Identification of bacteria on Thai banknotes and coins using MALDI-TOF mass spectrometry and their phenotypic antimicrobial susceptibility profiles

Background The existence and transmission of pathogenic and antibiotic-resistant bacteria through currency banknotes and coins poses a global public health risk. Banknotes and coins are handled by people in everyday life and have been identified as a universal medium for potentially microbial contam...

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Main Authors: Nattamon Niyomdecha, Suwitchaya Sungvaraporn, Arisa Pinmuang, Narissara Mungkornkaew, Thanchira Saita, Waratchaya Rodraksa, Achiraya Phanitmas, Nattapong Yamasamit, Pirom Noisumdaeng
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Language:English
Published: PeerJ Inc. 2025-05-01
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Online Access:https://peerj.com/articles/19465.pdf
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author Nattamon Niyomdecha
Suwitchaya Sungvaraporn
Arisa Pinmuang
Narissara Mungkornkaew
Thanchira Saita
Waratchaya Rodraksa
Achiraya Phanitmas
Nattapong Yamasamit
Pirom Noisumdaeng
author_facet Nattamon Niyomdecha
Suwitchaya Sungvaraporn
Arisa Pinmuang
Narissara Mungkornkaew
Thanchira Saita
Waratchaya Rodraksa
Achiraya Phanitmas
Nattapong Yamasamit
Pirom Noisumdaeng
author_sort Nattamon Niyomdecha
collection DOAJ
description Background The existence and transmission of pathogenic and antibiotic-resistant bacteria through currency banknotes and coins poses a global public health risk. Banknotes and coins are handled by people in everyday life and have been identified as a universal medium for potentially microbial contamination. Methods To ascertain existence of medically important bacteria, a total of 300 samples including 150 banknotes and 150 coins were randomly collected at onsite retail fresh meat stores, i.e., pork and chicken, fish, and seafood stores, from nineteen fresh markets distributed across Bangkok, Thailand. An individual banknote or coin was entirely swabbed, and bacterial culture was carried out using tryptic soy agar (TSA), sheep blood agar (SBA) and MacConkey agar (Mac). A colony count was performed and bacterial species identification was conducted using matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF) mass spectrometry. Phenotypic antimicrobial susceptibility testing was carried out using the Kirby–Bauer disc diffusion methods. Results The results demonstrated that the bacterial contamination rate was higher on banknotes than on coins (93.33% vs. 30.00%) in all three store types. A substantial number of colonies of >3,000 colony forming units (CFU) was predominantly found in banknotes (70.00%), especially from fish store (83.3%); meanwhile, <1,000 CFU was observed in coin sample (76.67%). MALDI-TOF mass spectrometry could identify 107 bacterial species, most of them were Staphylococcus kloosii (14.02%, 15/107), Staphylococcus saprophyticus (12.15%, 13/107), and Macrococcus caseolyticus (8.41%, 9/107). The prevalence based on genera were Staphylococcus (36.45%, 39/107), Acinetobacter (20.56%, 22/107), and Macrococcus (10.28%, 11/107). Almost all Staphylococcus isolates had low susceptibility to penicillin (21%). Notably, Staphylococcus arlettae, Staphylococcus haemolyticus and M. caseolyticus were multidrug-resistant (MDR). It is notable that none of the staphylococci and macrococci isolates exhibited inducible clindamycin resistance (D-test negative). Escherichia coli and Pseudomonas putida isolates were carbapenem-resistant, and Acinetobacter baumannii isolates were MDR with showing carbapenem resistance. Conclusion Our data demonstrated a high prevalence of medically important bacteria presented on Thai currency, which may pose a potential risk to human health and food safety. Food vendors and consumers should be educated about the possible cross-contamination of bacteria between the environment, food item, and currency.
