Pneumonia
IDSA recommended empiric abx regimen for non-severe inpatient pneumonia
What is B-lactam + macrolide or respiratory FQ
The most predominant uropathogen found in UTI
What is E. coli.
According to the National Kidney Foundation, 80 to 90 percent of UTIs are caused by E. coli
This is/are the most predominant pathogen in purulent SSTI
What is S. aureus or S.pyogenes
Typical duration of abx therapy for gram negative bacteremia
What is 7 days
Abx classes with concentration dependent killing property (at least 2)
What are aminoglycoside, fluoroquinolones, daptomycin, metronidazole
Two major criteria for defining severe CAP
What are
-Septic shock with need for vasopressor
-Respiratory failure requiring mechanical ventilation
Diagnostic criteria for UTI
What is urinary symptoms + presence of bacteria (UA, UCx)
IDSA guideline recommends against treating asymptomatic UTI with antibiotics
The reason erythema can worsen upon initiation of effective antibiotic therapy for cellulitis
Toxins and/or bacterial lysis can drive inflammation even though abx has achieved bactericidal effect
Criteria for defining uncomplicated S. aureus bacteremia (at least 2)
-No indwelling devices (prosthetic heart valves or vascular grafts)
-Excluded IE via Echo
-Negative follow up BCx in 2 to 4 days after initiating IV anti-staph therapy and source control
-Defervesced within 48-72 hrs after initiation of IV anti-staph therapy and source control
-No evidence of metastatic staph infection
PD target for gentamicin or tobramycin
What is Cmax/MIC ≥ 8-10 mg/L
Bacterial pathogens covered in an empiric antibiotic therapy for CAP
What are Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, and atypicals
This oral abx is used to treat cystitis, but it is considered a poor choice for pyelonephritis as it does not achieve therapeutically active concentrations.
What is nitrofurantoin (Macrobid)
An antibiotic treatment option for non-purulent cellulitis in a patient with severe beta-lactam allergy unable to tolerate penicillins or cephalosporins
(Bonus pts if you can explain why this agent is not ideal)
Clindamycin
Due to increased resistance and risk of C. diff.
S. pyogenes: 56% susceptible
S. aureus: 79% susceptible to clindamycin
3 Enterobacterales with moderate to high risk for clinically significant AmpC production
What are Enterobacter cloacae, Klebsiella aerogenes, and Citrobacter freundii
A phenomenon where bacterial growth suppression continues despite a drug concentration falls below the MIC of the bacteria
What is Post-antibiotic effect
The reason ciprofloxacin is not considered as a respiratory fluoroquinolone.
Ciprofloxacin demonstrated poor potency against Streptococcus pneumoniae, and its use has been associated with the emergence of resistance.
Resp FQ (Moxi, Gemi, Levofloxacin) based on their very low minimum inhibitory concentrations (MICs) for S. pneumoniae
Two conditions where treatment of asymptomatic bacteriuria is recommended by IDSA 2019 guideline
What are
-Pregnancy
-Undergoing endoscopic urologic procedures
An alternative treatment option to clindamycin which is used to inhibit toxin production in necrotizing fasciitis and streptococcal toxic shock syndrome
What is linezolid
It has same MOA as clindamycin (binds to 50s subunit) and there are case studies with successful tx of necrotizing fasciitis with linezolid
Abx treatment option for Fulminant C. diff infection (absence of ileus)
What is vancomycin 500 mg PO QID + metronidazole 500 mg Q8h for 10-14 days
Formal definition of a bacteriostatic agent in term of MBC to MIC ratio
What is MBC/MIC > 4
The clinical features that warrant the addition of anaerobic coverage for aspiration pneumonia
What are Lung abscess/empyema, cavitary pneumonia
This is a relatively new antibiotic that was FDA approved in 2019 for a complicated UTI including pyelonephritis caused by susceptible gram negative bacteria for patients who have limited or no alternative treatment options. It is well known for its unique MOA as a ‘trojan horse’ and it can be used for HAP and VAP.
What is cefiderocol (Fetroja)
Cefiderocol is actively transported across the outer cell membrane of bacteria into the periplasmic space using a siderophore iron uptake mechanism
Antibiotic prophylaxis option for preventing recurrent cellulitis
What is PCN, cephalexin or erythromycin
Based on a systemic review, antibiotic prophylaxis reduced the risk of recurrent cellulitis compared to no antibiotic prophylaxis, with an RR of 0.46 (95% CI 0.26–0.79) in patients with a history of cellulitis.
Alternative regimen to ampicillin/PCN + gentamicin in treatment of Enterococcus IE if a patient that cannot tolerate gentamicin due to renal function. (Mechanism for a bonus point)
What is ampicillin + ceftriaxone
MOA: Saturation of different PCN binding proteins.
How does CLSI breakpoint of an antibiotic change over time
Breakpoint tend to decrease over time
Many CLSI breakpoints were set decades ago when antimicrobial resistance was less prevalent and less complex
Pseudomonas-Levofloxacin
2018 (S, ≤2; I, 4; R, ≥8) vs 2019 (S, ≤1; I, 2; R, ≥4)