MRSP Consensus Statement Flashcards by Elana Vlodaver

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

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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

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Veterinarians should not use glycopeptides, linezolid, and anti-MRSA cephalosporins for animals

True. WAVD consensus statement recommends “restriction-of-use” policy

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Prognosis for MRS

Good, pending comorbidities and underlying cause

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T or F: routine decolonization of MRS should be pursued in animals

F. Not enough evidence

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Research tool to investigate epidemiology of MRS outbreaks

Molecular strain typing

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Best method to prevent personal MRS infection

Hand hygiene

Also consider labcoat/gown, disposable gloves

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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

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Should we test healthy humans and animals for MRS carriage?

Nope. Legal issues. Very few justifiable actions from the results, anyway

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What is the risk of MR CoNS

Can transfer resistance mechanisms to organisms with higher pathogenic potential

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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

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Gene that encodes for PCP2a with low affinity for all beta lactams

mecA

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Definition MDR

MRS that is resistant to 2+ other antimicrobial classes

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Definition XDR

MRS only susceptible to 2 or fewer antimicrobial classes

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How much does Staphylococcus like oxygen (aerobic vs anaerobic)

Facultative anaerobic cocci

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T or F: Staphylococcus is a normal inhabitant on birds

True

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Most common site for Staphylococcus carriage in dogs and cats

Mouth, then perineum

Sample these spot to assess longitudinal colonization

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Where in the cat’s body are they most likely to harbor Staphylococcus from their humans?

Nasal

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Definition of Staphylococcus colonization

Self-sustaining population for an extended time without disease

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How can a Staphylococcal infection get to the bone

1) Spread through epithelial tracts
2) Penetrating wounds
3) Hematogenous spread

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Adhesion virulence factor effect

Allows bacteria to bind to cells and extracellular matrix

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Biofilm virulence factor effect

Protects bacteria from immune response

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List of toxin virulence factors in Staphylococcus

*Cytolytic
*Exfoliative
*Enterotoxigenic
*Superantigenic

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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

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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?

If MRSP is S to tetracycline, can you assume it is S to doxycycline

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

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