African Journal of
Microbiology Research

  • Abbreviation: Afr. J. Microbiol. Res.
  • Language: English
  • ISSN: 1996-0808
  • DOI: 10.5897/AJMR
  • Start Year: 2007
  • Published Articles: 4962

Full Length Research Paper

Detection of pathogenic bacteria and fungi on biometric surface of Automated Teller Machines located in Brazilian public hospital

Simone Aquino
  • Simone Aquino
  • Health Department II and Professional Master Program in Environmental Management and Sustainability, Universidade Nove de Julho, Brazil.
  • Google Scholar
Jose Eduardo Alves de Lima
  • Jose Eduardo Alves de Lima
  • Health Department II and Professional Master Program in Environmental Management and Sustainability, Universidade Nove de Julho, Brazil.
  • Google Scholar
Moises Oliveira da Silva
  • Moises Oliveira da Silva
  • Health Department II and Professional Master Program in Environmental Management and Sustainability, Universidade Nove de Julho, Brazil.
  • Google Scholar
Gabriela Fabricio de Sousa
  • Gabriela Fabricio de Sousa
  • Health Department II and Professional Master Program in Environmental Management and Sustainability, Universidade Nove de Julho, Brazil.
  • Google Scholar

  •  Received: 21 January 2019
  •  Accepted: 06 March 2019
  •  Published: 21 March 2019


The Automated Teller Machine (ATM) is used by millions of people as an alternative to gain time instead of using traditional banking systems in Brazil and ATMs are frequently localized in São Paulo city around the hospitals. However, ATMs might be potential devices for microbial accumulation and transmission in the community. The objective of the present study was to evaluate forty-two ATMs, in two hospital areas (A and B) in São Paulo city for the presence of pathogenic fungi and bacteria. Samples were collected from biometric surfaces of the devices with sterile cotton swabs soaked in the sterile physiologic saline and were cultured on selective agar for yeasts, filamentous fungi and bacteria in the period of January 2017 to March 2018. Complementary biochemical tests were applied to confirm the bacteria and the taxonomic identification of molds was performed considering the morphological characteristics by microscopic observation. Our results suggest that the biometric surfaces in ATMs is an important environmental source of microbes, once that the genera Staphylococcus was predominant in all agencies of both hospital areas (83.3%), following of Streptococcus spp. (57%) and Enterococcus spp. (50%). The group of Enterobacteriaceae (Gram negative bacilli) were most frequent in both areas studied (57%). Seven different fungi genera were isolated from ATMs in area A and B and yeasts were predominant in all samples collected (47%), comparing with filamentous fungi (23%). We conclude that biometric ATM surfaces play an important role in microbial transmission in hospital settings, and healthcare professionals should wash and disinfect their hands carefully before touching patients.

Key words: Automated teller machine, bacteria, fungi, contamination, hospital.



