Microbiology - Phase C - 1st Half
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Microbiology - Phase C - 1st Half
Microbiology Phase 1st Half
Microbiology - Phase C - 1st Half
Microbiology - Phase C - 1st Half
What are the top 3 causes of genital ulcers?
1) HSV (herpes)
2) Primary Syphillis
3) Chancroid (hemophilus Ducreyi)
Does HPV cause ulcers?
What is a classic description of genital herpes?
painful, grouped vesicles on an erythematous base with or without prodromal sx
Can syphilis present with a painful lesion?
Yes, if there is a secondary infection.
Describe the details of the smears for: HSV, Syphilis, Chancroid
: Tzank smear (Tzank god it isnt herpes)
: silver stain
: "Shoal of fish"
What are 5 differentiating features for differentiating genital lesions
The 5 P's
2) Placement/arrangement (solitary, multiple, kissing lesions)
: hard or soft
With regards to prodrome, placement (arrangement), Pain, Purulence, and Palpation describe genital herpes, syphilis, and chancroid
What should you do if someone you suspect has primary syphilis tests negative for serology
Repeat the test in 2-4 weeks, they may not have seroconverted yet.
Briefly describe the 4 stages of syphilis
: genital ulcer and nodes
: systemic disease - multisystem manifestation
: end-stage disease with permanent damage to brain, heart, soft tissues/bone
What is the key pathological change that happens in tissues affected by syphilis?
How can you differentiate syphilis from psoriasis?
palms and soles are affected in syphilis
What is the classic triad of secondary syphilis?
-generalized non-tender lymphadenopathy
Describe treponomal and non-trepomonal tests for syphilis. How would you expect each stage of syphilis to test?
: once positive, are always positive (trepomonal Abs)
Non-trepomonal (RPR, VDRL)
: only positive when viable bacteria are present (responds to trepomonal lipid production)
What is the treatment for syphilis? What do you do if they are allergic to it?
Penicillin, ALWAYS penicillin. If they are allergic to it you need to sensitize them to it and THEN give it to them!
2 common causes of urethritis and cervicitis, which one is MOST common?
N. gonorrhea (ALWAYS a pathogen),
Chlamydia trochamonas (most common)
dysuria and thick yellow discharge in gonorrhea and thinner discharge in chlamydia
Describe the Sx of cervicitis
-can have spotting and post-coital bleeds
-change in discharge
Describe how you would swab (5) for gonorrhea, test for disseminated disease (3)
: urethral for males, endocervical for females, rectal swabs for MSM and women, pharynx if oral sex.
: blood culture, joint aspirate, skin lesion
How do you treat gonorrhea and chlamydia. Which drug is for which bug?
250 mg ceftriaxone (gonorrhea)
1 g azithromycin (Chlamydia, 2nd line gonorrhea)
What is one indication for doing C and S for gonorrhea?
MSM with symptomatic infection
With regards to NG and CT, why are are more females tested? Why are more of the men tested testing positive?
1. Women come in for care more often and get more screening
2. men only come in when symptomatic
Which of the following are "predominantly STI" and which are "not usually STI"
-PID, HPV, Molluscum contag., trich, BV, candida,
STI: PID, HPV, MC, Trich
not so: BV, candida
Definition of PID. Gold standard of Dx
polymicrobial infection affecting one of the following:
2) fallopian tubes
laparotomy with purulent draining of tubes
6 indications for hospital admission for PID?
2) Cannot exclude surgical criteria
3) Severe illness (N&v, fever)
4) tubo-ovarian abscess
5) poor compliance
6) no response to outpatient therapy
Inpatient PID tmt (main one)
Inpatient Cefoxitin IV and doxy po
Levofloxacin and metronidazole
What are the "big three" of vaginitis/vaginosis? What do you see on wet prep for each? Treatment
-BV (clue cells, metronidazole)
-Candidiasis (hyphae, fluconazole)
-Trichomaniasis (flagellated cells, metronidazole)
Diagnostic criteria for BV?
Need 3 out of 4
-homogenous, white, smooth discharge
-pH>4.5 (vagina usually acidic to prevent bacterial overgrowth)
Basic difference between Gardasil and Cervarix vaccines
Gardasil: for HPV 6, 11, 16, 18. only 68% seroconversion for 18 and 97% for rest after 24/12
Cervarix: for HPV 16,18 only. 100 % seroconversion after 51/12
Can you get herpes across intact healthy skin?
No. only mucosal surfaces
Where do the bugs come from in a bite wound?
mouth of biter
skin of bitee
infections of animals transmissible to man
What are the first steps in bite management?
1) control bleeding
2) Clean wound
3) Debride dead tissue
4) Check function
5) DO NOT SUTURE OR USE TISSUE GLUE (unless cosmetic)
Prevalence of infection in cat and dog bites
cats (80%) because the penetrate deeper
When would you use Abx prophylaxis for an animal bite (5 sub points)? How long?
Give for 3-5 days
Moderate wounds that are <8hours old.
-bites with significant edema or crushing
-bites involving hands or joints
-bites adjacent to prosthetic joints
-bites involving genitals
What abx should you use for bite tmt/prophylaxis? (3)
-clinda plus doxy if penicillin allergic
What are 3 complications that can arise from a tick bite besides lyme disease?
