ABSTRACT
In order to investigate whether Laribacter hongkongensis could be detected in stool samples of Rattus norvegicus in the wild,Rattus norvegicus were trapped alive in an urban community of Guangzhou,China over a period of one year from June 2015 to May 2016,and their stool samples were examined for the presence of L.hongkongensis strains.Isolates were identified based on phenotypic characteristics and 16S rRNA sequence analysis,and were examined for their susceptibility to 19 antimicrobial agents.Further typing of the isolates was performed using multi-loci sequence typing (MLST) analysis.A total of 191 R.norvegicus were trapped alive.L.hongkongensis was identified and successfully isolated from two samples,representing a prevalence of 1.05 ％.Although the two isolates possessed similar phenotypic characteristics and have no base difference of 16S rRNA gene,they constituted two new distinct sequence types (STs),ST-163 and ST-164.This is the first report that L.hongkongensis can be detected in the intestinal tract of R.norvegicus.Results suggest that R.norvegicus could serve as carriers of L.hongkongensis and therefore could be another potential source of infection.
ABSTRACT
Objective To establish the in vitro biofilm model of Laribacter hongkongensis(LH),to analyze the type Ⅰ integron related genes carried by LH and to investigate the mechanism of LH resistance to quinolones.Methods The biofilm forming abilities of LH clinical isolates were determined by Giemsa staining qualitative method and by crystal violet staining semi-quantitative method.The sensitivity of LH to norfloxacin,ofloxacin,levofloxacin,ciprofloxacin and lomefloxacin in both planktonic and biofilm conditions were dectermined by broth microdilution susceptibility tests.Type I integron related genes carried in 18 LH strains resistant to quinolone were detected by PCR amplification method.Results The detection results by Giemsa staining demonstrated that 36 strains in 55 LH clinical isolates formed visible biofilm,and the biofilm formation rate was 65.4%(36/55).In the biofilm forming ability detected by crystal violet staining semi-quantitative method,OD560≤0.15 was in 8 strains of LH,0.150.20 in 7 strains respectively.The levels of minimal biofilm inhibitory concentration in norfloxacin,ofloxacin,levofloxacin,ciprofloxacin and lomefloxacin to LH were respectively higher than the minimal inhibitory concentration(MIC) in the corresponding floating bacteria(P<0.05).Among 55 strains of LH,18 strains were resistant to quinolones,the resistance rate was 32.7%,and the type I integron in 18 strains of LH carried the drug resistant genes,these drug resistant genes played the drug resistance role in corresponding bacterial strains.Conclusion Drug resistance gene formation and widespread of LH may be associated with type I integron.
ABSTRACT
Objectives To investigate the prevalance of quinolone resistance in Laribacter hongkongensis and to evaluate the influence of agar dilution and disc diffusion methods on susceptibility testing for the bacterium. Methods Susceptibility to quinolones of L.hongkongensis was tested by agar dilution and disc diffusion methods. The results for both methods were compared. Results L.hongkongensis isolates exhibited different susceptibility rate for quinolones (levofloxacin>ciprofloxacin>norfloxacin>nalidixic acid). All of the fish isolates were susceptible to levofloxacin and more than 90%were susceptible to ciprofloxacin and Norfloxacin. However,by agar dilution, only 62.50%, 37.50%,48.21%, 19.64%of the frogs isolates were susceptible to levofloxacin, norfloxacin, ciprofloxacin, nalidixic acid, respectively. For fish isolates, comparision of susceptibilities between agar dilution and disc diffusion showed a high (> 95%) percentage agreement for levofloxacin and ciprofloxacin and the highest crepancies were observed with norfloxacin (100%) .But it showed a high discrepancy when comparing the two methods for frogs isolates. Conclusions The resistance rate of L. hongkongens to quinolones was high , especially for frog isolates. The results suggested the use of agar dilution on susceptibility testing for quinolones in L. hongkongensis.
ABSTRACT
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 38.6degrees C. The results of peritoneal fluid evaluation revealed a leukocyte count of 1,180/microL (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.