ID key points Flashcards
3 MCCs of viral meningitis?
- Enterovirus
- HSV 2
- Arboviruses
Viral meningitis + parotitis or orchitis is a clue to what bug?
Mumps
Viral meningitis + rash is a clue to which two bugs?
Enterovirus, HIV
Viral meningitis + pharyngitis is a clue to which bug?
HIV
Viral meningitis + genital lesions is a clue to which bug?
HSV2
General management of viral meningitis? When can you stop empiric anti-microbials?
Supportive, can stop once CSF Cx r/o bacterial meningitis
5 MCCs of bacterial meningitis?
- Strep pneumo
- N. meningitidis
- GBS
- H flu
- Listeria monocytogenes
When should you start empiric antimicrobial therapy in suspected bacterial meningitis?
Immediately
What non-antimicrobial drug should be started as adjunctive therapy in all cases of bacterial meningitis in developed countries?
Dexamethasone
When should you start empiric antimicrobial therapy in suspected brain abscess?
Immediately
Successful Tx of a brain abscess typically consists of what 2 therapeutic modalities?
- Anti-microbial therapy
2. Surgical drainage
Name 2 places that spinal epidural abscesses commonly arise from
Infected vertebral discs
Inected intervertebral body disc spaces
RFs for spinal epidural abscesses? (9)
- Prolonged epidural catheter placement
- Steroid or analgesic injections
- DM
- HIV
- Trauma
- IVDU
- Tattooing
- Alcoholism
- Accupuncture
How many sets of BCx should you get for a spinal epidural abscess?
2
Cranial subdural empyemas typically arise as a complication of which processes? (3)
Sinusitis
OM
Mastoiditis
Cranial subdural empyemas are a medical emergency. In addition to immediately evaluating the patient, which consult should you call?
Neurosurgery
Characteristic imaging findings of HSV encephalitis?
Unilateral or bilateral localized infection of the temporal lobes
CSF findings in HSV encephalitis?
Lymphocytic pleocytosis +/- rbcs (if necrosis is extensive)
What test is highly sensitive and specific for diagnosis of HSV encephalitis?
HSV PCR of the CSF
All patients suspected of having encephalitis should get what anti-viral drug empirically?
IV ACV
VZV encephalitis is MC in which 2 patient populations?
HIV/AIDS
Defects in cellular immunity
Dx of VZV CNS infection?
VZV PCR of the CSF
Tx of VZV encephalitis?
Parenteral ACV
Tx of VZV vasculopathy?
Parenteral ACV
What percent of patients with West Nile virus develop neuroinvasive disease?
Less than 1%
3 general presentations of West Nile neuroinvasive disease?
Meningitis, encephalitis, or myelitis. Note it can present with just one or with an overlap syndrome.
Dx of West Nile neuroinvasive disease?
CSF serology
When do most patients with West Nile neuroinvasive disease develop detectable IgM antibody to West Nile?
Within 1st week of Sx
Name 4 presenting features of anti-NDMA receptor encephalitis
- Choreoathetosis
- Psych Sx
- Seizures
- ANS instability
Anti-NDMA receptor encephalitis is associated with what underlying condition in over 50% of patients?
Ovarian teratoma
Dx of anti-NDMA receptor encephalitis?
Detection of anti-NDMAR antibody in serum
Tx of anti-NDMA receptor encephalitis?
Remove teratoma + immunosuppression with either steroids or IVIG
MC form of prion disease in humans?
CJD
Which form of CJD is most common?
Sporadic
2 major causes of iatrogenic CJD transmission?
- Use of growth hormone prepared from cadaveric pituitaries
2. Contaminated cavaderic dura mater allografts
2 major causes of variant CJD transmission?
- Eating contaminated beef
2. Blood/blood products from vCJD-infected donors
MCC of cellulitis w/ purulent drainage or exudates?
MRSA
MCC of non-purulent cellulitis?
Beta-hemolytic strep
Skin infections are typically diagnosed clinically. What are 3 circumstances when radiography would be considered?
- Dx is uncertain
- Nec fasc is suspected
- Concern for associated abscess or foreign body
Primary Tx of CA-MRSA cutaneous abscess?
