Table 4.

Isolation of Organisms from Blood Cultures, according to Prophylactic Antibiotic Regimen

Antibiotic Regimen	All	A	B	C	P value, A vs. B
No. evaluable courses	426	113	274	39
No. of courses with bacteremia	81	55*	22	4	<0.0001
No. of identified bacteria	94	59	31	4	<0.0001
Gram-positive bacteria (n)
Viridans group streptococci	37	33 (7)	3 (2)	1 (1)	0.001
Enterococcus species	8	1	7	0
Bacillus cereus	4	2 (1)	2	0
Coagulase-negative Staphylococcus	4	0	1	3
Stomatococcus mucilaginosus	4	3	1	0
Streptococcus pneumoniae	1	1	0	0
Abiotrophia defectiva	1	0	1	0
Lactobacillus rhamnosus/casei	1	0	1	0
Rothia dentocariosa	1	0	1	0
Granulicatella adiacens	1	0	1	0
Total gram-positive (n)	62	40	18	4	0.0003
Gram-negative bacteria (n)
Escherichia coli	11	7	4	0
Pseudomonas aeruginosa	7	3	4	0
Enterobacter cloacae	6	4	2	0
Klebsiella pneumoniae	3	2	1	0
Neisseria subflava/sicca	1	0	1	0
Moraxella nonliquefaciens	1	1	0	0
Burkholderia cepacia	1	1	0	0
Capnocytophaga sputigena	1	0	1	0
Sphingomonas species	1	1	0	0
Total gram-negative (n)	32	19	13	0	0.001

^*One patient had 2 episodes of bacteremia in a course.

Bloodstream infection was defined by Centers for Disease Control and Prevention (CDC) criteria, with the following exception for common commensals: even one positive blood culture was considered to indicate a bloodstream infection with viridans streptococci or Bacillus cereus in patients with grade 3 or 4 neutropenia. These episodes are shown in the parentheses.

A: Either patients received no prophylactic antibiotics or they received only prophylactic oral cephalosporins.

B: Prophylaxis with IV cefepime only or IV vancomycin plus an oral cephalosporin, oral ciprofloxacin, or IV cefepime.

C: Not evaluable.