laribacter hongkongensis is a facultative anaerobic , motile , non - sporulating gram - negative bacillus .
it belongs to the family neisseriaceae of the  subclass of proteobacteria ( 1 ) . since the first description of l. hongkongensis from the blood and empyema pus of a patient with alcoholic liver cirrhosis in 2001 , the bacterium has subsequently been associated with community - acquired gastroenteritis ( 1 , 2 )
however , accurate identification of l. hongkongensis is impossible using commercially - available phenotypic identification systems .
thus , the prevalence , pathogenic potential , and epidemiology of l. hongkongensis are unclear .
the identification based on a molecular approach could permit more accurate determinations of incidence and evaluation of clinical relevance .
although l. hongkongensis has been reported in hong kong , china , and hungary ( 3 ) , it has not hitherto been identified in korea .
a 24-yr - old male was admitted to a hospital , on august 16 , 2007 , with a 15-day history of abdominal distension .
the patient had been diagnosed with wilson 's disease at 17-yr - of - age and had since undergone treatment for liver cirrhosis complicated by wilson 's disease .
the patient had no history of overseas travel and had no recall of ingesting undercooked freshwater fish for at least the previous year . on physical examination , blood pressure was 98/49 mmhg , pulse rate was 96 beats per min , and body temperature ( 36.5 ) .
laboratory tests revealed a hemoglobin concentration of 8.3 g / dl , leukocyte count of 6,248/l , platelet count of 42,000/l , serum creatinine level of 0.94 mg / dl , serum bilirubin level of 6.7 mg / dl , and serum albumin level of 1.6 g / dl .
the analysis of peritoneal fluid demonstrated an albumin level of 202 mg / dl and leukocyte count of 130/l ( poly 15% ) .
but , on day 6 following admission , fever developed , with a body temperature reaching 38.6. examination showed diffuse tenderness of the entire abdomen .
the results of peritoneal fluid evaluation revealed a leukocyte count of 1,180/l ( poly 74% ) . empirical treatment with cefotaxime ( 2 g every 8 hr ) was commenced with a presumptive diagnosis of spontaneous bacterial peritonitis .
two days later , growth on blood culture was identified as a gram - negative bacillus using the bact alert 3d culture system .
the patient responded to cefotaxime and was discharged on post - admission day 12 . to identify isolate 07ac-292 , biochemical characterization by vitek2 with an id - gnb card
the isolate was identified as a. lwoffii at a confidence level of 94% . however , an acinetobacter differentiation method using the rpob gene ( 4 ) indicated that the isolate did not belong to the genus acinetobacter .
the dna of the isolate was extracted and a portion of the 16s rrna gene was amplified and sequenced using the primer set as previously described ( 5 ) .
the determined sequences were compared with the genbank public database using the blastn program ( http://blast.ncbi.nlm.nih.gov/blast.cgi ) .
the 16s rrna sequence of the isolate 07ac-292 showed complete identity with several l. hongkongensis strains in the database .
a phylogenetic tree constructed based on 16s rrna gene sequences also supported the identity of isolate 07ac-292 as l. hongkongensis ( fig .
antibiotic susceptibility testing ( ampicillin - sulbactam , cefepime , ceftriaxone , ceftazidime , amikacin , cefoperazone - sulbactam , imipenem , meropenem , doripenem , tetracycline , ciprofloxacin , rifampin , piperacillin - tazobactam , colistin , polymyxin b , and tigecycline ) was conducted using the broth microdilution method according to clinical and laboratory standards institute ( clsi ) protocol ( 6 ) .
minimum inhibitory concentration breakpoints and quality - control protocols were used according to non - fermenting gram - negative organism guidelines established by the clsi . isolate 07ac-292 was resistant to piperacillin , intermediate resistant to ceftriaxon , and susceptible to the other tested antibiotics ( table 1 ) .
