Tissue penetration of antimicrobials

Summary

Class	Antimicrobial	Blood	CNS	Urine	Prostate	Necrotic
Antibiotics: β-Lactams
Penicillins	β-lactamase inhibitors		–
	ampicillin		+			–
	piperacillin-tazobactam				+†
Cephalosporins	first-generation cephalosporins		–			–
	second-generation cephalosporins		–
	third-generation cephalosporins				+†
	cefepime					+
	ceftazidime		+			+
Cephamycins	cephamycins		–
	cefoxitin					–
Carbapenems	imipenem					+
Antibiotics: Non-β-Lactams
Aminoglycosides						–
Chloramphenicol	chloramphenicol					+
Fluoroquinolones			–?		+	+
Fosfomycin	fosfomycin				+
Lincosamides	clindamycin		–			+
Macrolides	macrolides		–		+
Nitrofurans	nitrofurantoin	–	–	+	–	–
Nitroimidazoles	metronidazole					+
Rifamycins	rifampin				+
Sulfonamides	trimethoprim-sulfamethoxazole				+
Tetracyclines	tetracyclines		–		+
	doxycycline				+	+
Antifungals
Azoles	fluconazole					+
Echinocandins		+		–
Class	Antimicrobial	Blood	CNS	Urine	Prostate	Necrotic

• † if inflammation present

Prostate

• Poorly penetrated by most antibiotics
• Penetration is higher with a high concentration gradient, high lipid solubility, low degree of ionization, high dissociation constant, low protein binding, and small molecular size
• Fluoroquinolones are the mainstay of therapy, though there is increasing resistance
• TMP-SMX often used, though conflicting data about its penetration into the prostate
• Minocycline, doxycycline, and macrolides achieve high levels in the prostate but are rarely indicated for the causative organisms
• Third-generation cephalosporins and carbapenems can be used
• Piperacillin, aztreonam, imipenem, and some aminoglycosides are likely useful

Bone

• Essentially all antibiotics achieve similar bone-to-serum levels, with the exception of oral β-lactams which nevertheless have no worse outcomes1