4 DISCUSSION
The World Health Organization has suggested that breast milk culture and sensitivity testing should not be routinely performed and should be performed if there is any of the following situations: (1) no response or poor response to the antibiotic within 2 days; (2) the mastitis recurs; (3) hospital-acquired mastitis; (4) allergic to the usual therapeutic antibiotic; and (5) in severe or unusual cases. Therefore, in clinical practice, antibiotic use for acute mastitis has always been empirical worldwide, and even in developed countries such as Australia,1,12 Spain13 and the USA,14,15 as high as 77-97% patients with breastfeeding mastitis are prescribed wih toral or intravenous antibiotics without direct evidence of bacterial infection. Indeed, in China mainland, antibiotic use is usually based on the level of SLCs and the severity of symptoms and signs, but not on the results of bacteriological analyses, although the latter has been helpful in determining the presence of pathogenic bacteria.
A previous study found that higher SLCs were associated with the existence of potentially pathogenic bacteria.10 Higher SLCs may indicate a higher chance of infection, which is useful in certain clinical conditions. For patient who is unwilling to undergo bacterial cultivation of breast milk or in the most of medical agencies where bacterial cultivation is not a routine practice, antibiotic use based on the SLCs seems to be a practical choice. SLC is routinely obtained in the work-up of patients with acute mastitis in China. If SLC is above the normal level, antibiotics are often recommended by attending physicians in the emergency department; otherwise, antibiotics are not advised. To the best of our knowledge, the study is the first to explore the value of SLCs for initial antibiotic use in breastfeeding mastitis.
In our study, the majority of (98.1%) patients with MELCs were prescribed an initial antibiotic, so we could not assess the necessity of initial antibiotic use effectively. However, we found a great difference in patients with MELCs; 5.5% (9/153) versus 100.0% (3/3) patients with MELCs had a disease progression when the antibiotic was or not given at their first presentation to the hospital. The result indicates that initial antibiotic use is still essential for acute mastitis with MELCs.
Our study also showed that there was a better clinical outcome in patients with SELCs when antibiotic was given initially. There should be two possibilities for mastitis: the presence of both inflammation and infection in the breast, or the presence of only inflammation but no infection in the breast. However, we could not distinguish these two situations clearly without the evidence of bacterial cultivation. Even so, for patients with SELCs, there was an absolute difference of 23.3% on the rate of treatment failure between patients with antibiotic use and without antibiotic use, which demonstrated that appropriate antibiotics should also be recommended for patients with SELCs.
In the current study, the rate of breast abscess was 7.1%, which was higher than that in the large Australian study which found that 3% of breastfeeding women with mastitis developed breast abscess.16 The difference in race and characteristics of patients in two studied may contribute to the different rate of breast abscess.
The limitations also should be acknowledged. First and most important, the present study was a single-institution, observational, retrospective study, which decreases the external validity of our work. Second, the level of SLCs in acute mastitis was always elevated, and acute mastitis patients with normal SLCs in clinical practice were rare; thus, the present study did not include such patients. Thus, the value of SLCs for antibiotic use in such patients could not be explored in the study. Third, in our study, milk cultivation and bacteriological analysis were not routinely performed, and antibiotics were initially used to targetS. aureus , which was found to be the most pathogenic bacteria in previous studies.17-20
In this study, we found that there was a better clinical outcome for patients with SELCs when antibiotic was given compared to when an antibiotic was not given. In addition, there was a good clinical outcome for patients with MELCs when antibiotic was given initially. These results suggest that, in China mainland, SLCs may have a reference value for antibiotic use in breastfeeding women with acute mastitis, and those sufferering from acute mastitis with elevated SLCs should be prescribed with antibiotic their first presentation to hospital. Of course, large-scaled, randomized controlled trials (RCTs) of higher quality are still required to confirm our findings.