Department of Microbiology,
Olabisi Onabanjo University, P.M.B. 2002,
Ago-Iwoye, Ogun State, Nigeria.
corresponding author: [email protected]

Automated teller machine (ATM) cards which are used for an alternative access to banking functions can serve as a potential source of infectious diseases. In this study fifty (50) ATM cards of students in Olabisi Onabanjo University was sampled for presence of enteric bacteria. Swab sticks soaked with normal sterile saline were used and cultured on Eosine Methylene Blue (EMB) Agar, MacConkey Agar (MAC) and Salmonella Shigella Agar (SSA) using standard microbiological procedures. Identification of Enteric microorganisms was done using colonial, microscopic and biochemical characteristics. The results revealedthe presence of organisms belonging to the Enterobacteriaceae family such as Klebsiella spp (33.3%), Escherichia spp (23.3%), Enterobacter spp (23.3%), Salmonella spp (13.3%), Shigella spp (3.4%) and Pseudomonas spp (3.4%). We concluded that ATM cards could play a significant role in the transmission of infectious diseases caused by enteric organism.


Automated teller machines (ATMs) are one of the most widely used and accepted technological advancement of banking system, which makes financial transaction a lot easier(Agu, Osondu-Anyanwu, and Nwachukwu. 2018). ATMs are highly exposed to pathogenic microorganisms due to the unlimited accessibility of the populace from all works of life (Marbel, Subathra, Shyamala, and Padma. 2014). Typically, accessibility of the ATM functions involves the use of debit cards referred to as ATM cards, which when slotted users can make cash withdrawals, transfer funds and check account balance prior to following some on screen instructions (Saha and Rahman 2018).

The wide acceptance of the advancement in banking technology has led to new public health challenges in the banking system due to the use of plastic cards which enables hand transmission of pathogenic microorganisms through dermal contact (Okoro, Oloninefa, Ojonigu, and Sani. 2018). Fomites such as ATM cards becomes colonized with pathogenic organisms and serves as potential sources of transmission of pathogens from or to humans (Stephens,Azimi, Thoemmes, Heidarinejad, Allen, and Gilbert2019). Fomites also serve as vehicles for cross-infections and recontamination of washed hands (Maryam, Hadiza, and Aminu 2014).

Contamination of fomites of the banking system by pathogenic organisms have been reported in studies carried out by earlier researchers (Adedeji 2019; Mahmoudi, Arabestani, Alikhani, Sedighi, Kohan, and Molavi 2017; Okoro, Oloninefa, Ojonigu, and Sani 2018; Onuoha and Fatokun 2014).However, Enteric bacteria are one the most commonly encountered pathogenic bacteria on inanimate sources which plays significant role in transmission of diseases through hands (Alkhamis and Noweir 2018). Duration of colonization of pathogenic microorganisms on these plastic cards are not definite, persistence may vary form hours to months due to factors that influence the colonization (Onuoha and Fatokun 2014).

The number of populace accessing the ATMs daily increases the chances of hand transmission of pathogenic microorganisms via ATM cards due to the difference in personal hygiene status(Mahmoudi et al. 2017). Microorganisms belonging to the Enterobacteriaceae family can be pathogenic and can be transferred from one individual to another or may result in autoinoculation (Reddy, Sanjai, Kumaraswamy, Papaiah, and Jeevan 2013).There is no scientific report to the best of our knowledge on the isolation and identification of bacteria from ATM cards in Olabisi Onabanjo University, Ago Iwoye, Nigeria. Thus, the research investigates the presence of enteric bacteria on the ATM cards of students of Olabisi Onabanjo University, Ago Iwoye.


Study Area

Automated teller machine cards of different banks at different locations in Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria were used in this study

Sample Collection

Fifty swab samples were collected from ATM card surfaces using standard methods (Cheesbrough, 2000). Surfaces of ATM cards were swabbed immediately after ejection from the ATMs and swabs were promptly transported to the laboratory for microbiological analysis.

Laboratory examination and procedure

Immediately after sample collection, the swab sticks were streaked on Eosine Methylene Blue Agar, MacConkey Agar and Salmonella Shigella Agar and was then incubated at 37oC for 24 hours. The resultant isolates were then subcultured for further identification and characterization using cultural and biochemical characteristics.


A total of thirty isolates was obtained from 50 ATM card samples. Isolates were identified based on their distinguishable colonial, morphological and biochemical characteristics. Thenumber of colonies on different media was obtained as heterogenous growth was observed on all media. The highest number of coloniesobserved from each sample in MacConkey, Eosine Methylene Blue and Salmonella Shigella Agar were 3, 6 and 2 colonies respectively (Table 3.1). The prevalence of isolated bacteria included Klebsiella spp (33.3%), Escherichia spp. (23.3%), Enterobacter spp. (23.3%), Salmonella spp. (13.3%), Shigella spp. (3.4%), Pseudomonas spp. (3.4%) (Table 3.2)

TABLE 3.1: Frequency of isolates obtained sampled ATM cards

TABLE 3.2: Percentage of Occurrence of Enteric Bacteria Isolates from ATM Cards.

Probable OrganismsFrequencyPercentage
Klebsiella spp.1033.3
Escherichia spp.723.3
Enterobacter spp.723.3
Salmonella spp.413.3
Shigella spp.13.4
Pseudomonas spp.13.4


Enteric organisms have been reported to live on fomites and plastic surfaces (Stephens et al. 2019). In this study, ATM cards of studentswere investigatedfor presence of enteric organisms and as a potential transmission route for infectious disease pathogens considering difference in the level of personal hygiene among students. In this study, Enteric bacteria which include Klebsiella spp, Escherichia coli, Shigella spp, Enterobacter spp, Shigella spp, Pseudomonas spp., were among the isolated microbes of the Enterobacteriaceae family. The results of this study was also similar to findings of Aquino et al (2019) and Tekerekoglu et al (2012) were members of the Enterobacteriaceae was found on banks’ automated teller machines, although the present study focuses on ATM cards but transmission from ATMs to ATM cards could occur during user interaction. The high level of bacteria colonization of ATM reported in this study is similar to studies carried out by Nwankwo & Offiah (2016) and Okunye et al (2020)where high level of bacteria colonization on metallic surface of ATMs, keypads of ATMs (Nwankwo and Offiah 2016; Okunye, Kotun, and Kolade-Titilayo 2020). The highest prevalence was recorded from Klebsiella species followed by Eschericha coli and Enterobacter species, this finding is in concordance with the study of Abban and Tano- Debrah (2011), where the presence of Klebsiella sps and Eschericha coli was reported on ATM keypads(Abban and Tano-Debrah 2011).This study has largely revealed the contamination of ATM cards with enteric pathogens as well as confirming the cards as a potential vehicle of transmission of clinically important pathogens thus might play significant role in transmission of infectious diseases.


The results of this study verified the potential transmission of enteric pathogens such as Klebsiella sps and Eschericha coli via ATM cards. These pathogens have been reported to show high resistance to some commonly used antibiotics. The flexibility, usability and mobility of ATM cards increases the risk of exposure to pathogenic microorganisms and could potentially harbor more pathogenic bacteria than other environmental surfaces such as keypads, table surfaces or electronic hardware. Also, Bacteria colonizing fomites could persist for varying duration ranging from hours to months and this could aid hand transmission of infectious diseases such as diarrhea, pneumonia or gastroenteritis.


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