CHRISMED Journal of Health and Research

: 2015  |  Volume : 2  |  Issue : 4  |  Page : 367--369

Leuconostoc lactis: An unusual cause for bacteremia

Bichitrananda Swain, Kundan Kumar Sahu, Subhrajita Rout 
 Department of Microbiology, Institute of Medical Sciences and SUM Hospital, SOA University, Bhubaneswar, Odisha, India

Correspondence Address:
Bichitrananda Swain
HIG 5/4 Ext. Phase-1, Housing Board Colony, Chandrasekharpur, Bhubaneswar - 751 016, Odisha


Leuconostoc species, the common saprophytic bacteria are now emerging as one of the important opportunistic pathogens. There are different risk factors such as compromised immunity, use of vancomycin, parenteral nutrition, and contaminated surgical implanted devices to contribute the human infection. We here present one of the unusual fatal cases of bacteremia in a cancer patient who was infected with a vancomycin-resistant strain of L. lactis.

How to cite this article:
Swain B, Sahu KK, Rout S. Leuconostoc lactis: An unusual cause for bacteremia.CHRISMED J Health Res 2015;2:367-369

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Swain B, Sahu KK, Rout S. Leuconostoc lactis: An unusual cause for bacteremia. CHRISMED J Health Res [serial online] 2015 [cited 2020 Sep 22 ];2:367-369
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Leuconostoc species, belonging to the genus II of the family Streptococcaceae [1] are usually found on herbage, vegetables, dairy products, and wine and sugar solutions. Leuconostoc lactis, one of the members in this family with a previous impression was nonpathogenic to humans may occasionally cause ventriculitis,[2] osteomyelitis,[3] and blood stream infection.[4],[5],[6] More recently these Gram-positive cocci have been recognized as the potential pathogens causing opportunistic infections.

With the increased use of vancomycin in clinical practice, some new vancomycin-resistant pathogenic bacteria are emerging. Although Leuconostoc infections have also been documented in otherwise healthy patients; compromised immunity,[7],[8] use of vancomycin, parenteral nutrition and contaminated surgical implanted devices, such as central venous catheters have been considered as risk factors for this type of infection.[9] Prompt and accurate identification of Leuconostoc species and knowledge regarding clinical significance of these potential pathogens is essential during treating the patient for a better outcome.

 Case Report

A 62-year-old male from Western Odisha, a known endemic area for Plasmodium falciparum infection admitted in our hospital with high-grade fever for 10 days had a history of Type 2 diabetes mellitus and hypertension since 4 years. He was also under treatment for myelofibrosis, a rare bone marrow cancer. He had pancytopenia with low hemoglobin level (5 g%) and biochemical parameters such as serum creatinine (2 mg/dL), urea (56 mg/dL), and sodium (160 mg/dL) were in the higher range. His tests for malaria parasite were negative. He had a very low blood pressure (90/60 mmHg) with feeble pulse rate. After excluding malaria parasite infection, empiric parenteral administration of vancomycin along with correction of electrolytes and blood transfusion was initiated. Subsequently, clean-catched midstream urine and two sets of blood samples in consecutive days were sent to our department for aerobic bacterial culture and sensitivity. Urine culture was negative by conventional method whereas repeated blood cultures were positive by automated Bact/ALERT 3D (Biomerieux) method. By doing subculture from the later, pure nonhaemolytic tiny bacterial colonies were isolated on blood agar [Figure 1] without showing any growth on MacConkey agar. The isolates from both the blood cultures were initially included in the Streptococcus viridians group as they were Gram-positive cocci and coccobacillary forms and arranged in pairs and chains. They were catalase and bile esculin negative. Antimicrobial susceptibility test was performed according to Clinical and Laboratory Standards Institute guideline on blood agar [Figure 2] by Kirby–Bauer disk diffusion method. Further, identification of the isolate was done by Vitek-2 Compact automated system (BioMerieux, France) using GP card. The organism was confirmed as L. lactis. In our case, the patient died before changing to suitable antibiotics, who was empirically treated with vancomycin for 48 h to which the bacterium showed resistance.{Figure 1}{Figure 2}


Bacteremia due to Leuconostoc spp. remains an uncommon clinical entity. Owing to the paucity of documented cases, the exact mode of transmission to humans and the pathogenesis of Leuconostoc infections remain poorly defined. Further, identification and reporting of Leuconostoc spp. is lacking. This is partly, because of the infrequent occurrence and sharing of many morphological and biochemical characteristics with viridians streptococci. Management of this infection becomes really difficult because of diagnostic difficulties and its intrinsic resistance to vancomycin.

Possible predisposing factors for Leuconostoc bacteremia include immunosuppression, prolonged hospitalization, presence of a central venous catheter, need for total parenteral nutrition, disruption of bowel mucosa, and long-term antibiotic treatment especially with vancomycin. In our case, as the patient had myelofibrosis, which might have increased susceptibility to different types of infection. Further, the outcome was worsened due to the bacterial intrinsic resistance to the vancomycin with which he was empirically treated.

Bacteremia due to Leuconostoc spp. remains an uncommon clinical entity. In our case, the patient died before changing to other antibiotics from the vancomycin as it was resistant to the later. Successful treatment strategies include removal of indwelling catheters and administration of intravenous penicillin [10] Alternative antimicrobials that have been suggested include clindamycin, ampicillin, macrolides, minocycline, aminoglycosides, and more recently daptomycin and tigecycline.[11],[12] When culture yields nonenterococcal Gram-positive cocci in pairs and chains with a decreased susceptibility to vancomycin, infection due to Leuconostoc spp. should always be suspected. Since, vancomycin remains a commonly used choice of empiric therapy for bacteremia with Gram-positive organisms, efforts should be made to alert clinicians of the possibility of vancomycin-resistant Leuconostoc spp. as soon as possible to prevent any delay in initiation of appropriate antibiotic therapy in patients.

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Conflicts of interest

There are no conflicts of interest.


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