Isolation of Laribacter hongkongensis from Little Egrets (Egretta garzetta) in Hangzhou, China

Xiaoping, Ni; Sun, Jiufeng; Kong, Qingxin; Kong, Fanrong; Brown, Martin; Shen, Liming; Cha, J.; Xiang, Hai-Qing; Xu, Hong; Jin, H.

doi:10.1111/j.1472-765x.2011.03024.x

Cited by 13 publications

(10 citation statements)

References 12 publications

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“…L. hongkongensis has been found in up to 60% of the intestines of commonly consumed freshwater fish of the carp family [7,8]. It has also been isolated from drinking water reservoirs and Chinese tiger frogs in Hong Kong and little egrets in Hangzhou [9-11]. Pulsed-field gel electrophoresis and multilocus sequence typing showed that the fish and patient isolates fell into separate clusters, suggesting that some clones could be more virulent or adapted to human [8,12].…”

Section: Introductionmentioning

confidence: 99%

Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication

et al. 2014

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BackgroundLaribacter hongkongensis is a Gram-negative, urease-positive bacillus associated with invasive bacteremic infections in liver cirrhosis patients and fish-borne community-acquired gastroenteritis and traveler’s diarrhea. Its mechanisms of adaptation to various environmental niches and host defense evasion are largely unknown. During the process of analyzing the L. hongkongensis genome, a complete urease cassette and two adjacent arc gene cassettes were found. We hypothesize that the urease cassette and/or the arc gene cassettes are important for L. hongkongensis to survive in acidic environment and macrophages. In this study, we tested this hypothesis by constructing single, double and triple non-polar deletion mutants of the urease and two arc gene cassettes of L. hongkongensis using the conjugation-mediated gene deletion system and examining their effects in acidic environment in vitro, in macrophages and in a mouse model.ResultsHLHK9∆ureA, HLHK9∆ureC, HLHK9∆ureD and HLHK9∆ureE all exhibited no urease activity. HLHK9∆arcA1 and HLHK9∆arcA2 both exhibited arginine deiminase (ADI) activities, but HLHK9∆arcA1/arcA2 double deletion mutant exhibited no ADI activity. At pH 2 and 3, survival of HLHK9∆arcA1/arcA2 and HLHK9∆ureA/arcA1/arcA2 were markedly decreased (p < 0.001) but that of HLHK9∆ureA was slightly decreased (p < 0.05), compared to wild type L. hongkongensis HLHK9. Survival of HLHK9∆ureA/arcA1/arcA2 and HLHK9∆arcA1/arcA2 in macrophages were also markedly decreased (p < 0.001 and p < 0.01 respectively) but that of HLHK9∆ureA was slightly decreased (p < 0.05), compared to HLHK9, although expression of arcA1, arcA2 and ureA genes were all upregulated. Using a mouse model, HLHK9∆ureA exhibited similar survival compared to HLHK9 after passing through the murine stomach, but survival of HLHK9∆arcA1/arcA2 and HLHK9∆ureA/arcA1/arcA2 were markedly reduced (p < 0.01).ConclusionsIn contrast to other important gastrointestinal tract pathogens, ADI pathway is far more important than urease for acid resistance and intracellular survival in L. hongkongensis. The gene duplication of the arc gene cassettes could be a result of their functional importance in L. hongkongensis.

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Section: Introductionmentioning

confidence: 99%

Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication

et al. 2014

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“…L hongkongensis has been found in up to 60% of the intestines of commonly consumed freshwater fish of the carp family 1. It has also been isolated from drinking water reservoirs and Chinese tiger frogs in Hong Kong and little egrets in Hangzhou 1 9 10. Pulsed field gel electrophoresis and multilocus sequence typing showed that the fish and patient isolates fell into separate clusters, suggesting that some clones could be more virulent or adapted to humans 1 11.…”

