chronic bacterial prostatitis ( cbp ) is diagnosed when a patient has recurrent urinary tract infections ( utis ) caused by bacteria localized in the prostate . because it is a relapsing and indolent disease with occasional acute exacerbations , cbp is difficult to treat . the clinical picture of chronic prostatitis or cbp is one of recurrent episodes of inflammatory voiding symptoms such as frequency , urgency , or dysuria , which are often associated with suprapubic , genital , perineal , or lower back pain . aerobic gram - negative enteric bacteria have been well documented as the pathogens commonly associated with cbp . even though the role of gram - positive bacteria in cbp has been controversial , it is well known that enterococcus faecalis is one of the most prevalent etiologic pathogens in cbp . trimethoprim ( tmp ) or trimethoprim - sulfamethoxazole ( tmp - smx ) , tetracycline , and macrolides are also well known as a traditional second - line treatment of cbp . to be effective as therapeutic agents for cbp , the ideal antibiotics must be able to diffuse and easily penetrate into the prostate tissue . the current management of chronic prostatitis is usually a long course of empirical antibiotic therapy . although fluoroquinolones are not the recommended antibiotic for treatment of enterococcal utis , fluoroquinolones are the drug of choice for chronic prostatitis . generally , these antibiotics are tried without performing a urine or prostate culture or susceptibility testing to guide the therapy . unfortunately , the increasing antibiotic resistance today affects the success rate of this empirical treatment . furthermore , fluoroquinolone resistance by gram - negative enteric bacteria has been detected at a high rate in the asia - pacific region in recent years . moreover , patients with cbp are usually treated with inadequate , longer , and repetitive empirical antibiotic therapies because of recurrent episodes of cbp . the fluoroquinolone - resistant patterns of gram - negative enteric bacteria in uti have been well studied . to our knowledge , however , few studies have focused on e. faecalis strains isolated from the prostate , even though these organisms are the second most common cause of cbp . furthermore , there are few reported data on the antibiotic resistance patterns of e. faecalis from cbp for clinicians to use when choosing an appropriate empirical therapy . many urologists believe that the bacterial culture step from prostatic secretion is critical or important for characterizing infection . however , they usually do not perform the time - consuming prostate culture step . nowadays , because the identification of enterococci and the determination of their resistance patterns are important for choosing an empirical treatment , we aimed to determine the antibiotic resistance patterns of e. faecalis strains isolated from cbp patients in korea . one thousand twenty - one patients visited a single university hospital owing to symptoms suggestive of chronic prostatitis from september 2007 to march 2012 . none had taken antimicrobial or anti - inflammatory drugs during the 4 weeks before the evaluation . according to the national institutes of health ( nih ) definition , cbp ( category ii , nih - national institute of diabetes and digestive and kidney diseases ) is diagnosed when pathogens are cultured from a chronically infected prostate in patients suffering from repeated prostate - specific symptomatic episodes . the syndrome is characterized by an array of signs and symptoms , including perineal pain , testicular pain and/or other forms of pelvic pain , irritative and/or obstructive bladder symptoms , ejaculatory pain , and sexual dysfunction . culture specimens for diagnosing cbp were obtained by using a modified meares - stamey method . in brief , after periurethral cleansing with an alcohol sponge , the patient provided a vb1 specimen consisting of the initial 5 to 10 ml of voided urine , followed by a vb2 urine specimen . after production of expressed prostatic secretions ( eps ) by digital prostatic massage , the patient provided 5 to 10 ml of voided urine for the vb3 specimen . each vb1 specimen was cultured within 4 hours of collection by spreading 100 l onto plates containing 5% sheep blood and macconkey 's agar , incubated aerobically , and examined for bacterial growth after 48 hours . similarly , 100 l of eps was cultured onto the same culture plates for 2 days . the criterion for cbp was that the bacterial colony concentration of the eps specimens increased by at least 10-fold ( one log ) compared with the colony numbers of the vb1 specimen . the minimal inhibitory concentrations ( mics ) of the antimicrobials were