Infectious Diseases Basics P2 Flashcards
What are the three classifications of ARF?
Definitie
- fulfills jones criteria
Probably
- Does not fulfil Jones diagnostic criteria, missing one
major or one minor criterion or lacking evidence
of preceding streptococcal infection, but ARF is
still considered the most likely diagnosis
Possible
- Does not fulfil Jones diagnostic criteria for ARF, missing one major or one minor criterion or lacking evidence
of preceding streptococcal infection, and ARF is
considered uncertain but cannot be ruled out
How long should ben pen be continued after AFR for the prevention of RHD?
Possible ARF
- continue for 1 year then ECHO
Probable or definite
- at least 5 years following last episode OR until age 21 (whichever is longer) then ECHO
-> if ECHO abnormal then could consider continuing further
Which antibiotics can cause seratonin syndrome?
Linezolin in combination with other seratinergic drugs
Which antibiotics can prolongue the QTc?
Quinolones
- moxifloxacin, ciprofloxacin, levofloxacin, norfloxacin
Macrolides
- azithromycin, clarythromycin, arrythromycin
Should not be combined with other agents that prolong QTc such as amiodarone
Which antibiotics can interacti which colchicine and how does this occur?
Macrolides such as clarythromycin are inhibitors of CYP450 3A4 and teh P-Glycoprotien dependent handling of colchicine in the liver, which can increase levels of cochicine leading to toxicity
Statin should be dose adjusted when combined with which antimicrobial class?
azoles
- these are potent inhibitors of CYP450 3A4 which can lead to high statin levels (statins are metabolised by Cyp 3a4)
Also macolides and fluroquinolones for the same reason
What is the the imaging finding on CT with pseudomembranous colitis?
THumbprinting
-represent thickening od the bowel wall due to oedema
Other features include toxic megacolon, obstruction, performation
How is C Dif infection diagnosed?
Detect C dif:
- GDH ELISA - tests that is very sensitive at detecting teh presence of C dif (ie if neg can be used to rule out C dif)
- does not differentiate between toxin and non toxin
Detect toxin:
- PCR for C dif toxin B
- Culture and toxin detection in lab (gold standard test)
Which antibiotics is most associated with C dif infection?
Clindamycin
Is handwashing effective against C dif?
Yes but need to use soap and water (alcohol not effective against spores)
What is the definition of community onset / acquired C dif infection?
Nil overnight hospital stay in last 12 weeks
What are some biochemical and clinical markers of severe C dif?
Clinical:
- Febrile >38.5
- Haemodynamic instability
- Illeus, obstruction, toxic megacolon
Lab:
- Albumin <25
- WCC >15
- elevated Lactate
- AKI (>50% rise in Cr)
Colonoscopy:
- severity of inflammation / pseudomembranous colitis
Note number of stools per day is technically not a marker of severity
How is non severe C dif infection treated? Including first and second recurrance?
Metronidazole 400mg PO TDS for 10 days
(americans suggest initial therapy with Vanc 125mg Po QID)
First recurrance / refractory disease (ie not responding to metro
- Vancomycin 125mg PO QID for 10 days
- Fidaxomicin 200mg BD 10d (if prieviously treated with vanc)
Second recurrence or more:
- FMT (recomended therapy for second or more recurrance)
- Vanc 14 days + taper
- Fidaxomycin
How is severe C dif infection treated?
Vancomycin 125mg PO/NG QID 10 days + metronidazole 500mf 12hr if complicated
- Can use colonic vancomycin if complicated by ileus
Is antibiotics or FMT more effective at curing C dif infection?
FMT
- response is more durable too
Is there a difference in efficacy between the dif modes of FMT administration?
No, all equal currently
What are some severe AE of FMT?
Transmission of infectious agents (ie transmission of infectious agents ie E coli, ESBL, norovirus)
When can neurosyphilus develop following an acute infection?
A singificant number of pts will develop neurosyphilus early
- need to be aware and treat is evident
This is different to the traditional way of thinking (ie tirtiary syphilus down the line)
Describe the natural history of syphillus infection?
Primary infection
can develop into secondary infection however primary infection can also develop into early latent infection (ie no secondary infection)
Early latent infection is asymptomatic latent infection <1 yrs following acute infeciton
Early latent infection can develop into secondary infection, however it can also go on to become late latent infection (asymptomatic, >1yrs following acute infection)
Most of these late latent infection will remain latent for life. Minority will develop tirtiary syphiluis.
Note a significant portion (40%) of people will develop early neurosyphilus following acute infection. Can also develop occular and otic syphillus at this time.
What are some symptoms / clinical findings in primary syphilus?
