Among patients who died within 30 days, the time from catheter insertion to bacteremia ranged from 2 to 9 days, and the time from bacteremia to death ranged from 5 to 23 days. Of the 14 patients with S. aureus bacteremia, five (35.8%) died within 30 days of its diagnosis. We found that S. aureus was the pathogen most commonly associated with PVC-BSI-related death in this study (Table 1).
Catheter removal is warranted when a CRBSI is suspected. The Infectious Diseases Society of America recommends diagnosing CRBSI when the same organism is grown in at least one percutaneous blood culture and catheter tip culture . However, the diagnosis of PVC-BSIs using this criterion may be difficult because the catheter has often already been removed when clinicians suspect a PVC-BSI. Only 13 (21.0%) patients underwent catheter tip culture in the present study; the catheter tips from the other 49 (79.0%) were not available to be tested. This indicates the possibility that PVC-BSIs are under-diagnosed and under-reported. We recommend culturing both the blood and catheter tip to ensure the correct diagnosis according to the IDSA guideline as soon as signs of infection, such as redness and swelling, are observed at the insertion site and the patient has a fever of unknown origin or a high C-reactive protein concentration. When two blood samples, one drawn from the catheter hub and the other from a peripheral vein, are cultured and they meet the CRBSI criteria for differential time to positivity, this can also be used for diagnosing CRBSI ; however, this criterion cannot be used for PVC-BSI diagnosis. Furthermore, the incidence of redness, tenderness, and pus at the catheter insertion site in patients with either type of CRBSI is only about 3% [12,13,14]; due to the low incidence of these symptoms, some clinicians may inadvertently overlook CRBSI. Diagnosis of PVC-BSIs is more difficult than diagnosis of CVC-BSIs for these reasons. It is important not only to examine the catheter insertion site but also to take aggressive measures to diagnose PVC-BSIs by performing blood and catheter tip cultures.
For PVC-BSI diagnosis, clinicians must both recognize the presence of PVC-BSIs and rule out other foci of infection. This study is focused only on cases in which the infections progressed to bacteremia and did not include cases with only localized infection. It is likely that the overall incidence of PVC infections is much greater than what is suggested by the number of total PVC-BSI cases in our study because the incidence of infections that remain localized is probably much greater than that of those that progress to bacteremia. It is imperative to carefully examine the insertion site daily to prevent PVC-BSIs from developing into bacteremia and to use assessment tools, such as the Visual Infusion Phlebitis score .
The patients in the present study were given antibiotics to treat PVC-BSIs for 5–100 days. The course of treatment, duration of antibiotics, and need for catheter removal depend on the causative organism. We recommend that primary physicians institute a therapeutic regimen according to the Infectious Diseases Society of America guidelines . Patients with hematogenous complications tend to require longer durations of therapy and hospitalization. The average duration of antibiotic treatment in cases with hematogenous complications was 33.5 days, while that in cases with only phlebitis was 15.8 days (p = 0.004).
According to a previous study, the risk factors for hematogenous complications of S. aureus infection are failure to remove the catheter (relative risk, 2.28; 95% confidence interval, 1.22–4.27) and, among patients for whom the catheter has been removed, a longer mean duration from symptom onset to catheter removal (5 vs. 2 days; p < 0.001) . The risk of increased disease severity is also higher among patients with persistent bacteremia; the interval in days between antibiotic initiation and the last positive blood culture tended to be longer in patients with delayed catheter removal than in patients with prompt removal, but this difference did not reach statistical significance in this small study (p = 0.07) . These results might be explained in part by the failure to carefully examine the insertion site; thorough examination is imperative to prevent hematogenous complications. While there are no reports on the average cost of PVC-BSIs, treating CVC-BSIs is quite expensive and it is likely that treating PVC-BSIs infections is also costly [18, 19]. Furthermore, both the potential harm to patients and the additional costs resulting from extended hospitalization are serious problems.
With respect to microbiological data, a previous study reported that patients with PVC-BSIs had a higher proportion of S. aureus infections than did patients with CVC-BSIs (53% vs. 33%) . When PVC-related bacteremia caused by S. aureus was compared with PVC-related bacteremia due to other pathogens, no differences were observed in age, sex, insertion site, time from catheter insertion to BSI, or complications.
In another study, the overall mortality rate was 29% among patients with nosocomial S. aureus bacteremia admitted to two hospitals in Oxford, UK ; however, we found a higher overall mortality rate (35.8%) among patients with S. aureus bacteremia in the present study. The high mortality rate observed in our study could be related to several factors, such as severe underlying disease, older age, and the presence of metastatic complications. Unfortunately, the retrospective nature of this study precluded our ability to distinguish between all-cause 30-day mortality and 30-day mortality related to PVC-BSIs.
Our study has a number of limitations, such as its retrospective nature and the lack of record concerning the infection site in 11 (17.7%) cases or the duration of catheter insertion in 26 (41.9%) cases. Furthermore, we were not able to identify cases in which only localized infection occurred at the insertion site and did not lead to bacteremia. Additional research is needed to reveal how many PVC infection cases only have a localized infection that does not lead to bacteremia. Moreover, the currently available information regarding the causative organisms of PVC-BSIs is inadequate because of a lack of surveillance data, making comparison of our data difficult. Furthermore, there is the possibility that our study had confounding factors; however, our sample size was not adequate to determine potential confounders. Future work will aim to adjust the data for the time from catheter insertion to bacteremia, department, and complications. Further investigation of these findings is warranted.