Introduction

Air-borne human pathogens are considered to be serious environmental hazards. Currency notes are handled and circulated by people with different health background and life styles. The level of contamination and risk of microbial transmission via currency notes are associated with the levels of community hygiene and economic status of the country (Saadabi et al. 2010; Fonseca et al. 2015). Although, the paper notes of currency which is handled by a large number of people increase the possibility of acting as environmental vehicle for transmission of potential pathogenic microorganisms i.e. bacteria and fungi (Abrams and Waterman 1972). The infected currency is therefore, identified as potential public health hazards as pathogen spread by circulating bank notes (Emikpe and Oyero 2007). Immuno-compromised persons stand the risk of acquiring opportunistic infection, through handling of contaminated currency (Opportunistic infection) which can occur when immune system is not competent so bacteria and fungi are usually harmful and cause diseases (Allen et al. 1972; Bodsworth 1990).

In literature there is a few data obtained from currency notes as a result of microbial contamination. For example in Ethiopia, Alemu (2014) investigated the prevalence of microorganisms in currency notes of the country and concluded that currency notes of lower denominations were the most contaminated because lower notes value pass through more hands in their lifetime than the higher ones. In Nigeria Emikpe and Oyero (2007) identified Entrobacter sp., Staphylococcus sp., Citrobacter sp., Klebsiella sp. and Proteus sp. as pathogenic bacteria resistant to Tetracycline and Cotrimoxazole and also sensitive to Amoxoftine, Gentamicin, Nalidixic acid and Ofloxacin. Similar data was also obtained from Nigeria by Enemuor et al. (2012) who identified Salmonella typhi, E. coli, Staphylococcus sp. and Enterococcus sp. and four fungal isolates from currency counting machines in selected banks of the country. In Nigeria, a study revealed that currency notes could cause diarrhea and urinary tract infection besides skin burn and septicemia infection (Kawo et al. 2009). Their research findings emphasized the economic importance of bank notes as a source of microbial contamination. In, Ajmer, Rajasthan (India) different isolates of E. coli grown on EMB from samples of currency from different social status were identified (Barolia et al. 2011). In India, Elumalai et al. (2012) similarly isolated E. coli, S. aureus, Bacillus sp., Klebsiella sp., Salmonella sp., Pseudomonas sp., P. mirabilis and Bacillus sp.  in currency note samples. In Sudan serious pathogenic fungi that cause mycoses have been isolated and identified from lower values of bank note currency of the country (Saadabi et al. 2011). In USA, Fonseca et al. (2015) isolated S. aureus, Klebsiella pneumoniae, Enterobacter sp., and Pseudomonas sp. with a 72% sample contamination.

In Saudi Arabia, there is a very limited documented data concerning the pathogenic bacteria which transmitted by currency notes (Al Ghamdi et al. 2011).The data of this publication concentrated on Riyal value only and not included fungal pathogens. Therefore, the objectives of the present research work are to investigate whether Saudi bank notes currency save as barriers for microbial contamination, highlight some environmental pollution due to currency microbial contamination and suggest some control measures to minimize contamination in Saudi bank note currency.

Materials and Methods

Survey

Banknotes from different marketing sources such as meat seller (meat market) or butchers, vegetable markets and fish market were obtained. The values of banknotes were: one, five and ten Saudi Riyals, which were collected randomly in sterile polyethylene bags. They were immediately transferred to the microbiology laboratory of clinical laboratory sciences department of Shaqra University to apply all microbiological examinations for the different values of collected banknotes.

Isolation of Microorganisms

Values of bank notes were rinsed and soaked separately in 100 ml normal saline in 250 ml beaker for 24 h (Carroll, 1974). Streaking and swabbing were done with washed water using sterile loop and swab (Baron, 1990; Saadabi et al. 2010) onto Nutrient Agar (Himedia laboratories, India). and MacConkey Agar(Himedia laboratories, India) (Cheesbrough, 1991) to obtain bacterial isolation for 48 h incubation period at 37⁰C. While, Sabouraud Dextrose Agar (SDA) (Himedia laboratories, India) (Baron, 1990), was used for fungal isolation for 1 week at 28⁰C.

Identification of Bacteria

Cultures in solid media were visually inspected for growth rate and colony characteristics (Baron, 1990; Saadabi et al. 2010). Different colonies were sub- cultured on Nutrient Agar and MacConkey Agar and incubated similarly as before. Different API tests were carried out for identification of bacteria such as Staphylococcus spp., (Kloos and Wolfshohl 1982), Enterobacteriaceae (Holmes et al. 1978) and for other Gram negative bacteria (Truu et al. 1999).

Identification of Fungi

The growth of fungi on SDA was examined critically after one week, using prepared microscope slides. The prepared specimens were mounted on Lacto phenol cotton blue and identification of the fungal species was performed with aid of binocular compound microscope (Bruge et al. 1977).

