. 2023 Dec 7;230(2):e447–e456. doi: 10.1093/infdis/jiad564

Table 3.

Quantification of Viable Mycobacterium tuberculosis (Mtb) by Different Microbiological Methods Demonstrates That the Drug-Sensitive and Drug-Resistant Cohorts Display Similar Mtb Counts in Their Sputa Prior to Therapy (Day 0) and at 2 Weeks Post–Initiation of Therapy

Method	Day 0 (Pretreatment)			Week 2 (Post–Initiation of Therapy)			Δ (Week 2 vs Day 0)
Method	DS-TB (n = 30–31)^a	DR-TB (n = 22–23)^a	P Value	DS-TB (n = 24–25)^a	DR-TB (n = 18–22)^a	P Value	DS-TB (n = 24–25)^a	DR-TB (n = 18–22)^a	P Value
Log₁₀ CFU, Mtb/mL	6.5 (6.1–6.8)	6.2 (5.2–6.7)	.24	3.6 (3.1–4.4)	3.7 (1.8–4.7)	.73	2.3 (2.0–3.1)	2.4 (2.0–3.2)	.96
Log₁₀ MPN^−CF, Mtb/mL	6.6 (6.2–6.9)	6.3 (5.6–6.8)	.21	4.0 (3.2–5.1)	3.7 (1.4–4.7)	.45	2.2 (1.2–3.0)	2.5 (2.1–3.4)	.26
Log₁₀ MPN^+CF, Mtb/mL	6.4 (6.1–6.7)	6.5 (5.6–6.9)	.62	4.2 (3.4–5.1)	4.0 (3.2–5.1)	.80	2.0 (1.3–2.8)	2.2 (1.5–3.3)	.41
Log₁₀Mtb^Max, Mtb/mL^b	6.7 (6.3–6.9)	6.5 (5.8–6.9)	.33	4.3 (3.6–5.1)	3.9 (2.7–5.0)	.55	2.1 (1.1–2.9)	2.3 (1.8–3.2)	.30
TTP, h	93.5 (79.0–102.5)	105.7 (90.1–152.2)	.13	230.5 (193.0–290.0)	238.0 (210.2–327.5)	.73	148.5 (118.5–178.0)	150.2 (127.6–199.5)	.47

Data are presented as median (interquartile range) unless otherwise indicated.

Abbreviations: CFU, colony-forming units; DR-TB, drug-resistant tuberculosis; DS-TB, drug-sensitive tuberculosis; MPN^–CF, most probable number from the liquid limiting dilution assay performed without culture filtrate; MPN^+CF, most probable number from the liquid limiting dilution assay performed with culture filtrate; Mtb, Mycobacterium tuberculosis; Mtb^Max, maximum Mycobacterium tuberculosis count; TTP, time to positivity.

^aVariable n value at each timepoint is a consequence of contamination events, missed collection timepoints, or insufficient sample quantity to perform microbiological assays.

^bThe maximum Mtb count obtained by CFU, MPN^−CF, or MPN^+CF.