Contamination of environmental objects and surfaces is a common phenomenon. Human beings have a marked tendency to pick up microorganisms from environmental objects, and the hand has been shown to play a role in the transmission of microrganisms (Onuoha and Fatokun, 2014). Few investigators, however, have examined in detail the bacterial species found in other surfaces or environments (Reacher et al., 2000).
Since the year 2000, infection with methicillin-resistant Staphylococcus aureus (MRSA) was becoming increasingly common in UK hospitals, contributing significantly to morbidity and mortality (Reacher et al., 2000). The risk of environmental contamination has also been highlighted by the isolation of S. aureus from commonly used hospital items, included stethoscopes, pens, tourniquets, computers and blood pressure cuffs (Devine et al., 2001; Cohen et al., 1997; French et al., 1998; Berman et al., 1986; Layton et al., 1993; Al-Ansari et al., 1999).
Blomeke et al. (2007) investigated bacterial recovery and transfer from fingerprint biometric sensors and the survivability of bacteria on the devices. Two species of bacteria, S. aureus and Escherichia coli and the survivability was investigated by sterilizing the sensor surface, applying a known volume of diluted bacterial culture to the sensor and allowing it to dry. Bacteria were recovered at 5, 20, 40 and 60 min after drying by touching the contaminated device with a sterile finger cot. The result of this comparison between S. aureus and E. coli is that neither bacterial species survived for a long time on the device surface, but even at 60 min a small quantity of bacteria was still recoverable (Blomeke et al., 2007).
Due to the ongoing development and expansion of urbanization, as well as the increasing population, people do not have enough time to use traditional banking systems and have embraced new developments in electronic banking, such as Automated Teller Machine (ATM) (Mahmoudi et al., 2017). The ATM is a computerized telecommunications device that enables the clients of a financial institution to perform financial transactions without the need for cashier, human clerk or bank teller (Rasiah, 2010). Today, the extended use of electronic technologies is considered a source of bacterial contamination. In general, microbes can persist or grow on many surfaces, such as those found in restaurant kitchens and hospital environments, as well as on standard office equipment such as computer keyboards, telephones, cellphones, and ATMs (Abban and Tano-Derah, 2011; Anastasiades et al., 2009; Anderson and Palombo, 2009).
Nowadays the ATM has been an important device in the banking sector and other financial institutions. The keyboards and screens of these devices are contaminated with pathogenic or non-pathogenic microorganisms (Mbajiuka, 2015). Hundreds of people whose socio-economic levels and hygienic status are quite different with each other use ATMs daily. Customers contact with their hand the surfaces of keypad and/or screen of these devices. However, there is limited data about their status for microbial colonization. Therefore, investigation of the bacterial load of these devices may be valuable to increase our awareness about the possible transmission ways of pathogens, some of them are pathogenic, especially in people with weakened immune system (Tekerekoğlu et al., 2013; Mahmoudi et al., 2017).
Bank ATMs are often located around hospitals. The objective of the present study was to evaluate the fungal and bacterial contamination of the biometric system of ATMs located around two public hospitals in the city of São Paulo and to investigate the risks of microbial transmission between health professionals and community that share banking branch services.


Sample location
São Paulo is a large city in South hemisphere (latitude -23.533773 and longitude -46.625290) and is the capital of São Paulo state of Brazil. Two large general hospitals (A and B) located in São Paulo were chosen because of the high complexity of care and belong to the Brazilian Unified Health System (UHS), in addition both are school hospitals. The hospital A is a large complex clinic comparing to hospital B, in despite that the hospital B was inaugurated in 1936. The hospital A was inaugurated in April 1944 and is pioneer in medical-hospital procedures with a great number of hospitalization and intensive care units. The considered research area was 300 m around the hospitals and swab samples were collected in the period of January 2017 to March 2018, from 14 different commercial banks situated in delimited area with the aid of sterile cotton swab sticks moistened with sterile physiological saline before swabbing the biometric fingerprint buttons of the ATM machines. All cotton swab sticks were immediately transported in sterile tubes and transferred to the microbiology laboratory of Nove de Julho University for analysis.
Isolation of bacteria
A total number of forty-two (n=42) samples were collected. The swabs (21 for each area) were inoculated onto nonselective media for bacteria (Nutrient agar and Blood agar) and selective medium (MacConkey agar, Enterococcus agar, Baird Parker agar and Mannitol agar) in triplicate plates and incubated at 37°C for 24 h.
Bacterial identification of single colonies grown or colony-forming units (CFU) on MacConkey agar plates were tested using colonial morphology, Gram stain colonial morphology, triple sugar iron agar (TSI) test and complementary biochemical tests according to Cheesbrough (2006) for Gram negative bacteria. To detect Gram positive bacteria, colonies on Blood, Enterococcus agar, Baird Parker agar and Nutrient agar were tested using colonial morphology with Gram stain and after confirmed in catalase and coagulase tests (Bartholomew and Mittewer, 2008). A selective media Mannitol and Baird Parker media was used to differentiate S. aureus from other coagulase-negative staphylococci.
Fungal isolation
To determine the presence of Candida species the samples were inoculated onto CHROMagar Candida and incubated at 37°C for 24 h to identification of mixed cultures by the colour of the colony and differentiate various Candida species. To isolation of filamentous fungi, the swabs were inoculated in Potato Dextrose Agar (PDA) and incubated at 25°C for 7 days. A portion of the colony was stained with lactophenol cotton blue. For the microscopic observation of the fungal morphology, the direct technique of mycological examination of the aerial mycelium, conidia and conidiogenic cells under a light microscope with an increase of 100 and 400-fold (100-400×). The taxonomic identification of fungi was performed considering the morphological characteristics of the vegetative mycelium and the reproductive structures (Pitt and Hocking, 2009). After incubation the CFU were counted and assigned values (+, ++, +++) to colony counting according to Nwankwo and Offiah (2016).
Statistical analysis
Data statistical analysis obtained from the isolation of bacteria in this study were analyzed by the T test applied to the two-tailed hypothesis was the best way to compare the mean between the two samples obtained for the hospital areas A and B. The statistical analysis of the data was performed in SPSS version 16.0 (SPSS Inc., USA).


