MRSP Consensus Statement Flashcards
T or F: Staphylococcus schleiferi is the only CoNS that can cause true infection
False. CoNS should be assessed on a case-by-case basis
T or F: empiric drug selection for systemic tx is always contraindicated when an MRS infection is suspected
TRUE.
High prevalence of MDR in these strains
Veterinarians should not use glycopeptides, linezolid, and anti-MRSA cephalosporins for animals
True. WAVD consensus statement recommends “restriction-of-use” policy
Prognosis for MRS
Good, pending comorbidities and underlying cause
T or F: routine decolonization of MRS should be pursued in animals
F. Not enough evidence
Research tool to investigate epidemiology of MRS outbreaks
Molecular strain typing
Best method to prevent personal MRS infection
Hand hygiene
Also consider labcoat/gown, disposable gloves
Recommendations to owners when a pet has MRS
*Social distancing from “at risk” individuals
*Enhanced cleaning for occupants and the environment
Do this until clinical response to treatment is evident
MRS CAN be spread to other individuals in the home
Should we test healthy humans and animals for MRS carriage?
Nope. Legal issues. Very few justifiable actions from the results, anyway
What is the risk of MR CoNS
Can transfer resistance mechanisms to organisms with higher pathogenic potential
Penicillinase activity
Enzyme that deactivates natural penicillins (Penicillin G and V) and aminopenicillins (ampicillin, amoxicilin)
–> breaks the core structure of beta lactams
Methicillin is a penicillinase-resistant penicillin
Gene that encodes for PCP2a with low affinity for all beta lactams
mecA
Definition MDR
MRS that is resistant to 2+ other antimicrobial classes
Definition XDR
MRS only susceptible to 2 or fewer antimicrobial classes
How much does Staphylococcus like oxygen (aerobic vs anaerobic)
Facultative anaerobic cocci
T or F: Staphylococcus is a normal inhabitant on birds
True
Most common site for Staphylococcus carriage in dogs and cats
Mouth, then perineum
Sample these spot to assess longitudinal colonization
Where in the cat’s body are they most likely to harbor Staphylococcus from their humans?
Nasal
Definition of Staphylococcus colonization
Self-sustaining population for an extended time without disease
How can a Staphylococcal infection get to the bone
1) Spread through epithelial tracts
2) Penetrating wounds
3) Hematogenous spread
Adhesion virulence factor effect
Allows bacteria to bind to cells and extracellular matrix
Biofilm virulence factor effect
Protects bacteria from immune response
List of toxin virulence factors in Staphylococcus
*Cytolytic
*Exfoliative
*Enterotoxigenic
*Superantigenic
2 virulence factors to help Staphylococcus evade the host immune response
*Coagulase (coa gene)– promotes fibrin clot scaffold for tissue invasion –> abscessation, protection of bacterial clusters from neutrophils
*von Willebrand factor-binding protein– known as an indicator of pathogenic potential
T or F: expression of antimicrobial resistance genes is a virulence factor
FALSE.
Not necessarily more invasive or proinflammatory
May need to trade a virulence factor in order to have a resistance mechanism (fitness cost)
What are the 2 most common Staphylococcal species on cats
*Staphylococcus pseudintermedius
*Staphylococcus aureus
Major risk factor for MRSA for dogs and cats
Living with a human with MRSA
T or F: Staphylococcus schleiferi is commonly culture from healthy skin of dogs and cats
False.
But it is common on skin/ear canals of dogs with previous antibiotic exposure
What are the 3 most common pathogens in SA Dermatology
*Staphylococcus pseudintermedius
*Staphylococcus schleiferi
*Staphylococcus aureus
What are the 2 variants of S. schleiferi (one is coagulase +, one is coagulase -)
Coagulase +: S. schleiferi coagulans
Coagulase -: S. schleiferi schleiferi
No difference in pathogenic effects.
What are the 2 major clonal lineages of MRSP?
ST 71 (Europe, Japan)
ST 68 (USA)
Same mecA gene as MRSA. Probably came from the same CoNS.
Is coagulase negative or coagulase positive Staphylococcus schleiferi more often associated with infections in humans
Both are RARE. But Coag negative is more common than positive! Weird!
Is coagulase negative or coagulase positive Staphylococcus schleiferi more often associated with infections in humans
Both commonly cause pyoderma and OE in dogs!
How can you speciate/ subspeciate Staphylococcus species effectively
PCR
or
MALDI-TOF mass spectrometry
Is S. schleiferi more or less likely to be MR
HIGH prevalence of MR. >50% of isolates are MR according to 2 USA studies
Gold standard method to find mecA gene
PCR amplification
or
Commercial Agglutination tests for PBP2a
Can you use a cefoxitin disc instead of oxacillin for MRSP
No. Can use this for MRSA, but less accurate in MRSP
If a S. pseudintermedius is R to oxacillin, which other antibiotics should be R (despite in vitro readings)
*Penicillins
*Cephalosporins (except IV 3rd/4th gen)
*Carbapenems
*Cephems
Why may cefpodoxime appear S on an MRSP in vitro?
