338 Table 4. Comparison of Patients With Bacteremia Due to Antiseptic-Tolerant Versus -Susceptible S. aureus Variable
Median Age, y (IQR) Age ≤ 28 d
Median duration of bacteremia, d (IQR) CLABSI
Line removal
Musculoskeletal infection CHG use in prior 3 mo 1 CHG use
Recurrent CHG use CVL in situ
Hospital admission in prior 3 mo Surgery in prior 3 mo Underlying conditions Acquisition
Community acquired
Community-onset healthcare associated Nosocomial
Antibiotics in prior 3 mo Recurrent infectionc Mortality
Median length of stay, d (IQR) Methicillin resistant Clindamycin resistant
Antiseptic Tolerant S. aureus (n=44), No. (%)
0.74 (0.13–8.3) 8 (18.2) 1 (1–2)
15 (34.1) 10 (66.7) 1 (2.3)
24 (54.5) 11 (24)
13 (29.5) 25 (56.8) 37 (84.1) 23 (52.3) 39 (88.6)
7 (15.9) 17 (38.6) 20 (45.5) 39 (88.6) 8 (18.2) 2 (4.5)
14 (6–84) 13 (29.5) 13 (30.2)
Antiseptic Susceptible S. aureus,(n=75), No. (%)
6.3 (1.1–12.6) 5 (6.7) 1 (1–2)
13 (17.3) 10 (76.9) 31 (41.3) 25 (33.3) 11 (14.6) 14 (18.6) 21 (28) 36 (48)
26 (34.6) 38 (51.3)
41 (54.6) 16 (21.3) 18 (24) 39 (52) 2 (2.6) 2 (2.6)
10 (6–35) 12 (16.2) 13 (17.6)
P Value .008 .07 .67
.046 .69
<.001 .034 .22 .18
.003
<.001 .08
<.001 <.001
Adjusted P Value
0.22a OR 1.97 95% CI 0.66–5.87
Lauren M. Sommer et al
.88
.03 .54
0.9
0.15 1.6
0.24–3.34
0.03–0.84 0.36–7.03
.89 .62 .22 .9
.049b
1.1
0.56 0.37 1.1 3.3
0.27–4.35 0.06–5.53 0.08–1.78 0.19–6.48 1.5–21.1
<.001 .005 .63 .19 .11 .17
0.25
2.94
0.47–18.24
Note. OR, odds ratio; CI, confidence interval; IQR, interquartile range; CLABSI, central-line–associated bloodstream infection; CHG, chlorhexidine gluconate; CVL, central venous line. aIn multivariable analyses, age was dichotomized as > vs ≤ 0.33 years (the bottom quartile of age for all patients with S. aureus bacteremia). bAcquisition of infection is dichotomized as healthcare associated (CO-HCA and nosocomial) vs community-acquired. c3 patients withantiseptic-tolerant
S.aureusandinfectionrecurrencehad CLABSI initially treated withCVL in situ comparedto 1 patient in the antiseptic-susceptible groupwith infection recurrence. If these 4 patients are removed from the analyses, a statistically significant relationship between antiseptic tolerance and infection recurrence remains (5/41 [12.2%] vs 1/74 [1.4%]; P = .03).
aureus and recurrence of infection; however, the reasons for this observation are unclear. Studiesusing ex vivo and in vivomodels sug- gest that S. aureus expressing such multidrug-resistance efflux pumps may have an enhanced ability to colonize surfaces as well as cause disease.38,39 Possibly, if such organisms have an enhanced coloniza- tion capacity, they may be more likely to cause recurrent infection despite appropriate treatment. This finding is, in part, also likely related to the higher rate of CLA-BSI in the tolerant group and recur- rences occurring as a result of not removing infected central lines in a minority of cases. Also, this phenomenonmight be a consequence of virulent strain types that happen to possess AT genes rather than a consequence of the genes themselves. Such findings further highlight the potential impact of AT strains for public health. Notably, however, the finding of higher recurrence in AT S. aureus infections may have been a result of these patients having a greater degree of medical complexity and thus being more likely to fail treatment. Additional limitations to this study should be acknowledged.
Foremost, these findings are from a single center with a previously described high prevalence of AT S. aureus20,21; thus, our findings may not be generalizable to all regions. The retrospective nature of
the study limits the degree to which clinical risk factors can be definitively associated with AT organisms. Additionally, given that colonization cultures were not examined in this study, we are unable to assess the impact of AT organism colonization on risk of subsequent bacteremia or the potential mitigating effects of anti- biotic/antiseptic use. In conclusion, genotypic AT is common among bloodstream
staphylococci and E. faecalis isolates at our institution. The pres- ence of AT genes was strongly associated with nosocomial acquis- ition of infection in staphylococci, implying a role for the hospital environment in selecting for these pathogens. Larger studies are needed to further explore and validate these findings.
Author ORCIDs. J. Chase McNeil,
http://orcid.org/0000-0002-0232-7491
Acknowledgements. Weare grateful toMsLinda Lamberth as well as the staff of the TCH clinical microbiology laboratory for their assistance with this project.
Financial support. This study was funded by the National Institute of Allergy and Infectious Diseases (NIAID grant no. K23AI099159) and The Texas Children’s Hospital Pediatric Pilot Research Fund (both to J.C.M.).
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