assessed by use of the vitek ii microbial identification system ( biomrieux , marcy - i'etoile , france ) as suggested by the clinical and laboratory standards institute . the test results were expressed as mics with interpretation of the category of microbial susceptibility as susceptible , intermediate , or resistant strains . patients were excluded from the analysis if they had active urethral discharge and were also excluded if they had bacteriuria , gross hematuria , or a urologic diagnosis other than cbp . forty - one samples from 1,021 patients ( mean age , 61.1212 years ) with significant e. faecalis loads for defining cbp were included in this study . for easy handling of the data , we placed the e. faecalis isolates with intermediate resistance into the resistant categories of each antimicrobial . all 41 stains from 41 patients were sensitive to ampicillin , ampicillin / sulbactam , nitrofurantoin , imipenem , vancomycin , and teicoplanin ; 90.3% were sensitive to penicillin ; 68.5% to tmp - smx ; and 53.7% to gentamicin . the quinolone sensitivity of the e. faecalis strains was as follows : 95.2% were sensitive to levofloxacin , 90.3% to ciprofloxacin , and 73.2% to norfloxacin , respectively . finally , e. faecalis strains in our study were highly resistant to quinupristin / dalfopristin ( 100% ) , erythromycin ( 95% ) , and tetracycline ( 97.5% ) ( table 1 ) . the ciprofloxacin intermediate - resistance strains revealed drug sensitivity to levofloxacin . however , ciprofloxacin - resistant e. faecalis consistently showed drug resistance to levofloxacin ( table 2 ) . finally , in table 3 we summarize the antimicrobial sensitivity of the e. faecalis isolates in this study and in prostatic penetration studies of the drugs as reviewed in the literature . it is commonly known that only 5% to 10% of chronic prostatitis patients have a bacterial infection detectable by conventional cultures . cbp is a persistent infection of the prostate characterized by poor quality of life mainly due to frequent relapsing episodes caused by incomplete eradication of the causative pathogens . aggressive antibacterial therapy is required to attenuate the severe symptoms of cbp and to achieve a permanent cure . broad consensus exists for the use of fluoroquinolones as first - line antibacterial agents for the treatment of cbp . international guidelines recommend a 4- to 12-week course of ciprofloxacin , lomefloxacin , ofloxacin , levofloxacin , or norfloxacin for the eradication of susceptible pathogens . norfloxacin and ofloxacin are indicated for the management of cbp caused by e. coli , and ciprofloxacin has been approved for cbp caused by e. coli or proteus mirabilis . in addition , levofloxacin is approved for the treatment of cbp caused by e. coli , e. faecalis , or staphylococcus epidermidis . however , the norfloxacin sensitivity of the e. faecalis strains from our study was 73.2% . even though norfloxacin has good penetration into the prostate , norfloxacin treatment for cbp caused by e. faecalis is not currently justified in korea . ciprofloxacin has good penetration into the prostate and a good prostate tissue - to - plasma ratio . it is well known that ciprofloxacin is currently the most appropriate antimicrobial agent for the treatment of cbp . thirty - seven samples revealed ciprofloxacin - sensitive e. faecalis , 2 samples had intermediate sensitivity to ciprofloxacin , and the last 2 samples showed ciprofloxacin resistance . furthermore , the samples that showed intermediate resistance to ciprofloxacin had antimicrobial sensitivity to levofloxacin . however , ciprofloxacin - resistant e. faecalis also consistently showed drug resistance to levofloxacin ( table 2 ) . this finding was also found in our previous study of antimicrobial resistance patterns in korean patients with acute uncomplicated cystitis . in addition , levofloxacin shows a broad antibacterial spectrum for both gram - negative and gram - positive pathogens from cbp . furthermore , it is dosed on a once - daily basis and displays significant penetration into the prostate with a favorable prostate tissue - to - plasma ratio . for these reasons , we conclude that levofloxacin may have better cure rates for e. faecalis from cbp than any other fluoroquinolones such as norfloxacin and ciprofloxacin . all e. faecalis strains from our study revealed 100% drug sensitivity to ampicillin and ampicillin / sulbactam and 90.3% drug sensitivity to penicillin . even though e. faecalis strains in vitro show high drug susceptibility to these antimicrobials , these drugs have typically shown very low pharmacokinetic levels in prostatic fluid or tissues . in addition , the e. faecalis strains in our study