Infectious Diseases Flashcards
(171 cards)
1
Q
Ceftaroline Generation
A
5th gen
2
Q
Ceftriaxone Generation
A
3rd gen
3
Q
Cefepime Generation
A
4th gen
4
Q
Cephalexin Generation
A
1st gen
5
Q
Cefuroxime Generation
A
2nd gen
6
Q
Cefprozil Generation
A
2nd gen
7
Q
Cefazolin Generation
A
1st gen
8
Q
Cefoxitin Generation
A
2nd gen
9
Q
Ceftazidime Generation
A
3rd gen
10
Q
Cefotaxime Generation
A
3rd gen
11
Q
Ceftobiprole Generation
A
5th gen
12
Q
Normal flora of the upper respiratory tract?
A
- Streptococci
- S. Aureus (nose)
- Neisseria
- Haemophilus
13
Q
Normal flora of the skin?
A
- Staphylococcus
- Micrococcus
14
Q
Normal flora of the mouth?
A
- Streptococci
- Candida
15
Q
Normal flora of the intestines?
A
- Bacteroidetes (bacteroides)
- Firmicutes (lactobacillus + clostridium)
- Actinobacteria (bifidobacterium)
- Proteobacteria (enterobacteriaceae)
- Candida
16
Q
What is the Minimum Inhibitory Concentration (MIC)?
A
The lowest concentration of antibiotic at which there is no visible growth.
17
Q
What is time dependent killing?
A
The duration of time the concentration of the drug is above the MIC is important for antibacterial effect.
18
Q
What is concentration dependent killing?
A
The ratio of the drug exposure to the MIC (AUC/MIC) is important for antibacterial effect.
19
Q
Gram negative bacteria?
A
- all pseudomonas
- E. coli
- Salmonella
- klebsiella pneumoniae
- Neisseria
- enterobacter aerugenes
- (bonus) - Serratia sp., acinetobacter, xanthomonas, zymomonas, pantoea, vibrio cholera
20
Q
Gram positive bacteria?
A
- All staph and strep
- Bifidobacterium
- mycobacterium tuberculosis
- enterococci
- clostridium botulinum.
- (bonus) - lactic acid bacteria, anthrax, hemolytic bacteria
21
Q
Which drugs are beta-lactams (by class)?
A
Penicillins, cephalosporins, carbapenems.
22
Q
Beta-lactams MOA?
A
Cell-wall inhibitor.
23
Q
Drugs that act on cell walls typically have good activity against gram positive or gram negative bacteria?
A
Good gram-positive activity!
24
Q
What does gram stain tell us about the thickness of the cell wall?
A
Gram positive = thick cell-wall
Gram negative = thin cell-wall
25
Penicillin VK/Penicillin G coverage?
Very narrow spectrum. Poor coverage of gram-negatives.
26
Cloxacillin coverage?
Very narrow spectrum. Effective against staph sp.
27
Amoxicillin/Ampicillin coverage?
Narrow-ish spectrum (broader than penicillin and cloxacillin), effective against Strep and Enterococcus, intermediate against Staph.
28
How does resistance to beta-lactam's develop? what causes the resistance?
resistance develops when antimicrobials are used inappropriately.
Resistance is caused by beta-lactamases.
29
Examples of beta-lactamase inhibitors?
Clavulanic acid, tazobactam, sulbactam
30
What types of bugs tend to produce beta-lactamases?
Generally gram negative bacteria produce them.
31
Amoxicillin spectrum?
Streptococci, enterococci, non-beta-lactamase producing organisms (e. coli, K. pneumoniae, H. influenzae)
32
Amoxicillin/Clavulanate spectrum?
Streptococci, Enterococci, Staphylococcus (not MRSA), anaerobes, some gram-negatives + beta-lactamase producing.
33
Cephalosporins 1st and 2nd gen coverage (Gram positive vs gram negative coverage)?
Better gram-positive coverage, weaker gram-negative coverage.
34
3rd and 4th generation coverage (gram positive vs gram negative)?
