Vandini et al. (1) evaluate the effect of a microbial cleaner, containing spores of food grade Bacillus subtilis, Bacillus pumilus and Bacillus megaterium in two Italian and one Belgium hospital.

According to the abstract 20,000 microbiological samples were taken from surfaces, during the 24-week investigation, which would equal approximately 120 samples per day!

While nothing about blinding or block-randomization (or any possible approach that would eliminate bias) was mentioned, it is stated that the cleaning staff was not aware which cleaning product they used. Seen the fact that chlorine based-cleaners were the standard products in the two Italian hospitals, this seems hard to believe. The study period started at different times in the hospitals (but not by design) and in opposite to the abstract for different periods of time, namely 6, 24, and 66 weeks, respectively.

Overall, it seems that this paper didnot follow a before planned protocol, but is actually an accumulation of data collected in several countries at various times, presented as one study. In the discussion the authors even don’t stop from suggesting a reduction of HAIs during the study period, while none of this had been mentioned in the methods or results section of the manuscript.

I did admire however that the authors took the effort to determine resistance-genes in Bacillus species to evaluate whether the original bacilli or new environmental isolates would serve as a source of resistance genes.

Still, while alternative cleaning methods are most certainly very welcome, including probiotic-based cleaners, they most certainly warrant sound study protocols and well-expressed publications.

1. Vandini A, Temmerman R, Frabetti A, Caselli E, Antonioli P, et al. (2014) Hard Surface Biocontrol in Hospitals Using Microbial-Based Cleaning Products. PLoS ONE 9(9): e108598. doi:10.1371/journal.pone.0108598