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Table 1 S. aureus isolates used in the study and their β-lactamase genotype and phenotype

From: Rapid optical determination of β-lactamase and antibiotic activity

# S. aureusisolate β-lactamase genotype*&(‘blaZ’PCR) β-lactamase phenotype by nitrocefin disk test
1 29213 Positive +
2 25923 Negative -
3 75391-09 Positive -
4 W5337 Negative -
5 W53156 Positive -
6 AI5070237 Positive +
7 AI5081845 Positive -
8 159570-08 Positive -
9 H30876 Positive -
10 32455-09 Positive$ -
11 HIP12052 Positive -
12 AI5090298 Positive -
13 F33263-2 Positive -
14 AI5090297 Positive -
15 HIP11033 Positive -
16 HIP11353 Positive$ -
17 158390-08 Positive$ -
18 F52670 Positive +
19 H63189 Positive +
20 M24125 Positive +
21 F20358.1 Negative -
22 H67147.3 Positive -
23 M60028 Negative -
24 KI58249.2 Unknown -
25 M69678 Negative -
26 X33116 Positive -
27 F29916-2 Positive -
  1. S. aureus strains 29213 (#1) and 25923 (#2) were obtained from ATCC and the S. aureus clinical isolates (#3 - #27) were provided by Dr. Mary Jane Ferraro (Microbiology Labs, Massachusetts General Hospital, Boston, MA, USA). Isolate numbers (e.g. #1 for 29213, etc) are used to refer to the different isolates throughout the study.
  2. *The β-lactamase genotype was determined by PCR to detect blaZ (staphylococcal β-lactamase gene). Genotype data for isolates #3 - #15 was kindly provided by Dr. Robert L. Skov, Statens Serum Institut (R. L. Skov, unpublished results) and for #16 - #27 by Dr. Mary Jane Ferraro.
  3. &All isolates are MSSA.
  4. $Special comment – blaZ contained Stop codon or deletion (so non-functional) (R. L. Skov, unpublished results).
  5. Nitrocefin disk test to determine β-lactamase production was performed as described in Methods. Development of orange colour uniformly, similar to positive control #1, was taken as positive reaction, indicated by ‘+’ symbols. ‘-’ denotes negative result (i.e. no colour change). The results are representative of three independent experiments, which gave consistent results.