Microbio exam 2 - gram negative bacteria

Aerobic

• Pseudomonas

• Legionella

• Neisseria (cocci)

• Brucella

• Bordatella

• Francisella

Facultative

Enteric bacteria

• Escherichia

• Shigella

• Salmonella

• Klebsiella

• Enterobacter

• Serratia

• Proteus

• Yersinia

Vibrio

Haemophilus

Gardnerella

Pseudomonas

• Straight or slightly curved rods

• Polar flagella (so it’s motile)

• Oxidase positive

Oxidase Test

• Tests for the presence of cytochrome oxidase (electron transport chain). 

• Rapid test

Pseudomonas aeruginosa

• common human infection, often hospital acquired

• Common colonizer of whirlpool baths

  • hard to eliminate

• Opportunistic pathogen

• UTI

• Skin lesions - folliculitis

• Eye and ear infections

• Septicemia (immunocompromised)

• Resistant to many antibiotics

• Resistant to Triclosan and chlorine 

  • it has a pump in its membrane and spits antibiotics right out

Legionella

• Not identified or named until 1976

• Weak gram stain (-) which makes it harder to identify it

• Polar flagella - motile

• Obligate aerobe 

  • Does not ferment sugars

• Oxidase + 

• Found in cooling towers/air conditioning systems, whirlpool baths

• Transmitted through droplets

• Cause of Legionnaire’s disease (pneumonia) and Pontiac fever

Neisseria

• Gram negative cocci in pairs/doublets = diblococci

• Non-motile

  • no flagella

  • no cocci have flagella in general

N. gonorrhoeae

• Causative agent of gonorrhea ~ 50% of those infected may be asymptomatic

• No vaccine, no immunity, organism becomes resistant 

• Can lead to PID (pelvic inflammatory disease). Can leave a woman sterile

• Can be transmitted to newborn during birth

N. meningitidis

• Meningococcal meningitis (meninges line the central nervous system)

• High levels of toxins released 

• 85% mortality if left untreated

• 15% mortality if treatment delayed

  • death within 12-48 hours

• Infants and 15-24 year-olds most susceptible

• Antibiotics

• Vaccine (dif. strain in Europe so have to ask for that vaccine)

• produces a toxin that will spread - starts with neck pain, then rash > gets bigger and needs amputation

• normal in nasal cavity

Brucella

• Aerobic, catalase + 

• Very small rod, non-motile

• Brucellosis, aka undulant fever, Bang’s disease, or Malta fever

• Each species has preferred host but can infect others - including humans. Can be infected by eating meat

  • Yellowstone Bison (need to vaccinate bison)

• In cattle - causes abortion/miscarriage

• not normally found in humans

Bordetella

• Small (0.2-0.7 micrometers)

• Obligate aerobe

• Catalase +

• ___. pertussis causes whooping cough

  • can cause death in infants

• ___. bronchiseptica causes kennel cough in dogs

• Vaccine - but not lifetime

  • DTP

  • DTaP

Francisella

• Small

• obligate aerobe (Catalase +)

• __. tularensis causes tularemia or rabbit fever 

  • Associated with rabbit hunting

• Can get disease by eating or skinning rabbits

  • normal host is rabbits

• Germ warfare? 

Bacterial Enteritis

• Enteritis = inflammation of the intestine

• Small intestine infected > causes diarrhea

• Large intestine infected > causes dysentery

• Systemic-enteric fever (if it gets into the blood stream)

Enteric bacteria

• Gram negative straight rods

• Facultative aerobes (can ferment glucose and do aerobic respiration)

• Fermentation of glucose (distinguish from obligate aerobes)

• Catalase + 

• Oxidase negative (distinguish from pseudomonads)

Sugar fermentation test

a biochemical test used to determine whether a microorganism can ferment a specific carbohydrate (sugar) and produce acid and/or gas as metabolic byproducts

Escherichia coli

• Peritrichous flagella (flagella all around - most motile)

