Learning Objectives - Infectious Disease Flashcards
1
Q
Bacteriostatic vs. bacteriocidal?
A
Static - stops bacteria from reproducing
Cidal - kills bacteria
2
Q
Minimum inhibitory concentration (MIC)?
A
Lowest concentration of a chemical that prevents visible growth of a bacteria
3
Q
Minimum bactericidal concentration?
A
Lowest concentration that results in microbial death
4
Q
List the 7 major classes of antibiotics.
A
- Pencillins
- Cephalosporins
- FQs
- AGs
- Monobactams
- Carbapenems
- Macrolides
5
Q
List the penicillins.
A
Natural: G, VK
Pencillinase-resistant: methicillin, nafcillin, oxacillin
Aminopenicillin: ampicillin
6
Q
List the 4 first generation cephalosporins.
A
- Cephalothin
- Cefazolin (Ancef/Kefzol)
- Cephapirin
- Cephalexin (Keflex)
7
Q
List the 2 second generation cephalosporins.
A
- Cefacor
2. Cefotetan
8
Q
List the 1 third generation cephalosporin.
A
- Ceftriaxone
9
Q
List the 2 fourth generation cephalosporins.
A
- Cefpirome
2. Cefepime
10
Q
List the 4 FQs.
A
- Ciprofloxacin
- Levofloxacin
- Moxifloxacin
- Norfloxacin
11
Q
List the 5 AGs.
A
- Amikacin
- Gentamicin
- Kanamycin
- Neomycin
- Tobramycin
12
Q
List the 1 monobactam.
A
- Aztreonam
13
Q
List the 3 carbapenems.
A
- Ertapenem
- Imipenem
- Meropenem
14
Q
List the 5 macrolides.
A
- Azithromycin
- Clarithromycin
- Erythromycin
- Clindamycin
- Dirithromycin
15
Q
List the 5 other major ABX.
A
- Vancomycin
- Rifampin
- Doxy/tetracycline
- Linezolid
- TMP-SMX
16
Q
What organisms are commonly associated with HEENT infections (pharyngitis, acute bronchitis, acute sinusitis, chronic sinusitis)?
A
Pharyngitis: viral, GAS
Acute bronchitis: viral
Acute sinusitis: viral, S. Pneumo, H. influenzae, M. catarrhalis
Chronic sinusitis: S. aureus, anaerobes
17
Q
What organisms are commonly associated with Lung infections (CAP, atypical CAP, HAP, aspiration pneumonia)?
A
CAP: S. pneumo (60%), H. influenzae (15%), M. cattarhalis (same as acute sinusitis)
Atypical: mycoplasma, Chlamydia pneumoniae/psittaci, Legionella, influenza, adenovirus, parainfluenza virus, RSV
HAP: E. coli, pseudomonas, S. aureus
Aspiration: oral anaerobes, GN rods, S. aureus
18
Q
What organisms are commonly associated with Cardiac infection (subacute endocarditis, acute endocarditis)?
A
Subacute: S. viridans (other GP)
Acute + IVDU: S. aureus, GN rods, enterococcus, yeast
Prosthetic: S. epidermidis
19
Q
What organism are commonly associated with Abdominal infections (gastroenteritis, intra-abdominal)?
A
Gastroenteritis: viral, Salmonella, Shigella, E. coli, Clostridium botulinum, Giardia, Helicobacter, Campylobacter
Intra: enterococcus, B. fragilis, E. coli
20
Q
What organisms are commonly associated with Skin infections?
A
S. aureus, GAS (pyogenes), C. perfringens, candidiasis
21
Q
What organisms are commonly associated with Bone infections?
A
S. aureus Coag-negative Staph Gonococcal arthritis (young adults) Salmonella Pseudomonas (sickle cell)
22
Q
What organism are commonly associated with GU infections?
A
E. coli (80%) S. saprophyticus Enterococcus Klebsiella Proteus Pseudomonas Enterobacter Yeast (candida)
23
Q
List 3 reasons why a particular antibiotic regiment may fail.
A
- Incomplete coverage of the infection
- Resistance
- Non-compliance
24
Q
List 16 infectious diseases that are potentially life-threatening.
A
- Diphtheria
- Hepatitis B and C
- HIV
- TB
- Viral hemorrhagic fevers
- Meningococcal disease
- Plague (Y. pestis)
- Rabies
- Anthrax
- Influenza
- MMR
- Pertussis
- SARS-CoV
- Smallpox
- Vaccinia
- Varicella
25
List 6 general clinical risk factors for nosocomial infection.
1. Immunocompromise
2. Immunosuppressive drugs
3. Extremes of age
4. Compromise of skin/mucosal surfaces secondary to:
- Drugs
- Irradiation
- Trauma
- Invasive procedures
- Invasive indwelling devices
5. Broad-spectrum ABX
6. Immobilization
26
Risk factors for UTI?
```
Females
Sexual intercourse
Pregnancy
Indwelling urinary catheters
Hx of UTIs
DM
Spinal cord injury
Immunocompromised
Structural/functional abnormality
Foreskin
Anal intercourse
```
27
Clinical features of UTI?
