Table 3. Alterations of the number of resistant bacteria strains isolated during the four sequential microbiological studies.

Time of sampling	Antibiotic resistance (No. of resistant strains)						Total
	S	R1	R2	R3	R4	R5
Admission	0	7	1	1	0	1	10
Completion of surgery	0	1	0	1	1	2	5
Endotracheal extubation	0	3	1	1	2	0	7
Post-operation	2	2	6	3	2	3	18

S, sensitive to all categories of the tested antibiotics; R1-5, resistant to 1 category to 5 categories of the tested antibiotics.