I&D
When are antibiotics indicated for CA-MRSA cutaneous abscess? (8)
- If I&D is ineffective
- Extensive disease
- Rapidly progressive disease w/ associated cellulitis
- Presence of immunodeficiencies or other CMx
- Very young or very old patient
- Clinical signs of systemic illness
- Involved area is difficult to drain
- Presence of septic phlebitis
Clues to an underlying necrotizing SSTI? (3)
- Systemic toxicity w/ fever, chills, AMS, hypoTN
- Pain out of proportion to exam
- Loss of sensation
Why can loss of sensation occur in nec fasc?
Destruction of cutaneous nerves
Gold standard for Dx and Tx of nec fasc?
Early surgical exploration
3 components of early management of toxic shock syndrome?
- Adequate resuscitation to maintain tissue perfusion
- Identification of the cause and focus of infection
- Source control
When managing toxic shock syndrome, what does source control typically involve?
Surgical debridement
3 ways to decrease the risk of infection in animal bites?
- Prompt wound irrigation w/ NS
- Removal of any foreign bodies
- Debridement of necrotic tissue
All patients with animal bites should be assessed for need for prophylaxis against which 2 infections?
Tetanus and rabies
Which animal bite patients require prophylactic amox-clavulanate? (5)
- Immunosuppressed
- Moderate-to-severe wounds, esp on face or hands
- Wounds near a joint or bone
- Wounds associated with significant crush injury
- Wounds associated with significant edema
Which human bite wounds require Abx Ppx, and which Abx is used?
All require ppx w/ amox-clavulanate
3 components of wound care for diabetic foot infections?
- Wound cleansing
- Debridement
- Off-loading of foot pressure
Which patients with new diabetic foot wounds get imaging?
All of them!
Which age group is more likely to get CAP?
Older adults
MCC of CAP?
Strep pneumo
2 MC respiratory viruses contributing to development of CAP?
Influenza A and B
MRSA as a cause of CAP is MC w/ nosocomial exposures. What are some other risk factors? (3)
- Hemodialysis
- SNF exposure
- Exposure to people with SSTI
5 clinical symptoms of CAP?
- Fever
- Cough
- Dyspnea
- Sputum production
- Pleuritic chest pain
What radiographic finding is required for a Dx of PNA?
Pulmonary infiltrate on CXR
Indications for microbiologic testing w/ sputum Cx and BCx in CAP? (8)
Hospitalized patients with one or more of the following:
- ICU admission
- Cpx like pleural effusion or cavitary lesion
- Underlying lung disease
- Active EtOH abuse
- Asplenia
- Liver disease
- Leukopenia
- Unsuccessful outpatient anti-microbial therapy
Empiric outpatient therapy for CAP in patients w/o CMx or recent antimicrobial use? (2 options)
- Macrolide
2. Doxy
Empiric outpatient therapy for CAP in patients w/ CMx, recent antimicrobial use, or living in an area with highly prevalent macrolide-resistant strep pneumo? (2 options)
- Respiratory FQ
2. Combo therapy w/ beta-lactam + macrolide (alternate to macrolide is doxy)
When can hospitalized CAP patients be switched from parenteral Abx to PO?
When clinically stable
Does it improve outcomes to continue inpatient monitoring of CAP patients who have been switched from parenteral to PO Abx?
Nope
Pts w/ PNA who are treated with the appropriate Abx typically show clinical improvement when?
Within 2-3 days
What are RFs for unsuccessful Tx of CAP?
- Multilobar PNA
- MRSA
- Legionella
- Gram-neg bacilli
- PNA severity index of 90 or more
- Initial Tx w/ an anti-microbial regimen to which the causative pathogen was not susceptible
Tx courses for CAP longer than _________ have not shown to have a clinical benefit
5 days
Why shouldn’t you routinely use follow-up CXR s/p CAP?
CXR findings may linger beyond clinical improvement and symptom resolution
When do Lyme disease Sx typically first appear?
1-4 weeks s/p infection
Characteristic initial Sx of Lyme?
Erythema migrans (single target lesion)
What percent of Lyme patients will develop erythema migrans?
60-80%
Dx of early Lyme disease if erythema migrans is present?
