Abstract:
This study was designed to investigate the in vitro activity of
Erythromycin compared with Azithromycin and Clarithromycin against
50 strains of streptococcal species isolated from patients present with
different diseases during the period between April to August 2003.
The results showed that Erythromycin has zones diameter of > 19
mm and MIC of < 0.5μg/ml against susceptible strains of S. pyogenes and
< 11 mm, and MIC > 4 μg/ml for resistant strains. Zones diameter > 20
mm and MIC < 0.5 μg/ml against susceptible strains of S. agalactiae; 14
mm, 1 μg/ml against intermediate susceptible strains; < 12 mm and > 2
μg/ml for resistant strains. Zones diameter > 19 mm and MIC < 0.5 μg/ml
against susceptible strains of V. streptococci; and < 3 mm, with MIC of >
16 μg/ml for resistant strains.
The zone diameter of > 18 mm and MIC < 0.5 μg/ml was recorded
for susceptible strains of S. pneumoniae; while 17mm, 1μg/ml for
intermediate susceptible strain; and > 10 mm, > 4 μg/ml for resistant
strains. All strains of Enterococcus faecalis were resistant to these
antibiotics with MIC > 16 μg/ml. The results also showed that 7 strains of
S. pyogenes out of 10 were sensitive to these antibiotics and 3 strains
resistant. Seven strains of S. agalactiae were susceptible to Erythromycin
and Azithromycin, but 8 strains were susceptible to Clarithromycin; one
strain was intermediate susceptible to Erythromycin and Azithromycin; 2
strains were resistant to these antibiotics. Two, 1 and 7, strains of V.
streptococci were resistant, intermediate susceptible and susceptible
respectively to these antibiotic. Three strains of S. pneumoniae were
resistant but 1 and 6, strains were intermediate and susceptible to
Erythromycin and Azithromycin respectively and 7 strains were
susceptible
to
Clarithromycin.
The
comparison
indicated
that
Clarithromycin more active than Erythromycin and Azithromycin, also
Erythromycin more active than Azithromycin.