l. hongkongensis was first isolated from a 54-yr - old chinese male with alcoholic cirrhosis and thoracic bacateremic empyema ( 1 , 2 ) .
subsequently , the bacterium has been isolated from patients in other parts of the world .
the isolation of l. hongkogensis from patients who are residents in , or recent travelers to , asia , europe , america , and africa imply the global importance of the bacterium ( 7 ) .
most reported cases were associated with recent travel and eating fish and symptoms are similar to salmonella and campylobacter gastroenteritis ( 2 ) . although freshwater fish is probably a major reservoir of l. hongkongensis , differences exist between isolates obtained from humans and fish using pulsed - field gel electrophoresis , suggesting that not all environmental clones are virulent ( 8) . the presently - reported patient , who had underlying liver cirrhosis associated with wilson 's disease , was suffering from neutrophilic ascites caused by l. hongkongensis .
in contrast to previous described cases , the patient denied a history of ingestion of undercooked freshwater fish and overseas travel . it may be that the infection was hospital - acquired .
previous studies reported that this bacterium was associated with community - acquired gastroenteritis and traveler 's diarrhea ( 2 ) .
it has been suggested that there was no carriage state of l. hongkogenesis ( 8) , although the gastrointestinal tract has been suggested as a possible primary site of infection and enteric bacteria could enter the systemic circulation from the portal vein by passage through the liver in patients with portal hypertension ( 1 , 2 ) . the present l. hongkongensis infection may have originated from the intestinal flora . if so , it indicates that l. hongkongensis may exist in a carriage state in his intestine flora . in someone suffering from liver cirrhosis
to date , all l. hongkongensis strains tested have been resistant to ampicillin and cephalosporins , but susceptible to the carbapenems , amoxicillin - clavulanate , aminoglycosides and fluoroquinolones ( 9 ) . the isolate in this study showed a somewhat different antibiotic susceptibility profile , in that it was susceptible to ampicillin - sulbactam and several cephalosporins .
a comparative study among l. hongkongensis isolates could more precisely determine the difference antibiotic susceptibility profiles , indicative of different origins . to our knowledge , this case is the first report of hospital - acquired l. hongkongensis bacteremia with neutrophilic ascites .
such misidentification might occur because l. honkingensis is not included in the database of commercial identification systems and biochemical tests are not enough to differentiate it from other species .
thus , it is conceivable that more l. hongkongensis infections have occurred , but have not been accurately identified due to the lack of proper identification tools . since multidrug - resistant acinetobacter sp
isolates are increasing in korea and l. hongkongensis is susceptible to most antimicrobial agents , correct identification of l. hongkongensis may reduce the inappropriate use of antimicrobial agents .
further clinical experiences with invasive diseases caused by l. hongkongensis are necessary to evaluate its potential pathogenesis .
extensive epidemiologic studies should be carried out to ascertain the etiologic association between l. hongkongensis and the intestinal normal flora , and to identify the host and the routes of transmission of l. hongkongensis .
 laribacter hongkongensis is an emerging pathogen in patients with community - acquired gastroenteritis and traveler 's diarrhea . 
 we herein report a case of l. hongkongensis infection in a 24-yr - old male with liver cirrhosis complicated by wilson 's disease . 
 he was admitted to a hospital with only abdominal distension . on day 6 following admission , he complained of abdominal pain and his body temperature reached 38.6. the results of peritoneal fluid evaluation revealed a leukocyte count of 1,180/l ( polymorphonuclear leukocyte 74% ) . 
 growth on blood culture was identified as a gram - negative bacillus . 
 the isolate was initially identified as acinetobacter lwoffii by conventional identification methods in the clinical microbiology laboratory , but was later identified as l. hongkongensis on the basis of molecular identification . 
 the patient was successfully treated with cefotaxime . to the best of our knowledge , 
 this case is the first report of hospital - acquired l. hongkongensis bacteremia with neutrophilic ascites . 