JH IM Board Review - Infectious Disease VI Flashcards
(112 cards)
1
Q
Meningitis - Definition:
A
Inflammation of the LEPTOMENINGES = Tissue surrounding the brain and spinal cord.
2
Q
Aseptic meningitis is defined as:
A
Meningeal inflammation with an absence of bacteria on CSF exam and culture.
3
Q
Some pathogens may cause chronic meningitis, in which symptoms are present for …?
A
4 or more weeks.
==> Cryptococcal meningitis (Rarely in seemingly healthy individuals).
==> TB meningitis.
4
Q
In meningitis, unlike encephalitis, …?
A
Brain function is normal.
==> Mental status changes and seizures can occur.
5
Q
Meningitis - PEx may reveal signs of meningeal irritation, but these findings occur in less than …?
A
5% of patients.
==> Kernig = Pain in the back is elicited with passive extension of the knee while the hip is flexed.
==> Brudzinski = Passive flexion of the neck results in spontaneous flexion of the hips and knees.
6
Q
Meningitis - Dx:
A
- Blood cultures should be obtained IMMEDIATELY.
- Dx relies on exam of the CSF.
- Neuroimaging with CT or MRI is only needed in select situations before performing a LP.
- If neuroimaging is needed, empiric abx (and dexamethasone if indicated) should be started BEFORE scanning.
7
Q
Bacterial meningitis - Empirical Tx - <1month:
A
Ampicillin + cefotaxime OR Ampicillin + aminoglycoside.
8
Q
Bacterial meningitis - Empirical Tx - 1month-50yr:
A
Vanco + 3rd gen cephalosporin (ceftriaxone or cefotaxime).
9
Q
Bacterial meningitis - Empirical Tx - >50yr:
A
Ampicillin (to cover Listeria spp.) + Vanco + 3rd gen cephalosporin.
10
Q
Bacterial meningitis - Empirical Tx - Penetrating head trauma, post-neurosurgery, CSF shunt:
A
Vanco + Cefepime, ceftazidime, or meropenem.
11
Q
Meningitis - Tx - Role of adjunctive dexamethasone:
A
Recommended in adults with suspected or proven pneumococcal meningitis.
==> 1st dose IDEALLY given 10-20min before the first dose of abx.
==> If not given before the first dose of abx, then give concomitantly with the 1st dose.
==> Dosing: 0.15mg/kg IV every 6h for 2-4 days.
12
Q
Common etiologic agents causing acute bacterial meningitis in adults - S.pneumo:
A
- MC etiologic agent in the USA.
- Mortality 19-26%.
- Sometimes associated with other foci of infection (eg pneumonia, endocarditis).
13
Q
Common etiologic agents causing acute bacterial meningitis in adults - S.pneumo - Tx:
A
Vanco + 3rd gen cephalosporin until antimicrobial susceptibility is known.
==> Some experts add rifampin if dexamethasone is given.
14
Q
Common etiologic agents causing acute bacterial meningitis in adults - N.meningitidis:
A
- Affects mostly children and young adults.
- Patients with terminal complement deficiency are at increased risk.
- Maculopapular rash progresses to petechiae on the trunk, extremities, and mucous membranes.
15
Q
Common etiologic agents causing acute bacterial meningitis in adults - N.meningitidis - Tx:
A
3rd gen cephalosporin.
==> Switch to penicillin G or ampicillin once confirmed to be highly sensitive.
16
Q
N.meningitidis - Chemoprophylaxis:
A
Rifampin (or ciproflox or ceftriaxone) recommended for household contacts, day care center members, those directly exposed to oral secretions.
17
Q
Common etiologic agents causing acute bacterial meningitis in adults - H.flu:
A
- Mostly occurs in children.
- Disease in adults usually associated with:
==> Sinusitis, otitis media, pneumonia, sickle cell disease, splenectomy, DM, immunodeficiency, head trauma with CSF leak, or alcoholism.
18
Q
Common etiologic agents causing acute bacterial meningitis in adults - H.flu - Tx:
A
3rd gen cephalosporin.
19
Q
Common etiologic agents causing acute bacterial meningitis in adults - Listeria:
A
- Disease of neonates, older adults, and immunocompromised (incl. poorly controlled diabetics and pregnant women).
- Outbreaks associated with contaminated produce, coleslaw, milk, cheese.
- Associated with hematologic malignancy, steroid use, iron overload.
