Lecture 64 - Bacteriology 2 Flashcards
enterobacterales general characteristics
- gram - rods
- facultative anaerobes
- opportunistic or primary
- GI, soil, water
T/F: enterobacterales can survive and reproduce in both aerobic and anaerobic environments
TRUE
what bacteria can ferment lactose
- E. coli
- Klebsiella
- enterobacter
habitat of escherichia
- lower GI tract, soil, water
- non-pathogenic, commensal
- host-dependent
E. coli O-antigen
LPS, heat stable
E. coli H-antigen
Flagella, protein, heat labile
E. coli K-antigen
capsule, carbohydrate or protein made
E.coli F-antigen
pilus or fimbrial
what is E. coli pathogenesis
- attachment to host cells
- invasiveness/biofilm
- toxin production
- endotoxin
- siderophores
what is the most common cause of canine pyometra
e. coli
how is E. coli caused UTI diagnosed
- aerobic culture
- susceptibility/PCR
- urinalysis
if UTI is recurrent, what follow-up diagnostics should be done
- clinical hx, rx
- abdominal ultrasound/rads
- bloodwork
- contrast radiography
E. coli UTI prevention strategies
- increase water intake
- frequent urination
- cranberry and d-mannose supplements
- probiotics
- regular monitoring
Klebsiella characteristics
- gram-negative rods
- facultative anaerobe
- lactose fermenter
- abundant capsular material (mucoid)
- opportunistic
- sawdust
what virulence factors does Klebsiella have
- capsule
- endotoxin
- adhesins
- siderophores
- urease production
how does endotoxin act as a virulence factor
released when cell wall is damaged to interact with macrophages and create inflammation, DIC, hypotension
explain siderophores as a virulence mechanism
bacteria will siphon iron from the host to use for growth
what does Klebsiella cause clinically
- equine metritis
- bovine coliform matitis
- navel ill/joint ill
- neonatal septicemia
- wound infections
T/F: Klebsiella is an important cause of resistant health-care associated infections
TRUE
proteus characteristics
- gram-negative rod
- facultative anaerobe
- non-lactose fermenter
- motile (swarming)
- soil, water, GI tract
what virulence factors do proteus have
- urease
- endotoxin
- fimbriae
- hemolysin
- siderophores
urease activity can cause
struvite stones and high urine pH
cystitis or pyelonephritis is commonly caused by
proteus infections
what type of resistance is common to proteus
plasmid-associated antibiotic resistance to tetracycline
streptococcus spp. characteristics
- gram-positive
- cocci
- facultative anaerobes
- non-motile
- commensal of mucous membranes
enterococcus characteristics
- previously classified as streptococcus (group D) but tolerates bile salts and some are motile
- opportunistic at sites with fecal contamination
how is enterococcus observed on bacterial culture
small, grey colonies
T/F: intrinsic AMR due to horizontal gene transfer is common among Enterococcus spp.
TRUE
staphylococcus spp. characteristics
- gram-positive
- clusters
- facultative anaerobes
- non-motile
- EXTRACELLULAR
- commensal on skin
what are the predisposing factors for pyogenic bacteria
- catheterization
- immunosuppression
describe staphylococcus clinically
- cystitis, pyoderma, otitis
- transient colonizer of normal skin
what species does S. aureus affect
cattle and poultry primarily
what species does S. pseudintermedius affect
dogs and cats
what species does S. hyicus affect
pigs
what gene should be tested for if staphylococcus is suspected
mecA gene for resistance
T/F: veterinary professionals are more frequently colonized with MRSA than the general population
TRUE
Brucella characteristics
- gram-negative
- small cocci
- INTRACELLULAR
- aerobic
- 2 chromosomes
how is brucella transmitted
- venereal
- penetration through skin abrasion
- ingestion of contaminated fluids
- inhalation
- transplacentally
if a brucella colony appears smooth on culture what can be inferred
pathogenic strain with LPS virulence
T/F: smooth brucella colonies do not survive in host cells
FALSE
describe brucella pathogenesis
- bacteria engulfed by phagocytes
- persistence in macrophages because LPS binds lipid rafts
- outer membrane prevents phagolysosome fusion
- replication within phagosome
- transport to regional lymph nodes
- localizes in reproductive organs, joints, and IV discs
what is a growth factor found in the placenta
erythritol
what brucella spp. can infect more than their preferred host and cause severe disease
- B. abortus
- B. melitensis
- B. suis
match the primary host of the brucella spp.
