FIG 4.

(A) Results obtained with different strains (colonies of equal sizes were tested). 1, NDM-4-expressing Escherichia coli; 2, NDM-1-expressing Klebsiella pneumoniae; 3, NDM-1-expressing Providencia stuartii; 4, NDM-1-expressing Providencia rettgeri. (B) Extraction buffer performance. For Escherichia coli and Klebsiella pneumoniae, 1 was colony suspended in 1 ml. For Providencia stuartii and Providencia rettgeri, 10 colonies were suspended in 300 μl. The suspension was separated in two parts. 1, extraction buffer only; 2, extraction buffer plus 5 freeze-thaw cycles and 1 min of sonication (14 W).