20
Q
Common etiologic agents causing acute bacterial meningitis in adults - Listeria - Tx:
A
Ampicillin (or PCN G) +/- aminoglycoside.
21
Q
Common etiologic agents causing acute bacterial meningitis in adults - S.aureus:
A
Usually seen after head trauma, in post-op settings, or when hardware is present.
22
Q
Common etiologic agents causing acute bacterial meningitis in adults - S.aureus - Tx:
A
Nafcillin or oxacillin (if methicillin-susceptible).
==> Vanco +/- rifampin (if methicillin-resistant).
23
Q
Causes of aseptic meningitis - Categories:
A
- Viral.
- Bacterial.
- Fungal.
- Miscellaneous infections.
- Non infectious diseases.
- Drugs.
24
Q
Causes of aseptic meningitis - Viral:
A
- Enteroviruses.
- Mumps.
- Echovirus.
- Poliovirus.
- Coxsackie.
- HSV.
- CMV.
- VZV.
- Arbo.
- Acute HIV.
- Influenza.
25
Causes of aseptic meningitis - Bacterial:
1. TB.
2. Rickettsiae.
3. Syphilis.
4. B.burgdorferi.
26
Causes of aseptic meningitis - Fungal:
1. Cryptococcus.
2. Coccidioides.
3. Histoplasma.
4. Candida.
5. Molds (aspergillus, exserohilum).
27
Causes of aseptic meningitis - Miscellaneous infections:
1. Toxo.
2. Malaria.
3. Whipple.
4. Leptospira.
28
Causes of aseptic meningitis - Noninfectious disease:
1. Brain tumors.
2. Sarcoidosis.
3. Lupus.
4. Meningeal carcinomatosis.
29
Causes of aseptic meningitis - Drugs:
1. TMP-SMX.
2. Ibuprofen.
3. Carbamazepine.
30
Encephalitis frequently occurs with ...?
MENINGITIS ==> Meningoencephalitis.
MYELITIS ==> Encephalomyelitis.
31
In pts who had a recent viral illness or vaccination and who present with encephalitis, consider ...?
A diagnosis of acute disseminated encephalomyelitis (ADEM).
32
West Nile virus may be associated with ...?
FLACCID WEAKNESS + Reduced or absent reflexes.
33
Encephalitis - Dx - CSF PCR:
1. HSV.
2. CMV.
3. EBV.
4. VZV.
5. JC virus.
6. West Nile virus.
7. Enteroviruses.
34
Encephalitis - Dx - CSF serology is useful for ...?
Detection fo ARBOviruses.
35
Encephalitis - Dx - Serum +/- CSF serologic testing and PCRs can help diagnose:
Tick-borne + Spirochetal disease.
36
Encephalitis - Dx - Brain Bx when?
ONLY needed in pts who continue to deteriorate on acyclovir and who have a negative Dx workup.
37
Encephalitis - Dx - CSF culture is useful for:
1. Fungal.
2. Mycobacterial.
3. Bacterial.
causes of encephalitis.
38
Encephalitis - Dx - Perform respiratory viral panel testing if ...?
There is a suspicion of resp. viral disease.
39
Encephalitis - Dx - MRI?
ALWAYS. If not possible, then CT.
40
Indications for head CT before LP when acute bacterial meningitis is suspected - Immunocompromised host:
1. HIV/AIDS.
2. Transplant patient.
3. Patient on immunosuppressive medications.
41
Indications for head CT before LP when acute bacterial meningitis is suspected - Hx of CNS disease:
1. Mass lesion.
2. Stroke.
3. Focal infection.
42
Indications for head CT before LP when acute bacterial meningitis is suspected - Papilledema:
Especially if no venous pulsations.
43
Indications for head CT before LP when acute bacterial meningitis is suspected - New-onset seizure:
Onset within 1 week of presentation.
44
Indications for head CT before LP when acute bacterial meningitis is suspected - Focal neurologic deficit:
1. Dilated nonreactive pupil.
2. Ocular motility abnormalities.
3. Abnormal visual fields.
4. Gaze palsy.
5. Arm or leg drift.
45
Indications for head CT before LP when acute bacterial meningitis is suspected - Abnormal level of consciousness:
Inability to follow 2 consecutive commands or answer 2 consecutive questions.
46
Selected pathogens causing encephalitis - West Nile:
1. Transmission ==> Mosquito.
2. Dx ==> PCR and IgM in CSF or serum/ Convalescent titers in serum.
3. Tx ==> Supportive.
==> Most infected pts present with febrile illness/ Advanced age is GREATEST risk factor for severe disease.
