Microbiological contamination of the inner surface of reusable bottles at bottled drinking water production in Khanh Hoa province, 2022

Abstract

A cross-sectional study was conducted to evaluate microbiological contamination on the inner surface of bottles sized 19 - 21 liters at bottled drinking water producers in Khanh Hoa province in 2022. A total of 186 swab samples of the inner surface of bottles before and after the washing process at 93 producers were subject to test for ATP (Adenosine Triphosphate), the aerobic plate count (TSVSVHK), coliform, Escherichia coli using the following methods as AOAC 041901, ISO 4833-1:2013, ISO 4832:2006, ISO 16649-2:2001, ISO 16266:2006, ISO 7899-2:2000, and ISO 6461- 2:1986, respectively. The average ATP and TSVSVHK on the inner surface of bottles after washing decreased by 4.3 and 3.4 times compared to those before the washing process. However, the prevalence of bottles with an average ATP of greater than 300 RLU/100 cm2 was still high (49.5%). The bacteria of coliform (52.7%), P. aeruginosa (25.8%), E. coli (6.5%), and Str. feacal (2.2%) were detected on the inner surface of bottles before washing. Moreover, bottles after the washing process were still contaminated with coliform (36.6%), P. aeruginosa (14%), and E. coli (3.2%). Our finding indicated that the washing and cleaning process of reusable bottles at many bottled drinking water producers in Khanh Hoa province might not be proper and did not completely eliminate bacterial contamination on the inner surface of reusable bottles, thereby increasing the risk of bacterial contamination into the finished water and resulting health risk of consumers.