Bacterial load comparison of the three main lineages of Mycobacterium tuberculosis complex in West Africa

Stephen Osei-Wusu; Portia Morgan; Prince Asare; Godfrey Adams; Abdul B. Musah; Ishaque M. Siam; Stephen Henry Gillespie; Wilber Sabiiti; Dorothy Yeboah-Manu

doi:10.3389/fmicb.2021.719531

Bacterial load comparison of the three main lineages of Mycobacterium tuberculosis complex in West Africa

Stephen Osei-Wusu^*
, Portia Morgan
, Prince Asare
, Godfrey Adams
, Abdul B. Musah
, Ishaque M. Siam
, Stephen Henry Gillespie
, Wilber Sabiiti
, Dorothy Yeboah-Manu^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

Studies have shown an association between bacterial load and virulence; however, not much is known about the diversity in this phenotypic characteristic of Mycobacterium tuberculosis complex (MTBC). This study was therefore aimed to determine the differences in bacterial load of the three most prevalent MTBC genotypes (L4, L5 and L6) in West Africa at the time of diagnosis. A total of 170 paired fresh sputum samples were collected; one part in guanidinium thiocyanate (GTC) was used for RNA extraction and tuberculosis Molecular Bacterial Load Assay (TB-MBLA) and the other part without GTC was confirmed for TB positivity using Gene Xpert MTB/RIF, smear microscopy grading and culture on Löwenstein-Jensen media slants. The 170 sputum samples comprised of 155 new cases, 3 follow-up cases and 12 TB negative sputum samples. The time-to-culture-positivity (TTP) and degree of culture positivity (DCP) were recorded. All 122 isolates obtained were Spoligotyped for lineage (L) classification but spoligotypes were obtained from 120 isolates. Of the typed isolates, 70.0%, 10.8%, 10.8%, 4.2%, 2.5%, 0.8% and 0.8% were Lineage- 4, 5, 6, 2, 3, 1, and M. bovis respectively. Further analysis of the three most prevalent lineages showed significantly shorter TTP and higher DCP by L4 compared to L5 and L6 respectively: TTP 20.8, versus 26.5, and 28.2 days; p-value=0.005 and DCP 1.27, versus 0.81 and 0.29, p<0.001. Average TB-MBLA measured bacterial load of L4 was 3.82 Log10eCFU/mL which was not significantly different from 3.81 and 3.80 Log10eCFU/mL of L5 and L6 respectively, p=0.84. Degree of smear microscopy: L4=1.20, L5=1.20, L6=0.92 and Gene Xpert Cq values: L4=17.08, L5=18.37, L6=17.59; showed no significant difference between the lineages, p=0.72 and p=0.48 respectively. Retrospective analysis of a larger sample confirmed the difference in TTP, p<0.001. In conclusion, the observed shorter TTP and high DCP of L4 could signify high growth rate in culture that is independent of total bacterial load at diagnosis.

Original language	English
Article number	719531
Journal	Frontiers in Microbiology
Volume	12
Early online date	27 Oct 2021
DOIs	https://doi.org/10.3389/fmicb.2021.719531
Publication status	E-pub ahead of print - 27 Oct 2021

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 3 Good Health and Well-being

Keywords

West Africa
Mycobacterium africanum
Bacterial load
Mycobacterium tuberculosis
TB/MBLA

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Copyright © 2021 Osei-Wusu, Morgan, Asare, Adams, Musah, Siam, Gillespie, Sabiiti and Yeboah-Manu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
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@article{2a837711de514f15876abdfabd7c531e,

title = "Bacterial load comparison of the three main lineages of Mycobacterium tuberculosis complex in West Africa",