47
Skin and soft tissue infections - Basic info:
1. Range from minor superficial infections to life-threatening conditions, such as necrotizing fasciitis.
2. Generally categorized into purulent vs non purulent infections ==> Purulence usually denotes Staph.
3. Incr. incidence of infections caused by CA-MRSA.
48
Skin and soft tissue infections - CP:
1. Most present with isolated skin or soft tissue findings.
2. Some develop necrotizing pneumonia, necrotizing fasciitis, endocarditis, osteomyelitis, sepsis.
3. Erythema without pain, fever, warmth, or leukocytosis should lead to consideration of alternative diagnoses.
49
Skin and soft tissue infections - Tx - MRSA:
1. Incision + Drainage is the primary treatment for cutaneous abscesses.
2. Vanco is the DoC for hospitalized pts. Linezolid is an alternative.
3. Many CA-MRSA strains may be sensitive to TMP-SMX. Other options for outpatients include clindamycin (although resistance can be inducible) and doxycycline.
4. Newer agents ==> Daptomycin, telavancin, ceftaroline can be considered.
50
Skin and soft tissue infections - Tx - NON purulent:
Most are caused by beta-hemolytic strep, making beta-lactam Tx (eg amoxicillin) the Tx of choice.
51
Acute bacterial arthritis - Organisms:
1. N.gono ==> <30.
2. S.aureus.
3. S.pneumo.
4. Mycoplasma spp. ==> 1o Ig deficiency.
5. Salmonella spp. ==> HIV/SCA.
6. P.multocida ==> Cat bites or scratches.
7. Other Gram(-) bacilli.
52
Acute bacterial arthritis - S.aureus - Risk factors:
1. Glucocorticoid Tx.
2. RA.
3. DM.
4. Post-op.
5. Injection drug use.
53
Acute bacterial arthritis - S.pneumo - Risk factors:
1. HIV.
2. Alcohol.
3. SCA.
==> LESS THAN HALF have another focus of S.pneumo infection.
54
Acute bacterial arthritis - Other gram(-) bacilli - Risk factors:
1. Injection drug use.
2. Immunodeficiency.
3. Neonates.
4. Elderly.
5. Nursing home residents.
55
Acute bacterial arthritis - Dx:
ASPIRATION OF SYNOVIAL FLUID IS ESSENTIAL.
==> US/CT/MRI may be helpful for detection and aspiration with involvement of certain joints (eg hip, sacroiliac).
==> WBC in the fluid >50.000 with >75% neutros.
==> Glucose is <40mg/dL.
56
Acute bacterial arthritis - Dx - The presence of crystals ...?
DOES NOT R/O INFECTION.
==> Crystal-induced arthritis and septic arthritis can occur together.
57
Acute bacterial arthritis - Dx - Gram stain:
Positive in 1/3.
58
Acute bacterial arthritis - Dx - Synovial fluid cultures:
Positive in up to 90% of nongonococcal bacterial arthritis, but in less than 50% of gono arthritis.
59
Acute bacterial arthritis - Dx - What is often needed to confirm GC arthritis?
Genital or pharyngeal culture +/- NAA to confirm GC, or NAA on joint fluid or urine.
60
Acute bacterial arthritis - Dx - Blood cultures:
SHOULD BE OBTAINED.
==> Up to 60% positive in S.aureus cases. LESS Se in Dx other pathogens.
61
Acute bacterial arthritis - Tx - Empirical abx after blood cultures and joint aspiration largely depends on gram stain:
1. If GC arthritis is suspected ==> CEFTRIAXONE.
2. If S.aureus is suspected ==> Vanco (if MSSA then oxacillin/nafcillin).
3. If Streptococcal disease is suspected ==> Penicillin/ampicillin.
4. If gram(-) is suspected ==> Ceftazidime or cefepime are appropriate empiric choices.
62
Acute bacterial arthritis - Tx - Indications for surgical drainage:
1. Hip joint involvement (except in cases of GC).
2. Delay of therapy (>1week after onset of symptoms).
3. Loculated infection or exudate too thick to aspirate.
4. Poor response to Tx (eg failure to decr. synovial WBC).
5. Prosthetic joint infection.
63
Viral arthritis:
1. Caused by direct invasion of the synovium OR by an immune reaction involving certain joints.
2. USUALLY Migratory polyarthritis.
64
Viral arthritis - Many viruses implicated:
1. Rubella.
2. Mumps.
3. B19.
4. Hep B.
65
Rubella arthritis:
1. Can occur following infection or immunization.
2. Usually seen in women.
3. Disease typically self-limited but can rarely persists for years.
66
Mumps arthritis:
1. More common in men.
| 2. Develops within 2 weeks of parotitis.