a. B. abortus
b. B. melitensis
c. B. suis
d. B. canis
e. B. ovis
- sheep
- pigs
- small ruminants
- dogs
- cattle
a = 5
b = 3
c = 2
d = 4
e = 1
bovine brucellosis
- reduced fertility and milk production
- “abortion storms” in mid to late gestation
- cows remain infected in LN and mammary gland
- infection through ingestion
ovine and caprine brucellosis
- high abortion rate
- orchitis
- arthritis
porcine brucellosis
- rare in USA
- prolonged bacteremia
- chronic inflammatory lesions in repro tract, bones, and joints
- abortion, stillbirth, temporary sterility
- lameness
Canine brucellosis
- permanently in the rough form (low virulence and asymp infections)
- abortion, decreased fertility, reduced litter size
brucellosis in humans
- contact through excretions or secretions of infected animals
- “Undulant fever” = fluctuating pyrexia
- fatigue, muscle/joint pain, osteomyelitis, hypersensitivity
clinical signs of brucella
- abortions
- swelling and edema in scrotum
diagnostic tests for identifying brucella organism
- modified Ziehl-Neelsen stain
- culture
- PCR
diagnostic tests for identifying brucella antibody
- ELISA
- agar gel immunodiffusion
- serum agglutination
- complement fixation
what are 2 specific tests for brucella
- rose-bengal plate test
- brucella milk ring test
rose bengal plate test
screening test
antigen suspension added to allow for agglutination of antibodies
brucella milk ring test
conducted in bulk milk
brucella tx
long term antimicrobial therapy in dogs (tetra+fluoroquinolone for 4-6weeks)
detection and cull in food animals
what are the 2 vaccine used in cattle
- S19 - female calves up to 5m/o
- RB51 - stable, rough mutant
T/F: B. melitensis and B. suis have vaccines available
TRUE
how is brucella prevented
- closed herds/groups
- isolate and retest after 30 days
- sanitation
- spay/neuter
campylobacter characteristics
- gram-negative rod
- curved
- motile
- microaerophilic
- commensal GI and genital tracts
what virulence factors does campylobacter have
- flagella
- adhesion and invasion
- toxin (CDT)
- endotoxin
what limits campylobacter pathogenesis
complex nutritional requirements limit capacity for environmental growth
what is the unique structural component of C. fetus
microcapsule (or “S” layer) allowing protection against bacteriophages, phagocytosis, lytic enzymes, and pH
describe C. fetus subsp. venerealis
- tropism for bovine host
- survives in prepuce or infected semen
- cows are asymptomatic
describe ovine genital campylobacteriosis
- C. fetus subsp. fetus or C. jejuni
- GI tract
- fecal-oral transmission
- bacteremia, necrotic placentitis
how is bovine campylobacteriosis diagnosed
- hx
- fluorescent antibody
- culture
- PCR (abomasal fluid)
- ELISA
how is ovine campylobacteriosis diagnosed
- hepatic lesion
- culture
bovine are treated with ____ and ovine are treated with ____ for campylobacteriosis
dihydrostreptomycin; chlortetracycline
chlamydia characteristics
- gram-negative cocci/rod
- cell wall with outer LPS but lacking peptidoglycan
- aerobic, obligate INTRACELLULAR
- cannot synthesize ATP
describe chlamydia’s biphasic life cycle
Elementary (EB) is infectious but metabolically inactive whereas reticulate body is when the EB transforms into a larger metabolically active form
summarize chlamydia pathogenesis
- EB bind to host cell using adhesions
- Ebs inject effector proteins into host cells using T3SS (uptake and prevent apoptosis)
- EBs transition to RBs and new effector proteins are synthesized
- RBs begin to divide causing the inclusion to expand
- RBs transition back to EBs
- new EBs released by lysis or extrusion
C. abortus clinically
enzootic abortion of ewes (EAE) characterized by late-term abortion, stillbirth, and weak lambs
T/F: C. abortus is zoonotic
TRUE
