Thread by @khalideljaaly

Two oral💊 antibiotics can be used for Pseudomonas aeruginosa👾: Ciprofloxacin (usually preferred) & levofloxacin. Typically, go with the high dose (750mg/dose).
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Beta-lactamase inhibitors (clavulanate,sulbactam,tazobactam) broaden activity spectrum of penicillins for MSSA, anaerobes, & more Gram-negatives (not pseudomonas). Sulbactam can be used for its activity against Acinetobacter baumannii. Clav cause > GI side effects
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Aminoglycosides active against several MDR Gram -ve but prefer combination (one exception: UTI). Used as adjunctive agent for Gram +ve as it does not penetrate cell wall to act on protein synthesis except when cell wall is opened by cell wall inhibitors (BL/vanco)
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Example of adjunctive aminoglycosides with G+ve👾 is Endocarditis💗:
1- Viridans group Streptococci: shorten Abx course for Pen-S, while added to b-lactam for Pen-R
2- S. aureus: No longer for NVE, but added for PVE⚙️
3- Enterococci: added to b-lactam as 1st line
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Beta-lactams
🖌Most effective & safe antibiotics (typically 1st line).
🖍The most important offending agent for drug allergy. Do not go to another class if allergy is mild & not IgE-mediated. Just choose BL with different side chain pharmacytimes.com/publications/h…
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Beta-lactams not used for MRSA except 2 (ceftaroline & ceftobiprole). None active vs atypical bacteria (legionella, mycoplasma./chlamydia. pneumoniae). Therefore, some countries for community-acquired PNA add macrolide or doxycycline (or fluoroquinolone alone)
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Cephalosporins
👾The Gram-ve activity increase from 1st to 4th generation (ceftazidime, ceftolozane & cefepime used for Pseudomonas)
👾Generally not used for Enterococci, minor differences with Streptococci
👾MSSA activity: 1st (& ceftar/ceftobip) > 2nd/4th > 3rd
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Carbapenems
👾Broad spectrum & drug of choice for ESBL
🔐Reserve them as much as you can. We suffer from CRE now. Also associated with high C. difficile🦠 risk & superinfection
💊💥💊Avoid use with valproate (serious level reduction)
🧠lower seizure with meropenem
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Vancomycin is the drug of choice for most MRSA👾 cases. However, it needs TDM📉& is less effective for MSSA so de-escalate as soon as possible. For some infections such as skin & soft tissue, you can use some PO💊 Abx if susceptible (TMP/SMX, doxycycline, clinda).
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Linezolid
👾For G+ve (MRSA, VRE)
💊Available PO
💊💥💊DDI: with adrenergic drugs (pseudoephedrine, norepinephrine)>>> hypertension🤯 & serotonergic drugs (SSRI)>>> serotonin syndrome🥵
🚨Beware of side effects >2wks: thrombocytopenia & periph neuropathy
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Nitrofurantoin
💊Only PO & for uncomplicated cystitis (even if ESBL)
👨🏼‍🦳No longer contraindicated if CrCl<60ml/min (can use up to 30ml/min)
💊Know the hospital formulation you have (usually, 50mg q6h while 100mg q12h)
🤰Avoid nearterm (hemolytic anemia)
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Co-trimoxazole (SMX/TMP: 5:1 ratio)
💊DS tab (800/160); 💉IV (400/80); dose based on TMP🧐
🚨No longer empiric 1st-line for UTI in most countries due to resistance
👾Uses: purulent skin/soft tissue infections (even MRSA); High doses for PCP/PJP & Stenotrophomonas
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Continued (co-trimoxazole)
🧐Side effects: hyperkalemia, allergy (common cause), SCr elevation, bone marrow suppression
🤰Pregnancy: debatable 1st term (neural tube effect; if must be used, give floc acid) & contraindicated near term (kernicterus); safe otherwise
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