Medicine- Infectious Diseases Flashcards
Sepsis definition
Severe organ dysfunction resulting from dysregulated host response to infection
Sofa score for sepsis- criteria
- Resp rate >22 2. Systolic BP <100mmHg 3. Altered mentation (GCS<15)
Pathophysiology of sepsis
Bacteremia - local immune response - pro-inflammatory cytokine release - spread of immune response beyond local environment - unregulated, exaggerated systemic immune response - vasodilation and hypotension - distributive shock and reduced O2 delivery to tissues - anaerobic metabolism and lactic acid production - metabolic acidosis - multiple organ failure
Erythema migrans + cranial nerve lesion, name the likely infection
Lyme Disease
Cat scratch disease organism
Bartonella henselae
Rocky Mountain Spotted Fever- organism and treatment
Rickettsia rickettsii Rx Doxycycline
Rocky Mountain Spotted Fever Investigations
Skin biopsy and serology (indirect fluorescent antibody test)
Rocky Mountain Spotted Fever vector
Ticks (Dermancentor)
Features of secondary syphilis (3)
- Maculo-papular non-pruritic rash including palms and soles
- Generalized lymphadenopathy, low grade fever, malaise, headache, aseptic meningitis, ocular/otic syphilis
- Condylomata lata: painless, wart-like lesion on palate, vulva, or scrotum (highly infectious)
Confirmatory investigations for syphilis
- TPI (T pallidum immobilization assay)
- FTA-ABS (fluorescent treponema antibody absorption)
- Darkfield microscopy with silver stain (Warthin-starry stain)
Diagnosis of Lyme disease
by enzyme linked immunosorbent assay for Borrelia burgdorferi
TB risk factors
- Immunocompromised/ (especially HIV, including extremes of age)
- Immunosuppressed (TNF inhibitors, glucocorticoids)
- Silicosis
- Chronic kidney disease requiring dialysis
- Diabetes
- Malignancy and chemotherapy
- Substance use (e.g. drug use, alcoholism, smoking)
- At risk pop- indigenous, E European
- Crowded accommodation IVDU Homeless
Classic triad on CXR of active TB
apical-posterior infiltrates
lung volume loss
cavitation
TB Rx
TB Treatment RIPE Rifampin, INH, Pyrazinamide, Ethambutol
Viral load in HIV is a measurement of what?
HIV RNA
What is the confirmatory test for HIV?
Western blot confirmation by detection of antibodies to at least two different HIV protein bands (p24, gp41, gp120/160); specificity >99.99%
Initial screening test for HIV
Enzyme linked immunosorbent assay (ELISA) detects serum antibody to HIV; sensitivity >99.5%
Pneumocystis jiroveci treatment first line
TMP/SMX Trimethoprim + sulfamethoxazole
Pneumocystis jiroveci classic X-Ray findings
Interstitial pneumonia
The leading cause of meningitis in patients with HIV
Crypotoccus sp
Rx of cryptococcus in HIV+ men
Amphotericin B (+ flucytosine) is used in the first 2 wk for induction therapy; limited duration dt SFX Switch to fluconazole for at least 8 wk as consolidation therapy, then continue at lower dose for prolonged maintenance
Rx invasive aspergillosis
Voriconazole or amphotericin B
Leprosy Rx
Dapsone & rifampicin
Clostridium tetani- type of organism
motile, spore forming, anaerobic Gram-positive bacillus
The action of tetanus toxin
Toxin travels via retrograde axonal transport to the CNS where it irreversibly binds presynaptic neurons to prevent release of inhibitory neurotransmitters (e.g. GABA) Results in disinhibition of spinal motor reflexes which results in tetany and autonomic hyperactivity
Diagnosis of tetanus
Clinical CK may be elevated
Management of tetanus
Stop toxin production
Wound debridement to clear necrotic tissue and spores
Antimicrobial therapy: IV metronidazole; IV penicillin G is an alternative
Neutralize unbound toxin with tetanus immune globulin (TIg)
Supportive therapy: intubation, spasmolytic medications (benzodiazepines), quiet environment, cooling blanket Control autonomic dysfunction: - and -blockade (e.g. labetalol), magnesium sulfate
Empiric therapy for bacterial meningitis >3months of age
age >3 mo: ceftriaxone + vancomycin
Most commonly affected valve in infective endocarditis
MV
Minor Duke criteria for infective endocarditis
- Predisposing condition (abnormal heart valve, IVDU)
- Fever (38.0°C/100.4°F)
- Vascular phenomena: major arterial emboli, septic pulmonary infarcts, mycotic aneurysms, ICH, conjunctival hemorrhages, Janeway lesions
- Immunologic phenomena: glomerulonephritis, rheumatoid factor, Osler’s nodes, Roth’s spots
- Positive blood culture but not meeting major criteria OR serologic evidence of active infection with organism consistent with IE
Modified Duke Criteria- number for a definite Dx of Infective Endocarditis
2 major OR 1 major + 3 minor OR 5 minor
The organism responsible for most cases of non-gonococcal arthritis in adults
staph aureus
Characteristics of infected synovial fluid
opaque, increased WBCs (>15,000/mm3: likelihood of infection increases with increasing WBCs), PMNs >90%, culture positive
Most common cause of cellulitis
Beta-hemolytic streptococci
Diagnosis of necrotising fasciitis
Clinical
Typical cause of monomicrobial infection in necrotising fasciitis
Group A Strep
Blind Rx of necrotising fasciitis
meropenem or piperacillin/ tazobactam + clindamycin IV
Influenza incubation period
incubation period 1-4 d
Gold standard diagnostic test for influenza