Dysuria, frequency, urgency, suprapubic tenderness, gross hematuria
28
Presentation of typical CAP?
Acute onset fever, shaking chills, cough productive of thick, purulent sputum, pleuritic chest pain, dyspnea
Tachycardia, tachypnea, late inspiratory crackles, bronchial breath sounds, increased tactile and vocal fremitus, dullness on percussion, pleural friction rub
29
Presentation of atypical CAP?
Insidious onset, headache, sore throat, fatigue, myalgias, dry cough, fevers
Pulse/temperature dissociation (normal pulse with high fever), wheezing/rhonchi/crackles
30
Compare CXR of typical vs. atypical CAP.
Typical: lobar consolidation
Atypical: diffuse reticulonodular infiltrates
31
Most common organisms causing intravascular device-related bacteremias?
S. aureus, S. epidermidis
32
Most common organisms causing cellulitis?
GAS, S. aureus
33
Presentation of cellulitis?
Inflammatory condition of the skin and subcutaneous tissue with erythema, warmth, pain, swelling, fever
34
Most common cause of erysipelas?
GAS
35
Presentation of erysipelas?
Well-demarcated fiery red painful lesion, high fever, chills; confined to the dermis and lymphatics
36
Common causes of necrotizing fasciitis?
GAS, C. perfringens
37
Which has a higher risk of infection - PICC or central line?
Central line
38
Common causes of central-line associated bloodstream infections?
Coag-negative staph, S. aureus, candida, enterococcus
39
When are empiric antibiotics indicated in a possible hospital-acquired infection?
Unstable patient
Sepsis
Neutropenia
Significant immunocompromise
40
List the top 8 pathogens for hospital-acquired infections.
1. S. aureus
2. Enterococcus
3. E. coli
4. Coag-negative staph
5. Candida
6. K. pneumonia/oxytoca
7. P. aeruginosa
8. Enterobacter
41
Empiric therapy for central line associated bloodstream infection (CLABSI)?
Vancomycin (also remove the line)
42
Empiric therapy for CAUTI?
Ceftriaxone 1 g IV
| If pseudomonas is suspected, use Ceftazidime
43
Empiric therapy for pneumonia (VAP, HAP, HCAP)?
Levofloxacin
Other reasonable options include ceftriaxone, unasyn, and ertapenem
If concern for resistant GN rods, use Zosyn (pip/tazo)
44
Empiric treatment for C. difficile infection?
Oral metronidazole or oral vancomycin
45
Prophylactic treatment for surgical site infection?
Cefazolin
46
SIRS?
2+ of the following:
RR>20
HR>90
T>38 C or <36 C
WBC >12K, <4K, or if >10% bandemia
47
Sepsis?
SIRS + suspected source of infection
48
Which types of shock have cool extremities?
Cardiogenic
| Hypovolemic
49
Which types of shock have warm extremities?
Septic shock
50
Septic shock?
Sepsis
Persistent hypotension requiring vasopressors to maintain a MAP of 65+
Serum lactate >2 mmol/L (18 mg/dL)
All despite adequate volume resuscitation
51
qSOFA?
GCS <15 (AMS)
Systolic BP <100
RR 22+
52
Which type of shock presents with bradycardia rather than tachycardia?
Neurogenic shock (associated with severe SC/CNS injury)
53
Best immediate treatment for sepsis?
Fluid challenge/bolus (typically 10-30 cc/kg) or NS or LR over 30 minutes
54
Empiric treatment for patients with life-threatening sepsis?
IV Vancomycin + Zosyn + Aztreonam
55
True or false - gram positive organisms account for most cases of sepsis, but gram negatives are responsible for the majority of UTI_associated sepsis.
True
56
Most likely causes of community-acquired UTI-associated sepsis?
E. coli, Klebsiella, Proteus (nitrite + on UA)
57
Empiric antibiotic treatment of community-acquired UTI-associated sepsis?
TMP-SMX
If community resistacne exceeds 10%, treat with a FQ.
Ampicillin may still be effective, but high resistance rates preclude treatment as empiric first-line therapy.
3rd and 4th generation cephalosporins are also good choices (broad GN and partial GP coverage)
Consider AG if Pseudomonas is possible
58
In general, what are empiric antibiotics indicated for a suspected GN negative source?
```
Third- or fourth-generation cephalosporin
Pip/tazo
Ticarcillin/clavulanate
Imipenem/meropenem
Aztreonam
```
Add AG if immunocompromised
59
Normal opening pressure range (CSF)?
60-200 mmH2O
60
CSF opening pressure above ___ mm H2O are diagnostic of what?
250; intracranial hypertension
61
Normal CSF color?
Crystal clear
62
Orange CSF?
Rifampin
63
What is xanthochromia and what does it indicate?
Orange-brown discoloration of the CSF resulting from the presence of Hgb breakdown products
In a patient WIHTOUT jaundice, this raises suspicion of occult intracranial hemorrhage (subarachnoid)
64
Presence of RBCs in CSF?
- Intracranial hemorrhage
| - Nicking of a dural blood vessel when advancing the needle
65
How can a traumatic tap be ruled out?