Documentation of erythema migrans + compatible epidemiologic history
Why isn’t serologic testing indicated in early Lyme?
Antibodies may not be present yet, leadign to false negative testing in early localized disease
Are antibodies typically present during disseminated Lyme?
Yup
Dx of disseminated Lyme?
2 step serologic testing: ELISA followed by confirmatory Western blot
Mx of post-lyme disease syndrome?
Treat the symptoms. No Abx bc they’re no longer infected!
STARI is clinically indistinguishable from what other infectious disease?
Localized Lyme
Tx of STARI?
Oral antibiotic active against localized Lyme disease (bc impossible to tell if it’s Lyme vs STARI). Thus doxy is best, amoxicillin if can’t take doxy (young kids, pregnant women)
Describe typical presentation of babesiosis
Either ASx or mild febrile illness w/ myalgias, HA, fatigue
What are 4 potential features of severe babesiosis?
- Acute respiratory failure
- AKI
- DIC
- Splenic rupture
What’s the most sensitive test for diagnosis of mild babesiosis?
PCR bc these patients typically have low parasite counts
Sensitivity of microscopy of Giemsa or Wright-stained blood smears in the diagnosis of babesiosis depends on what?
Level of parasitemia
Tx of choice for mild-moderate babesiosis?
Atovaquone + azithro
Tx of choice for severe babesiosis?
Clinda + quinine
Human monocytic ehrlichiosis and human granulocytic anaplasmosis typically present as non-specific febrile illnesses accompanied by what 4 Sx?
- HA
- Myalgia
- Arthralgia
- Meningismus
What test is extremely sensitive for ehrlichiosis and anaplasmosis if done before initiation of Abx?
Whole blood PCR
What drug should be given empirically when considering ehrlichiosis or anaplasmosis? Why?
Doxy- delay in therapy is a/w adverse clinical outcomes
What diagnosis should be considered in any patient presenting w/ fever and possible tick exposure?
RSMF
Describe utility of serologic testing during acute illness w/ RSMF
Limited utility
DOC for all spotter fever group rickettsioses? Alternate in pregnancy?
Doxy. Alt is chloramphenicol
RF for MDR UTI? (6)
- Current or recent hospitalization
- Immunocompromise
- Presence of underlying structural abnormalities of the urinary tract
- Previous UTI
- Kidney Tpx
- Recent anti-microbial therapy
3 major reasons for the increasing frequency of anti-microbial resistance among urinary pathogens in the community and hospitals?
- Abx overuse
- Inappropriate Tx of ASx bactiuria
- Local differences in Abx use
5 indications for a culture of midstream, clean-void urine in the Dx of UTI?
- Suspected pyelo
- Complicated UTI
- Recurrent UTI
- Multiple anti-microbial allergies
- Suspect resistant bug
Describe utility of UA/UCx as part of routine health surveillance in ASx patients
Not indicated
In women with acute uncomplicated cystitis, why are TMP-SMX or nitrofurantoin better options than fosfomycin?
Fosfomycin has lower efficacy and is more expensive
Acute uncomplicated pyelo: DOC and duration of treatment?
FQ for 5-7 days
Duration of Tx for acute complicated pyelo?
14 days
When can hospitalized patients w/ pyelonephritis be switched from IV to PO Abx?
Once can take PO and have clinical improvement
2 best options for PO Tx of acute pyelo?
TMP-SMX or FQ
What 2 drugs are options for Ppx in women with recurrent cystitis?
TMP-SMX or nitrofurantoin
While once-daily dosing of TMP-SMX or nitrofurantoin reduces episodes of cystitis in women w/ recurrent cystitis, what is the downside of using Abx Ppx?
ADEs are common
What is an option for Ppx of UTI in women with recurrent UTIs linked to sexual activity?
Abx Ppx with single dose given after sex. Options include nitrofurantoin or TMP-SMX
DOC for acute uncomplicated prostatitis? Duration?
PO FQ (levo or cipro) for 4-6 wk
After completing Tx for acute uncomplicated prostatitis, how can you check for response?
Repeat Cx
What percent of cases of TB in the US are in foreign-born people?
65%
What percent of HIV-associated deaths occur 2/2 TB (worldwide)?
