Microbiology: Zoonotic Infections Flashcards
Pasturella multocida
Gram (-) cocobacilli
- zoonotic infection from cats/dogs that is known to cause cellulitis and osteomyelitis most commonly*
Characteristics:
- non motile
- non sporeforming
- facultative anaerobic
- (+) catalase
- (+) oxidase
Virulence:
- capsule
- lipopolysacchrides: inhibits compliment system
- pasteurella multocida toxin (PMT)*: damages endothelial cells directly and causes edema, redness and swelling.
Complications:
respiratory tract infections
Cellulitis
Osteomyelitis
Septic arthritis
Bacteremia/sepsis (only in immunocompromised people)
Treatment:
- penicillin
- tetracyclines
- cephalosporins
Francisella tularensis
rabbit fever/tularemia
Gram (-) cocobacilli
zoonotic infection from infected rabbits, ticks and deer flies and is mostly found in the northern US
Characteristics:
- non spore forming
- non motile
- facultative intracellular
- obligate aerobe
- (-) oxidase
- (-) urease
- Fastidious bacterium* (can only grow on cysteine agars (BYCE and chocolate ONLY)
Virulence:
- capsule
- inactivated lipopolysacchrides (prevents pro inflammatory cytokine release)
- acid-phosphatase (AcpA)*: prevents phagolysosome fusion
- siderophores: helps bind iron from host cells
Complications:
- tuleremia (sepsis of tularensis w./ 6 forms)
Treatment:
- Aminoglycosides (gentamicin/streptomycin)*
- tetracyclines or fluroquinolones ( if allergic to Aminoglycosides)
Bartonella henselae
Cat scratch fever
Gram (-) bacilli
zoonotic infection from cats and cat flies
Characteristics:
- facultative intracellular
Virulence:
- increases IL-10 production endogenously*: leads to suppression fo immune cells
- Complications:
- cat-scratch fever:* regional lymphadenopathy that is extremely tender due to granuloma formation in the lymph node from the bacterium itself, fever, ab pain and fatigue.
(this is the form found in immunostable individuals) - bacillary angiomatosis:* benign papular vascular lesions filled with neutrophils that are widespread throughout the body (similar to kaposi sarcoma lesions) w/ fever, fatigue and weight loss.
(this is the form found in immunocompromised individuals, ESPECIALLY HIV patients)
Treatment: all reduce symptoms, cure comes naturally overtime)
- azithromycin (for life-treating complications)
- erythromycin, doxycycline tetracycline (bacillary angiomatosis ONLY)
Salmonella species (not typhoid)
Gram (-) bacilli
Characteristics:
- encapsulated
- motile
- facultative intracellular
- facultative anaerobes
- (-) oxidase*
- (-) lactose fermentation*
- (+) sulfate fermentation*
- (+) triple sugar iron agar* (turns black)
Complications:
- ulcerative colitis
- bacteremia/sepsis
- zoonotic infection very common type of food poisoning, especially among eggs and poultry and infected animals such as reptiles and dogs*
- requires a large amount of bacterium to infect due to acid-liable*
Treatment:
- symptomatic treatment
- antibiotics are only given if bacteremia/sepsis and/or patient is immunocompromised
Mycobacterium leprae
Leprosy/Hansen disease
Acid-fast (stains red with Ziehl -neelsen stains ONLY) Bacilli
causes leprosy and is a zoonotic infection from armadillos and other infected humans
Characteristics:
- obligate intracellular
- obligate aerobe
- 27-33C growth best (skin, mucosa of URT and peripheral nerves in humans)
Virulence:
- PGL-1 protein*: allows bacterium to attach to laminitis-2 proteins on peripheral nerves and demyelinate nerves
Complications:
1) (multibacillary)lepromatous leprosy: TH2 mediated infection where a humoral immune inflammation occurs in nerves and skin.
- symmetric nerve demyelination (parasthesia) and high number of raised/poorly demarcated skin lesions are seen
- lion-like facies and is both highly infectious and lethal
- loss of hair (especially facial hair)
- necrosis of extremities
- chronic uveitis and facial nerve paralysis
* high levels of bacterium are present*
2) (paucibacillary) tuberculoid leprosy: TH1 mediated infection where a cell-mediated immune information occurs in nerves/skin.