nasopharyngeal swabs for RT-PCR (gold standard)
For whom is influenza vaccine indicated?
Vaccine for influenza A and B viruses is recommended annually for all ages 6 mo (according to TN)
Clinical evidence of consolidation
dullness to percussion, bronchial breath sounds, crackles
Airborne infections
M. tuberculosis, disseminated VZV, measles
Things you can’t see on a gram stain
Mycobacteria Ricketsii Chlamydia Mycoplasma Treponema
Anaerobic gram positive rods
Clostridium sp C. difficile C. tetani C. botulinum C. perfringens
Aerobic gram negative cocci
Neisseria N. meningiditis N. gonorrhoeae Moraxella M. catarrhalis
Shigella- describe the organism
Aerobic gram negative rod
Listeria- describe the organism
Aerobic gram positive rod
Campylobacter-describe the organism
Aerobic gram negative rod
What is a typical source of vibrio vulnificus septicaemia?
Eating raw oysters
First line treatment for anogenital warts (HPV)
Podophyllotoxin 5% solution
TOC for dental abscess
Clindamycin, or amoxycillin/ clavulanate
Management of infectious tenosynovitis
Surgery and IV Abx
What does positive Hep B surface antigen imply?
That the individual is infectious
What does the presence of hep B surface antibody imply?
That the individual is immune, either through previous infection or vaccination
What do IgG antibodies indicate in Hep B serology?
Chronicity IgM signifies acute infection
Screening for asymptomatic bacteriuria - which conditions?
All immunosuppressed pts whether through meds or pathology Pregnancy Renal transplant pts
The DOC for lung abscess
Clindamycin
Characteristics of giardiasis
non-bloody, watery diarrhoea, abdominal cramps, foul flatus, vomiting, fever and malaise.
Stools are malodorous, mushy and greasy.
Anorexia, fatigue and weight loss common.
Characteristics of campylobacteriosis
inflammatory sometimes bloody diarrhoea or dysentery syndrome 1-3 days post ingestion of infected food (poultry)
Characteristics of amebic colitis
Gradual onset over 1-2 weeks (cf bacterial dysentery). Cramp abdominal pain, watery or bloody diarrhoea, anorexia/ weight loss. Fever in about 30%
What is elevated in 90% of HIV pts with PCP?
LDH
Diagnosis of PCP
Examination of induced sputum
Pasteurella multocida is associated with what?
Cat bites
What tends to cause rapid onset nausea, diarrhoea + vomiting?
staphylococcal food poisoning
What is the cause of tinea versicolor?
Malassezia yeast
Prophylactic Rx for contacts of ppl with meningococcal meningitis should include what?
Rifampicin
The most frequent cause of urethritis in men
Chlamydia
Combination of DKA and sinus inflammation might indicate what?
Mucormycosis
Management of Mucormycosis
surgical debridement and IV amphoteracin B
Prophylaxis of mycobacterium avium intracellulare in HIV pt with a CD4 <50
Azithromycin
Diagnosis of pseudomembranous colitis *hot topic*
cytotoxin assay of the stool
Management of pseudomembranous colitis
Stop antibiotics and give oral vancomycin
Treatment for gonorrhoea
Ceftriaxone IM as a single dose
TOC for lung abscess
Clindamycin
A drug approved for HIV associated lipodystrophy
Tesamorelin
If someone presents with a dirty wound + hx of tetanus vx, when would you re-administer the vaccine?
If the vaccine was >5 years ago
Fungal disease associated with bats and birds
Histoplasmosis
What Ix is necessary in a sexually active woman of repro age with LUTS?
HCG
Sputum culture for Legionella sp should be on which medium?
Buffered charcoal yeast agar
The best way to evaluate the severity of PCP pneumonia
Alveolar-arterial P02 difference
Management of latent TB infection in HIV
Isoniazid monotherapy
First line antibiotic therapy for animal bites
Amoxycillin-clavulanate
What type of virus is Epstein Barr?
Human Herpes Virus type 4 (dsDNA)
Fever + pharyngitis + lymphadenopathy (posterior cervical LNs) + fatigue
Infectious Mononucleosis
False negatives to the Monospot test (2)
1) Early infection (in which case re-test) 2) <4 years old (look for EBV specific antibodies like IgM VCA or IgG (EBNA)
What are HIV+ pts with EBV at risk of developing?
Oral hairy leukoplakia
Pulmonary tuberculosis is associated with what as an occupational disease?
Silica dust exposure
Eaton’s agar media can be used to grow what from sputum culture?
Mycoplasma pneumonia
Who tends to get mycoplasma pneumonia?
School kids, teenagers, military recruits
Most reliable diagnostic tests for mycoplasma pneumonia
PCR and DNA probes
A positive Widal test suggests what?
Typhoid fever
Main routes of spread Hep C
IVDU Tattoos Not sexual contact!
Investigation to assess severity of Hep C
Liver biopsy
Blind Rx meningitis in >50s or immunocompromised pts
Vancomycin + ampicillin + ceftriaxone
Diagnostic investigation for osteomyelitis
X-Ray
X-Ray findings in osteomyelitis
- Soft tissue swelling
- Periosteal reaction
- Cortical irregularity
- Demineralisation
Should an adult with a reported history of VZV be offered the VZV vaccine?
Yes according to the CDC and Canada Q Bank because the history may be unreliable
For whom is pneumococcal 23-valent polysaccharide vaccine recommended
- All adults over 65 2. Adults <65 in care facilities or with LTCs that out them at risk 3. Alcoholics 4. Smokers 5. Homeless people 6. Asthma with COPD or on steroids 7. Drug users

