TABLE 2.

Antibiotic susceptibilities (MICs and MBCs in micrograms per milliliter) of clinical B. burgdorferi sensu lato isolates obtained before and after antimicrobial chemotherapy and reference strain B31 to seven antimicrobial agents as determined in BSK medium^a

Patient and isolateb	Drug (test range [μg/ml])
	Erythromycin (0.0002-0.5)		Azithromycin (0.0002-0.5)		Telithromycin (0.0002-0.5)		Amoxicillin (0.0078-16)		Cefuroxime (0.0156-16)		Ceftriaxone (0.0078-16)		Doxycycline (0.125-8)
	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC
Patient 1
1A	0.0156	>0.5	0.0019	0.125	≤0.0002	0.0312	0.25	4	0.0625	16	0.0156	0.25	≤0.125	1
1B	0.0078	>0.5	0.0009	0.0625	≤0.0002	0.0312	0.25	8	0.0625	16	0.0312	0.5	≤0.125	0.5
Patient 2
2A	0.0039	0.5	0.0004	0.0312	≤0.0002	0.0039	0.0312	0.5	0.0625	8	0.0156	0.5	≤0.125	0.25
2B	0.0019	0.5	0.0004	0.0156	≤0.0002	0.0019	0.0625	1	0.0312	8	0.0156	0.5	0.25	0.25
Patient 3
3A	0.0078	0.5	0.0009	0.0156	≤0.0002	0.0312	1	8	0.0625	8	0.0156	1	0.25	0.5
3B	0.0078	0.5	0.0019	0.0156	≤0.0002	0.0625	0.5	4	0.125	16	0.0312	1	≤0.125	0.25
Patient 4
4A	0.0019	0.125	0.0004	0.0312	≤0.0002	0.0312	0.5	4	0.0625	8	0.0156	0.25	≤0.125	0.5
4B	0.0019	0.062	0.0004	0.0312	≤0.0002	0.0156	0.5	8	0.0625	8	0.0156	0.25	≤0.125	0.5
Patient 5
5A	0.0156	>0.5	0.0039	0.125	0.0004	0.0312	0.0312	2	0.0312	8	0.0625	0.5	≤0.125	0.25
5B	0.0078	>0.5	0.0019	0.125	0.0009	0.0312	0.0625	4	0.0625	16	0.0312	0.25	≤0.125	0.5
Range	0.0019-0.0156	0.062->0.5	≤0.0002-0.0039	0.0156-0.125	≤0.0002-0.0009	0.0019-0.0625	0.0156-2	0.25-16	0.0312-0.125	8->16	0.0078-0.0625	0.125-2	≤0.125-0.25	0.125-1
Reference strain B31 (ATCC 35210)c	0.0156	>0.5	0.0019	0.125	≤0.0002	0.06	0.5	8	0.125	16	0.0625	1	0.25	0.5

^aAntimicrobial susceptibility was determined on three different days, and the MIC and MBC for each isolate are reported as the median of three experiments. Boldface indicates the initial antibiotic treatment regimen.

^bIn isolate designations, A refers to the initial borrelial isolate and B refers to the borrelial isolate obtained after the conclusion of therapy.

^cMICs and MBCs are in range of ranges specified for these antimicrobial agents in our recent publications by use of our well-defined assay method for in vitro susceptibility testing of B. burgdorferi sensu lato under controlled test conditions (11-14, 17).