TABLE 2

Related prevalence studies of cefazolin InE associated with blaZ gene typesa

Study information; CInE definition(s) usedbla type or statusNo. (%) of isolates:
With indicated bla statusMeeting indicated CInE definition
≥4-fold increase SI to HI≥16 μg/ml at HI
This study, 4 hospitals in Chicago, IL, 269 isolates from all sources except CSF and urine; ≥4-fold increase in cefazolin MIC (SI to HI) and/or a pronounced InE with a nonsusceptible MIC of ≥16 μg/ml at HIA61 (23)16 (26)3 (5)
B25 (9)2 (8)0
C108 (40)25 (23)1 (1)
D2 (1)1 (50)1 (50)
Total bla positive196 (73)44 (22)b5 (3)b
bla negative73 (27)5 (7)1 (1)
Song et al. (46), 10 hospitals in South Korea, 303 isolates from blood; an increased cefazolin MIC of ≥16 μg/ml at HI from a susceptible MIC at SIA41 (13.5)23 (56)
B80 (26)1 (1)
C132 (44)37 (28)
D1 (0.5)0
Total bla positive254 (84)61 (24)b
bla negative49 (16)0
Wi et al. (47), 9 hospitals in South Korea, 146 isolates from blood; cefazolin MIC of ≥16 μg/ml at HIA60 (41)16 (3)
B32 (22)0
C30 (21)0
D3 (2)0
Total bla positive125 (86)16 (13)b
bla negative21 (14)0
Chong et al. (59), 1 hospital in South Korea, 218 isolates from blood; ≥4-fold increase in MIC (SI to HI) resulting in a nonsusceptible MIC at HIA38 (17)23 (61)
B43 (20)2 (5)
C117 (54)4 (3)
D3 (1)0
Total bla positive201 (92)29 (14)b
bla negative17 (8)0
Lee et al. (60), 3 hospitals in South Korea, 113 isolates from blood; ≥4-fold increase in MIC (SI to HI) and an increased MIC of ≥16 μg/ml at HIA17 (15)16 (94)11 (65)
B24 (21)4 (17)0
C46 (41)44 (96)12 (26)
D1 (1)00
Total bla positive88 (78)65 (74)b23 (26)b
bla negative25 (22)1 (4)0
Livorsi et al. (57), 5 hospitals in Georgia, 185 isolates from blood; ≥4-fold increase in MIC (SI to HI) and a nonsusceptible MIC of ≥16 μg/ml at HIA48 (26)22 (46)8 (17)
B43 (23)3 (7)0
C49 (27)22 (45)0
D2 (1)00
Total bla positive142 (77)42 (30)b8 (6)b
bla negative43 (23)3 (7)0
Nannini et al. (58), multiple countries, 98 isolates from cSSTI, HAP, IE, and blood; pronounced InE with MIC of ≥16 μg/ml at HIA25 (26)9 (36)
B15 (15)0
C45 (46)10 (22)
D00
Total bla positive85 (87)19 (22)b
bla negative13 (13)0
  • a CInE, cefazolin inoculum effect; bla, β-lactamase gene; SI, standard inoculum; HI, high inoculum; CSF, cerebrospinal fluid; cSSTI, complicated skin-soft tissue infection; HAP, hospital-acquired pneumonia; IE, infective endocarditis.

  • b Percent CInE was calculated using the total number of bla-positive isolates as the denominator.