General Bacteria fun facts (virulence factors, unique characteristics) Flashcards
Which virulence factors allow for adhesion to fibronectin and vitronectin
*Protein A
*Techoic acid
3 mechanisms of bacterial gene transfer
1) Transduction
-Bacteriophage
2) Conjugation
-Sex pili to share plasmid
3) Transformation
-Uptake of DNA from lysed bacteria
What is a biofilm? How do bacteria survive in it?
Aggregate of bacteria with a polymer matrix
Has water channels within to disseminate O2 and nutrients?
What makes the cell wall of mycobacteria special
NO cell wall!
They have a plasma membrane
Do not pick up gram stain, variable
What is the benefit of a peptidoglycan layer for Gram + bacteria
Resist heat and dessication
List superantigens
Staph enerotoxins A, B, C, D (SE-B)
Toxic shock syndrome toxin-1 (TSST-1)
Protein A (avoids complement binding by FcR; upregulates KC adhesion mc)
Staphyloferrins function
Lyse RBC
Use the iron for growth
CHIPS protein function
Evade C5a
SCIN function
Staph complement inhibitor protein
Virulence factors of Streptococcus
*M protein (inhibits phagocytosis)
*Streptolysin O
S equi: ELISA for M protein for Strangles/Purpua hemorrhagic diagnosis
Virulence factors of Pseudomonas
*Biofilm
-Increases MIC
-In 40% of OE isolates
-Quorum sensing, slime, plasmid exchange
*Pyocyanin
-Pigment, proinflammatory
*Elastase
-Cleaves collagen
Virulence factors of Nocardia
*Thick peptidoglycan layer (heat, dessication resistance)
*Superoxide dismutase
*Catalase
Virulence mechanism of Mycobacteria
*Intracellular: Block fusion of lysosome in macrophage
Prevents MHC2 expression
*No cell wall, so resistant to B-lactams
*Can act as a SUPER ANTIGEN- strong T cell response
*Can vary surface antigens to avoid immune identification
Function of coagulase
Converts fibrinogen to fibrin (clot scaffold)
-Tissue invasion
-Microabscesses
-Protection from granulocytes
Indicator of pathogenicity
BlaZ gene
In Staphylococcus
Encodes for beta lactamase
Which Streptococcus are more pathogenic: alpha or beta hemolytic
Beta: lysis RBCs
Alpha are commensals on MM and skin
Bacteria that can cause:
-Necrotizing Fasciitis and Myositis
-Toxic Shock Syndrome
Streptococcus canis!
-M Protein: antiphagocytic, destroys C3 convertase
-Proteases: help spread through fascial planes and into muscle
Which Mycobacteria causes conjunctivitis in cats
*Mycoplasma felis
T or F: detection of Mycoplasma in lungs of dogs is diagnostic for infection
False. Mycoplasma is a commensal in respiratory tract of dogs
What do Mycoplasma colonies look like on culture plate
Fried eggs!
Central zone of growth
Treatments for mycoplasma
BACTERIOSTATIC – long duration of tx
Macrolides, clindamycin, FQs, tetracyclines, chpc, aminoglycosides
Streptococcus that causes mastitis in cows
S. agalactiae
What do superantigens bind to induce a massive inflammatory response
MHC cl II and TCR
Which antibiotic can TRIGGER Toxic Shock Syndrome
Fluoroquinolones.
Can trigger more expression of superantigen TSST-1 by S. canis!
Best treatment for Toxic Shock Syndrome
Clindamycin
-Inhibits M protein synthesis
-Suppresses LPS-induced TNF production
Age, Inciting incident for Toxic Shock Syndrome
<1 year old
Bite wound, URI
Best antibiotic for Enterococcus
Worst antibiotic for Enterococcus
Best = ampicillin, penicillin
Worst = TMS (even if S in vitro. can bypass folic acid synthesis blockade)
Luckily, rarely pathogenic
Doppleganger for Enterococcus
Streptococcus
Both cocci, grow in chains. Enterococcus less pathogenic than Strep. Some sp of strep have been reclassified as Enterococcus
Where does Rhodococcus equi invade?
Lymphatics, macrophages
Facultative intracellular bacteria
Virulence factor that allows Rhodococcus equi to persist inside macrophages
VapA
Clinical signs in CATS with Rhodococcus equi infections
Abscesses! Check FIV/FeLV
(Horses = pyogranulomatous pneumonia.