Better gram negative coverage, weaker gram positive coverage.
35
5th gen cephalosporins coverage?
Good for both gram positive and gram negative.
36
Where do fluoroquinolones work?
inside the cell - inhibit RNA and DNA synthesis.
37
Fluoroquinolones MOA?
Inhibit DNA topoisomerase.
38
When are fluoroquinolones used?
They are broad-spectrum and are typically reserved for treatment failure or allergy.
39
Examples of fluoroquinolones?
Ciprofloxacin, moxifloxacin, levofloxacin.
40
Clinical Pearl: When thinking of urinary bugs, which FQ should be used?
Ciprofloxacin.
Can be used for gram-negative aerobes (E. coli, Klebsiella) and pseudomonas (notable gram-negative bug)
41
Clinical Pearl: when thinking of respiratory bugs, which FQ should be used?
Moxifloxacin, Levofloxacin.
Used for enteric gram-negatives, S. pneumoniae (MSSA), pseudomonas (levofloxacin only), anaerobes (moxifloxacin only).
42
Where do tetracyclines work?
inside the cell.
43
What are some tetracyclines?
Doxycycline, Minocycline, Tetracycline.
44
Tetracycline MOA?
Bind bacterial ribosome and inhibits proteins synthesis.
45
Tetracyclines bug coverage?
- broad spectrum coverage of gram-positive organisms (but increasing resistance)
- good coverage of atypicals
- moderate coverage of MRSA, S. pneumoniae
- NOT FOR Group A Strep (S. pyogenes)
46
Do macrolides work inside the cell or outside?
Inside the cell.
47
Macrolides MOA?
Bind bacterial ribosome + inhibits protein synthesis.
48
Examples of macrolides?
Clarithromycin, Azithromycin, erythromycin.
49
Macrolides coverage?
- Broad coverage of respiratory bugs BUT high resistance rates.
- Good coverage of atypical and less-common respiratory bugs.
- Only moderate coverage of S. pneumoniae (high rates of resistance).
50
Where does Clindamycin work?
Inside the cell.
51
Examples of lincosamides?
Clindamycin
52
Clindamycin MOA?
Bind bacterial ribosome and inhibits protein synthesis.
53
Clindamycin coverage?
- Good for gram-positive anaerobes, S. pyogenes
- useful in penicillin allergic patients
- Moderate coverage for S. aureus, including MRSA (increasing resistance)
54
Clinical Pearl: What are we concerned about with macrolides?
Drug interactions - ALWAYS check.
55
What is clindamycin notable for?
High rates of antibiotic-associated diarrhea and C. difficile diarrhea.
56
Example of Folate Antagonists?
Sulfamethoxazole/Trimethoprim
57
Sulfamethoxazole/Trimethoprim MOA?
inhibits folate synthesis which is required for DNA synthesis.
58
Sulfamethoxazole/trimethoprim bug coverage?
- S. aureus, including MRSA
- Gram-negative bacilli (E. coli, K. pneumoniae) - UTIs!
59
Sulfamethoxazole/trimethoprim use?
Used less often as first line therapy due to unpredictable resistance. Culture is usually required.
60
Azolidines (class) drug?
Nitrofurantoin
61
Nitrofurantoin MOA?
Nitrofurantoin is metabolized to toxic metabolite in bacteria.
62
Nitrofurantoin elimination?
It is eliminated rapidly by the kidneys and moves to the bladder quickly.
63
Nitrofurantoin coverage?
- Used predominantly for UTIs. Excellent coverage of common UTI bugs (E. coli).
64
Fosfomycin MOA?
Inhibits bacterial wall synthesis.
65
Fosfomycin use?
One main use: UTIs.
66
Fosfomycin bug coverage?
E. coli
67
What antibiotic is a glycopeptide?
Vancomycin.
68
Vancomycin MOA?
Cell-wall inhibitor.
69
Vancomycin coverage?
- gram-positive only
- MRSA, Enterococcus, Staphylococcus
70
Vancomycin concerns?
ototoxicity, nephrotoxicity, infusion-related reactions
71
What needs to be done when a patient is on vancomycin?