From the 42 samples collected (N = Σ NA + NB), 21 samples were obtained near the hospital area A and 21 from hospital area B. Forty samples (95%) presented growth and 2 (5%) showed no bacterial growth. Different fungi (molds and yeasts) were isolated from ATMs in areas A and B. The frequency of yeasts was predominant in all samples collected (47%) compared to filamentous fungi (23%). The number of microorganisms recovered from ATMs located near hospitals A and B was compared to each other, as shown in the Figures 1, 2, 3 and 4.
The ATM is used by millions of people in a day and it is meant to be a public utility device, but dirty surfaces such as ATMs can bring them into the source of infection and may pose a risk to public health. Mbajiuka (2015) gave the definition of ATMs as “pathogen city‟ and the risk of transmission of pathogens from devices or computer keyboards to patients would be prevented by compliance with current hand hygiene guidelines. Unfortunately, studies have demonstrated that the mean rate of compliance with the Centers for Disease Control and Prevention (CDC) guidelines on hand hygiene is approximately 40% among healthcare workers, which is a likely explanation for the frequent contamination of computer keyboards (Boyce and Pittet, 2002).
In the present study, the Gram-positive Staphylococcus genera showed a profuse growth (above 71 colonies) in both areas in all ATMs, following by Streptococcus spp. The group of Gram-negative bacteria, the family Enterobacteriaceae was present in a moderate growth (31-70 colonies). The Table 1 shows the enumeration of each genera or bacteria group isolated from ATMs in hospital A area and hospital B area. The Gram-positive Staphylococcus genera showed a profuse growth (above 71 colonies) in both areas in all ATMs, following by Streptococcus spp. The group of Gram-negative bacteria, the family Enterobacteriaceae was present in a moderate growth (31-70 colonies). Table 2 shows the enumeration of each genera or bacteria group isolated from ATMs in hospital A area and hospital B area in São Paulo city. Between of Gram-positive bacteria, the genera Staphylococcus was predominant in all agencies of both hospital areas (83%), following of Streptococcus spp. (57%) and Enterococcus spp. (50%). Among the Gram-negative bacilli, the group of Enterobacteriaceae were most frequent in both areas studied (57%). Table 3 represents the morphological and biochemical characteristics of isolated bacteria in ATMs.
The Gram positive bacteria (Staphylococcus, Streptococcus and Enterococcus) and Gram negative bacteria (Enterobacteriaceae group, Escherichia coli, Salmonella spp., Klebsiella spp., and Pseudomonas aeruginosa) in ATMs revealed that there is no statistical significance between the means of these bacteria in samples collected near hospitals A and B. However, the number of isolated fungi was significant, showing that the results of hospital A area was more expressive than those collected near the B hospital region, as shown in Table 4.
In occupational activities environments many individuals are exposed to risks of microbial origin, in a special concern is transmission of pathogens that have been demonstrated to be present on environmental surfaces in proximity to colonized or infected patients (Rutala et al., 2006). In a study performed in New York city, Bik et al. (2016) suggested that ATM keypads amalgamate microbial assemblages from different sources, including the human microbiome, eukaryotic food species, and potentially novel extremophilic taxa adapted to air or surfaces in the built environment. The authors obtained microbial DNA from ATM keypads may thus provide a record of both human behavior and environmental sources of microbes.