• Indole positive

  • produces gas from glucose

  • produces acid from lactose

• Most strains non-pathogenic

• Normal flora of intestinal tract

• Synthesizes vitamins

Indole test

• Deamination of tryptophan to indole

• some amino acids could deaminate trytophane and produce indole

• negative (yellowish green)

• positive (purple/pink)

E. coli

• Pathogenic strains have a capsule or fimbriae to allow attachment to cells

  • Cause diarrhea, UTIs

• Fecally contaminated water

• Contaminated beef

  • cow’s fecal matter is contaminated

Shigella

• Genetically closely related to E. coli but usually pathogenic

• Non-motile

• No gas from glucose, no acid from lactose

• Shigellosis or bacillary dysentary (severe diarrhea)

• Associated with poor sanitation and overcrowding (daycare or dorm)

• Food or water-borne

Salmonella

• Also similar to E.coli but most are pathogenic to humans (not typically found in humans)

• Motile

• S. enteritidis found in GI tract of birds, rodents, and reptiles

  • cause of salmonellosis (gastroenteritis)

Hydrogen sulfide production test

• Thiosulfate reductase catalyzes sulfur to H2S gas 

  • (if sugar produces H2S gas, then positive test)

• H2S reacts with FeS to form black precipitate 

  • turns black 

• Kilgler’s iron agar (KIA) 

Typhoid fever

• Caused by different strain of Salmonella (S. typhi) in contaminated food or water

• Systemic infection 

• Rare if there are good sanitation practices

  • there can be “silent carriers” (____ Mary)

  • put her on island the rest of her life

Klebsiella

• Most found in soil and non-pathogenic

• Non-motile

• Urease + 

• __. pneumoniae forms a capsule and can cause pneumonia, UTI, and infant diarrheas

  • 50% mortality with this pneumonia 

Urease test

• enzyme = urease

• urease catalyzes the breakdown of urea to ammonia and bicarbonate (gas)

  • bicarbonate is very basic

• Urea broth, pH indicator

  • pink = basic 

  • urea = breakdown product of protein digestion

• negative = acid produced = yellow

• positive = base/alkaline produced = pink

Eneterobacter aerogenes

• usually has yellow pigmentation

• Butanediol fermentation 

  • Vogues - Proskauer (VP) test positive 

  • produces butanediol and turns red

• Motile

• Water and sewage

• Opportunistic infections and UTIs

Serratia

• Motile

• Produces red pigmentation and lower temperature

• DNase + , gelatinase + 

• Opportunistic infections

  • Septicemia

  • UTI

  • Pneumonia

Proteus

• So motile that swarming happens

• Highly motile

  • Peritrichous flagella

• Urease + 

• Swarming phenomenon - waves of growth

• UTIs

Yersinia

• Short thick rod, bipolar staining

• Urease + 

• __. pestis is cause of bubonic, pneumonic and septicemic plague

• Prevalent in various rodents (sylvatic plague)

• Humans are accidental hosts

Vibrio

• means comma, but also the genus name

• Curved rods (comma)

• Facultative but oxidase positive 

• Polar or peritrichous flagella

• Aquatic, halophile

• __. parahaemolyticus causes gastroenteritis from raw fish (Japan)

• Bioluminescent 

Vibrio cholerae

• most famous vibrio

• Causative agent of Cholera

  • found in fecally contaminated water

• High incidence in Asia, South America, Africa

  • Gulf coast states of US

• Shredding of intestinal lining

• “Rice-water stools”

• Can lose 22 liters fluid/day (~6 gal)

• Must replace fluids and electrolytes

• toxin that gets produced and messes with your gut, fluids rush into your intestines

Haemophilus

• “loves blood”

• requires blood proteins to grow in the lab

• Short rod, non-motile

• May form capsule

• Grown on enriched BAP or chocolate agar (when you heat the blood)

  • needs blood proteins

• _. ducreyi causes chancroid (STD)

  • soft painful lesions on genitals which bleed easily. Very infective. Can spread to groin and lead to buboes. 

