First case of Lactococcus sp. bacteremia in Misiones, Argentina

CARBALLO, GM; CORTESE IJ; VILLALBA APESTEGUI, PA; MACIEL, DA; LACZESKI, ME

Congreso; 32º Congresso Brasileiro de Microbiología -SBM; 2023

The genus Lactococcus comprises gram-positive bacteria belonging to the Streptococcaceae family. These bacteria are commonly found in various environments, including dairy products, plants, and the gastrointestinal tract of humans and animals. L. garvieae is primarily associated with infections in fish but can cause opportunistic infections in humans, particularly endocarditis. Other species such as L. petauri can cause localized cellulitis, abscess formation, and lymphadenitis in humans. It is important to note that both species are considered rare pathogens causing human infections. The aim of this study was to identify a bacterial strain isolated from the blood cultures of a 78-year-old male patient with a history of treatment for aortic stenosis with mild coronary atheromatosis. The blood cultures were incubated in the bacteriology laboratory, with BactAlert equipment (Biomeriux SA). Subsequently, biochemical tests of catalase, hypurate hydrolysis, tellurite, and mobility were negative, and bile hydrolysis esculin, growth in 6.5% sodium chloride, and pyrrolidinyl arilamidase (PYR) were positive. The automated identification system VITEK-2 Compact (Biomérieux SA) allowed us to identify the strain as Lactococcus garvieae, with 98% certainty. Due to microbiological suspicion, the isolated strain Lactococcus was sent for PCR sequencing. DNA was extracted using a commercial kit (Inbio Highway, Argentina). The 16S rRNA gene was amplified using universal primers EUB9_27 and EUB1542. The obtained product was sequenced by Macrogen (Seoul, South Korea). Gene analysis was performed using Geneious 11.0.1 software and the sequence was compared with the nucleotide database of the National Center for Biotechnology Information (NCBI) using the BLASTn platform. The strain was identified as a member of L. garvieae subsp. garvieae and L. petauri group coincided with the clinical stability and sensitivity profile. Finally, the GenBank database reported the sequence under accession number OQ878683. This study contributes to understanding Lactococcus species and their potential involvement in human infections The identification of L. garvieae and L. petauri as rare pathogens causing human infections highlights the importance of further investigation of the pathogenic mechanisms and clinical implications of these bacteria.