spontaneous bacterial peritonitis ( sbp ) is the most common infection with a high morbidity and mortality , occurring in 10% to 30% of cirrhotic patients with ascites , and associated with a very high rate of recurrence ( 1 ) . prophylaxis based on selective intestinal decontamination ( sid ) with oral antibiotics such as quinolones and trimethoprim / sulfamethoxazole , therefore , has been recommended to reduce the rate of recurrence and initial occurrence of sbp . however , this approach potentially selects highly resistant gram - negative bacilli and may lead to the emergence of gram - positive cocci . consequently , recent studies have virtually demonstrated the increased proportion of quinolone - resistant bacteria or gram - positive cocci as a causative agent in sbp , though predominant microbiologic findings are still gram - negative bacteria ( 2 ) . enterococci , gram - positive facultative anaerobes , are part of the normal gut flora . the main pathogenic species in humans are e. faecalis and e. faecium , which have become an important cause of nosocomial infections . e. hirae is known to cause infection in animals , but is rarely isolated in human clinical samples ( 3 ) . we recently experienced sbp caused by e. hirae , an unusual pathogen in humans , which was the first case of sbp with septicemia in a cirrhotic patient to our knowledge . a 61-yr - old male with decompensated cirrhosis and type 2 diabetes mellitus was admitted to emergency room because of abdominal pain , fever , chills and generalized weakness on november 20th , 2011 . he had been diagnosed as alcoholic liver cirrhosis 5 yr ago and followed up with regular examinations . he had received norfloxacin ( 400 mg per day ) for secondary prevention of sbp after hospitalization by klebsiella pneumoniae - associated sbp 4 months ago . he looked vitally stable at first with blood pressure of 110/80 mmhg , heart rate of 92 beats / min , and body temperature of 39.3. however , blood pressure rapidly declined to 80/50 mmhg in 3 hr of admission , which prompted a sufficient fluid replacement and even inotropics . on physical examination , initial laboratory findings were as follows : white blood cell ( wbc ) 7,590/l with left deviation ( neutrophil 90% ) , hemoglobin 13.4 g / dl , platelet 87,000/l , c - reactive protein ( crp ) 50.2 mg / l , total bilirubin 3.2 mg / dl , albumin 2.7 g / dl , inr 1.63 , aspartate transaminase 16 iu / l , alanine transaminase 9 iu / l , serum creatinine 1.7 mg / dl . based on the finding of physical and laboratory examination , his stage of cirrhosis was classified as child - pugh class c. analysis of ascitic fluid revealed a wbc count of 6,560/l with 90% neutrophil and a red blood cell count of 1,440/l , the protein levels of 1.6 g / dl , albumin levels of 0.7 g / dl . intravenous cefotaxime ( 2 g every 12 hr ) was empirically started on the presumptive diagnosis of sbp , pending the results of culture . two days even after antibiotic coverage , the patient was still febrile and laboratory findings did not improve in terms of serum crp ( 138 mg / dl ) and wbc count in the ascitic fluid . antibiotics were changed to vancomycin ( 1 g every 12 hr ) combined with ciprofloxacin ( 200 mg every 12 hr ) when gram positive cocci were isolated in both ascitic fluid and blood cultures . ascitic fluid and blood cultures obtained on admission yielded an enterococcus spp . , which was identified at the species level as e. hirae using automated microscan walkaway system ( microscan walkaway-96 plus , siemens healthcare diagnostics inc . , the strain was sensitive to ampicillin , vancomycin , teicoplanin , erythromycin , tetracycline , and high - level streptomycin and gentamicin . according to antibiotic sensitivity test , it was replaced by intravenous ampicillin ( 2 g every 6 hr ) . enterococci have been increasingly identified as important causes of severe infections in humans , such as septicemia , endocarditis and urinary tract infections . there are more than 20 recognized species within the genus enterococcus , in which e. faecalis and e. faecium account for up to 90% of the clinical isolates ( 4 ) . other enterococcal species are rarely isolated , although the increased prevalence of unusual species of enterococci and the emergence of multidrug resistance have been emphasized recently ( 5 ) . e. hirae , originally described by farrow and collins in 1985 ( 6 ) , is known to cause infections in different animals species ( chickens , rats , birds and cats ) ( 7 , 8) , but is very rare in humans . to the knowledge , there are only eight case reports describing human infection in the literatures ( table 1 ) ( 9 - 15 ) . our case constitutes the first description of sbp as well as the ninth case of clearly established human infection caused by e. hirae . it is practically difficult to differentiate e. durans and e. hirae due to similarity in phenotypic and biochemical activity , and they might be misidentified using phenotypic methods . it , therefore , might require a genetic method for the exact identification of strains at the species level . e. durans and e. hirae differ by two fermentation sugar tests : acid production by using raffinose and sucrose tend to be positive with e. hirae but negative with e. durans . therefore , sugar fermentation tests could be used to distinguish these strains in clinical practice . in our study , the results of sugar fermentation tests were comparable with e. hirae though the genetic assay was not done . regarding the antimicrobial susceptibility of e. hirae , the emergence of ampicillin - resistance and high - level resistance to gentamicin has been reported , though there is little data in the literature , but , so far , fortunately glycopeptides - resistant e. hirae not reported yet ( 16 - 19 ) . patients with liver cirrhosis are vulnerable to bacterial infections due to defects in various host defense mechanisms . sbp is the most common infection in cirrhotic patients followed by urinary tract infections , pneumonia , and bacteremia . although the precise pathogenesis of sbp has not been clearly defined , overgrowth and translocation of intestinal bacteria appears to be the most important step in the pathogenic process . despite the early diagnosis and the introduction of effective antibiotics moreover , recurrence rate reaches up to 70% during the subsequent year of the initial resolution . therefore , the oral administration of antibiotics such as quinolones and trimethoprim / sulfamethoxazole have been attempted to sid of mainly aerobic gram - negative bacilli , and such trials have significantly reduced the rate of recurrence as well as initial occurrence of sbp ( 20 ) . however , this approach potentially selects highly resistant gram - negative bacilli and may lead to the emergence of gram - positive cocci . it has been a problem of major concern in prophylaxis of sbp in cirrhotic patients . in our case , the patient had been treated for sbp caused by klebsiella pneumoniae 4 months before admission with ensuing antibiotic coverage as norfloxacin for secondary prevention of sbp . it is possible that it might lead to selection of the bacterial species isolated from the patient . intestinal e. hirae might translocate to ascites and cause sbp with septicemia in this patient who had uncontrolled ascites . for the first time , our case illustrates the possibility of e. hirae to cause sbp and septicemia in humans .
selective intestinal decontamination ( sid ) with norfloxacin has been widely used for the prophylaxis of spontaneous bacterial peritonitis ( sbp ) because of a high recurrence rate and preventive effect of sid for sbp . 
 however , it does select resistant gut flora and may lead to sbp caused by unusual pathogens such as quinolone - resistant gram - negative bacilli or gram - positive cocci . 
 enterococcus hirae is known to cause infections mainly in animals , but is rarely encountered in humans . 
 we report the first case of sbp by e. hirae in a cirrhotic patient who have previously received an oral administration of norfloxacin against sbp caused by klebsiella pneumoniae and presented in septic shock .