  • Seen mostly in developing countries where it is more prevalent than other STDs

• _. influenza causes meningitis, conjunctivitis, ear infections, and pneumonia (does NOT cause influenza, forgot to change name)

  • thought to be cause of influenza until virus was discovered

Gardnerella

• Tiny rod

• Once classified as haemophilus 

  • chocolate agar 

• Normal in female urogential tract 

• In combination with various anaerobic bacteria can cause vaginitis (pH is important)

• Can be side effect of antibiotic treatment

Anaerobic rods

Bacteroides

Spirilla

• Campylobacter

• Helicobacter

Spriochetes

• Treponema

• Borrelia

• Leptospira

Intracellar

• Rickettsia

• Chlamydia

Bacteroides

• Gram (-) short rod

• Obligate anaerobe

• 10^10 cells per gram of human feces 

  • Symbiotic relationship 

  • Break down polysaccharides

• Opportunistic infections 

• extremely common in our intestines, competes out bad organisms

  • if it gets somewhere else outside intestines, it can cause infections

Spirilla

• Gram negative

• Spiral shaped

• Motile

• Single or multiple polar flagella

  • gentle coil to it

• Camplylobacter

• Helicobacter

Campylobacter

• gentle spiral, motile

• Microaerophilic, optimum growth at 42 C

• 2nd leading cause of food borne illness in US (after salmonella)

• Severe diarrhea - often bloody

• Normal flora in many animals, especially birds

  • Kangaroo and wombat (bushwalkers diarrhea)

• Chicken and raw milk are common sources 

Helicobacter (H. pylori)

• gentle spiral

• Closely related to Campylobacter

• Microaerophile

• Knobs on ends of flagella (help it attach to stomach lining)

• ______ is the cause of ulcers

  • Stomach cancer?

• Survives in acidic condition of stomach by producing urease

• Urease + (breaks down bicarbonate and ammonia)

• Nobel prize 2005

Spirochetes

• Gram (-)

• Motile

• Tightly choiled

• Found in aquatic environments and in animals

• 3 genus

  • Treponema

  • Borrelia

  • Leptospira

Spirochete motility

• have endoflagella (flagella within the body of organism)

  • polar flagella fold back into periplasmic space 

    • body of organism and house outer sheath

• Protoplasmic cylinger

• Outer sheath

• Corkscrew motion

Treponema

• Anaerobic

• Flattened coil/wave

• Very thin - difficult to see with regular light microscope

• Dark field and phase contrast

• _. palladum in causative agent of syphils

  • causes syphilis

Borellia

• Microaerophilic

• Large spirals - easy to see

• _. recurrentis is carried by lice and ticks and causes relapsing fever

• Replace surface antigens

Borellia burgdorferii

• causes lyme disease

• described in 1982

• ticks carry it

Leptospira

• found in lots of mammals, not humans really

• Aerobic

• Thin, finely coiled, bent at end

• _ - zoonosis

• contact with contaminated urine

Intracellular bacteria

• Rickettsias

  • Rickettsia

  • Rochalimaea

  • Erlichia

  • Bartonella

• Chlamydia

Rickettsias

• Gram negative

• Obligate intracellular (inside another cell) parasites

  • Can only be cultured within cells

  • Replicated in host cell cytoplasm and eventually burst cell

• Carried by arthropod vectors (insects or arachnids)

• Highly infectious

• Howard Ricketts (died from this disease)

Rickettsial diseases

• Rocky mountain spotted fever

• Erlichiosis

• Trench fever

• Q fever

• Cat scratch fever

• Typhus

  • disease carried by lice that killed a lot of people in concentration camps during the holocaust

Chlamydia

• Extremely small

  • Not sure at first if cellular

• Parasitic

• Too small for gram stain but biochemically look gram (-)

• Simple biochemical capacities

• No arthropod vectors (spread human to human)

• Airborne (elementary body)

Chlamydia life cycle

• 1) elementary body

  • means of dispersal

• 2) reticulate body

  • binary division, vegetative

1. elementary body attacks host cell

2. phagocytosis of elementary body

3. conversion to reticulate body

4. release of elementary bodies

5. conversion to elementary bodies

6. multiplication of reticulate bodies