Using a triple agar layer technique and enzymatic inactivation of penicillin, the occurrence of a paradoxical zone phenomenon (illustrated by a typical ‘target’ image around the reservoir of antibiotic) was determined for several bacterial species specially chosen with regards to their taxonomic position, clinical importance and penicillin susceptibility. Among gram-positive bacteria, a paradoxical zone was obtained for approximately 43% of the strains studied here (all 10 strains of Staphylococcus aureus
, all 10 strains of Streptococcus faecalis
, 7 of 10 strains of group B β
-hemolytic streptococcci, 1 of 10 group A strains, 3 of 10 strains of α-hemolytic streptococci, 3 of 10 strains of Clostridium perfringens
but for none of 10 strains each of Streptococcus pneumoniae
, and Listeria monocytogenes
). Among gram-negative bacteria, a target image was regularly obtained with Haemophilus influenzae
(all 10 strains tested) and Proteus species (9 of 10 strains) but with none of the following species: Escherichia coli
, Pseudomonas aeruginosa
, Neisseria gonorrhoeae
, Neisseria meningitidis
and Bacteroides fragilis
. Therapeutic implications of these observations are difficult to assess, and need further investigation.
Prof. E. Yourassowsky, Université Libre de, Bruxelles, Hôpital Universitaire Brugmann, Service de Biologie clinique, Av. J.-J.-Crocq 1, B–1020 Bruxelles (Belgium)
Number of Print Pages : 5
Chemotherapy (International Journal of Experimental and Clinical Chemotherapy)
Vol. 24, No. 2, Year 1978 (Cover Date: 1978)
Journal Editor: Sörgel F. (Nürnberg-Heroldsberg)
ISSN: 0009-3157 (Print), eISSN: 1421-9794 (Online)
For additional information: http://www.karger.com/CHE
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