Therapeutic drug monitoring.
72
What antibiotics cover MRSA? (11)
- ceftaroline
- tetracycline
- doxycycline
- minocycline
- SMX/TMP
- clindamycin
- vancomycin
- daptomycin
- linezolid
- fosfomycin
- rifampin
73
What antibiotics are anti-pseudomonals? (12)
- Piperacillin-tazobactam
- ceftazidime
- cefepime
- imipenem-cilastatin
- meropenem
- aztreonam
- ciprofloxacin
- levofloxacin
- gentamicin
- tobramycin
- amikacin
- colistimethate
74
What drugs are aminoglycosides?
Gentamicin, Tobramycin, amikacin
75
Aminoglycosides MOA?
bind irreversibly to the 30S subunit of the bacterial ribosome, which results in inhibition of protein synthesis and induction of translational errors (sorry its long).
76
Aminoglycosides coverage?
- gram-negative coverage (Pseudomonas, E. coli, klebsiella)
77
Aminoglycosides excretion?
High urine concentration (70% excreted unchanged)
78
What can we add to aminoglycosides to work synergistically?
Antibiotics that work on the cell wall.
79
What are we worried about with aminoglycosides?
Ototoxicity, nephrotoxicity
80
What must be done with aminoglycosides?
Therapeutic drug monitoring
81
What is valacyclovir commonly used for?
HSV - treatment or prophylaxis
Varicella-zoster virus (VSV) - treatment
82
What is acyclovir commonly used for?
HSV - treatment
83
What is oseltamivir used for?
Influenza - only in specific cases
84
What is Nirmatrelvir-Ritonavir used for?
COVID-19
85
Metronidazole MOA?
Activated by anaerobic bacteria and protozoa into free radicals which cause DNA damage and eventually cell death.
86
Metronidazole use?
think of it as the "antibiotic scavenger". Covers organisms that other large classes don't.
Good coverage of anaerobes, but poor coverage of aerobic.
87
Two types of antifungals?
Azoles and polyenes
88
What is an important target for antifungal drugs? Why?
Ergosterol because it is an important component of fungal cell membranes.
89
Azole antifungal MOA?
Inhibit ergosterol production in cell membrane.
90
What are some examples of azole antifungals?
Fluconazole, clotrimazole, ketoconazole
91
What is important to note about azole antifungals?
MANY drug interactions when taken orally.
92
What is an example of a polyenes drug?
Nystatin
93
Nystatin MOA?
bind to ergosterol leading to leakage of cell membrane.
94
What species is fluconazole active against?
Candida
95
Which bacteria are considered "atypicals"?
* mycoplasma pneumoniae
* chlamydia pneumoniae
* legionella pneumoniae
96
What class is used to treat atypical infections?
Macrolides.
97
What are the predominant organisms in AOM?
M. cattarhalis, S. pneumoniae, H. influenzae.
98
Rationale for high-dose amoxicillin in AOM?
overcome penicillin binding protein resistance of causitive organism.
99
AOM diagnostic criteria?
- acute (< 48H) onset of sxs
- middle ear fluid
- TM bulging OR acute perforation with purulent discharge
100
Criteria for watchful waiting for AOM?
- >6m
- mild illness
- present within 48H of onset of ear pain
- have not had AOM in previous month + not recurrent
- no cochlear implants or other hearing impairment
- no hx of another condition that could make recovery more difficult
101
Standard amox dose for AOM? high dose?
Standard: 45-60 mg/kg/day divided TID
High: 80-90 mg/kg/day divided BID or TID
102
Who should get high dose amox for AOM?
those suspected to have resistant S. pneumoniae or if failed standard dose.
103
Risk factors for resistant S. pneumoniae?
- < 2 yrs old
- daycare (or family in daycare)
- any abx exposure within 3 months
- under-vaccinated or unvaccinated
104
What is the criteria for alternative therapy (i.e., not amoxicillin)?