20%
Immunocompromise is obviously a RF for development of TB. Name specific groups to be worried about? (8)
- Immunosuppression 2/2 meds
- HIV
- Malignancy
- DM
- CKD
- IVDU
- Smokers
- Malnutrition
What percent of active TB is pulmonary?
70%
9 s/s of pulmonary TB?
- Fever
- Chronic cough
- Purulent or blood-streaked sputum
- Chest pain
- Malaise
- Wt loss
- Night sweats
- Anorexia
- Fatigue
What is latent TB?
ASx patient w/o clinical evidence of active TB is diagnosed w/ positive PPD or interferon gamma release assay
4 causes of false negative TB PPD
- Very old
- Very young
- Immunosuppressed
- Overwhelming active TB
2 reasons for false positive TB PPD?
- Infection w/ atypical mycobacteria
2. Hx of bCG vaccine or chemo
What test is preferred for diagnosis of TB in patients who for the bCG vaccine or in those who are unlikely to return to have their skin test read?
interferon gamma release assay
For otherwise healthy adults, what is an alternative to the standard 9 months of INH for latent TB?
12 wk of once weekly INH/RIF
First line treatment plan for active TB?
8 wk of RIPE followed by 4-7 months of RI
How often should patients RTC for clinical evaluations during TB treatment?
At least monthly
Which patients getting TB treatment should get routine labs?
Those w/ baseline abnormalities or with increased risk of ADE
What vaccine is used in endemic countries to prevent disseminated TB and TB meningitis in kids?
bCG vaccine
What further identification do you need to do after documenting a mycobacterial infection?
Species-level identification
Specific DNA probes exist for which two non-TB mycobacteria? What species-level identification technique can identify the remaining mycobacteria?
Mycobacterium kansasii and MAC
HPLC can ID the other species
MC manifestation of non-TB mycobacterial infection?
Pulmonary disease
MC non-TB mycobacterial species causing infection?
MAC
Which AIDS patients are at risk of disseminated MAC?
Those with CD4 under 50 who aren’t getting MAC Ppx
How does mycobacterium kansasii typically present?
With a lung infection mimicking TB w/ cough, fever, weight loss, and cavitary lung disease
Name 3 rapidly growing mycobacteria that are becoming increasingly relevant as a cause of disseminated disease in immunosuppressed patients
M. abscessus
M. fortuitum
M. chelonae
Name 4 scenarios associated with SSTI 2/2 mycobacterium abscessus, fortuitum, and chelonae
- Trauma
- Surgery (esp w/ implanted prosthetics)
- Catheter insertion
- Cosmetic procedures (tattoos, piercing, pedi)
Name 4 common focal infections in systemic candidiasis
- UTI
- CNS infection
- Bone and joint infection
- Peritonitis
Typical DOC for most patients w/ candidemia?
An echinocandin
Candidemia patients with which 3 types of infection shouldn’t get an echinocandin bc of poor tissue penetration?
- UTI
- Endophthalmitis
- Meningitis
2 aspects of therapy in non-neutropenic patients w/ candidemia?
Antifungal therapy + intravascular catheter removal
2 indications for Tx of ASx candiduria?
- Neutropenia
2. About to undergo a urologic procedure
4 potential manifestations of aspergillus pulmonary disease?
- Colonization
- ABPA
- Aspergilloma (fungus ball)
- Invasive aspergillosis
Definitive diagnosis of invasive aspergillosis? What’s a helpful serologic diagnostic method?
Definitive: tissue Bx
Sero: Galactmannan antigen immunoassay
MC presentation of mucormycosis?
Rapidly fatal rhinocerebral infection
5 main s/s of rhinocerebral mucormycosis?
HA, epistaxis, proptosis, periorbital edema, decreased vision
MC site of disseminated cryptococcus?
CNS
Latex agglutination assay is highly sens/spec for Dx of cryptococcal meningitis in what group of patients?
Symptomatic pts w/ AIDS
How long do you continue maintenance therapy for pts w/ AIDS + cryptococcal meningitis?
Until both of the following:
- they’ve responded to anti-retroviral therapy (with CD4 above 100 for at least 3 months
- They’ve been getting anti-fungal therapy for at least 1 yr