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spelling doaj-art-51a38c79de6e4f7ab6734b27ec73a3d12025-08-20T02:25:48ZengPeerJ Inc.PeerJ2167-83592025-05-0113e1946510.7717/peerj.19465Identification of bacteria on Thai banknotes and coins using MALDI-TOF mass spectrometry and their phenotypic antimicrobial susceptibility profilesNattamon Niyomdecha0Suwitchaya Sungvaraporn1Arisa Pinmuang2Narissara Mungkornkaew3Thanchira Saita4Waratchaya Rodraksa5Achiraya Phanitmas6Nattapong Yamasamit7Pirom Noisumdaeng8Department of Medical Technology, Faculty of Allied Health Sciences, Thammasat University, Khlong Luang, Pathum Thani, ThailandDepartment of Medical Technology, Faculty of Allied Health Sciences, Thammasat University, Khlong Luang, Pathum Thani, ThailandDepartment of Medical Technology, Faculty of Allied Health Sciences, Thammasat University, Khlong Luang, Pathum Thani, ThailandMicrobiology Laboratory, Thammasat University Hospital, Thammasat University, Khlong Luang, Pathum Thani, ThailandFaculty of Public Health, Thammasat University, Khlong Luang, Pathum Thani, ThailandFaculty of Public Health, Thammasat University, Khlong Luang, Pathum Thani, ThailandFaculty of Public Health, Thammasat University, Khlong Luang, Pathum Thani, ThailandFaculty of Public Health, Thammasat University, Khlong Luang, Pathum Thani, ThailandFaculty of Public Health, Thammasat University, Khlong Luang, Pathum Thani, ThailandBackground The existence and transmission of pathogenic and antibiotic-resistant bacteria through currency banknotes and coins poses a global public health risk. Banknotes and coins are handled by people in everyday life and have been identified as a universal medium for potentially microbial contamination. Methods To ascertain existence of medically important bacteria, a total of 300 samples including 150 banknotes and 150 coins were randomly collected at onsite retail fresh meat stores, i.e., pork and chicken, fish, and seafood stores, from nineteen fresh markets distributed across Bangkok, Thailand. An individual banknote or coin was entirely swabbed, and bacterial culture was carried out using tryptic soy agar (TSA), sheep blood agar (SBA) and MacConkey agar (Mac). A colony count was performed and bacterial species identification was conducted using matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF) mass spectrometry. Phenotypic antimicrobial susceptibility testing was carried out using the Kirby–Bauer disc diffusion methods. Results The results demonstrated that the bacterial contamination rate was higher on banknotes than on coins (93.33% vs. 30.00%) in all three store types. A substantial number of colonies of >3,000 colony forming units (CFU) was predominantly found in banknotes (70.00%), especially from fish store (83.3%); meanwhile, <1,000 CFU was observed in coin sample (76.67%). MALDI-TOF mass spectrometry could identify 107 bacterial species, most of them were Staphylococcus kloosii (14.02%, 15/107), Staphylococcus saprophyticus (12.15%, 13/107), and Macrococcus caseolyticus (8.41%, 9/107). The prevalence based on genera were Staphylococcus (36.45%, 39/107), Acinetobacter (20.56%, 22/107), and Macrococcus (10.28%, 11/107). Almost all Staphylococcus isolates had low susceptibility to penicillin (21%). Notably, Staphylococcus arlettae, Staphylococcus haemolyticus and M. caseolyticus were multidrug-resistant (MDR). It is notable that none of the staphylococci and macrococci isolates exhibited inducible clindamycin resistance (D-test negative). Escherichia coli and Pseudomonas putida isolates were carbapenem-resistant, and Acinetobacter baumannii isolates were MDR with showing carbapenem resistance. Conclusion Our data demonstrated a high prevalence of medically important bacteria presented on Thai currency, which may pose a potential risk to human health and food safety. Food vendors and consumers should be educated about the possible cross-contamination of bacteria between the environment, food item, and currency.https://peerj.com/articles/19465.pdfBacteriaMALDI-TOF mass spectrometryCurrencyMarketsAntimicrobial susceptibility testThai
spellingShingle Nattamon Niyomdecha
Suwitchaya Sungvaraporn
Arisa Pinmuang
Narissara Mungkornkaew
Thanchira Saita
Waratchaya Rodraksa
Achiraya Phanitmas
Nattapong Yamasamit
Pirom Noisumdaeng
Identification of bacteria on Thai banknotes and coins using MALDI-TOF mass spectrometry and their phenotypic antimicrobial susceptibility profiles
PeerJ
Bacteria
MALDI-TOF mass spectrometry
Currency
Markets
Antimicrobial susceptibility test
Thai
title Identification of bacteria on Thai banknotes and coins using MALDI-TOF mass spectrometry and their phenotypic antimicrobial susceptibility profiles
title_full Identification of bacteria on Thai banknotes and coins using MALDI-TOF mass spectrometry and their phenotypic antimicrobial susceptibility profiles
title_fullStr Identification of bacteria on Thai banknotes and coins using MALDI-TOF mass spectrometry and their phenotypic antimicrobial susceptibility profiles
title_full_unstemmed Identification of bacteria on Thai banknotes and coins using MALDI-TOF mass spectrometry and their phenotypic antimicrobial susceptibility profiles
title_short Identification of bacteria on Thai banknotes and coins using MALDI-TOF mass spectrometry and their phenotypic antimicrobial susceptibility profiles
title_sort identification of bacteria on thai banknotes and coins using maldi tof mass spectrometry and their phenotypic antimicrobial susceptibility profiles
topic Bacteria
MALDI-TOF mass spectrometry
Currency
Markets
Antimicrobial susceptibility test
Thai
url https://peerj.com/articles/19465.pdf
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