-Delayed type hypersens
: urticaria, fever, pruritus after tick removal
: pruritic papule due to retained mouth parts
: ascending paralysis caused by neurotoxins secreted by tick. Resolves with tick removal
How to avoid tick bites
_avoid long grass
->20% DEET spray
Three things you should NOT do with a tick bite and one thing you SHOULD do?
-routinely use abx after bite
-screen for lyme disease
-attempt to recover pathogens from tick
DO monitor for 30 days for rash and febrile illness.
What are the the pets you definitely need to remove from the home of an immunocompromised person? (2)
: reptiles, exotics (high risk of salmonella)
: cats infected with feline immunodeficiency virus (OI's from this can be passed to humans)
What is the bottom line on having pets in the home of an immunocompromised patient?
-pets provide real and important benefits
-risks exist - but can be managed
-detailed Hx is key to understanding the risks
-be prepared to discuss risks and benefits with patients
What should you do at the first visit with a refugee (4)
-assess for acute illness
-assess for chronic health concerns
-RF assessment for STI, HIV, genetic disease, and other disorders
Testing that should be done at first visit?
(9 over 3 categories)
: screen for anemia
: malaria, stool O&P, blood-borne pathogens, strongyloides, schistosoma
: G6PD, Sickle cell disease, thalassemia
Describe the effects that hookworm has on children
anemia, cognitive impairment
25% of this type of refugee suffers from G6PD deficiency
Bhuatanese (south central african countries
What should you do with a refugee with an unknown vaccination status (2)
-Start from scratch and give him everything OR
-get more Hx, selected serology, and make a targeted immunization plan
When you see a refugee with an eosinophilia what additional testing should you do (4)
When to look for parasites
General unexplained Sx (4)
Specific unexplained Sx (5)
-failure to thrive in children
-Urinary Sx, portal HTN, ascites
: sleeping sickness
-Hepatosplenomegaly, cytopenias, fever
3 critical tests for unexplained fever in a refugee
-blood smear/rapid diagnostic test for malaria
How long, on average, does a refugee await resettlement?
4 key things to think about when treating refugees
-Consider medical geography
-Don't assume Canadian Standard of care in past (immunizations, preventative care, etc)
-Remember that multiple Dx are COMMON
-Think outside the box. These are not routine patients.
Describe the mortality of the following conditions in travellers:
: 25-50%, = the non travelling population
: 25% of deaths, >> non travellers
: cause <4% of deaths
Describe the relationship between hypoxemia and high altitude flight
As you go to altitude there is less O2, as long as it stays above 60 mmHg there is no problem (Hg dissociation curve)
Describe the difference between the different malaria species:
P. vivax and ovale
P. falciparum: high risk, severe disease, widespread resistance
P. vivax: dormant liver phase, some resistance
Describe the contraindications to the 4 main malaria drugs.
Mefloquine: cardiac probs, seizure disorder, psychiatric disorder
Chloroquine: Seizure disorder, lots of resistance
Doxycycline: pregnancy and young children
Malarone: pregnancy and end stage renal disease.
3 important points for travelers to know regarding malaria
-all antimalarials have adverse effects
-No antimalarial is 100% effective (must use personal protective measures too)
-Fever during or within 3/12 of travel = EMERGENCY!
5 contraindications for yellow fever vaccine
What congenital diseases are you concerned about in a pregnant woman displaying:
-fever without any other manifestations
-painless genital ulcer
Fever without any other manifestation: Toxo, CMV, Parvo B19, HIV
: rubella, syphilis
Painless genital ulcer: syphilis
What would you do to asses for congenital CMV in the infant? (3) Mother (2)
-Urine PCR and viral culture within first 3 weeks of birth
How would you assess for toxo in mom? (2) Infant? (4)
-Serology Toxoplasma IgM
-CT (or U/S) head looking for intracranial calcification or hydrocephaly
-ophthal looking chorioretinitis
- Blood PCR
treat with pyrimethamine+sulfadiazine+folate for both. Regular developmental assessment
How to rule out rubella in the mom (3)? Infant (3)?
-serology for IgM and IgG
-nasopharygeal or urine PCR
-any fluid PCR
-cardiology, ophthal, and hearing consult
What do you do with a mom who tests positive for rubella?
discuss termination of pregnancy
You see an infant delivered with a blueberry muffin rash, lymphadenopathy, hepatosplenomegaly, and thrombocytopenia. What should you be thinking
How do you rule out VZV in mom (1)? in infant (3)?
-serology (high PPV if Hx of chickenpox, otherwise unreliable)
: VZV IgM
Differentiate congenital varicella from neonatal varicella
-typical symptoms of varicella (characteristic rash, etc)
What are the manifestations of congenital HSV?
-Skin (skin lesions, scars)
-CNS (microcephaly, hydranecephaly)
-eye (microphthalmia, chorioretinitis)
What can cause microcephaly, hearing loss, and hepatomegaly in a 4 month old (congenital illnesses)(4)
toxo, syphilis, CMV, HIV
Specific Sx of congenital CMV (3)
Specific Sx of congenital rubella (3)
-congenital heart disease
-radioluscent bone disease
Specific Sx of congenital syphillis (4)
-skeletal abnormalities (e.g. osteochondritis)
-maculopapular rash on palms and soles
Specific Sx of congenital toxo (4)
-DIFFUSE intracranial calcifications
-unexplained CSF pleocytosis
Specific Sx of congenital varicella (2)
-vesicular skin lesions