In this present study, it was observed a great variety of microbes in ATMs biometric surfaces around hospital areas. It is important to note that in a same surface there were various bacteria and fungi that represents a potential pathogenicity. The findings are represented in Table 5. Regarding the bacteria species, S. aureus were the species most frequent among the bacteria (Figure 5) and the results obtained in the present study are according of the isolates obtained from the data reported by Onuoha and Fatokun (2014) that observed that S. aureus (28%) was the commonest organism isolated from ATMs of seventeen different banks in two major towns in Nigeria. 
Nwankwo and Offiah (2016) reported that the ATM machines are one of the most commonly touched surfaces today. Onuoha and Fatokun (2014) described six different bacteria isolates in ATMs located in Nigeria, such as Staphylococcus spp., Streptococcus spp., Pseudomonas spp., Enterobacter spp. and Escherichia spp.
Mahmoudi et al. (2017) evaluated 96 ATM keyboards at four locations in Hamadan (Iran) and they observed that all tested ATM keyboards were contaminated with at least one species of bacteria. The most frequently isolated bacteria were Staphylococcus epidermidis in 12 (18.5%) ATMs, Pseudomonas aeruginosa in 12 (18.5%), Bacillus subtilis in 11 (16.9%), Escherichia coli in 6 (9.2%), Klebsiella spp. in 8 (12.3%), Enterobacter spp. in 2 (3.1%), Bacillus cereus in 6 (9.2%), Staphylococcus aureus in 3 (4.6%), and Micrococcaceae spp. in 5 (7.69%) cases. The bacteria contamination of 14 commercial banks randomly scattered within the Umuahia Metropolis in Southeastern Nigeria showed a total of 102 bacterial organisms comprising nine different species in ATMs.
Two Gram positive bacteria, S. aureus and Streptococcus spp. showed 17.6 and 13.7% respectively while two Gram negative bacteria, E. coli and Pseudomonas spp. showed 26.5% and 9.8% respectively (Nwankwo and Offiah, 2016). The results revealed by Mbajiuka (2015) in Abia state (Nigeria) showed that 14 ATM devices were contaminated, being a potential disease dispensing machines as bacterial isolates such as Staphylococcus spp. about 82.5%, Bacillus spp. 62.5%, Escherichia spp. 22.5% and Streptococcus spp. 15%.
Okoro et al. (2018) showed that there is a strong relationship between the isolated pathogenic bacteria and the ATMs. Pathogenic bacteria such as E. coli, P. aeruginosa, Shigella dysenteriae, Salmonella typhimurium, S. aureus and Klebsiella pneumoniae were isolated from seven (7) different banks within Kaduna Metropolis. The samples (n= 200) were contaminated with K. pneumoniae, that had the largest percentage of isolates with 46 (23%), followed by S. dysenteriae with 37 (18.5%). S. aureus, S. tyhimurium, and P. aeruginosa had 33 (16.5%), 32 (16%) and 29 (14.5%) respectively, while E. coli had the smallest percentage of isolates with 22 (11%).
Onuoha and Fatokun (2014) observed that S. aureus (28.57%) was the commonest organism isolated followed by E. coli (21.43%), Coagulase negative Staphylococcus (CoNS) (21.43%) and Streptococcus species (14.29%). P. aeruginosa and Enterobacter species showed the least percentage occurrence with (7.14%) respectively, in ATMs of Nigeria. Nagajothi et al. (2015) collected 92 swabs from ATM centers in Puducherry (India) and observed microbial growth in 88 (95.7%) swabs. One hundred and sixty (160) microorganisms were isolated: Klebsiella species (42.5%); Coagulase-negative Staphylococcus (CoNS) 20.62%; P. aeruginosa (15%); E. coli (10.6%) and S. aureus (3.75%).
The family Enterobacteriaceae consists of a number of species that are gram-negative bacilli (GNB) such as Salmonella, E. coli, Klebsiella and others that cause a wide variety of intestinal and extra-intestinal infections. Clinically, many members of the family of Enterobacteriaceae are among the most potent and prevalent pathogens, indeed, many of them have acquired resistance to most antibiotics (Al-Kharousi et al., 2016).