abstract = "Studies have shown an association between bacterial load and virulence; however, not much is known about the diversity in this phenotypic characteristic of Mycobacterium tuberculosis complex (MTBC). This study was therefore aimed to determine the differences in bacterial load of the three most prevalent MTBC genotypes (L4, L5 and L6) in West Africa at the time of diagnosis. A total of 170 paired fresh sputum samples were collected; one part in guanidinium thiocyanate (GTC) was used for RNA extraction and tuberculosis Molecular Bacterial Load Assay (TB-MBLA) and the other part without GTC was confirmed for TB positivity using Gene Xpert MTB/RIF, smear microscopy grading and culture on L{\"o}wenstein-Jensen media slants. The 170 sputum samples comprised of 155 new cases, 3 follow-up cases and 12 TB negative sputum samples. The time-to-culture-positivity (TTP) and degree of culture positivity (DCP) were recorded. All 122 isolates obtained were Spoligotyped for lineage (L) classification but spoligotypes were obtained from 120 isolates. Of the typed isolates, 70.0\%, 10.8\%, 10.8\%, 4.2\%, 2.5\%, 0.8\% and 0.8\% were Lineage- 4, 5, 6, 2, 3, 1, and M. bovis respectively. Further analysis of the three most prevalent lineages showed significantly shorter TTP and higher DCP by L4 compared to L5 and L6 respectively: TTP 20.8, versus 26.5, and 28.2 days; p-value=0.005 and DCP 1.27, versus 0.81 and 0.29, p<0.001. Average TB-MBLA measured bacterial load of L4 was 3.82 Log10eCFU/mL which was not significantly different from 3.81 and 3.80 Log10eCFU/mL of L5 and L6 respectively, p=0.84. Degree of smear microscopy: L4=1.20, L5=1.20, L6=0.92 and Gene Xpert Cq values: L4=17.08, L5=18.37, L6=17.59; showed no significant difference between the lineages, p=0.72 and p=0.48 respectively. Retrospective analysis of a larger sample confirmed the difference in TTP, p<0.001. In conclusion, the observed shorter TTP and high DCP of L4 could signify high growth rate in culture that is independent of total bacterial load at diagnosis. ",

keywords = "West Africa, Mycobacterium africanum, Bacterial load, Mycobacterium tuberculosis, TB/MBLA",

author = "Stephen Osei-Wusu and Portia Morgan and Prince Asare and Godfrey Adams and Musah, \{Abdul B.\} and Siam, \{Ishaque M.\} and Gillespie, \{Stephen Henry\} and Wilber Sabiiti and Dorothy Yeboah-Manu",

note = "Funding: This work was funded by The Royal Society Africa Prize 2018 awarded to Dorothy Yeboah-Manu and supported by funding from Scottish Funding Council (SCF)-Global Challenges Research Fund (GCRF) to Prof Stephen Gillespie and Dr Wilber Sabiiti. ",

year = "2021",

month = oct,

day = "27",

doi = "10.3389/fmicb.2021.719531",

language = "English",

volume = "12",

journal = "Frontiers in Microbiology",

issn = "1664-302X",

publisher = "Frontiers Media S. A.",

}

TY - JOUR

T1 - Bacterial load comparison of the three main lineages of Mycobacterium tuberculosis complex in West Africa

AU - Osei-Wusu, Stephen

AU - Morgan, Portia

AU - Asare, Prince

AU - Adams, Godfrey

AU - Musah, Abdul B.

AU - Siam, Ishaque M.

AU - Gillespie, Stephen Henry

AU - Sabiiti, Wilber

AU - Yeboah-Manu, Dorothy

N1 - Funding: This work was funded by The Royal Society Africa Prize 2018 awarded to Dorothy Yeboah-Manu and supported by funding from Scottish Funding Council (SCF)-Global Challenges Research Fund (GCRF) to Prof Stephen Gillespie and Dr Wilber Sabiiti.