Section: Introductionmentioning

confidence: 99%

Matrix-assisted laser desorption ionisation–time of flight mass spectrometry for rapid identification ofLaribacter hongkongensis

et al. 2013

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Laribacter hongkongensis is a Gram-negative, facultative anaerobic, motile, S-shaped, urease-positive bacillus associated with invasive infections in liver cirrhosis patients and community-acquired gastroenteritis. Most cases of L hongkongensis infections occur in eastern countries. Information is lacking on the usefulness of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of bacteria important in eastern countries. Using the Bruker database extended with 21 L hongkongensis reference strains, all 240 L hongkongensis isolates recovered from patients, fish, frogs and water were correctly identified, with 224 (93.3%) strains having top match scores ≥2.0. Notably, the strain of Chromobacterium violaceum was not reliably identified although it is included in the database. MALDI-TOF MS is useful for the accurate routine identification of L hongkongensis after adding reference L hongkongensis main spectra to the database. The number of strains for each species in MALDI-TOF MS databases should be expanded to cover intraspecies variability.

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“…In all previous cases of human L. hongkongensis infection and in reports of the detection of this species in animal specimens, the strains were identified using a combination of phenotypic tests and 16S rRNA gene sequencing. 2,7,8,9,10,11,19,20,21 In recent years, MALDI–TOF MS has emerged as a revolutionary technique for rapid bacterial identification at a low cost. Using an expanded Bruker database with L. hongkongensis reference strains, we recently found that all 240 L. hongkongensis isolates could be correctly identified using MALDI–TOF MS, demonstrating the importance of expanding the MALDI–TOF MS database with bacteria endemic to different localities.…”

Section: Discussionmentioning

confidence: 99%

“…2,8 This species has also been isolated from drinking water reservoirs, Chinese tiger frogs and little egrets. 9,10,11 Pulsed-field gel electrophoresis and multilocus sequence typing (MLST) demonstrated that the fish and patient isolates fall into separate clusters, suggesting that some clones could be more virulent or adapted to humans. 8,12 The complete genome of L. hongkongensis was recently sequenced, and this bacterium's mechanism of acid resistance was characterized.…”

Section: Introductionmentioning

confidence: 99%

A novel MLST sequence type discovered in the first fatal case of Laribacter hongkongensis bacteremia clusters with the sequence types of other human isolates

Tse

Curreem

Cheung

et al. 2014

Emerging Microbes & Infections

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Laribacter hongkongensis is a gram-negative, facultative anaerobic, motile, S-shaped, asaccharolytic, urease-positive bacillus in the Neisseriaceae family of β-proteobacteria. To date, all patients with L. hongkongensis infection have survived, including the two patients with L. hongkongensis bacteremia and patients with L. hongkongensis gastroenteritis. In this study, we describe the clinical, microbiological and molecular characterization of the first fatal case associated with L. hongkongensis bacteremia in a patient with colonic carcinoma that metastasized to the liver. The identity of the isolate was confirmed via phenotypic tests and 16S rRNA gene sequencing. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI–TOF MS), using the Bruker database extended with L. hongkongensis reference strains, also identified the isolate as L. hongkongensis, with a top match score of 2.473. Multilocus sequence typing revealed a new sequence type (ST), and phylogenetic analysis and eBURST demonstrated unambiguously that the ST of the isolate was clustered with two other STs found exclusively in human patients, consistent with the theory that some clones of L. hongkongensis could be more virulent than others. Underlying liver diseases and ascites potentially represent distinct risk factors for invasive L. hongkongensis infection. More widespread use of MALDI–TOF MS for identification and improvements of selective media should facilitate the identification of more cases of L. hongkongensis infection.

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Isolation of Laribacter hongkongensis from Little Egrets (Egretta garzetta) in Hangzhou, China

Cited by 13 publications

References 12 publications

Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication

Arginine deiminase pathway is far more important than urease for acid resistance and intracellular survival in Laribacter hongkongensis: a possible result of arc gene cassette duplication

Matrix-assisted laser desorption ionisation–time of flight mass spectrometry for rapid identification ofLaribacter hongkongensis

A novel MLST sequence type discovered in the first fatal case of Laribacter hongkongensis bacteremia clusters with the sequence types of other human isolates

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