Behavior of Pseudomonas aeruginosa and Enterobacter aerogenes in Water from Filter Jugs

Abstract

Careless use conditions of filter jugs were applied to simulate and evaluate the behavior of two ubiquitous aquatic bacterial species, Pseudomonas aeruginosa and Enterobacter aerogenes. According to a reference protocol, nine different jugs of popular brands sold in the Italian market were used for the test. Separately, a suspension of the two bacteria was spiked in water used for filling the jugs. The concentration of the test organisms and total aerobic microbial count (TAMC) was measured daily in the filtered water along a period corresponding to the cartridge lifetime. Results showed a different trend of bacterial behavior. E. aerogenes was detectable exclusively on the first day after jug filling, while P. aeruginosa confirmed its persistence over time in all the jugs and its ability to potentially colonize surfaces and cartridges. The TAMC was detected at a concentration range from 102 to 107 CFU/100 mL in all the tests, high values that were not far from those raised in bottled flat natural mineral water weeks after bottling.

An Italian survey on the microbiological safety of toys containing aqueous media

“…It is conceivable that over time manufacturers have considered it appropriate to add bacteriostatic substances capable of minimizing microbial concentrations, thereby reducing the risks associated with the presence of micro‐organisms in the liquids. However, the initial hygiene characteristics of the aqueous medium and the nature of the biocides used is still unclear, as most of the isolated microbial species are environmental species and at the same time have the potential to cause human diseases (Briancesco et al, 2020; Paduano et al, 2020). Despite belonging to the normal human flora, many of these micro‐organisms may occur as opportunistic pathogens in immunocompromised individuals and in susceptible population groups, such as children (Riccardi et al, 2019).…”

“…Most of the noncompliant samples (84.6%) exceeded the limit for TAMC, a microbiological parameter of negligible value as an indicator of pathogen presence (Briancesco et al, 2020), since most of the micro‐organisms included under the term TAMC are nonhazardous water and biofilm bacteria, and in some instances organisms from diverse pollutant sources. Nevertheless, exceeding the TAMC limit is an indicator of poor microbial water quality.…”