Microbio Module 5

Strep bacteria

gram +

cocci chains

catalase neg (no H2O2 breakdown, no bubbles), coagulase neg (no blood clots)

grown on BAP

Strep infections (3)

1. S. pharyngitis: strep throat

• caused by Group A S. pyogenes

• FLR (fever, lymph nodes, red throat

2. Rheumatic fever: if S. pharyngities goes untreated 2-3 wks

• antigen mimicry

• damage = cross-reacting antibodies

• heart valvage damage

3. S. septicemia: blood poisoning

• caused by Group B Strep

• septicemia (infection, bacteria enters bloodstream) —> sepsis (extreme immune response) —> shock (low BP, organ failure)

• can be caused by lots of bacteria not just strep

• treatment: AB, IV, O2

Staph bacteria

gram +

cocci clusters

catalase + (bubbles)

coagulase + (blood clots)

facultative anaerobe

commensal

Staph infections (5)

*all caused by S. aureus

1. Folliculitis

• infected hair follicles

• pus + boils

2. Scalded Skin Syndrome

• kids

• exfoliative toxin —> damaged skin —> blisters, peeling (2 days) —> inc risk of secondary infection

3. Impetigo

• kids

• contagious sores around mouth/nose

• treatment: penicillin

4. Conjunctivitis (pink eye):

• infection of conjunctiva (thin transparent tissue covering sclera—white part of eye)

• multi cause: viral (common cold symptoms) or bacterial (Staph or sometimes Strep)

• dirty hands —> rub eyes —> infection

5. Opthalmia Neonatorum: newborn pink eye

• bacterial conjunctivitis in newborn

• exposed to chlamydia/gonorrhea while passing through birth canal

• treatment: AB (NEOmyocin eye ointment)

Mycobacterium bacteria

acid-fast

bacillus

transmission: airborne (must be inhaled)

Mycobacterium infections (2)

1. TB: cough

• caused by M. TB

• infectious: if inside lung (if outside = non-infectious)

• long lasting cough, cough blood/sputum

• treatment: 6-9 mos

  • RIPE

• incomplete treatment:

  • stopped early: some bacteria survive + return

  • taken incorrectly: surviving bacteria become drug resistant

2. Leprosy/Hansen’s Disease: nerve

• caused by M. leprae

• long latency (can be asymptomatic for long timer)

• nerve damage —> loss of sensation —> repeated damage

• treatment: DRC

Clostridium bacteria

gram +

bacillus

anaerobic

spore-forming (harmless until anaerobic)

• diseases caused by TOXINS not direct bacterial invasion: spore enters body —> anaerobic cond —> active bacteria —> toxin production —> disease symptoms

Clostridium infections (4)

1. Botulism: body goes limp

• botulin toxin —> blocks motor neurons —> paralysis

• 3 cond types:

  • foodborne (improperly canned)

  • infant (lack adult microbiota)

  • wound (puncture, drugs)

2. Tetanus: tight mucles

• tetanospasmin toxin —> affects inhibitory neurons —> uncontrolled muscle contraction

  • opp of botulism

• lockjaw (masseter jaw muscle spasms), resp muscles may stop working (fatal)

• no cure

• prevention: vaccine

3. Gas Gangrene: tissue death

• perfringens toxin —> alpha toxin perfringolysin —> holes in cell membrane —> ion imbalance —> cell death —> tissue destruction

• everywhere in nature

• muscle necrosis

• gas production (anaerobic bacteria ferments carbs)

• treatment: surgical removal of infected tissue

4. C. Diff: colon damage

• spores resistant to ABs

• Recent AB use —> ABs kill normal gut bacteria —> dec microbiota —> C. diff overgrowth —> toxin production —> colon inflammation —> diarrhea/colitis

• transmission: contact

  • fecal-oral

• hospitalized patients

• treatment: rehydration, ABs, fecal transplant (restores normal microbiota to compete with C. diff)

Other Bacterial diseases (4)

1. Legionnaires’ disease: pneumonia

• caused by L. pneumophila

  • gram neg, rod, aerobic, 1 flagellum, motile

• freshwater, contaminated in hot small areas

• transmission: droplet

  • aspiration: water enters lungs instead of stomach through liquid mist

• pneumonia: 2-10 days post-exposure

2. Plauge: Bubonic Plague (fleas)

• Yersinia pestis

  • gram neg, rod, facultative anaerobe

• rodent —> flea —> human

• 3 types:

  • bubonic: painful swollen lymph nodes

  • pneumonic: lungs

  • septicemic: bacteria spread through blood stream (can infect entire body)

• seizures, bleeding, low BP, organ failure

• treatment: ABs

3. Antrhax

• anthrax = endospores in soil (can survive harsh environments)

  • gram pos, rod, spore

• not spread person-person, 3 types of entry points:

  • cutaneous: most common, entry through skin wound — boil + black center

  • pulmonary: entry through spore inhalation — fever, cough, headache

  • GI: entry through contaminated foods — diarrhea, vomiting

4. Lyme Disease: Tick saliva

• Borrelia burgdorferi

  • spirochete, negative staining, multi-flagella, motile

• animal reservoir —> tick —> injects bacteria in saliva —> human

• bulls-eye target rash

• if untreated: can spread systematically

STIs (3)

1. Gonorrhea

• Neisseria gonorrhoeae

  • gram neg, diplococci, fastidious (CHOC plate), oxidase POS (blue/purple color change), uses pili (protein filament)

• pus discharge (from infected mucuous membranes)

• often asymptomatic

  • symptoms: burning pee, discharge, vaginal bleeding

• common in women

• common co-infection w/ chlamydia

• treatment: AB-resistant so IM injection of ceftriaxone

2. Chlamydia

• C. trachomatis

  • gram neg, rod, non-motile, rod-shaped, obligate intracellular parasite (must live inisde living cell to reproduce)

• life cycle 2 forms:

  • Elementary Body: entry = gets inside cells

    • infectious, dormant, enters host cells

  • Reticular Body: replicate = make more bacteria

    • non-infectious, active, replicates inside cell

• mostly asymptomatic, symptoms similar to gonorrhea

• women untreated —> PID —> infertilit

• newborn complication: newborn exposed to bacteria in birth canal —> opthalmia neonatorum —> blindness)

• treatment: ABs: DA

• high reinfection rate, also treat partners

3. Syphilis:

• Treponema pallidum

  • gram neg, spirochete (dark-field microscopy)

• congenital

• 4 stages: primary, secondary, latent (symptoms disappear, bacteria remains present), tertiary (sever complications)

  • primary: chancre = painless sore/ucler at infection site