Non-fermenting Gram-negative bacilli (NFGNB) have emerged as important healthcare-associated pathogens. NFGNB have emerged as important healthcare-associated pathogens and is important to identify these bacilli members considering the intrinsic multidrug resistance exhibited by these bacteria and NFGNB are representing by Pseudomonas aeruginosa, Acinetobacter spp. and Burkholderia cepacian. The importance of isolation of non-fermenters has increased after reports that are correlating them with the respiratory infection outbreaks in hospitals, or healthcare-associated infections (Chawla et al., 2013).
It was observed that yeasts were predominant in all samples collected from area A, with Rhodotorula spp. (50%), and Candida albicans (7%). Non-albicans Candida group was isolated in both areas (48%). Among the filamentous fungi, Aspergillus spp. were predominant (21%) and Trichoderma spp., Cladosporium spp. and Rhizopus spp. were present in 14% of all ATMs, respectively. Penicillium spp. were isolated in only 7% of samples. The results of CFU fungal enumeration is demonstrated in Table 6. Data about fungal contamination in ATMs were described in a few studies. Nagajothi et al. (2015) reported a small frequency in ATMs in Puducherry (India), such as Aspergillus spp. (4.76%) and Mucor spp. (2.38%). The ATMs in Madurai city (India) fungal contamination included Aspergillus spp., Mucor spp., Penicillium spp. and Fusarium spp. (Mabel et al., 2014). Mbajiuka (2015) described that on the keyboards of ATMs in Nigeria were contaminated with fungi such as Rhizopus spp. (47.5%), Aspergillus spp. (22.5%) and Penicillium spp. (20%), corroborate the data of the present study in São Paulo city. 
Özkan (2016) compared the fungal contamination on 30 ATMs and 30 bank cards in Marmaris (Turkey). The Aspergillus genera were the most dominant followed by Alternaria, Cladosporium and Penicillium genera. According to the author, Aspergillus spp. are widespread in nature because they produce many spores, have wide ecological tolerance, can easily spread through the atmosphere, and they can contaminate almost any kind of surface. It was observed Cladophialophora, Cuninghamella, Drechslera, Fusarium, Geotrichum, Rhizopus, Scopulariopsis and Trichoderma in ATMs located in Turkey.
Filamentous fungi vary quantitatively and qualitatively because of different geographical and climatological factors and the number and diversity of users. However, the author did not research yeasts in samples. In the present study, the yeasts Candida albicans, Non-albicans Candida and Rhodotorula spp. were isolated from ATMs in São Paulo city. Some authors have been documented that even low levels of bacteria such Salmonella spp. and some E. coli strains survive on dry surfaces for long periods and can easily be transferred from the fingers to food surfaces, which lead to acute ailments. E. coli serovars has been implicated in major food borne disease outbreaks and infections, mainly from eating contaminated hamburger. S. aureus, K. pneumoniae and P. aeruginosa are all well documented for their high pathogenicity, causing death in outbreaks and respiratory infections. Other microbes isolated such Streptococcus spp. are known opportunistic pathogens in infections and food spoilers (Rusin et al., 2002; Mead et al., 1999; Kaluski et al., 2006; Mabel et al., 2014).
About the fungi, Cladosporium species show a world-wide distribution and they are the most common airborne fungi and they are isolated at high frequency as contaminants. Penicillium species are common contaminants on various substrates and are known as potential mycotoxin producers. Opportunistic infections leading to mycotic keratitis, otomycosis and endocarditis have been reported. Its spores and components in atmosphere entering from respiratory tract affect the human health and may cause allergic reactions. Rhizopus species is one of the factors of opportunistic fungal infection, as skin and mucous membranes allergies. Trichoderma is a very common genus particularly in soil and decaying wood that attacks to hair keratin by boring hyphae (Özkan, 2016; Domsch et al., 1980; Ellis et al., 2007). Table 7 describes the microbiological risks of pathogens isolated in the present study.