- used amoxicillin in previous 30 days
- hx of AOM unresponsive to amoxicillin (treatment failure)
- concurrent purulent conjunctivitis (likely H. influenzae or M. catarhalis)
- immunocompromised
105
What are the two gram negative bugs that can be seen in AOM that can develop beta lactamase resistance?
H. influenzae and M. catarrhalis
106
What are the alternative antibiotic regimens in AOM? (i.e., when cannot give amoxicillin)
- 2nd gen cephalosporins (cefuroxime, cefprozil)
- amoxicillin-clavulanate
107
How is treatment failure in AOM defined?
no symptomatic improvement in 2-3 days with proper treatment
108
What are the 2 reasons for treatment failure in AOM?
- wrong drug (need broader spectrum)
- dose too low (high dose amox regimen)
109
What are we concerned about with the clavulanate portion with amoxi-clav dosing?
clavulanate can cause bad diarrhea (dose dependent)
110
When is 5 days of treatment for AOM appropriate?
- uncomplicated infection
- greater than or equal to 2 years of age
** most patients**
111
When is 10 days of treatment for AOM appropriate/necessary?
- child less than 2 years of age
- perforated TM
- recurrent AOM
- failed initial therapy
- high risk children
112
How long can effusion persist after AOM infection?
50% of patients will have effusion remaining after treatment and can persist up to weeks
** does not mean treatment failure
113
What bacteria are commonly associated with community acquired pneumonia (CAP)?
- streptococcus pneumoniae
- haemophilus influenzae
- mycoplasma pneumoniae
114
What classifies early hospital acquired pneumonia and what bugs are common?
< 4 days hospitalization
same bugs as CAP (S. pneumoniae, H. influenzae, M. pneumoniae)
115
What classifies late hospital acquired pneumonia and what bugs are common?
> 4 days hospitalization
Klebsiella, E. coli, Enterobacter
116
What classifies "later" hospital acquired pneumonia and what bugs are common?
<3 months
pseudomonas aeruginosa, acinetobacter, S. aureus/MRSA
117
What needs to be considered when hospital acquired pneumonia is suspected/confirmed?
duration of hospital stay
impacts the potential bugs involved
118
With pneumonia the causative organism can be affected by certain factors and disease states - what are some examples of these factors/states that might make us have to change empiric therapy?
- heart, lung disease (COPD), diabetes
- recent antibiotics within the last 3 months
- aspiration pneumonia, cystic fibrosis
119
Signs and symptoms of community acquired pneumonia?
- up to 50% of patients report URTI
- abrupt onset of: fever, chills, dyspnea, cough (prod or non prod), rust colored sputum or hemoptysis, pleuritic chest pain
120
What will a physical exam for a patient with community acquired pneumonia look like?
- tachypnea (quick shallow breathing)
- tachycardia
- dullness to percussion (could indicate consolidation)
- diminished breath sounds over affected area
- inspiratory crackles
- low oxygen saturation
121
What does a beta lactamase do to a penicillin molecule?
disrupts the beta-lactam portion (destroys the beta-lactam ring)
results in an inactivated drug that cannot kill the bacteria
122
What is recommended in all adults to confirm suspected pneumonia?
chest x-ray
will see pulmonary infiltrates or consolidation
123
What bloodwork is recommended to diagnose pneumonia?
- CBC, lytes, liver function, renal function
- arterial blood glass
- sputum sample (may reveal PMNs and causative organism)
- blood culture
124
For a patient to be diagnosed with CAP they must have:
- infiltrate on CXR
- at least one respiratory symptom (new or increased cough, new or increased sputum, dyspnea, pleuritic chest pain)
- at least one other sign/symptom (fever >38C, leukocytosis, hypoxia (O2 SAT <90%)
125
What are 2 risk severity assessment tools for pneumonia?
- pneumonia severity index (PSI)
- CRB-65 (simpler to use)
126
What does CRB-65 tell us?
WHERE a patient should receive treatment (outpatient, inpatient, etc) - not if they should receive treatment
127
What are some comorbidities or risk factors for resistant S. pneumonia?
