The Study Of Bacterial Contamination Of Currency And Antimicrobial Capability Of Metal Coins

In this paper,paper notes and coins were collected from general public in Beijing area where ready-to-eat food can be served,in order to survey for bacterial contamination.The total bacterial number and potentially pathogenic organisms loading on currency were tested.All isolated potential pathogens were also tested for antibiotic resistance against four most commonly prescribed antibiotics.1.The bacterial counts on one hundred paper notes sample were ranging between 6～10918/cm~2,the median was 141/cm~2,according to the data it was much higher than credit cards and Australian notes which were made of polymer.The bacterial counts on sixty coin samples were ranging between 2～380/cm~2,much less than paper notes.2.Coliform(65.6%),E.coil(45.9%),S.aureus(41.7%),B.cereus (67.7%),Salmonella(19.8%)were isolated on one hundred paper notes. Coliform(22.4%),E.coil(5.2%),S.aureus(24.1%),B.cereus(34.5%), Salmonella(10.3%)were isolated on sixty coin samples.These results suggested a high rate of potential pathogens contamination of paper notes than coins.3.Antibiotic resistances are commonly in most of the pathogens isolated on currency.Ampicillin resistance was found in 60%of Staphylococcus aureus isolated on currency,as well as 76.6%of E.coil and 40%of Salmonella.Erythromycin resistance was detected in 56.6%of S.aureus and in 80.0%of E.coil.All the pathogens isolated were sensitive to Norfloxacin,salmonella and S.aureus also sensitive to Cefaclor.In this paper we also studied the antimicrobial capability of metal coins,coins collected from different countries were tested for the ability to inhibite the growth of E.sakazakii,S.aureus,E.coil,L.monocytogenes and S.typhimurium.1.E.sakazakii appeared very sensitive to metal coins,the secondly is S.aureus,but E.coil,L.monocytogenes and S.typhimurium are more resistant to these metal coin samples.2.Coins made of Nickel-brass alloy and Copper-nickle alloy showed a better effect in anti-microbe than other metal coins,especially the ability to inhibited growth of E.sakazakii and S.aureus,all the inhibition zones produced on nutrient agar are more than 20.6 mm.Aluminium-bronze alloy revealed weak anti-microbe activity to S.aureus and no effect to kill other pathogens.Coins made of stainless steel also can't resist bacteria growth.3.Surprisingly,one cent coins of USA which were made of 97.5% Znic and 2.5%Cu showed a significant Antimicrobial capability,the average inhibition zone of these five pathogens is 45.5mm.