- low levels of hypopigmented, well demarcated skin lesions with asymmetric nerve involvement
- claw fingers and foot drop
* low levels of bacterium are present
Treatment:
1) clofazimine* (for lepormatous form ONLY)
2) dapsone + rifampin* (for tuberculoid form ONLY)
Borrelia burgdorferi (Lyme disease)
Acid-fast spirochete (thin spiral shaped)
zoonotic infection spread by the vector Ixodes deer tick from infected deers and mouses and lizards mostly endemic to northern US
3 stages:
1) localized stage:
- classic “bulls-eye” pattern rash (not always present though) called “erythema migrans”
- vague flu-like symptoms
2) early disseminated stage:
- symptoms from #1 and
- secondary lesions
- AV nodal blocks (1/2)
- facial nerve (bells) palsy
- myalgia and arthritis
3) late disseminated
- symptoms from #2 and
- encephalopathy/ meningitis
- chronic arthritis
* this stage usually kills*
Treatment:
- doxycycline*
- amoxicillin + ceftriaxone ( if serious illness)
What is Jarisch-hexheimer reactions?
An immunogenicity reaction that some spirochete bacterium get when exposed to proper treatment
The bacterium will rupture open, releasing tons of antigens that elicits a broad immune reaction
Symptoms: (all while on proper treatment)
- fever
- sweating
- muscle pains
Treatment:
- symptomatic, if gets bad remove antibotics and use another one
Rickettsia rickettsii
rocky mountain spotted fever
Microscopic bacteria that dont stain but are considered gram (-)
- zoonotic infection endemic to south Atlantic states and is spread via tricks (Dermacentor species)*
- cant make NAD+ and CoA enzymes so is an obligate intracellular pathogen*
Virulence:
- lipopolysacchrides
- Rickettsia Outer Membrane Proteins (ROMPs)*: helps bind to host cells and activates Ku70 proteins, promoting ubiquination and subsequent phagosome formation, ultimately getting into the cell.
(rickettsii species has both A/B, prowazekii and typhi only have B) - phospholipase D and tlyC*: enzymes that allow the bacterium to break out of phagosome and into the cell cytosol to replicate.
- actin-based motility*: allows rickettsia rickettsii to spread from cell-to-cell with out having to wait for cell lysis . (Only found in this sub-species)
Symptoms:
- non specific flu symptoms (immediately)
- classic triad (a couple days after exposure)
1) erythematous macules on wrists first, then trunk and soles and palms which turn into purple petechiae
2) severe headache
3) severe fever
Treatment:
- doxycycline or chloramphenicol*
Rickettsia typhi and rickettsia prowazekii
Endemic and epidemic typhus
Microscopic bacteria that dont stain but are considered gram (-)
- zoonotic infection that is spread via flea feces and human louse feces respectively*
- cant make NAD+ and CoA enzymes so is an obligate intracellular pathogen*
Virulence:
- lipopolysacchrides
- Rickettsia Outer Membrane Proteins (ROMPs)*: helps bind to host cells and activates Ku70 proteins, promoting ubiquination and subsequent phagosome formation, ultimately getting into the cell.
(rickettsii species has both A/B, prowazekii and typhi only have B) - phospholipase D and tlyC*: enzymes that allow the bacterium to break out of phagosome and into the cell cytosol to replicate.
