FQ, sulfa, met/dapto

Fluoroquinolone overuse

Increases antibiotic resistance.

Fluoroquinolone resistance: efflux

Multidrug efflux pumps contribute to resistance in Pseudomonas aeruginosa.

Fluoroquinolone resistance: target mutations

Mutations at drug target sites can confer resistance.

Plasmid-mediated fluoroquinolone resistance

The qnr gene protects drug targets and confers low-level resistance.

Ciprofloxacin and Pseudomonas

The most potent fluoroquinolone against Pseudomonas aeruginosa.

Ciprofloxacin and pneumococcus

Activity against Streptococcus pneumoniae is poor.

Levofloxacin and pneumococcus

Active against Streptococcus pneumoniae.

Levofloxacin and Pseudomonas

Active, but less potent than ciprofloxacin.

Moxifloxacin and Pseudomonas

Does not cover Pseudomonas aeruginosa.

Moxifloxacin and anaerobes

Covers Bacteroides fragilis, although resistance is increasing.

Delafloxacin and MRSA

Active against methicillin-resistant Staphylococcus aureus.

Delafloxacin and Enterococcus faecalis

Can be used for nonurinary infections.

Delafloxacin and Pseudomonas

Active, but less potent than ciprofloxacin.

Fluoroquinolone first-line use

Rare because of collateral damage and serious adverse-effect warnings.

Fluoroquinolone collateral damage

Includes increased bacterial resistance and risk of Clostridioides difficile infection.

Fluoroquinolone stewardship

Reserve for suspected or documented multidrug-resistant gram-negative infections or intolerance of alternatives.

Fluoroquinolone oral step-down

May complete an antibiotic course in the outpatient setting.

Ciprofloxacin clinical uses

Includes urinary tract, intra-abdominal and bloodstream infections.

Levofloxacin and tuberculosis

A second-line treatment option.

Moxifloxacin clinical uses

Includes intra-abdominal infection and pneumonia; also second-line tuberculosis therapy.

Delafloxacin clinical use

Skin and soft tissue infections.

Ciprofloxacin usual dosing

250-750 mg orally or 200-400 mg intravenously every 12 hours.

Levofloxacin usual dosing

250-750 mg orally or intravenously daily.

Moxifloxacin usual dosing

400 mg orally or intravenously daily.

Delafloxacin usual dosing

450 mg orally or 300 mg intravenously every 12 hours.

Fluoroquinolones and renal adjustment

Ciprofloxacin, levofloxacin and delafloxacin require adjustment; moxifloxacin does not.

Levofloxacin oral bioavailability

99%.

Fluoroquinolone pharmacodynamics

Bactericidal with a prolonged post-antibiotic effect.

Fluoroquinolone exposure target

The pharmacodynamic goal is based on the 24-hour AUC-to-MIC ratio.

Fluoroquinolone target: gram-positive cocci

AUC24/MIC greater than 30.

Fluoroquinolone target: gram-negative rods

AUC24/MIC greater than 125.

Fluoroquinolone tendon warning

Increased risk of tendinitis and tendon rupture.

Fluoroquinolone neuropathy warning

Peripheral neuropathy may be irreversible.

Fluoroquinolone CNS warning

Serious effects include seizures and psychiatric reactions.

Fluoroquinolones and myasthenia gravis

Avoid because they may exacerbate the condition.

Fluoroquinolone QT risk

Moxifloxacin carries more risk than levofloxacin, which carries more than ciprofloxacin.

Fluoroquinolone glucose effects

Can cause hyperglycemia or hypoglycemia; use precautions in diabetes.

Fluoroquinolone age and pregnancy precautions

Avoid in children under 18 and during pregnancy.

Fluoroquinolones in older adults

Use caution because tendon rupture and CNS-effect risks increase.

Fluoroquinolones and multivalent cations

Chelation forms insoluble, inactive complexes and reduces absorption.

Fluoroquinolone and cation separation

Separate administration by at least two hours.

Fluoroquinolone and cation bioavailability

Concomitant cations can reduce bioavailability by approximately 90%.

Ciprofloxacin and theophylline

Ciprofloxacin can decrease theophylline clearance by 25%.

Fluoroquinolones and warfarin

May increase INR through disruption of vitamin K synthesis.

Fluoroquinolone tendon counseling

Stop the drug and contact a provider for ankle pain, swelling or inflammation.

Fluoroquinolone neurologic counseling

Stop the drug and contact a provider for neuropathy or severe psychiatric symptoms.

Fluoroquinolone diarrhea counseling

Stop the drug and contact a provider for severe watery diarrhea or bloody stools.

Sulfonamide activity

Broad-spectrum activity is now limited by acquired resistance.

Sulfonamide classifications

Sulfamethoxazole is short- or medium-acting; sulfasalazine is limited to the gastrointestinal tract.

Topical sulfonamides

Include silver sulfadiazine and sulfacetamide ophthalmic solution.

