One previous report described that approximately 6 % of prostatic abscesses develop in patients during the follow-up period after acute prostatitis [9]. However, prostatic abscess are often found in patients who do not improve with initial antibiotic therapy [6, 10]. Therefore, without routine imaging study, a prostate abscess present initially may be missed rather than developing from acute prostatitis during the follow-up period. In our 111 cases of confirmed acute prostatitis without abscess, abscess formation was not identified during the treatment period. Routine imaging studies such as CT or TRUS should be considered in cases of acute prostatitis for this reason, especially in patients with long-term symptom duration and voiding disturbances. Such imaging will allow physicians to anticipate a treatment method for an abscess, since these abscesses may require drainage [3, 7]. Ludwig et al. found that fluctuation during the digital rectal exam was present in 83.3 % of prostate abscesses. The group agreed that additional imaging is necessary to avoid missing a diagnosis of prostate abscess [2].
DM was a predisposing factor for abscess formation in univariate analysis. Studies of prostate abscesses commonly emphasize that DM is the most important predisposing medical condition [2, 3, 11]. However, diabetes by itself was not a risk factor for prostate abscess in multivariate analysis in the present study. DM is undoubtedly a serious condition that increases the risk of infection with uro-pathogens [12, 13]. However, its role in the development of prostatic abscess remains unclear and requires further investigation. Voiding disturbance was a significant risk factor for prostate abscess in the present study. Therefore, physicians should monitor voiding status in patients with acute prostatitis. In doing so, a physician can decide whether or not to perform a urinary diversion, such as suprapubic cystostomy, or to conduct imaging for the early diagnosis of a prostate abscess.
Abscess drainage with transurethral resection of prostate (TUR-P) was done in 45.2 % (14/31) of patients with prostatic abscess. The other 55.8 % of patients with abscesses only required medical treatment. We excluded confounding factors including one patient death, and 4 patients with other abscess foci when comparing the TUR-P group and medical treatment group in 31 abscesses. With regard to the length of hospital stay, it seems that medical treatment was non-inferior to surgical procedures in the treatment of prostatic abscesses. If we did not perform TUR-P in patient with prostate abscess over 20 mm, hospital stay might be longer in abscess patients. The duration of antibiotic treatment was longer in the medical treatment group (Table 1) than it was in the surgical group despite the cases treated with TUR-P had larger size of abscess pockets than the medical cases. Because TUR-P group and medical treatment group have different sizes of prostate abscess, and relevant cases in prostate abscess (n = 26) were small for comparison between TUR-P (n = 13) and medical treatment (n = 13), comparing treatment outcomes in 26 prostate abscesses may have potentially less clinically significant in the present study. However, considering there are wide concerns of antibiotic resistance in the community, minimizing the duration of exposure to antibiotics is an important issue. Furthermore, voiding disturbances were reflected in a large proportion of patients with prostate abscesses according to the present study. So, patients who underwent TUR-P might have an advantage. Therefore, TUR-P should be recommended to patients with prostate abscesses, although surgical procedures are not necessary for relatively small abscesses.
Regardless of the surgical procedure, the presence of a prostatic abscess did not increase the risk of septic shock during treatment. In our experience, patients with prostate abscesses require long-term antibiotic treatment and potentially surgery depending on abscess size. However, abscess formation may not exert an influence on the prognosis, such as septic shock or death, under the assumption that they were treated appropriately.
The vast majority of acute prostatitis were infected by gram negative bacteria. Regardless of the presence of an abscess, the selection of empirical antibiotics with cefoxitin, cefotaxime or ciprofloxacin would be appropriate in patients with acute prostatitis who have not undergone urological procedure (s) in Korea. Nevertheless, clinicians should be ready to adjust the antibiotic regimen according to susceptibility data, especially in the case of prostate abscess. This is because unexpected microorganisms are more likely to be isolated in acute prostatitis with abscess than in those without abscess.
This study has limitations. It is a retrospective, multi-centre chart review in design which has potential biases associated with it, however designing a randomised control trial comparing treatment outcome in 2 groups of equally matched patients with prostatic abscess is not feasible given the rarity, severity of the disease and heterogeneity of management for this condition throughout the urological community.