Symptoms:
Epidemic typhus
- similar to Rocky Mountain spotted fever, except the rash is reveresed (starts at trunk and spreads to extremities and spares hands)*
(Murine)Endemic typhus:
- similar to a common flu infection
- similar to rash in epidemic typhus
Treatment:
- doxycycline or chloramphenicol*
Coxiella Burnetii
Q-fever
Gram (-) bacilli
zoonotic infection that is spread via infected cattle and food products
Characteristics
- extremophile (likes extreme environments and cant be easily kill)*
- spore former
- obligate intracellular* (cant make NAD+/ CoA so needs host cells to make ATP)
- does not grow on agar
Complications:
(Q-fever)*
- is an atypical pneumonia that presents with fever, malaise, headache, coughing fits, diarrhea/vomiting
- THERE IS NO RASH
(Culture (-) endocarditis)*
- is the most common cause of this
- diagnosis is beyond tricky and is usually dependent on:
- history
- serologic testing
- Weil-Felix test (+) (no clumping)
- Increased WBC w/ increased ESR/CRP*
Treatment:
- doxycycline (14 days)*
- need to be tested again in 3-6 months serologically to confirm disease is killed*
Yersinia pestis
Plaque
Gram (-) cocci-bacilli
causes plaque and is transmitted by fleas and rodents
Characteristics:
- non motile
- non spore former
- facultative anaerobe/intracellular
- (-) oxidase*
- (-) urease*
- (+) catalase
- (-) indole*
- (-) lactose fermentation*
- (-) hydrogen sulfate fermentation*
Virulence:
- type 3 secretion system: (needle like projection that spurts out proteins into the cytosol of cells and the environment to decrease immune response)
- Yersinia outer proteins (YOPs)*: prevents pro inflammatory cytokines to be secreted And inactivates macrophages
- siderophores: helps it get iron from the environment
Complications:
- *bubonic plaque: limited sepsis that is marked by extreme lymphadenopathy since it is only in lymph nodes
- cancer symptoms but can see Buboes in the inguinal or axilla region*
- *septicemic plaque: sepsis that is marked by increased presence of blood stream and DIC prominence
- hypotension, purpura skin lesions, tissue necrosis*
- *Pneumonic plaque: get plaque into the lungs via the bloodstream (secondary) or from respiratory droplets from infected individuals (primary)
- dyspnea, hemoptysis and cough*
Treatment: (lasts 14 days)
- Aminoglycosides (gentamicin/streptomycin)*
- doxycycline/tetracycline (only if Aminoglycosides dont work)
Borrelia recurrentis
Relapsing fever
acid fast Spirochete bacterium
- zoonotic infection from louse/lice*
- enters humans via lice feces and bites via scratch sites*
Virulence:
- antigenic variation*: (cant build adaptive response)
Complications:
relapsing fever*:
- recurrent episodes of shaking./chills/seats/head have/fever/ myalgia/arthralgia/ altered senses/ nausea/diarrhea.
- each episode ends with a “crisis” and two phases. Then an afebrile stage.
- the time between relapses becomes shorter and milder overtime w/ increased asymptomatic phases.
- thrombocytopenia
- myocarditis
- hepatitis
- myocarditis
Treatment:
- penicillin G or doxycycline*
- must monitor for Jarisch-herxheimer reactions*
What are the two phases in releasing fever associated with the end crisis?
1) chill phase (10-30 min)
- major fever
- delirious/agitated
- tachypneic and tachycardia
2) flush phase (1 days)
- sweats
- hypothermia
- hypotension
When is a gimesa stain used?
To stain for spirochete species
- borrelia
- leptospira
- treponema
BLT
Leptospira species
leptospira interrogans
Acid fast (-) Spirochete bacteria
- zoonotic infection caused by infected water and rat/rodent urine*
- common in people who live in tropical regions, work in sugarcane plantations, sewage operations, rice fields. And people who swim in contained waters*
- also outbreaks can occur during and after floods*
Characteristics:
- motile
- non spore former
- obligate aerobe
Virulence factors:
- LPS
- various toxins
- adhesins
- sphingomyelinase C toxin*: destroys RBCs and capillary epithelium (causes internal hemorrhage if chronically present)
Complications:
- leptospirosis (1st phase) *: generalized flu-like symptoms, calf myalgia (almost always present), mild jaundice, photophobia/headache, conjunctival suffusion (erythema without exudate)
- Weil disease*: severe leptospirosis which causes major jaundice and azotemia (elevated liver/kidney/urea enzymes). Also causes intense fever, renal failure/widespread edema, hemoptysis, spontaneous hemorrhages and anemia.
Treatment:
- penicillin G*
- doxycycline (if cant use penicillin)
- supportive therapy is also required (especially in Weil disease)