Tinea versicolor

Erythema migrans
Lyme disease

Oral hairy leukoplakia
EBV infection in HIV

Secondary syphilis

Historical illustration of chancoid ulcer and buboes

Strawberry cervix, trichomonas

Tinea corporis ring worm

Argyll Robertson pupil
Tertiary syphilis
Accommodates but doesn’t react

Pneumocystis carinii pneumonia
There are diffuse bilaterally symmetric interstitial patterns noted in the perihilar region and extending towards the periphery

Tetanus

Leprosy
Leonine facies

Darkfield microscopy
Treponema pallidum
Spirochaetes

Syphilitic aortitis
Tertiary syphilis

Teritary syphilis
Posterior column degeneration
Tabes dorsalis

TB- large cavitating lesion

The auramine-rhodamine fluoresecent stain for acid fast bacilli has now repaced the Ziehl-Neelsen stain for sputum because it has higher sensitivity for diagnosing TB. Cultures take 3-4 weeks to grow.

The PPD aka Mantoux test for TB
The initial test for screening pts for TB when primary Tb is suspected

This is the rapid ELISA HIV test, with 99.5% sensitivity, if positive arrange Western blot confirmation by detection of antibodies to at least two different HIV protein bands (p24, gp41, gp120/160); specificity >99.99%

Aspergilloma.
Ball of hyphae in a pre-existing lung cavity
Symptoms range from asymptomatic to massive hemoptysis
CXR: round opacity surrounded by a thin lucent rim of air, often in upper lobes (“air crescent” sign)

Mucormycosis
Fungal pathogen of mold subtype
Usually caused by Rhizopus
Problematic in uncontrolled diabetics
Rx requires surgical debridement and IV amphoteracin B

Computer illustration of Borrelia burgdorferi bacteria, the cause of Lyme disease in humans. These spiral-shaped spirochaete bacteria are passed on to humans by tick bites, commonly Ixodes ricinus in Europe and Ixodes pacificus in North America.

Roth spots
Osler nodes
Janeway lesions
Splinter haemorrhages
Due to embolised bits of septic vegetation in infective endocarditis
Treatment of latent TB in healthy individuals
Isoniazid 9 months
What must always been done before a lumbar puncture?
Check for raised intracranial pressure.
Look for papilledema
Significance of numerous RBCs in serial CSF samples
Subarachnoid haemorrrhage
Significance of low glucose and PMN predominance in CSF sample
Bacterial meningitis
Significance of normal glucose and lymphocytic predominance in CSF sample
Aseptic (viral) meningitis
Risk factors for pyelonephritis
- Pregnancy
- Vesicoureteral reflux
- Anatomical abnormalities
- Indwelling catheters
- Kidney stones
Name the bug - an alcoholic with pneumonia
Klebsiella
Name the bug- infection in a burns patient
Pseudomonas
Name the bug- perianal itching
Enterobius vermicularis
Name the bug- raw pork
Trichinella spiralis