Le Infezioni in Medicina, n. 1, 75-76, 2017 CASE REPORT 75

From soil to blood: first human case of hotanense bacteraemia

Vesselina Kroumova1, Antonella Rossati2, Olivia Bargiacchi2, Pietro Luigi Garavelli2, Anna Camaggi3, Simona Caroppo3, Stefano Andreoni3 1Infection Control Unit, University Hospital “Maggiore della Carità”, Novara, Italy; 2Infectious Diseases Department, University Hospital “Maggiore della Carità”, Novara, Italy; 3Microbiology and Virology Department, University Hospital “Maggiore della Carità”, Novara, Italy

SUMMARY This report describes a case of Sphingobacterium hotan- is the first case of Sphingobacterium hotanense bacterae- ense bacteraemia in a patient scratched by a rooster on mia reported in the medical literature. the right arm. Diagnostic, clinical and therapeutic fea- tures are discussed. To the best of our knowledge, this Keywords: Sphingobacterium hotanense, human infection.

n INTRODUCTION be scratched by a rooster on the right arm two days before the admission; subsequently contin- phingobacterium hotanense is an aerobic uous high fever above 39°C occurred together SGram-negative rod belonging to the genus with signs of inflammation and lymphangitis in of Sphingobacterium, usually isolated from soil the injured limb. At admission, Reactive C Pro- and rarely found in human specimens from im- tein (RCP) was equal to 7·88 mg/dl, white blood munocompromised hosts. Isolations of such rare cells (WBC) 12.420/mmc. Blood samples for cul- microorganisms in humans rise concern about tures were collected and the following day intra- their pathogenicity and reliability of diagnostic venous empiric antibiotic treatment was started techniques. In this report, we describe a case of with amoxicillin-clavulanate (2·2 g three times a Sphingobacterium hotanense bacteraemia diag- day, having the patient a glomerular filtration rate nosed by MALDI-TOF and sequencing pointing lower than 50 mL/min). Quickly the fever disap- out strength and weaknesses of these microbio- peared and after few days of treatment WBC and logical techniques. RCP normalized. One out of two blood cultures resulted positive for Sphingobacterium mizutaii. A transthoracic echocardiogram excluded the pres- n CASE REPORT ence of endocarditis. Blood cultures vials were incubated in Bactec (Becton Dickinson, BD). Af- An 86-year-old patient, with a pacemaker placed ter turning positive, 10 µL of blood were sown on in 2006 for second degree atrioventricular block Columbia Blood Agar plates (BD) and Chocolate and a biological aortic valve prosthesis from Agar plates (BD) to identify aerobic microorgan- 2008, was hospitalized for fever and soft tissues isms and Columbia Blood Agar plates (BD), Choc- infection of the right upper limb. He reported to olate Agar plates (BD) and Schaedler Agar plates (BD) for anaerobic microorganisms. Plates were placed in an incubator at 37° C for 24 hours under Corresponding author aerobic and anaerobic conditions. A Gram stained Pietro Luigi Garavelli slide was also set up, which resulted positive for E-mail: [email protected] Gram-negative bacilli. The plates incubated in 76 V. Kroumova, et al.

aerobic conditions, showed the growth of small and can be updated with new sequenced species. colonies, non-haemolytic, smooth, with a very In our case, MALDI-TOF identified Sphingobac- clear yellow pigment. Microbiological identifica- terium mizutaii which, probably is close to Sphin- tion of Sphingobacterium mizutaii was made with gobacterium hotanense as proteomic profile. Thus, MALDI-TOF Biotyper (Bruker) with a score >2. even from the genetic point of view Sphingobacte- The 16S rRNA gene sequencing identifiedSphin - rium mizutae was found to be the closest strain to gobacterium hotanense instead of Sphingobacterium Sphingobacterium hotanense [3]. In the case we de- mizutaii obtained by MALDI-TOF. Susceptibility scribed, clinical significance ofSphingobacterium tests showed susceptibility to all beta-lactams, hotanense isolation has been supposed considering fluoroquinolones, and cotrimoxazole, but resis- that the skin wound has been contaminated with tance to aminoglycosides. soil conveyed by the animal scratch. This caused soft tissue infection which lead to bacteraemia. Prompt antibiotic therapy prevented from infec- n DISCUSSION tious valvular complications. However, it must be considered that Sphingobacterium hotanense has The genus Sphingobacterium belongs to the fami- never been recognized as a human pathogen, so it ly of , phylum ; is not possible to assume neither potential clinical it has been isolated from Antarctic soil, clinical impact nor the onset of a bacteraemia in the ab- specimens, roots, compost from cow dung, rice sence of antibiotic therapy. However, if we look at straw, farm and forest soil. Very rare cases of mi- the old age of the patient, the presence of valvular croorganisms belonging to this genus have been prosthesis and pacemaker, we considered appro- reported from blood and urine in immunocom- priate prolonging intravenous antibiotic therapy promised patients [1]. To date Sphingobacterium for 14 days and following the patient after dis- hotanense has never been found in human hosts. charge to rule out persistent infection. Finally, our Sphingobacteriaceae family is characterized by antibiotic susceptibility data are consistent with the presence of sphingolipids in the cell wall. those reported in the literature. The only isolation The genus Sphingobacterium consists of aero- of Sphingobacterium hotanense from an inorgan- bic, Gram-negative rods. Genetic analysis and ic material resulted resistant to aminoglycosides concentration of sphingolipids in the cell wall is and susceptible to ceftazidime, but not to ampi- used to distinguish Sphingobacterium from Fla- cillin [3]. In accordance with microbiological data, vobacterium genus [2]. Sphingobacterium mizutae indeed, the patient improved with high dose of is a Gram-negative rod, oxidase and catalase pos- empirical treatment with protected beta-lactam itive, gelatinase negative and, like others from (amoxicillin-clavulanate). the same genus, was isolated from the soil, while Sphingobacterium hotanense, was first isolated from Conflict of interest.The authors have no conflicts soil of a Populus euphratica forest in the Hotan of interest to disclose. River valley in China and has never been previ- ously found in human beings [3]. MALDI-TOF al- lows to distinguish very similar microorganisms n REFERENCES between them through the comparison of the protein spectra produced by the microorganism [1] Holmes B., Owen R.J., Hollis D.G. Flavobacterium and those present in a database. Despite the score spiritivorum, a new species isolated from human clinical >2 obtained by MALDI-TOF, which represents a specimens. Int. J. Syst. Bacteriol. 32,157-165, 1982. high probability of correct identification, we per- [2] Naka T., Fujiwara N., Yano I. et al. Structural analy- formed confirmation tests, since the comparison sis of sphingophospholipids derived from Sphingobac- terium spiritivorum, the type species of genus Sphingo- of the protein spectra of rare microorganisms with bacterium. Biochim. Biophys. Acta 1635, 83-92, 2003. those present in MALDI-TOF database, still has a [3] Xiao T., He X., Chenq G., Cheng G., et al. Sphingobac- certain level of uncertainty. The different results terium hotanense sp. nov., isolated from soil of a Populus obtained from MALDI-TOF and sequencing, euphratica forest, and emended descriptions of Sphin- come from the lack of Sphingobacterium hotanense gobacterium daejeonense and Sphingobacterium shayense. in the instrument database. The database is open Int. J. Syst. Evol. Microbiol. 63, 815-820, 2013.