67
B19 arthritis:
1. Small joints of the hands most frequently invovled.
2. Infection in adults can occur without fever or rash.
3. Self-limited: usually resolves within 8-10 weeks.
68
HBV arthritis:
1. Can manifest as arthralgias or symmetrical arthritis.
| 2. Symptoms (arthralgias or arthritis) occur before jaundice and resolve when jaundice develops.
69
Prosthetic joint infection - Early infection:
1. Within 1-3 months.
2. Acquired at surgery.
3. Acute symptoms (cellulitis, erythema, pain, drainage).
==> Usually caused by S.aureus, Gram(-) bacilli, anaerobes, or polymicrobial.
70
Prosthetic joint infection - Delayed infection:
1. 3-12months.
2. Acquired at surgery.
3. Indolent symptoms of joint pain and/or loosening of prosthesis.
==> Usually low-virulence pathogens (eg Propionibacterium acnes, CN staph, enterococci).
71
Prosthetic joint infection - Late infection:
After 12 months, commonly via hematogenous seeding.
==> Usual pathogens are S.aureus, beta-hemolytic strep, gram(-) bacilli.
72
Prosthetic joint infection - Dx and Tx:
Definitive Dx made by arthrocentesis or surgival debridement.
Most successful Tx is removal of entire prosthesis with 6 weeks of abx therapy.
73
Osteomyelitis - 2 basic types:
1. Hematogenous.
| 2. Contiguous.
74
Osteomyelitis - Hematogenous source - Etiology:
1. Seeding of the bone during bacteremia.
2. Primarily occurs in children and older adults.
3. Injection drug users.
75
Osteomyelitis - Hematogenous - Involvement:
1. Vertebrae.
2. Sternoclavicular.
3. Sacroiliac joints.
4. Syphysis pubis.
76
Osteomyelitis - Hematogenous - Organisms:
1. S.aureus (MC).
2. Pseudomonas.
3. Serratia.
4. Eikenella.
77
Osteomyelitis - Pts with SCA:
1. S.aureus.
| 2. Salmo.
78
Osteomyelitis - Hematogenous - Vertebral involvement:
1. S.aureus.
2. Gram(-) bacilli.
3. TB.
4. Candida.
79
Osteomyelitis - Contiguous source:
1. Most cases in adults.
2. Infections from adjacent soft tissue, injury, or surgery.
3. Presentation is more indolent than with hematogenous spread.
4. DM foot ulcers + decubitus ulcers are common sources.
==> S.aureus MC, although most are POLYMICROBIAL. Pseudomonas ==> Puncture wound of the foot.
80
Osteomyelitis - Dx - Blood studies:
1. ESR/CRP elevated.
| 2. Blood cultures more likely to be positive in cases of hematogenous spread.
81
Osteomyelitis - Dx - Radiologic and imaging studies - Plain radiographs:
1. May show periosteal elevation, soft tissue swelling, or lytic changes.
2. Findings may not be present during early or acute infection, but if seen are adequate for diagnosis.
82
Osteomyelitis - Dx - Radiologic and imaging studies - MRI:
1. Best identifies early changes consistent with acute osteomyelitis ==> Such as bone marrow edema.
2. Test of choice for vertebral osteomyelitis because it better defines the surrounding soft tissue.
83
Osteomyelitis - Dx - Radiologic and imaging studies - CT:
Can be helpful if hardware present.
84
Osteomyelitis - Dx - Radiologic and imaging studies - Tc bone scan:
1. Can detect early lesions with high sens.
2. Can be falsely negative in acute and chronic infection.
3. Best when bone was previously normal (false positive common with previously abnormal bone).
4. Cannot distinguish infection from tumor, fracture, or infarction.
85
Osteomyelitis - Dx - Bone Bx for culture:
Is recommended to make a definitive diagnosis if blooc cultures are negative.
86
Osteomyelitis - Dx - Swab cultures of sinus tract or ulcer base:
UNRELIABLE for making a microbiologic Dx.
==> However they can be useful if treatment is to be empiric to determine if therapy needs to include coverage against virulent pathogens such as S.aureus, P.aeruginosa.