Trimethoprim alone

Used singularly for prostatitis.

TMP-SMX and MRSA

Active against Staphylococcus aureus, including MRSA.

TMP-SMX and streptococci

Less potent against Streptococcus species and Streptococcus pneumoniae.

TMP-SMX and Stenotrophomonas

Active against Stenotrophomonas maltophilia.

TMP-SMX and Pneumocystis

Used for both prophylaxis and treatment of Pneumocystis jirovecii pneumonia.

TMP-SMX and toxoplasmosis

Used for Toxoplasma gondii prophylaxis.

TMP-SMX urinary indications

Used for uncomplicated UTI, complicated UTI, pyelonephritis and prostatitis.

TMP-SMX skin indication

Used for skin and soft tissue infections, including MRSA infections.

TMP-SMX single-strength tablet

Contains 80 mg trimethoprim and 400 mg sulfamethoxazole.

TMP-SMX double-strength tablet

Contains 160 mg trimethoprim and 800 mg sulfamethoxazole.

TMP-SMX dose calculation

Dosing is based on the trimethoprim component.

TMP-SMX UTI dose

5 mg/kg/day of trimethoprim.

TMP-SMX systemic infection dose

10-20 mg/kg/day of trimethoprim.

TMP-SMX Pneumocystis pneumonia dose

15 mg/kg/day of trimethoprim.

TMP-SMX administration and renal function

Divide the daily dose into two or three doses; adjust for renal dysfunction.

TMP-SMX serious skin reactions

Rare reactions include erythema multiforme, Stevens-Johnson syndrome and toxic epidermal necrolysis.

TMP-SMX hematologic effects

Can cause thrombocytopenia, neutropenia and hemolytic anemia in G6PD deficiency.

TMP-SMX metabolic effects

Can cause hyperkalemia, hyponatremia and hypoglycemia.

TMP-SMX hepatic effects

Can cause elevated transaminases, hyperbilirubinemia and cholestatic hepatitis.

TMP-SMX and sulfonylureas

Can potentiate hypoglycemia through protein-binding displacement.

TMP-SMX and phenytoin

Trimethoprim decreases phenytoin clearance by inhibiting its metabolism.

TMP-SMX and warfarin

Can potentiate anticoagulation and increase bleeding risk.

TMP-SMX and methotrexate

Additive folate inhibition and protein-binding displacement can increase methotrexate toxicity.

TMP-SMX in pregnancy

Safety is not established; avoid during the first and last trimesters.

TMP-SMX monitoring

Monitor fluid status and complete blood counts for blood dyscrasias.

TMP-SMX photosensitivity counseling

Use sunscreen.

Nitrofurantoin urinary indication

Used for lower UTI and secondary prophylaxis against recurrence.

Nitrofurantoin and Proteus

Not active against Proteus.

Nitrofurantoin and anaerobes

Has no anaerobic activity.

Nitrofurantoin urinary concentrations

Therapeutic concentrations are achieved in urine only.

Nitrofurantoin macrocrystal dose

Macrodantin: 50-100 mg orally every six hours.

Nitrofurantoin monohydrate/macrocrystal dose

Macrobid: 100 mg orally every 12 hours.

Nitrofurantoin absorption

Approximately 80% bioavailability; food enhances absorption.

Nitrofurantoin elimination

Predominantly renal; approximately 30-50% is excreted unchanged.

Long-term nitrofurantoin toxicity

Older patients may develop peripheral neuropathy or pulmonary fibrosis.

Nitrofurantoin renal contraindication

Contraindicated when creatinine clearance is below 30 mL/min.

Nitrofurantoin pregnancy contraindication

Contraindicated at term, defined in the source as 38-42 weeks.

Nitrofurantoin infant contraindication

Contraindicated in infants younger than one month.

Nitrofurantoin and G6PD deficiency

Use caution because of hemolytic anemia risk.

Nitrofurantoin food counseling

Take with meals to improve absorption and reduce gastrointestinal upset.

Nitrofurantoin urine counseling

May discolor urine brown.

Nitrofurantoin warning symptoms

Report respiratory symptoms, rash, peripheral tingling or intolerable gastrointestinal upset.

Fosfomycin spectrum

Covers urinary pathogens including ESBL- and CRE-producing PEK organisms.

Fosfomycin and anaerobes

Has no anaerobic activity.

Fosfomycin fasting bioavailability

37%.

Fosfomycin uncomplicated cystitis dose

3 g orally once, mixed in 3-4 ounces of water.

Fosfomycin complicated UTI dose

Off-label: 3 g orally every two to three days for three doses; data are limited.

Fosfomycin outpatient role

Can be used as step-down therapy for ESBL-producing Enterobacteriaceae.

Fosfomycin for multidrug-resistant UTI

Optimal dosing frequency and duration remain controversial.

Fosfomycin in pregnancy

Crosses the placenta and is used for cystitis and asymptomatic bacteriuria.