Open AccessAgar‐entrapped bacteria as an in vitro model of biofilms and their susceptibility to antibiotics
Author(s) -
Jouenne Thierry,
Tresse Odile,
Junter GuyAlain
Publication year - 1994
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1994.tb06894.x
Subject(s) - microbiology and biotechnology , agar , biofilm , bacteria , agar plate , chemistry , antibiotics , latamoxef , biology , genetics , cefotaxime
A simple in vitro system was developed as a model structure of biofilms and to evaluate their susceptibility to antibiotics. Viable Escherichia coli cells were entrapped in agar gel layers and incubated for 2 days in a minimal salt medium supplemented with glucose. After subsequent culture for 3 weeks under metal ion depletion, the biomass distribution inside the gel layer was highly heterogeneous. The cell concentration reached 10 11 cfu/g gel in the outer regions of the agar structure whereas the inner gel areas were less colonized (10 9 cfu/g gel). Immobilized cells displayed enhanced resistance to latamoxef as compared with free microorganisms. Moreover, a 3‐week‐old immobilized‐cell membrane was less susceptible to the antibiotic than a younger (2 days old) one. The exposure for 11 h to 64 μg/cm 3 latamoxef killed about 90% of the bacteria entrapped in the older agar layer, whereas the number of killed cells was 100‐fold higher in the younger structure. Effective diffusivity measurements showed that the diffusion of latamoxef in the biofilm‐like agar structures was moderately restricted as compared to that in water, and independent of the immobilized‐cell content.