Chancre + regional lyphadenopathy (inguinal)
- Be wary if someone presents with isolated lymphadenopathy in the right demographic
What are some symptoms / clinical findings in secondary syphilus?
Presents 2-10 weeks following initial infection usually
Rash, fever, generalized lymphdenopathy
Mucosal leisions
Allopecia
Can present as nephritis, hepatitis
What syphilus test is non treponeal? What does this mean for furture testing?
RPR is the only non-treponeal test
- means it will not always remain positive (like the treponeal tests will once exposed to syphillus)
What are the two syphillus tests? what do they test for?
RPR (rpaid plasma reagin)
- Non specific cardiolipin antibody tests
- very sensitive (so if negative then dont have acute infection, but may have latent or past infection)
Treponeal specific tests (TPPA/TPHA/ FTA-Abs)
- FTA-abs and TPHA measure specific antibodies to Treponema pallidum antigens (will always be present post exposure)
What is considered a high RPR titre?
> 1:32
(ie 1:64 would be positive, 1: 200 would be very positive)
Negative RPR, postive TPHA. Possible interpretation?
Prievious infection, treated
Latent infection
Tertiary infection
- need to obtain CSF if concerned for tertiary neurosyphillus
High titre (>1:32) RPR, postive TPHA. Possible interpretation?
What if the titre was coming down but then rebounded?
Acute infection = infectious pt
Consider re-infection if rebound RPR titire
Low titre (< 1:32) RPR, postive TPHA. Possible interpretation?
Treated / resolving infection
Any stage
Low titre (< 1:32) RPR, negatiuve TPHA. Possible interpretation?
Very early infection (ie prior to seroconversion)
- repeat in 5 days time
False negative
Treatment of early syphylis (acute, secondary, early latent)?
Single dose of benazthine penecillin 2.4g IM
Treatment of late latent syphylis?
Benzathine penecillin 2.4g IM weekly for 3 weeks
Treatment of tertiary syphillus?
If nil evidence of CNS, otic or optic inv
-Benzathine penecillin 2.4g IM weekly for 3 weeks
If evidence of involvment
- IV ben pen q4h
Treatment for Uncomplicated genital or anorectal gonnococal infection?
Treatment for Uncomplicated pharyngeal gonnococal infection?
Ceftriaxine 500mg IM stat
Azithromycin 1g PO stat
Ceftriaxine 500mg IM stat
Azithromycin 2g PO stat
Why is azithromycin added to treatment regimes for gonnoicocal infections?
2 reasons:
- assume chlamydia is co-infection
- gonnococal resistance to ceft monotherapy is prevenlent
TImeframe of acute pelvic inflammatory disease?
<30 days
Treatment of acute pelvic inflammatory disease?
Ceftriaxone 500mg IM stat
+ metronidazole 400mg 12hrly 14 days
+ Doxy 100mg q12h 14d OR azithromycin 1g PO stat then reapeated 1 week later (for preg, or likely to be non compliant
Treatment of severe acute pelvic inflammatory disease?
IV ceft + azithro + metro
Presentation (Hx and Ex) of PID?
- Lower abdo pain / pelvic pain
- Pelvic organ tenderness (ie cervical hyperexcitability or pain during sex)
- evidence of inflamation of genital tract
Onset of pain shortly after or during menstruation is suggestive
cute cervical motion, uterine, and adnexal tenderness on bimanual pelvic examination are the defining characteristic of acute symptomatic PID [7,8]. Purulent endocervical discharge and/or vaginal discharge is also common.
What needs to be excluded before considering Dx PID?
acute abdomen (ie apendicitis)
Ectopic pregnancy
Investigations for PID?
Speculum for endocervical swab
- NAAT for CHlamydia trachamonis, Neisseria gonorrhoea, Mycoplasma genitalium
- Gram stain and culture for Gonnorhoea for susceptibility testing
BC if hospitalized or severe
How is PID due to M genitalium treated?
moxiflox 400mg OD 14d
How is PID, chlamydia and gonnorhoea followed up?
Test of Cure 3 weeks
How is chlamydia treated?
doxycyclin 100mg q12h 7d
OR
azithromycin 1g oral as single dose (if preg)
Common organism causing urethritis in men?
N. Gonorrhoeae
Mycoplasma genitalium
Neisseria Meningitis (no capsule)
Should recommenced MSM (esp MSM with HIV) to get meningococcal vax
Common organism causing proctitis (STI)? How does this inform teh work up investigations?
Chlamydia trachomatis L1,2,3 (causes Lymphogranuloma venereum)
N gonorrhoeae
HSV
Monkeypox
Need to rest for all of these, including monkey pox
Need to test for L1,2,3 if Ct positive