cause: Bacillus anthracis

• Symptoms:

  • Painless ulcer with black center (eschar)

  • Swelling around lesion

• Treatment:

  • Antibiotics (ciprofloxacin, doxycycline)

  • Early treatment is very effective
    
    Bacillus anthacis is a gram-positive endospore-forming bacteria

    Black eschar formation and tissue necrosis

    Transmission: zoonotic disease in which endospores enter through small cuts or abrasions from contact w animals or animal products

    Treatment: Penicillin and ciprofloxacin

Trachoma

• Cause: Chlamydia trachomatis

• Symptoms:

  • Eye irritation, redness

  • Repeated infections → scarring → blindness

• Treatment:

  • Antibiotics (azithromycin)

  • Improved hygiene

Infection of epithelial cells of the eye

Pebbled appearance to inner upper eyelide, scarring upper eyelide, lashes turn inwards/down

Major cause of blindness

Chlamydia trachomatis

Transmission: fingers, fomites, flies, hot/dry climate

Treatment: Azithromycin or doxycycline

Necrotizing fasciitis

• Cause: Usually Streptococcus pyogenes (can be mixed bacteria)

• Symptoms:

  • Rapidly spreading tissue destruction

  • Severe pain, fever

  • Skin discoloration, blisters

• Treatment:

  • Emergency surgery

  • IV antibiotics

  • Intensive care
    
    Flesh eating disease

    Enters via damaged skin

    S. pyogenes produces enzymes that degrade connective tissue

    Treatment: IV antibiotics, debridement of skin

    40% mortality rate

Chicken pox

• Cause: HHV-3, Varicella-zoster virus

• Symptoms:

  • Itchy vesicular rash → fluid-filled blisters

  • Fever, fatigue
    
    Transmission:

  • Respiratory droplet and direct contact with lesions

  • Highly contagious

• Treatment:

  • Usually self-limited

  • Antivirals (acyclovir) if severe

  • Vaccine prevents it
    
    Virulence: may travel to peripheral nerves and become latent

Warts

Human papillomaviruses (HPV)

Benign, squamous epithelial growths

Common, plantar, genital, flat

Transmission: direct contact, autoinoculation, indirect contact, fomites

Harmless and resolve over time

Treatment: cauterization, chemicals, cryosurgery, laser

Measles

aka rubeola or measles virus

Virulence: disables aspects of the host immune response, hides from host immune defenses

Transmission: respiratory droplet, highly contagious, no reservoir other than humans

Signs: Kopliks spots, Maculopapular rash

Treatment: supportive therapy

Prevention: vaccine

Rubella

German measles

Transmission: respiratory droplets

Postnatal: rash starts on face and spreads. Fever, swollen lymph nodes, muscle and joint aches, runny and stuffy nose

Congenital rubella syndrome (CRS): 1st trimester: stillbirth or miscarriage. 2nd or 3rd trimester: blindness, deafness, heart defects, mental retard)
treatment: symptomatic therapy
Prevention: MMR vaccine

Herpes simplex

HSV-1

Oral herpes, cold sores or fever blisters

Virulence: latency

Transmission: respiratory droplets/saliva, fomites

Initial infection may include sore throat or flulike symptoms

Migrates to trigeminal nerve to become latent and flare up

reactivation caused by UV radiation, menstruation, hormonal changes, stress

No cure or vaccine

topical or oral antivirals reduce freq and severity

Tinea

• Cause: Dermatophyte fungi

• Symptoms:

  • Ring-shaped red rash

  • Itching, scaling

• Treatment:

  • Topical antifungals (clotrimazole)

  • Oral antifungals if severe

Genera: Trichophyton, Microsporum, Epidermophyton

Mycoses causes dermatophytes that area confined to the non-living epidermal tissues, hair, and nails

Transmission: direct and indirect contact with infect animals/humans/soil

Virulence: keratinase, spores may remain for years on fomites

Treatment: topical antifungal (miconazole, itraconazole) or oral drugs (terbinafine or griseofulvin)

Cutaneous Sporotrichosis

• Cause: Sporothrix schenckii (from soil/plants)

• Symptoms:

  • Nodules under skin

  • Spread along lymph vessels

• Treatment:

  • Oral antifungal (itraconazole)

  • Potassium iodide (older treatment)

Sporothrix schenckii (rose gardener’s disease)

Red, pink, or purple bump usually appears where the fungus has entered through a break in the skin

Transmission: contaminated plant matter

Treatment: Supersaturated potassium iodide (SSKI) or intraconazole

Prevention: gloves/long sleeves

Polar vs non-polar covalent bonds?

Polar: unequal sharing of electrons, causes ends of the molecule to have partial positive and negative charges.

Non polar: equal sharing of electrons, no charge separation in the molecule.