A novel bioassay for evaluating the efficacy of biocides to inhibit settling and early establishment of marinebiofilms

This paper presents a novel assay that allows a quick and robust assessment of the effects of biocides on the initial settling and establishment of marine photoautotrophic biofilms. The assay integrates the response of the multitude of indigenous fouling organisms, which overcomes a major limitation of existing assays which are largely limited to testing only lab-cultivatable species. The assay was evaluated using eight antifouling biocides, for which full concentration-response curves are presented. The efficacy ranking, based on EC 98 values from most to least efficacious compound is: copper pyrithione >TPBP >DCOIT >tolylfluanid>zinc pyrithione >medetomidine >copper (Cu 2+ ), while the ecotoxicological ranking (based on E C10 values) is irgarol, copper pyrithione >zinc pyrithione >TPBP >tolylfluanid >DCOIT >copper (Cu 2+ ) > medetomidine. The algaecide irgarol did not cause full inhibition. Instead the inhibition leveled out at 95% effect at 30 nmol l -1 , a concentration that was clearly lower than for any other of the tested biocides.

A novel bioassay for evaluating the efficacy of biocides to inhibit settling and early establishment of marinebiofilms

This paper presents a novel assay that allows a quick and robust assessment of the effects of biocides on the initial settling and establishment of marine photoautotrophic biofilms. The assay integrates the response of the multitude of indigenous fouling organisms, which overcomes a major limitation of existing assays which are largely limited to testing only lab-cultivatable species. The assay was evaluated using eight antifouling biocides, for which full concentration-response curves are presented. The efficacy ranking, based on EC 98 values from most to least efficacious compound is: copper pyrithione >TPBP >DCOIT >tolylfluanid>zinc pyrithione >medetomidine >copper (Cu 2+ ), while the ecotoxicological ranking (based on E C10 values) is irgarol, copper pyrithione >zinc pyrithione >TPBP >tolylfluanid >DCOIT >copper (Cu 2+ ) > medetomidine. The algaecide irgarol did not cause full inhibition. Instead the inhibition leveled out at 95% effect at 30 nmol l -1 , a concentration that was clearly lower than for any other of the tested biocides.

Inhibition of Aminoglycoside 6′-N-Acetyltransferase Type Ib-Mediated Amikacin Resistance in Klebsiella pneumoniae by Zinc and Copper Pyrithione

ABSTRACTThein vitroactivity of the aminoglycoside 6′-N-acetyltransferase type Ib [AAC(6′)-Ib] was inhibited by CuCl2with a 50% inhibitory concentration (IC50) of 2.8 μM. The growth of an amikacin-resistantKlebsiella pneumoniaestrain isolated from a neonate with meningitis was inhibited when amikacin was supplemented by the addition of Zn2+or Cu2+in complex with the ionophore pyrithione. Coordination complexes between cations and ionophores could be developed for their use, in combination with aminoglycosides, to treat resistant infections.