Cows/Pigs = pyogranulomatous lymphadenitis)
Treatment Rhodococcus equi
Erythromycin/ Clarithromycin + rifampin
–> lipophilic drugs to penetrate cell wall
Surgical excision + drainage
What’s special about Listeria monocytogenase
Facultative intracellular gram + rod in MACROPHAGES
Escapes humoral immune response
What type of immune response is important for clearing Listeria monocytogenes
Cell mediated
It’s hiding in macrophages, where Ig can’t find it
What virulence factor allows Listeria monocytogenes to be phagocytosed by macrophages
Internalin
=induces phagocytosis by KCs, then pushes pseudopod projections out to be ingested by macrophage
What enables Listeria monocytogenes to escape host cell killing
Listeriolysin O
Where in the body can Listeria monocytogenes be found
GI, CNS, placenta
Form intestinal inflammation, fever, v+, abscesses
–> die from septicemia
How do animals get Listeria monocytogenes
Ingestion of contamination food
Causative agent of Anthrax
Bacillus anthracis
Large, gram +, aerobic, spore-forming
What induces Bacillus anthracis to produce spores
Exposure to atmospheric O2
(Spores are NOT produced in intact carcasses!)
Bacillus anthracis on cytology
String of box cars
Virulence factor for Bacillus anthracis
Thick capsule to avoid phagocytosis (plasmid pX02)
Stains to ID Bacillus anthracis
Methylene blue, Giemsa stain
Pick up polypeptide capsule around organism
Clinical sign of Bacillus anthracis
Swelling of the head and neck
GI, inhalation, cutaneous forms
*Acute hemorrhagic gastroenteritis
*Black eschar if cutaneous exposure (cut)
*Pulmonary nodules
How do animals develop Bacillus anthracis
Eat grass contaminated with spores; Eat infected meat –> GI signs
What is unique about Bacillus anthracis carcuses
No rigor mortis, blood oozing from orifices is non-clotting.
DO NOT NECROPSY
Most common bacteria in cat bite wound abscesses?
Pasteurella multocida
Why do cats readily develop abscesses
More elastic skin– seals over contaminated puncture wound sites
Other names for Botryomycosis
-Bacteria pseudomycetoma
-Cutaneous bacterial granuloma
Clinical lesions of botryomycosis
Nodules with draining tracts
(Distal extremities, cervical region, ventral abdomen in cats)
Yellow-white tissue grains (like Actinomyces, Nocardia!) = bacteria + immunoglobulin + fibrin
Most common causative agent for botryomycosis
S. pseudintermedius
What stain will highlight the Splendore-Hoeppli reaction (antigen-antibody complexes, complement, major basic protein from eos)
PAS stain
Treatment for botryomycosis
Surgical removal + drainage
> 4 months systemic antibiotic tx
How do dogs become infected by Brucella canis
Penetrating mucous membranes (oral, vagina, conjunctiva)
Infectious material = placenta, semen, urine, feces, nasal/ocular secretions
Clinical signs of Brucella canis
*Testicular enlargement, scrotal dermatitis
*Pyogranulomatous dermatitis
*Dry, lustrous hair coat
What should you be aware of when interacting with dogs with Brucella canis
Zoonotic, reportable!
Causative agent of Glanders in horses
Burkholderia mallei
ZOONOTIC, REPORTABLE
Clinical lesions of Burkholderia mallei
“Farcy”
Ulcerating SQ nodules along lymphatics on distal limbs
Respiratory signs
Causative agent of Plague
Yersinia pestis
ZOONOTIC, REPORTABLE
Lifecycle of Yersinia pestis
Flea-rodent-flea
C. felis is a poor vector; usually in rodents!
Season of Yersinia pestis infection
March-October, when high flea burden
Clinical signs of Yersinia pestis
*Bubonic
*Pneumonic
*Septicemic
-Lymph nodes will abscess and drain
-Necrotic stomatitis
-Facial ulceration
Tularemia causative agent
Francisella tularensis
ZOONOTIC, REPORTABLE
How is Francisella tularensis spread
Tick bite
-Wood tick (Dermacentor andersoni)
-American dog tick (Dermacentor variabilis)
-Pacific Coast tick (Dermacentor occidentalis)
-Lone Star tick (Amblyomma americanum)
Where does Tularemia affect in the body? Clinical lesions
Intracellular macrophages
SQ draining abscesses, icterus, panleukopenia
RABBITS, CATS»_space;>dogs
Actinomyces vs Nocardia: affected signalment
Actinomyces: young adult hunting dogs w/ grass awns; cats = pyothorax»_space;> bite abscesses. NOT immunosuppressed
Norcardia: IMMUNOCOMPROMISED; fight wounds in cats
Actinomyces vs Nocardia: O2
Actinomyces: Facultative, obligate anaerobe
Nocardia: Aerobe
Actinomyces vs Nocardia: ease of culture
Actinomyces: Not easily cultured
Nocardia: usually cultured
Actinomyces vs Nocardia: Coinfections?
Actinomyces: usually! Strep, mycobacterium
Nocardia: usually a sole isolate
Actinomyces vs Nocardia: acid fast (Fite-Faraco, Ziehl-Neelson)
Actinomyces: NON-acid fast
Nocardia: PARTIALLY acid fast
Actinomyces vs Nocardia: beading
Actinomyces: slight beading
Nocardia: marked beading
Actinomyces vs Nocardia: cytology
Actinomyces: Mixed bacteria. Filamentous. Dense mats of bacteria
Nocardia: Long, branching bacteria in single or loose aggregates. Few mats
Actinomyces vs Nocardia: mortality
Actinomyces: low
Nocardia: moderate-high
Actinomyces vs Nocardia: treatment
Actinomyces: penicillin
Nocardia: TMS
Actinomyces vs Nocardia: gram, branching, beading
Both are gram +, filamentous, w/beads….
