Antibiotic susceptibility test is an essential part of clinical bacteriology because many
of the clinical isolates are resistant to various chemotherapeutic agents, and one can
hardly predict the susceptibility without an appropriate laboratory procedure. According
to the recommendation of WHO, Yonsei Medical Center Clinical Pathology has been
using the Kirby-Bauer method. As a quality control, tests have been done using S.
aureus ATCC 25923, E. coli ATCC 25922 and p. aerugosa ATCC 27853.
This study was carried out to investigate the current susceptibility of clinical isolates
to those antibiotics used most widely. The bacteria tested were isolated from the clinical
specimens of Yonsei Medical Center between January to July of 1976. The following
results were obtained.
1. Only 15% of S. aureus isolates were susceptible to penicillin. 92% were susceptible
to cloxacillin, 97% to cephaloridine and 98% to minocycline.
2. Thirty eight per cent of enterococcus were susceptible to cephaloridine and to
chloramphenicol.
3. Ninety three per cent of E. coli were susceptible to gentamicin. But the rates to
chloramphenicol, streptomycin and tetracycline were very low.
4. The susceptibility rate of Llebsiella to gentamicin was 73%. To ampicillin, only 4%
were susceptible. The rate of enterobactor to gentamicin was 74% and to ampicillin 9%.
5. Sixty seven Per cent of Citrobactr were susceptible to gentamicin. All of the serratia
were susceptible to chloramphenicol, gentamicin and kanamycin.
6. The susceptibility rate of p. vulgaris was 88% to gentamicin an4 84% to kanamycin.
The rates to gentamicin were p. mirabilis 76%, P. morganii67% and P. rettgeri 60%.
7. All of the isolates of S. typhy were susceptible to ampicillin, chloramphenicol,
gentamicin and kanamycin.
8. All of the Shigella isolates were susceptible to ampicillin, gentamicin and kanamycin.
9. Eighty one per cent of P. aeruginosa were susceptible to gentamicin and 80% of
Alcaligens to minocycline.
10. The susceptibility rates of A. calcoaceticus were 75% to minocycline and 74% to
gentamicin.
11. Minocycline showed higher rate of susceptibility than tetracycline in S. aureus, E.
coli and A. calcoaceticus.
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