- age>65 years
- cardiac, pulmonary, renal or hepatic failure,
- smoking, alcoholism
- diabetes, malignancy
- malnutrition/acute weight loss
- immunosuppressive treatment
128
What is empiric treatment for pneumonia?
High dose amoxicillin (1000mg TID)
- no atypical coverage (need to add a second drug (macrolide) if you think your patient needs this)
129
What type of pneumonia patients is amoxicillin. monotherapy appropriate for?
healthy patients with no recent antibiotic use
130
What are the atypicals we need to cover for in pneumonia?
Mycoplasma pneumoniae
Chlamydia pneumoniae
131
Who does Mycoplasma pneumoniae usually affect?
- young healthy patients
- resolves without antibiotics
- "walking pneumonia"
132
Who does chlamydia pneumoniae usually affect?
affects patients in long-term care, immunocompromised or have multiple comorbidities
133
When are macrolides (azithromycin and clarithromycin) used in pneumonia?
- used in combination with beta-lactam for atypical coverage
- s. pneumoniae coverage, but high resistance so monotherapy is not recommended
134
When is doxycycline used in pneumonia patients?
- may be used in patients with a beta-lactam allergy or other comorbidities/risk factors for resistant S.pneumoniae
- or if someone couldn't adhere to two medications
- doxy has atypical and gram negative coverage and is not associated with S. pneumoniae resistance
135
When is Amoxi/Clav used in pneumonia?
- patients with comorbidities (heart, lung disease, DM) are at increased risk of having gram negative, atypical infections along with S. pneumoniae so a broader spectrum antibiotic is needed for additional organism coverage (beta-lactamase inhibitor has increased spectrum of activity for gram negatives)
- this has no atypical coverage
136
When are fluoroquinolones used in pneumonia?
levofloxacin and moxifloxacin reserved for:
- treatment failure
- comorbidities with recent antibiotic use
- allergies
- documented highly drug-resistant bacteria
137
Duration of therapy for treatment of pneumonia
- traditionally thought to be 7-10 days but recent RCTs have shown similar cure rates with shorter duration
- patients require a minimum of 3 days (typical durations 3-5 days)
- longer durations are seen with complex pneumonia (like abscess)
138
Types of Lower UTIs
- bladder infection (cystitis)
- urethral infection (urethritis)
139
Types of upper UTIs
- kidney infection (pyelonephritis)
- ureter infection (ureteritis)
140
Uncomplicated UTI classification
- no structural or functional abnormalities
- immunocompetent host
- female
- no recent instrumentation/catheterization
141
Uncomplicated UTI etiology
- E.coli (gram neg) - 80-90% infections
but also...
- K. pneumoniae (gram-neg)
- K. ocytoca (gram neg)
- Proteus spp. (gram neg)
- Enterococcus (gram pos)
142
Complicated UTIs etiology
- E.coli (50% infections)
- Enterobacter spp. (gram neg)
- Pseuomonas aeruginosa (gram neg)
- Staph aureus (gram pos)
143
What are some risk factors for developing a UTI?
- age (older age)
- gender (female)
- recent sexual intercourse
- diabetes
- pregnancy
- renal disease
- structural or functional urologic abnormalities (indwelling catheter, neurologic dysfunction, vesicoureteral reflux, incomplete bladder emptying)
- urinary tract obstruction (including drugs like anticholinergics)
- diaphragms/spermicides
144
What are some classic signs and symptoms of uncomplicated cystitis?
- dysuria (painful or difficult urination)
- frequency (urinating often)
- nocturia (nighttime urination)
- urgency (the feeling of needing to urinate)
- suprapubic pain (pain or discomfort in the lower abdomen)
- gross hematuria (blood in the urine)
- absence of vaginal discharge (presence could indicate vaginitis)
NO systemic illness (fevers, chills, vomiting)
145
Classic signs and symptoms of pyelonephritis?
- flank pain (pain in the lower back)
- fever/chills
- nausea/vomiting
- malaise
146
How might UTIs present differently in an older adult?