87
Osteomyelitis - Tx - Acute event:
Tx of acute osteomyelitis usually consists of 6 WEEKS of IV abx directed by the culture results.
==> Depending on the organism and antimicrobial susceptibilities, oral Tx after an initial 2 weeks of IV abx may be considered in select cases if the abx to be used has adequate bioavailability and bone penetration.
88
Osteomyelitis - Tx - Chronic:
1. Often requires surgical debridement to remove devitalized bone ore restore vascular supply in conjunction with antimicrobial therapy.
2. Antimicrobial therapy in the absence of debridement is suppressive, not curative.
==> Monitoring of CRP/ESR over time is helpful.
89
Classification of FUO:
1. Classic FUO.
2. Nosocomial FUO.
3. Neutropenic FUO.
4. HIV-associated FUO.
90
Classic FUO - Def:
1. Fever >38.3 for 3 weeks.
2. Blood cultures negative.
3. Lack of Dx with 3 outpatient visit or 3 inpatient days.
91
Classic FUO - Etiology:
1. Infection.
2. Malignancy.
3. Collagen vascular diseases.
4. Granulomatous disease.
92
Nosocomial FUO - Definition:
Hospitalized patient with NO fever on admission.
==> 3 days of investigation + 2 days of negative incubating cultures.
93
Nosocomial FUO - Etiology:
1. C.diff.
2. Phlebitis or venous thromboembolism.
3. Sinusitis.
4. Drug fever.
94
Neutropenic FUO - Definition:
Absolute neutros <500.
==> 3 days of investigation.
==> 2 days of negative incubating cultures.
95
Neutropenic FUO - Etiologies:
1. Perianal infection.
2. Aspergillus spp.
3. Candida spp.
96
HIV-associated FUO - Def:
HIV(+).
==> Fever > 3weeks in outpatients or >3days for inpatients.
==> 3 days of investigation.
==> 2 days of negative incubating cultures.
97
HIV-associated FUO - Etiology:
1. Mycobacteria, incl. TB.
2. Lymphoma.
3. Drug fever.
4. CMV.
5. PCP.
98
Etiologic considerations for classic FUO - Foreign-born:
Extrapulmonary TB.
99
Etiologic considerations for classic FUO - Age >50:
1. Malignancy.
2. Giant cell arteritis.
3. Polymyalgia rheumatica.
100
Etiologic considerations for classic FUO - High fevers with arthralgias/arthritis and rash:
Adult Still disease.
101
Etiologic considerations for classic FUO - Medical background with undocumented fever:
Factitious fever.
102
Etiologic considerations for classic FUO - Returning traveler:
From endemic countries:
1. Plasmodium spp.
2. Dengue.
3. Salmonella spp.
4. Tick-borne diseases.
103
Etiologic considerations for classic FUO - Recurrent episodic fevers:
Hereditary periodic fevers.
104
FUO - Dx - Hx/PEx:
A thorough Hx including travel, hobbies, history of TB exposure, HIV, risk factors, medications, should be obtained to guide the evaluation.
==> Repeated PEx may be necessary to detect slowly progressing diseases.
105
FUO - Basic testing should include the following:
1. CBC.
2. Comprehensive metabolic panel.
3. Urinalysis.
4. ESR/CRP.
5. Blood cultures (greater than 3 sets).
6. CXR.
7. ANA.
8. HIV.
106
FUO - Dx - IGRA and PPD:
Should be considered.
107
FUO - Dx - CT:
CT scan of the chest, abdomen, and pelvis should be considered in the absence of other localizing signs.
108
FUO - Dx - Administration of NAPROXEN ...?
May help distinguish between neoplasia and infection.
==> The fever from neoplasms is thought to be more responsive to the medication.
109
FUO - Dx - Empirical abx:
Try to avoid empirical abx.
==> They may suppress an occult infection without curing it, and may interfere with the ability to make a diagnosis.
110
FUO - Drug-induced fever:
Should be considered a Dx of exclusion.
==> It is confirmed by stopping the potentially offending agent.
111
Drug-induced fever - Features:
1. Usually pts do not appear as toxic as with other causes of FUO.
2. RASH + EOSINOPHILIA are sometimes present, but their ABSENCE does NOT rule out drug fever.
==> Common causes ==> Sulfonamides, beta-lactam abx, phenytoin, amiodarone, nitrofurantoin.
112
FUO - The cause of may NOT be found in approx. ...?
30% of adults.
==> Most of those without a Dx have a good prognosis.
