Does antimicrobial use density at the ward level influence monthly central line-associated bloodstream infection rates?

Figures & data

Table 1 Antimicrobials given prior to the onset of central line-associated bloodstream infection (n=33 cases)

	Total dose (g)	Cases
	Median (range)
Ampicillin-sulbactam	9 (7.5–10)	n=4
Cefazolin	6 (2–6)	n=3
Cefmetazole	24 (24)	n=1
Cefoperazole-sulbactam	9 (8–10)	n=2
Ceftazidime	28 (2–38)	n=3
Ceftriaxone	6 (2–14)	n=3
Ciprofloxacin	0.6 (0.6)	n=1
Clindamycin	8.4 (8.4–8.4)	n=2
Fluconazole	1.0 (1.0)	n=1
Flomoxef	18 (8–28)	n=2
Imipenem-cilastatin	3.5 (3.5)	n=1
Levofloxacin	6.0 (6.0)	n=1
Linezolid	17.6 (8.4–16.8)	n=2
Meropenem	5.5 (4–14)	n=5
Minocycline	8.4 (8.4)	n=1
Piperacillin	11 (4–14)	n=2
Piperacillin-tazobactam	189 (189–189)	n=2
Sulfamethoxazole/trimethoprim	16/3.2 (16)/(3.2)	n=1/1
Teichoplanin	12 (12)	n=1
Vancomycin (parenteral)	1 (0.5–10)	n=3
Subtotal		n=42a
None		n=5b
Total		n=47

Notes:

a Twenty-eight cases had been administered a total of 42 antimicrobials permitting repetition;

b five cases had received no antimicrobials prior to central line-associated bloodstream infection.

Table 2 Logistic regression analyses on the risk factors for CLABSI, including ward-specific AUD of multiple agents

Factor	Univariate analysis	P-value	Multivariate analysis	P-value
AUDs
Ampicillin	0.26 (0.06–1.07)	0.06
Ampicillin-sulbactam	0.70 (0.35–1.39)	0.31
Cefazolin	1.76 (0.88–3.55)	0.11
Cefmetazole	0.69 (0.24–1.95)	0.47
Ceftazidime	0.68 (0.33–1.41)	0.31
Cefoperazole-sulbactam	1.46 (0.51–4.16)	0.48
Cefotaxim	1.14×10^−8 (1.14×10^−8–1.14×10^−8)	N/A
Cefotiam	0.21 (0.05–0.89)	0.03*	0.22 (0.05–0.92)	0.04*
Cefmetazole	0.69 (0.24–1.95)	0.48
Cefozopran	0.73 (0.31–1.79)	0.50
Cefpirome	1.06×10^−7 (1.06×10^−7–1.06×10^−7)	N/A
Ceftriaxone	0.41 (0.16–1.08)	0.07
Clindamycin	0.62 (0.31–1.24)	0.18
Flomoxef	0.87 (0.43–1.74)	0.68
Fosfomycin	1.01 (0.48–2.08)	0.99
Gentamicin	1.34 (0.67–2.68)	0.40
Imipenem-cilastatin	1.86 (0.83–4.13)	0.13
Linezolid	1.89 (0.95–3.76)	0.07
Meropenem	0.65 (0.30–1.39)	0.26
Minocycline	1.34 (0.68–2.67)	0.40
Panipenem-betamipron	0.78 (0.23–2.56)	0.68
Piperacillin	0.87 (0.43–1.73)	0.69
Piperacillin-tazobactam	1.87 (0.91–3.86)	0.09
Vancomycin	1.16 (0.58–2.31)	0.66
Surgical ward	1.40 (0.70–2.80)	0.34
CL-day	5.60 (1.97–15.94)	<0.01*	5.51 (1.94–15.69)	<0.01*
Male sex	0.62 (0.29–1.35)	0.23
Age >75 years	0.90 (0.45–1.81)	0.76
DU ratio	1.43 (0.72–2.86)	0.30

Notes:

* P<0.05. DU ratio is defined as number of CL-days/number of patient-days.

Abbreviations: AUD, antimicrobial use density; CLABSI, central line-associated bloodstream infection; N/A, not available due to sample deviation; CL-day, days of central line placement; DU, device utilization of the former half as the index study period.

Figure 1 Correlation between susceptibility ratio (horizontal axis) defined as the number of susceptible strains divided by the number of all strains undergoing susceptibility versus the median values for antimicrobial use density (AUD, vertical axis). They show a negative correlation (superimposed line) with R²=0.1897 for ten drugs available indicating increase in AUD was associated with decrease in susceptibility of the same antimicrobial.