What comprises a Splendore Hoeppli reaction
Antigen-antibody complexes, complement, major basic protein from eos
T or F: Actinomyces is a commensal
True
Species of Nocardia most common in dogs in the Western USA
Nocardia nova
If you have a pet with Nocardia, what should you look out for
Underlying immunosuppression
Cyclosporine, neoplasia
Not all cats are immunosuppressed
Predisposed sex for Nocardia in cats
Male (bite wounds)
Retroviral status, steroid therapy
What virulence factor do anaerobic bacteria NOT have, making them unable to break down ROS
Superoxide dismutase
Catalase
What is different about GSD to cause GSD pyoderma
Increased CD8+
Decreased CD4+, CD21+ lymphocytes
Exaggerated response to Staph; inappropriate release of Cytokines
Treatment of Post Grooming Furunculosis
Fluoroquinolones
Usually due to Pseudomonas sp
T or F: Mycobacteria are + acid fast staining
True
High mycolic acid lipid content in cell wall holds the acid!
Mycobacteria virulence factors to cause host granulomatous response (aka Tubercles)
Cord factor
waxD
Gold standard for diagnosis of Slow Growing Mycobacteria
Culture
Species most susceptible to Mycobacteria avium complex
Poultry, swine»_space; dogs, cats
Transmitted from feces of birds, consumption of infected birds
Causative agents of “Feline Leprosy”
Mycobacterium lepraemurium (related to M avium)
Clinical lesions of Mycobacterium lepraemurium in cats
SC and cutaneous nodules
Limbs/scrotum of young, male cats!!
painless, firm
Most reliable way to diagnose Mycobacterium lepraemurium
PCR
Fastidious to grow on culture
Treatment for Mycobacterium lepraemurium
Surgical excision +
clofazimine, clarithromycin, rifampin
Cause of canine leproid granuloma
Novel mycobacterial organism
Likely related to M simiae
Breeds predisposed to Canine Leproid Granuloma
Short coated breeds (Boxers >50% of cases)
Transmission of Canine Leproid Granuloma
Fly bites
Pinnae, head > paws
Cytology of Canine Leproid Granuloma
Negative staining bacilli in histiocytes
Treatment of Canine Leproid Granuloma
Spontaneous resolution in 1-2 months common
If persistent: Surgery
Rifampin, Clarithromycin, Doxycycline, Clofamizine x4-8w
Most common clinical sign for Rapidly Growing Mycobacteria
Panniculitis
Most common species causing Mycobacterial panniculitis in the USA
Mycobacteria fortuitum
Body site most commonly affected by Mycobacteria fortuitum
Inguinal fat pad
Triglycerides help organism survive
Clinical lesions Mycobacteria fortuitum
Cats: circumscribed plaques/nodules –> draining tracts w/lymphatic fluid
(2’ bite/penetrating wounds!)
Dogs: nonhealing wound
Labwork finding from chronic granulomatous disease
Hypercalcemia
What is different about Rapidly Growing Mycobacterium (like M fortuitum) than Slow Growing forms (leprosy)
Rapidly Growing is gram positive (slow is non-gram staining)
Rapidly Growing is not as acid-fast as slow growing
Gold standard culture for Rapidly Growing Mycobacteria
Broth microdilution
From within macrophages, what cell does Mycobacteria activate
NK cells (directly or via IL-12)
NK cells then produce IFN gamma to activate more macrophages
Which media should be used to grow Mycobacteria
Egg enrichment media (Lowenstein-Jensen)
Agar-based media (Middlebrook)
T or F: Mycobacterium lepraemurium (feline leprosy) is zoonotic
False
Medium for Mycobacterium lepraemurium culture
Ogawas egg yolk medium
Clinical sign of Rickettsia Rickettsii (RMSF)
Fever, epistaxis, infarct, sloughing/necrosis of scrotum
Fibrinous and necrotizing vasculitis
Vector for Baronella hensalae (cat scratch fever); if not spread by a cat bite/scratch
Fleas! C felis
Lesions:
*Dog ear tip vasculitis
*Panniculitis and nodular skin diseases
Causes of Burkholderia cepacia complex
NOT commensal; infection in immunocompromised animals
From CsA/Keto, Westies
Draining tracts/ulcers
Tx: TMS, Marbo
Cause of melioidosis
Burkholderia pseudomallei
Reportable
Possible zoonosis
Nodular disease in dogs/cats
L-form bacteria
Partially cell wall deficient
Penetrating wounds
Strain of MRSA important in horses
USA500