- altered mental status/confusion
- change in eating habits
- GI symptoms
- but can still exhibit other classic symptoms too
147
What are the two components of a urine dipstick test?
- leukocyte esterase test (enzyme in neutrophils)
- nitrate reductase test (common urinary tract pathogens will convert nitrate to nitrite -- E.coli will produce nitrites)
148
What information does a urinalysis (UA) tell us?
- microscopic examination of urine (color, clarity, specific gravity)
- presence of protein, glucose, RBCs, WBCs, bacteria and epithelial cells
- increased suspicion of infection if pyuria (>10 WBC/mm3, bacteriuria 10^8 CFU/L) ** without pyuria unlikely to have UTI
149
What does urine culture tell us?
- takes 24-48 hours for results
- tells us gram stain, quantity of bacteria, identification of organism, suceptibility
150
What quantity of bacteria is indicative of a UTI?
10^5 - 10^8 CFU/L
151
What is asymptomatic bacteriuria?
when patients have a positive urine culture but NO symptoms
152
Who is asymptomatic bacteruria common in?
- elderly patients, like long term care
- chronic catheter
153
Who do we treat for asymptomatic bacteruria?
- pregnant women
- children
- patients who will undergo urologic procedures
154
Nitrofurantoin Efficacy Safety and Convenience in UTIs
Efficacy: 97% susceptible to E.coli
- ineffective if CrCl < 30 mL/min
Safety: well tolerated, pregnancy considerations
Convenience: cheap, BID dosing with MacroBID
155
SMX/TMP efficacy, safety and convenience with UTIs
Efficacy: ~20% E.coli resistance
Safety: well tolerated, renal dose adjustment
Convenience: BID
156
Fosfomycin efficacy, safety and convenience in UTIs
Efficacy: good susceptibility but want to reserve for more resistant bugs, broad spectrum
Safety: CI in renal dysfunction
Convenience: single dose
157
What do we need to consider when selecting an agent for uncomplicated pyelonephritis?
- need to consider if the medication will penetrate the kidney
- nitrofurantoin and fosfomycin - do not use for pyelonephritis as does not provide adequate renal tissue concentrations
158
Duration of therapy of SMX/TMP in uncomplicated cystitis?
3 days
159
Duration of therapy of nitrofurantoin in uncomplicated cystitis?
5 days
160
Duration of therapy in uncomplicated pyelonephritis?
10-14 days
161
Empiric Therapy Options for Uncomplicated Pyleonephritis - IV therapies
- Ceftriaxone
- Ampicillin
- Amoxi-Clav
- Ciprofloxacin
- Aminoglycosides
162
Empiric Therapy Options for Uncomplicated Pyleonephritis - Oral Therapies
- Amoxi-Clav
- Cefixime
- Ciprofloxacin
163
What do we avoid as empiric monotherapy in UTIs due to increasing resistance?
beta lactams
(need culture and sensitivity to confirm susceptibility)
164
Which two antibiotics for uncomplicated pyelonephritis should not be used if no culture result is available?
SMX/TMP
Cephalexin
165
Why is UTI common in pregnancy?
because body changes predispose to infection:
- dilation of renal pelvis and ureters
- decreased ureteral peristalsis
- reduced bladder tone
166
What if asymptomatic bacteriuria is untreated in pregnant patients?
prematurity, low birth weight, and still birth
- routine screening is part of pre-natal care
167
If a pregnant patient is positive for asymptomatic bacteriuria how long do we treat?
treat for 3-7 days and follow up culture to document eradication
168
First line treatment for UTI in pregnancy
- cephalexin (7 days)
- amoxicillin (7 days)
- nitrofurantoin (5 days) (avoid >36-38 weeks GA)
169
Second line treatment for UTI in pregnancy
- TMP/SMX or TMP (avoid in first trimester and in last 6 weeks of pregnancy)
170
UTI in Males
- traditionally considered complicated infections
- may need to consider prostatitis (prostate infection)
- same antibiotics, as long as no prostate involvement
- longer duration of therapy (7 days)
171
Finished short snappers