CSF fails to clear (if traumatic tap, the CSF should become progressively clearer and tests for xanthochromia should be negative)
66
Presence of WBCs in CSF?
Monocytes are normal WBCs in the CSF, should only be present in low numbers
>5 WBCs/mL is abnormal, as is the presence of neutrophils (suggest bacterial infection)
67
Typical ratio used to determine the # of WBCs that can be accounted for by a traumatic tap is?
1 WBC for each 500 RBCs
68
Increased protein in the CSF?
Found when cells are dying and decaying (intracerebral bleed, demylination, tumor invasion, infection)
NON-SPECIFIC FINDING
69
Typical ratio used to determine the amount of protein accounted for by a traumatic tap?
1 g/dL protein for each 1,000 RBCs
70
CSF glucose?
When infection or inflammation disrupt the activity of glucose transport pumps, CSF glucose declines below normal levels
Hypoglycorrhachia - depression of CSF glucose below 40% of the simultaneous serum value
71
GP diplococci in CSF?
S. pneumonia
72
GP bacilli in CSF?
L. monocytogenes
73
GN diplococci in CSF?
N. meningitidis
74
GN bacilli in CSF?
E. coli or Pseudomonas
75
GN coccobacilli in CSF?
H. influenzae
76
Compare opening pressure in bacterial vs. viral vs. fungal vs. tubercular meningitis.
B - elevated
V - usually normal
F - variable
T - variable
77
Compare WBC count in bacterial vs. viral vs. fungal vs. tubercular meningitis.
B - 1000+ per mm^3
V - <100/mm^3
F - variable
T - variable
78
Compare cell differential in bacterial vs. viral vs. fungal vs. tubercular meningitis.
B - PMN predominance
| V/F/T - Lymphocyte predominance
79
Compare protein levels in bacterial vs. viral vs. fungal vs. tubercular meningitis.
B - mild to marked elevation
V - normal to elevated
F/T - elevated
80
Compare CSF:Serum glucose ratio in bacterial vs. viral vs. fungal vs. tubercular meningitis.
B - normal to marked decrease
V - usually normal
F/T - low
81
When is contact isolation indicated?
Infections spread by fecal-oral route or skin colonization
82
When is droplet isolation indicated?
Pathogens spread through close respiratory or mucous membrane contact with respiratory secretions
Does NOT require special air handling/ventilation; wear a mask
Pertussis, N. meningitidis, GAS
Influenza, adenovirus, rhinovirus
83
When is airborne isolation indicated?
Pathogens that remain infectious over long distances when suspended in the air
Smallpox, measles, varicella, TB, SARS/MERS
84
What is Brudzinski's sign?
Increased pain and involuntary flexion of the legs at the hip and knee with passive neck flexion
85
What is Kernig's sign?
Increased neck pain and resistance to extension of the knee when the hip is flexed at 90 degrees
86
DDx - Vomiting + Photophobia + Headache without Localizing Neurologic Deficits
1. Bacterial/viral meningitis
2. Subarachnoid hemorrhage
3. Migraine
Less likely:
4. CVA
5. Cerebral vasculitis
6. Intracerebral abscess
7. Temporal arteritis
8. Tension and cluster headache
9. Toxo
10. Primary CNS lymphoma
87
Presentation of meningitis?
Acute onset of headache after a prodromal illness, associated fever, photophobia, N/V, meningismus
88
Presentation of subarachnoid hemorrhage?
"Worst headache of my life"
Vomiting
[Meningeal signs/fever/photophobia may be present, but uncommon]
89
Empiric treatment of suspected bacterial meningitis?
ABX within 1 hour: empiric vancomycin + third-generation cephalosporin; add ampicillin if 50+, hx alcohol abuse, and/or immunocompromise
Corticosteroids (dexamethasone): significant protection against death and neurologic sequelae (subgroup analysis shows this benefit only exists when S. pneumonia was the cause)
90
Indications for head imaging prior to LP to evaluate for brain shift and herniation risk?
Clinical signs of increased ICP/cerebral edema, patients with confusion, decreased level of consciousness, focal neuro abnormalities, associated head trauma, recent seizures
Historical risk factors: immunosuppressed patients, history of stroke, history of space-occupying lesion
91
Indications for urgent LP?
Bacterial meningitis
| Subarachnoid hemorrhage
92
Common causes of bacterial meningitis?
Adults: N. meningitidis, S. pneumonia
>50: also L. monocytogenes and aerobic GN bacilli
Alcohol abuse/immunocompromise: H. influenzae
93
Treatment of endocarditis?
Empiric treatment: vancomycin or Unasyn + AG +rifampin IF prosthetic valves
If non-hemolytic strep (likely enterococcus): uniformly resistant to penicillin, treat with ampicillin, AG, or vancomycin
Beta-lactams + AG -> bacteriocidal synergy
94
Rx cellulitis?
Without an ulcer - coverage for staph and strep is reasonable (oral/parenteral beta-lactams, 1st gen cephalosporin, clinda)
If complicated/contaminated infection - broad-spectrum to cover anaerobes, pseudomonas, bacteroides
95
Rx HSV meningitis?
Acyclovir