showed high drug sensitivity to this antibiotic . nitrofurantoin is a lipid - soluble weak acid that is somewhat favorable for diffusion into prostatic fluid . however , low levels of nitrofurantoin were achieved in prostatic fluid in dogs , and the administration of standard oral doses of this drug to men results in lower therapeutic levels in blood . aminoglycosides do not penetrate prostatic tissue well , and the prostatic tissue levels of these antibiotics are probably inadequate to eradicate gram - negative bacteria . for these reasons , aminoglycosides can not be recommended as the ideal therapeutic drug for e. faecalis strains isolated from cbp . tmp with or without smx has traditionally been the first - line treatment of cbp . it has been shown that tmp concentrations in the human prostate are 2 to 3 times higher than those in plasma . tmp with or without smx can be both theoretically and to some extent experimentally ideal for gram - negative enterococcal strains from cbp . however , increased drug resistance to tmp - smx , probably as a result of the indiscriminate use of this drug in cbp patients , has recently been evidenced [ 27 - 29 ] . furthermore , tmp may appear active in vitro but is not effective clinically . we suggest that tmp - smx may not be an ideal antibiotic for e. faecalis in cbp because the drug sensitivity of the strains in our study to tmp - sxm was 68.5% . tetracycline or tetracycline most tetracyclines have high lipid solubility , an important factor for ideal antibiotics for the treatment of cbp . however , quinones et al   reported that the tetracycline resistance rate in e. faecalis was 78.6% , which is similar to our findings . for this reason , tetracycline is not recommended for eradicating the e. faecalis infection in cbp in korea . imipenem , vancomycin , and teicoplanin have traditionally been reserved as drugs of last resort and are used after treatment with other antibiotics has failed . , we did not find any drug resistance to imipenem , vancomycin , or teicoplanin among the e. faecalis strains isolated from patients with cbp . from a pharmacokinetic aspect quinupristin / dalfopristin is a combination of two antibiotics used to treat infections by staphylococci and by vancomycin - resistant enterococcus faecium . however , we can not recommend this drug for treatment of e. faecalis isolates from cbp patients because of high drug resistance . we have summarized the antimicrobial sensitivity of the e. faecalis isolates in this study and in prostatic penetration studies of the drugs from literature reviews in table 3 . fluoroquinolones are strongly recommended as a standard therapeutic agent for cbp caused by e. faecalis . even though levofloxacin and ciprofloxacin are suitable therapeutic agents for the treatment of patients with cbp , levofloxacin may have better cure rates for e. faecalis from cbp than any other fluoroquinolones such as norfloxacin and ciprofloxacin .
purposeenterococcus faecalis is one of the most common pathogens linked to chronic bacterial prostatitis ( cbp ) . owing to a limited number of previous studies addressing this topic , we aimed to determine the drug resistance patterns of e. faecalis strains isolated from cbp patients.materials and methodsone thousand twenty - one patients visited a single hospital owing to chronic prostatitis for 5 years . 
 culture specimens were obtained by use of a modified meares - stamey method . 
 the minimal inhibitory concentrations of the antimicrobials were assessed by use of the vitek ii microbial identification system as suggested by the clinical and laboratory standards institute.resultsforty-one samples from 41 patients who had significant e. faecalis loads for defining cbp were included in this study . 
 the e. faecalis strains in our study were resistant to penicillin ( 9.7% ) , ampicillin ( 0% ) , ampicillin / sulbactam ( 0% ) , nitrofurantoin ( 0% ) , imipenem ( 0% ) , vancomycin ( 0% ) , teicoplanin ( 0% ) , quinupristin / dalfopristin ( 100% ) , ciprofloxacin ( 9.7% ) , levofloxacin ( 4.8% ) , norfloxacin ( 26.8% ) , erythromycin ( 95% ) , gentamicin ( 46.3% ) , tetracycline ( 97.5% ) , and trimethoprim / sulfamethoxazole ( 31.5% ) , respectively.conclusionsfluoroquinolones have been the preferred antibiotics for treating cbp . because of their low rate of drug resistance , fluoroquinolones are suitable therapeutic agents for e. faecalis strains causing cbp in korea . 
 even though tetracycline , erythromycin , and trimethoprim / sulfamethoxazole have been prescribed as an empirical antimicrobial therapy for chronic prostatitis , we can not recommend these drugs for treatment of e. faecalis isolates because of the high rates of drug resistance .