Se cultivaron 81 hisopados rectales en el medio CHROMagar KPC y por el método del CDC. Fueron positivos para Klebsiella pneumoniae KPC en CHROMagar KPC, 9/81 y 6/81 con el método del CDC. El medio ...CHROMagar KPC tuvo dos falsos positivos: 1 K. pneumoniae y 1 Acinetobacter sp. Los falsos positivos del método CDC fueron: 25 Acinetobacter spp., 2 Escherichia coli y4K. pneumoniae. El empleo del medio CHROMagar KPC resultó ser un método con mayor recuperación de aislamientos productores de KPC y menos falsos positivos que el método del CDC. Para evaluar los falsos positivos en el medio CHROMagar KPC se cultivaron 1247 hisopados rectales. Se obtuvieron 1021 negativos, 171 K. pneumoniae KPC y 55 (4,4 %) falsos positivos. Debido al desarrollo de falsos positivos en el medio CHROMagar KPC, se debe confirmar por caracterización fenotípica la presencia de KPC en las bacterias aisladas.
Weakly beta-haemolytic spirochaetes related to human intestinal spirochaetosis produced a cooperative haemolysis together with
S. aureus consisting of an enhanced haemolysis in the zone of the ...spirochaetal growth which was overlapped by the zone of activity of the staphylococcal β-haemolysis. The cooperative haemolysis was observed in sheep blood agar media when the concentration of spirochaetes ranged from 1.5 × 10
3 to 1.5 × 10
8 CFU/ml and the concentration of
S. aureus from 4 × 10
3 to 4 × 10
8 CFU/ml. With the increase of the distance between the streaks of the spirochaetes a
S. aureus from 3 to 10 mm, the period of incubation needed to observe the cooperative haemolysis also increased from 18 to 72 hours. When the spirochaetes and
S. aureus were streaked at the same time and when
S. aureus was streaked earlier than the spirochaetes, the phenomenon was observed after anaerobi incubation of the plates for 24–72 hours but not after incubation in 10% CO
2 under atmospheric conditions. A cooperative haemolysis was also observed between
S. aureus and spirochaetes related to the porcine and avian intestinal spirochaetosis and the spirochaete causing swine dysentery when the same experimental conditions were used which allowed an observation of the phenomenon involving human spirochaetes and
S. aureus.