PY - 2021/10/27

Y1 - 2021/10/27

N2 - Studies have shown an association between bacterial load and virulence; however, not much is known about the diversity in this phenotypic characteristic of Mycobacterium tuberculosis complex (MTBC). This study was therefore aimed to determine the differences in bacterial load of the three most prevalent MTBC genotypes (L4, L5 and L6) in West Africa at the time of diagnosis. A total of 170 paired fresh sputum samples were collected; one part in guanidinium thiocyanate (GTC) was used for RNA extraction and tuberculosis Molecular Bacterial Load Assay (TB-MBLA) and the other part without GTC was confirmed for TB positivity using Gene Xpert MTB/RIF, smear microscopy grading and culture on Löwenstein-Jensen media slants. The 170 sputum samples comprised of 155 new cases, 3 follow-up cases and 12 TB negative sputum samples. The time-to-culture-positivity (TTP) and degree of culture positivity (DCP) were recorded. All 122 isolates obtained were Spoligotyped for lineage (L) classification but spoligotypes were obtained from 120 isolates. Of the typed isolates, 70.0%, 10.8%, 10.8%, 4.2%, 2.5%, 0.8% and 0.8% were Lineage- 4, 5, 6, 2, 3, 1, and M. bovis respectively. Further analysis of the three most prevalent lineages showed significantly shorter TTP and higher DCP by L4 compared to L5 and L6 respectively: TTP 20.8, versus 26.5, and 28.2 days; p-value=0.005 and DCP 1.27, versus 0.81 and 0.29, p<0.001. Average TB-MBLA measured bacterial load of L4 was 3.82 Log10eCFU/mL which was not significantly different from 3.81 and 3.80 Log10eCFU/mL of L5 and L6 respectively, p=0.84. Degree of smear microscopy: L4=1.20, L5=1.20, L6=0.92 and Gene Xpert Cq values: L4=17.08, L5=18.37, L6=17.59; showed no significant difference between the lineages, p=0.72 and p=0.48 respectively. Retrospective analysis of a larger sample confirmed the difference in TTP, p<0.001. In conclusion, the observed shorter TTP and high DCP of L4 could signify high growth rate in culture that is independent of total bacterial load at diagnosis.

AB - Studies have shown an association between bacterial load and virulence; however, not much is known about the diversity in this phenotypic characteristic of Mycobacterium tuberculosis complex (MTBC). This study was therefore aimed to determine the differences in bacterial load of the three most prevalent MTBC genotypes (L4, L5 and L6) in West Africa at the time of diagnosis. A total of 170 paired fresh sputum samples were collected; one part in guanidinium thiocyanate (GTC) was used for RNA extraction and tuberculosis Molecular Bacterial Load Assay (TB-MBLA) and the other part without GTC was confirmed for TB positivity using Gene Xpert MTB/RIF, smear microscopy grading and culture on Löwenstein-Jensen media slants. The 170 sputum samples comprised of 155 new cases, 3 follow-up cases and 12 TB negative sputum samples. The time-to-culture-positivity (TTP) and degree of culture positivity (DCP) were recorded. All 122 isolates obtained were Spoligotyped for lineage (L) classification but spoligotypes were obtained from 120 isolates. Of the typed isolates, 70.0%, 10.8%, 10.8%, 4.2%, 2.5%, 0.8% and 0.8% were Lineage- 4, 5, 6, 2, 3, 1, and M. bovis respectively. Further analysis of the three most prevalent lineages showed significantly shorter TTP and higher DCP by L4 compared to L5 and L6 respectively: TTP 20.8, versus 26.5, and 28.2 days; p-value=0.005 and DCP 1.27, versus 0.81 and 0.29, p<0.001. Average TB-MBLA measured bacterial load of L4 was 3.82 Log10eCFU/mL which was not significantly different from 3.81 and 3.80 Log10eCFU/mL of L5 and L6 respectively, p=0.84. Degree of smear microscopy: L4=1.20, L5=1.20, L6=0.92 and Gene Xpert Cq values: L4=17.08, L5=18.37, L6=17.59; showed no significant difference between the lineages, p=0.72 and p=0.48 respectively. Retrospective analysis of a larger sample confirmed the difference in TTP, p<0.001. In conclusion, the observed shorter TTP and high DCP of L4 could signify high growth rate in culture that is independent of total bacterial load at diagnosis.

KW - West Africa

KW - Mycobacterium africanum

KW - Bacterial load

KW - Mycobacterium tuberculosis

KW - TB/MBLA

U2 - 10.3389/fmicb.2021.719531

DO - 10.3389/fmicb.2021.719531

M3 - Article

SN - 1664-302X

VL - 12

JO - Frontiers in Microbiology

JF - Frontiers in Microbiology

M1 - 719531

ER -

Bacterial load comparison of the three main lineages of Mycobacterium tuberculosis complex in West Africa

Abstract

UN SDGs

Keywords

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