TABLE 1.

Numbers of isolates per month and incidence rates of TEM-24- and SHV-4-producing E. aerogenes strains over the course of the study period

Mo	No. of E. aerogenes isolates			Incidence/1,000 PD
	Total non-ESBL and ESBL producers	TEM-24 producers	SHV-4 producers	TEM-24	SHV-4
10-96	13	2	3	0.044	0.066
11-96	12	0	0	0	0
12-96	16	1	1	0.023	0.023
01-97	7	0	0	0	0
02-97	20	1	2	0.024	0.047
03-97	18	1	1	0.022	0.022
04-97	19	0	1	0	0.023
05-97	9	1	0	0.023	0
06-97	9	2	1	0.045	0.022
07-97	15	1	2	0.024	0.047
08-97	17	1	0	0.025	0
09-97	15	3	1	0.071	0.024
10-97	14	3	2	0.066	0.044
11-97	21	3	0	0.068	0
12-97	22	2	1	0.046	0.023
01-98	22	2	2	0.045	0.045
02-98	15	1	1	0.024	0.024
03-98	22	2	2	0.043	0.043
04-98	17	4	1	0.089	0.022
05-98	21	6	1	0.133	0.023
06-98	26	4	0	0.090	0
07-98	16	2	1	0.047	0.023
08-98	15	1	1	0.025	0.025
09-98	26	13	0	0.306	0
10-98	16	8	0	0.175	0
11-98	29	16	0	0.361	0
12-98	35	15	0	0.356	0
01-99	50	33	0	0.724	0
02-99	41	18	0	0.420	0
03-99	24	17	0	0.358	0
04-99	26	5	1	0.113	0.023
05-99	25	7	0	0.158	0
06-99	33	12	0	0.272	0
07-99	23	13	2	0.316	0.049
08-99	34	10	0	0.250	0