Infectious Disease Flashcards
Which methodology is considered to be most sensitive for detecting cytoisospora in cats?
PCR, the other method is faecal flotation.
What percentage of dogs with Trypanosoma cruzi infection will have ECG abnormalities?
95% - with ventricular arrhythmia (65%) and AVB being most common
What echocardiographic abnormalities are common in dogs with Trypanosoma Cruz?
RV or LA enlargement
What factors are associated with increased risk of cardiac death in dogs with Trypanosoma Cruz infection?
RV enlargement
Higher bodyweight
+/- modified Lown score > or = 2
https://paperpile.com/app/p/6824a4e1-2932-0775-bec9-889a9064bcff
Which of the following is true regarding measureement of serum and urine antigen concentrations in the treatment of feline histoplasmosis?
a) Both tests were sensitive but not specific for detection of disease remission
b) Both tests were specific but not sensitive for detection of remission
a
Also note that urine was positive for antigen in more cases at diagnosis than serum was.
https://paperpile.com/app/p/65b2a280-ad0c-0a26-bf7f-a4a8815d53bc
Prevalence of subclinical bacteria in older cats?
10 - 13%, being female increased the risk
https://paperpile.com/app/p/9b6f555b-6171-02ac-ac8c-3ca80a4dc5a6
Based on testing by Nichols et. al 2017, what may be said of POC ELISA and PCR testing for diagnosis of FIV?
Generally there was good agreement between tests although there was 6% of results that were discordant.
Only one PCR result was a false negative and there was a low rate of false positives for both tests.
https://paperpile.com/app/p/21a6d59a-97d4-05ca-bf04-db0537de1cfe
What is the most common haematologic abnormality in dogs with leptospirosis?
a. Thrmobocytopenia
b. Hyperfibrinogenaemia
c. Hypercoaguable state
d. Hypocoaguable state
a
The most common was acutally anaemia, dogs with hypercoaguable states had better survival than those with hypocoaguable states. Interestingly, DIC was not a prognostic factor.
https://paperpile.com/app/p/facb2d28-4eaa-08d0-8709-207b4eeea666
What is the most likely bacteria when cocci are identified on skin cytology of a dog?
Staphylococcus pseudintermedius
Give examples of antibiotics that have concentration dependent killing and what are their doses based on?
Aminoglycosides - should have a Cmax:MIC >8 - 10x
Fluroquinolones- should have an AUC24:MIC >100-125x
What is the ‘post-antibiotic effect’?
The ability of antibiotics to kill bacteria beyond the time/concentration at which they are above MIC
How long should time be greater than MIC as a general rule for time dependent antibiotics?
40 - 50%
How should time vs. concentration dependent antibiotic dosing be adjusted in renal failure?
Conc = decrease dose
Time = increasing dosing interval
Why are enterococcal species inherently resistant to cephalosporins?
They lack PBPs
Meaning of ESBL
Ability to hydrolyse penicillins, 1st generation cephalosporins AS WELL AS extended spectrum cephalosporins.
ESBL has only been described in E. coli and Klebsiella with CTX-M beta-lactamases being the most important at conveying ESBL resistance
Which genetic modification allows evasion of beta-lactam antibiotics by staphylococci
MecA
Which retroviral drug (other than GS…) has shown to have efficacy in feline retroviral infections?
Zidovudine
Mechanism of action of acyclovir drugs
Both are guanosine analogues that are activated by viral thymidine kinase into monophosphate forms which is then subsequently phosphorylated by host machinery into monophosphate forms.
Which anti-viral drugs have been shown to have efficacy in feline herpesviral infections?
Famciclovir (penciclovir) = may be administered orally.
Acyclovir (Valacyclovir) = topical only
Lysine (amino acid) = effective orally for conjunctivitis but NO EFFECT OR MAY WORSEN URT FHV
Cidofovir = topical, nasolacrimal irritation/stenosis reported in humans and rabbits
Which anti-viral has been used in canine parvovirus infections?
Oseltamivir (Tamiflu)
Can’t find the paper that documents this from JVIM or JAVMA but a JVECCS article showed they had better WBC count and gained weight compared to controls. Although no survival benefit was demonstrated.
https://pubmed.ncbi.nlm.nih.gov/20230441/
What immunomodulatory dry has been used in grey collies with cyclic neutropenia? What is the disadvantage of this drug?
Filgrastim
Not great for long term use as antibodies will develop to it within 2 - 3 weeks
What are the potential indications for feline interferon omega?
FIP = no good in clinical trials
FCV = stomatitis improves with administration
FIV/FeLV = may improve clinical scores and some laboratory parameters
FPLV = no effect
CPV = may reduce disease severity and reduce mortality
MoA of penicillins
Binding to penicillin binding proteins inhibits transpeptidation of the peptidoglycan layer of the cell wall. Meanwhile, cell wall hydrolysis continues and cell wall breakdown will occur.
Penicillin binding types and effect when bound
PBP 1a & 1b inhibition leads to cell lysis
PBP2 leads to change in cell shape but not necessarily bacterial death
Which penicillins have poor bioavailability?
Penicillin G
Ampicillin
What is the mechanism by which bacteria become methicillin resistant?
PBPs switch to PBP2a, this conveys resistance to all beta-lactams
Which cephalosporin has activity against methicillin resistant staphylococci?
Ceftaroline - as it has affinity for PBP2a
Which antibiotics can cause a false positive on a glucose test strip?
Cephalosporins and fluroquinolones
Which antibiotics antagonise vitamin K reductase?
Cefoteta and ceftriaxone
Weird side effect of ceftiofur, cefonicid and cefazedone
Bone marrow suppression
True or false: bacteria with methicillin resistance are susceptible to carbapenems
False
If you have a Klebsiella pneumoniae resistant to crabapenems, what other antibiotic classes will you expect resistance to?
Beta lactase
Aminoglycosides
Fluroquinolones
What is the role of cilastatin in antimicrobial drug prescribing?
Imipenam can cause nephrotoxicity through its degradation by dehydopeptidase-1, which is inhibited by cilastatin
Mechanism of action of vancomycin
Vancomycin is a glycopeptide that binds to D-ananyl-D-alanine preventing addition of further cell wall sub units.
What are the clinical indications for vancomycin use?
Note that it is not absorbed orally.
MRSA/MRSP
Enterococcal infections (VRE can occur here)
Corynebacterium urealyticum
Clostridium difficile
What antimicrobial has been associated with ‘red-man syndrome’?
Vancomycin
Relasionship between fluoroquinolone targets of action and type of bacteria affected
Toipoimerase II (DNA gyrase) is the target of most earlier generation fluroquinolones and is the main target for gram NEGATIVE organisms.
Toipoimerase IV inhibition can occur with newer drugs (e.g. pradofloxacin) and is the main target for gram POSITIVE bacteria
Which fluroquinolones have greater activity against pseudomonas than the others?
Ciprofloxacin and pradofloxacin