With isolated 165 strains of coagulase-negative staphylococci(CNST) from various specimens, such as blood, cerebrospinal fluid, pus, urine, etc., we performed experiments to detect slime-production using polyethylene tube, micro-plate and congo
red
agar
methods and their antimicrobial susceptibility against several antibiotics.
The results can be summarized as followes;
1. To see observer variation, two observers read the findings of polyethylene tube and congo red agar tests separately. There showed 43.6%(72/165) of positive agreement and 3.8% (5/165) of discrepancy.
2. To see interassay reproducibility, we repeated each assay with tested strains 3 times, 36.4%(60/165) of polyethylene tube, 43.6%(72/165) of micro-plate and 26.6%(43/165) of congo red agar methods were all positive in 3 set of assay and
46.1%(76/165)
of polyethylene tube and micro-plate and 71.5%(18/165) were al negative.
3. Positive result agreement was shown 24.3%(40/165) and negative result agreement 49.1%(81/1650 in 3 used methods. 18.8%(31/165) in both polyethylene tube and micro plate, 1.2% in both micro plate and congo red agar and both polyethylene tube
and
congo red agar showed positive correspondence, respectively.
4. There were slime-producing CNST in larger portions of peritoneal fluid, catheter tip, pus, blood, urine and slime-nonproducing strains in that of eye and cerebrospinal fluid etc.
5. There were 38.1%(16/42) of pathogens and 30.4%(24/79) of contaminants in slime-producing CNST and 69.1%(26/42) of pathogens and 69.6%(55/79) of contaminants in slime-nonproducing.
6. The antimicrobial susceptibility results of 121 strains of CNST showed 81.2% resistance in penicillin, 73.9% in ampicillin, 68.5% in gnetamicin, 63.6$ in methicillin and erythromycin, 37.6% in clindamycin, 24.2% in amikacin, 15.8% in
cephalothin and
cefamandole and 3.6% in vancomycin. The difference of resistance against in amikacin, cephalotin, cefamandole and clindamycin between slime-producing and slime-monproducing CNST showed statistical significance(P<0.05, P<0.01).
7. It was revealed 40.4% of strains from blood as pathogen and 59.6% as contaminant. 58.3% from catheter tip, 27.3% from cerebrospinal fluid, 38.7% from urine and 13.3% from miscellanenous specimens revealed as pathogen.
As you see, with comparing three methods and examining the antibiotic sensitivity of CNST to find out merits and demerits of all and to use these practically, we think that the above results will be helpful to the precise diagnosis and treatment
on diseases.
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