Results and Discussion

Microbiological methods which were adopted in this study (Bjerring and Oberg, 1986; Saadabi et al. 2010) indicated that various species of bacteria (Figure 1) and fungi have been isolated from different Saudi bank notes. The genera of isolated bacteria are the members of the family Enterobacteriaceae i.e. Citrobacter frendii, Citrobacter koseri, Escherichia coli, Klebsiella ozaeni, Klebsiella pneumoniae, Klebsiella rhinosclrematis, Proteus vulgaris, Shigella flexneria and Shigella dysenteryiae which were shown in Table 1 and Table 2. The identified Gram positive bacteria were Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus and spore- forming bacteria such as Bacillus subtilis, Bacillus pemulus, Bacillus megaterium, Bacillus firmus, Corynbacterium haemolyticum, C. hafmainaii and Lactobacillus caserii (Tables 1, 2 and 3). Bacteria which isolated from different bank notes that showed high rate of occurrence were Staphylococcus aureus and E. coli. While genera such as Bacillus sp., Klebsiella sp., Citrobacter sp., Proteus sp. and Shigella sp. were found in a limited colony numbers especially in bank notes value of five and ten Riyals  (Tables 1, 2 and 3).

Figure 1: Total viable counts of bacteria isolated from currency notes collected from different locations   Click here to View figure

Table 1: Total counts and preliminary microbiological tests of  bacteria isolated from some Saudi currency notes collected from different locations.

Table 2: Gram positive pathogenic bacteria isolated from some Saudi currency notes with different values.

Table 3: Gram negative pathogenic bacteria isolated from some Saudi currency notes with different values.

The most predominant fungal species isolated were Epidermophyton sp., Saccharomyces sp., Cladosporium sp., Microsporum sp., Candida sp. & Aspergillus sp. those found abundantly in bank note values of one Saudi Riyals. While species such as Penicillium sp., and Aspergillus niger were isolated from a very limited numbers of samples. The occurrence of some species such as Microsporum sp, is somewhat negligible and in a limited manner of prevalence with some percentage of less than 25%. (Figure 2). Moreover, some species of the genus Aspergillus sp. were found very low as compared to the other isolated genera of fungi (Table 4).

Figure 2: Total viable counts of fungi isolated from currency notes collected from different locations   Click here to View figure

Table 4: Identification of pathogenic fungi isolated from some Saudi currency notes with different values collected from different sources.

From the present investigation, it was clearly observed that there is a negative correlation between value of bank notes decrease and increase in microorganisms that were found (Emikpe and Oyero 2007), regardless of the species found. Areas within Shaqra province  are more contaminated with pathogenic fungi and bacteria because it is near Riyadh area a capital city of Saudi Arabia  and involve a large population, which means more handling, more frequent exchange of currency leading to more contamination. There were also a large number of pathogenic bacteria and fungi that isolated from samples collected from meat markets. The bacteria isolated belong to Enterobacteriaceae family and this family is more frequency found in the air (air-borne) and was found also in large quantity in faces (Bjerring and Oberg 1986). This reflects that faucal pollution appears as a result of poor hygienic attitude in the community of the market. Moreover, the genera of Enterobacteriaceae are usually hazardous such as Salmonella typhi and Shigella dysenteryiae that are pathogenic to human and animals. Furthermore, it was observed that high values of currency are less contaminated than a low values currency, because a low values are more wide spread and exchangeable between people in population (Emikpe and Oyero 2007; Saadabi et al. 2010). Our results are closely related and similar to those obtained in Saudi Arabia Riyadh area (Al Ghamdi et al. 2011) and in Nigeria who isolated Enterobacter sp., Staphylococcus sp., Citrobacter sp., Klebsiella sp. and Proteus sp. from different samples of Nigerian (Enemuor et al. 2012). Also from this investigation and others (Moss, 1994), we have reached the point that Saudi  currency gives a positive appearance of some species of pathogenic bacteria and fungi due to the absence of antimicrobial agent in row material used for manufacture (Baron, 1990). We also found bacterial contamination in significant number of samples from vegetable markets, which also indicated lack of hygienic attitude within labors. Therefore, a recommendation should be pointed out such as awareness of people is how to handle money emphasizing to reduce their hand contamination, so reducing currency pollution. Emphasis is also to be stressed in the handling of bank notes by children so as to keep them safe from infectious diseases because they may enter all type of currency on their mouth. It is also recommended to develop bank notes manufacture by adding antimicrobial agents as a row material during processing. Re -sterilization of currency when it is dirty and returns it back to reduce the risk of infection especially for children. Plastic bank notes are strongly recommended, along with coin currency which is sometimes needed.

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