Poor expression of mecA for B-lactams other than oxacillin (which is why we use oxacillin as our tester!)
Topicals best for canine pyoderma:
2-3% chlorhexidine
Benzoyl peroxide is ok, but not as good
Work within 3 weeks for majority of MSS pyoderma
T or F: Chlorhexidine bath 2x/week + daily chlorhexidine spray is as good as oral Clavamox x4 weeks
True!
T or F: there is genuine resistance to topical fusidic acid
True
But only approved in UK, Asia, Aus
T or F: even if C&S says Staph may be resistant to mupirocin, it still may work
True. Can get a much higher topical concentration
Only approved in the US
If MRSP is S to doxycycline, can you assume it is S to minocycline?
Y
If MRSP is S to tetracycline, can you assume it is S to doxycycline
Y
Are amoxicillin, FQs, Cefovicin and cefpodoxime considered critically important antimicrobials or highly important for human medicine
Critically important
Are cephalexin, clindamycin, fusidic acid, tetracyclines, and sulfonamides considered critically important antimicrobials or highly important for human medicine
Highly important
SIET
Exfoliative toxin made by Staphylococcus pseudintermedius
bullous impetigo exfoliative pyodermas
Exfoliative toxin made by Staphylococcus pseudintermedius. Involved in bullous impetigo exfoliative pyodermas pathogenesis
SIET
SHETA and SHETB
ExhA, ExhB, ExhC, ExhD
Exfoliative toxins made by Staphylococcus hyicus that causes exudative epidermitis in pigs
Exfoliative toxins made by Staphylococcus hyicus that causes exudative epidermitis in pigs
SHETA, SHETB
ExhA, ExhB, ExhC, ExhD
luk l (toxin gene)
Pore forming toxin made by S pseudintermedius
T or F: S pseudintermedius can easily be transmitted to other dogs
True
T or F: S pseudintermedius significantly adheres better to canine corneocytes than human
True
T or F: S aureus significantly adheres better to canine corneocytes than human
False.
Adheres better the human squames
In which circumstances can carrier swabbing and management of healthy carrier animals be beneficial
Places with low rates of MRSP
It’s a lost cause in the USA.
T or F: MRSP carriage is common for up to 11 months after clinical cure of infection
True
What causes “natural decolonization” of MRSP
Natural decolonization = loss of MRS carriage without treatment
It occurs 2’ competition within the bacterial microflora
T or F: Resistance genes has a fitness cost, so MRS is more likely to decolonize then MSS microbes
True
(proven in MRSA in humans)
T or F: A dog can recolonize with MRSP due to environmental contamination
True
Why MAY it be beneficial to continue chlorhexidine baths after MRSP infection is cleared
You can decolonize with topical antimicrobials– at least for short periods
(shown with BID fusidic acid)
Do we recommend natural decolonization (isolation and cleaning) for MRSP, or antimicrobial decolonization in dogs?
Currently not enough evidence for routine decolonization at all
But natural decolonization would be better than antimicrobial tx
How do we establish a “strain concordance” in an outbreak situation?
“Typing”
-Next Generation Sequencing (NGS)
-Whole genome sequencing
Other options:
*Pulsed field gel electrophoresis
*Spa typing
*Dru typing
*Multi-locus sequence typing
*SCCmec typing
T or F: S schleiferi can be a human pathogen
True
What is the next step you should take after removing your gloves
Wash your hands!
Gloves alone aren’t enough
T or F: Staphylococcus is resistant to quaternary ammonium disinfectants and accelerated hydrogen peroxide
False. Staph is readily inactivated by routine disinfectants
Why do you have to clean before you disinfect?
Organic debris (dirt, hair, pus) and biofilm can inhibit disinfection efficacy
MRS genes that offer resistance to disinfectants
1) norA (drug efflux pump. FQs, quaternary ammonium, antiseptics)
2) qacA/B (efflux pump. Chlorhexidine)
What gene encodes for chlorhexidine resistance in Staphy
qaxA/B
What gene encodes for an efflux pump that removes fluoroquinolones and antiseptics?
norA
T or F: Dogs can shed MRSP for weeks after resolution of a clinical infection— making them a potential complication for control measures
True
Which MRSP dogs are the highest risk of spreading to the community
Those with active infections–though no actual studies on this
(avoid dog parks, kennels, etc. Unknown for how long post-infection)
They recommend restriction from contact until some clinical response to abx treatment
How should bedding with MRSP squames be cleaned
Normal, low temperature laundering w/ normal detergent is effective at killing MRSP
In which case may it make sense to screen healthy dogs for MRSP carriers?
If they are going to undergo surgery
*higher risk with TPLO in dogs with MRSP carriage
T or F: Veterinary personnel are at higher risk of MRSA and MRSP carriage
True
