Final published version
Licence: CC BY: Creative Commons Attribution 4.0 International License
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Optimized methods for detecting Salmonella Typhi in the environment using validated field sampling, culture and confirmatory molecular approaches. / Rigby, J.; Elmerhebi, E.; Diness, Y. et al.
In: Journal of Applied Microbiology, Vol. 132, No. 2, 28.02.2022, p. 1503-1517.Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Optimized methods for detecting Salmonella Typhi in the environment using validated field sampling, culture and confirmatory molecular approaches
AU - Rigby, J.
AU - Elmerhebi, E.
AU - Diness, Y.
AU - Mkwanda, C.
AU - Tonthola, K.
AU - Galloway, H.
AU - Miles, R.
AU - Henrion, M.Y.R.
AU - Edwards, T.
AU - Gauld, J.
AU - Msefula, C.
AU - Johnston, R.
AU - Nair, S.
AU - Feasey, N.
AU - Elviss, N.C.
PY - 2022/2/28
Y1 - 2022/2/28
N2 - Aims: This study evaluated detection methods for Salmonella Typhi (S. Typhi) in the environment, to establish a novel pathway from field sampling to isolation of viable organisms and molecular confirmation from complex environmental samples, thus enabling environmental surveillance of typhoid. Methods and Results: Multiple media were assessed using clinical isolates from the Public Health England's (PHE) Culture collection. The culture pathway selected consisted of a primary 2% bile broth and secondary Selenite F broth, followed by modified Chromogenic Agar for Salmonella Esterase (mCASE). A qPCR assay was adapted from a validated S. Typhi PCR panel for confirmation of isolates, with comparison to biochemical and serological tests showing good specificity. Sampling locations in Blantyre, Malawi were used to compare sampling methods. Viable S. Typhi were isolated from a mixture of trap and grab river water samples on six occasions. Conclusions: Culture of viable S. Typhi from environmental samples was possible using effective capture and culture techniques. Significance and impact of study: Whilst several studies have attempted to detect S. Typhi from the environment, this is the first successful attempt to isolate the organism from river water since the 1980s. Supplementing clinical data with environmental screening offers the potential for enhanced surveillance, which might inform interventions and assess vaccination programmes.
AB - Aims: This study evaluated detection methods for Salmonella Typhi (S. Typhi) in the environment, to establish a novel pathway from field sampling to isolation of viable organisms and molecular confirmation from complex environmental samples, thus enabling environmental surveillance of typhoid. Methods and Results: Multiple media were assessed using clinical isolates from the Public Health England's (PHE) Culture collection. The culture pathway selected consisted of a primary 2% bile broth and secondary Selenite F broth, followed by modified Chromogenic Agar for Salmonella Esterase (mCASE). A qPCR assay was adapted from a validated S. Typhi PCR panel for confirmation of isolates, with comparison to biochemical and serological tests showing good specificity. Sampling locations in Blantyre, Malawi were used to compare sampling methods. Viable S. Typhi were isolated from a mixture of trap and grab river water samples on six occasions. Conclusions: Culture of viable S. Typhi from environmental samples was possible using effective capture and culture techniques. Significance and impact of study: Whilst several studies have attempted to detect S. Typhi from the environment, this is the first successful attempt to isolate the organism from river water since the 1980s. Supplementing clinical data with environmental screening offers the potential for enhanced surveillance, which might inform interventions and assess vaccination programmes.
KW - bile broth
KW - biofilm
KW - biofilms
KW - Identification
KW - Malawi
KW - mCASE
KW - Moore swabs
KW - PCR (polymerase chain reaction)
KW - river water
KW - salmonella
KW - selenite broth
KW - typhoid
KW - water
U2 - 10.1111/jam.15237
DO - 10.1111/jam.15237
M3 - Journal article
VL - 132
SP - 1503
EP - 1517
JO - Journal of Applied Microbiology
JF - Journal of Applied Microbiology
SN - 1364-5072
IS - 2
ER -