Özkan (2016) found in ATMs a fungi mycotoxin producer which can cause allergic diseases and various mycoses in humans and pointed the importance of complying with environmental and personal hygiene, because the ATMs were more contaminated than the bank cards in terms of fungal contamination. This can be explained by the situation of ATMs which are open to the atmosphere (without being in a cabin) and are cleaned rarely.
Many devices as cell phones are used in hospital indoor areas and presents risks to external population or community. Therefore, they can be vehicles for transmitting pathogens to patients and these contaminants moved by people may cause an epidemic or even pandemic situation (Zakai et al., 2016). This gains more importance in tourism and resort cities which is visited by several million people each year. Therefore, the common tools and goods used by people must be cleaned necessarily for not being a source of infection. Because visitors can bring any infection and can lead the infection spread where they contact (Özkan, 2016).
Frequent disinfection of the keyboards and screen parts, using antibacterial covers for the contact surfaces, or using alcohol wipes before and after use may be benefit for limiting the bacterial accumulation and transmission with cash machines (Tekerekoğlu et al., 2013). Based on these findings, it is recommendable to disinfect the hands after entering work area, mainly in a hospital, in order to hinder the spread of critical pathogens in the personal environment or in the hospital (Mahmoudi et al., 2017).
ATMs must be cleaned frequently with appropriate disinfectant for not being the source of infection. Such technological tools which are used by a large part of the population should be cleaned carefully to supply personal and environmental hygiene to not take the risk of causing epidemics or pandemics. The promotion of such research in order to protect the public health and to control the fungal disease is becoming a necessity. It is expected that this study will provide benefits to other studies and serve as a resource (Özkan, 2016).
According to Mbajiuka (2015) no reported outbreak of infectious or no-infectious epidemic has been noted in connection with the use of ATM, there is all indications that this device that serve as a cash dispensing machine may also serve as disease dispensing machine due of various hygienic conditions users, for daily financial transactions. It is imperative to adopt some measures aimed at curtailing the outbreak of disease transmission by the ATM surfaces and the author suggested some measures:
(i) Regular washing of hands before and after using the machines.
(ii) Regular maintenance of cleaning regime of these devices by the managements.
(iii) Avoiding using hands to eat snacks before and after using this device as it may lead to cross-contaminations of customers fingers.
(iv) Using alcohols and other antiseptics to clean all the surfaces that people can place their hands while using the ATM.
(v) Persons who have sign of contagious or infectious diseases should refrain from using this device until health conditions becomes stable again.



Such technological tools which are used by a large part of the population should be cleaned carefully to supply personal and environmental hygiene to not take the risk of causing epidemics. ATMs are used by many people must be cleaned frequently with appropriate disinfectant for not being the source of infection. Therefore, adequate personal hygiene and regular routine cleaning of these machines by the authorities is recommended. The promotion of such research in order to protect the public health and to control the fungal disease is becoming a necessity. It is expected that this study will provide benefits to other studies and serve as a resource to prevent the spread of infection diseases in hospital areas.


The authors have not declared any conflict of interests.



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