Both, Limited and Often Fatal Systemic Infections Caused by Leuconostoc spp. in Older, Previously Ill Men Are Usually Acquired in the Outpatient Setting

Abstract

Leuconostoc spp. are vancomycin-resistant Gram-positive cocci that are used in food production and as pre- and probiotics. However, Leuconostoc spp. can also cause infections. In the present study, the records of patients with Leuconostoc spp. detection between January 2012 and March 2025 were analyzed, inclusive of the underlying risk factors. Leuconostoc spp. was isolated from 32 patients (21 male, 11 females), including nine patients with blood culture evidence. In the majority of patients, Leuconostoc spp. were obtained on the day of admission to the hospital or in the first few days thereafter, arguing against nosocomial acquisition. The median age of men and women (65.3 and 67.8 years) was similar, but seven of the 14 male patients over the age of 65 had the bacteria in blood culture. The female patients with blood culture evidence had suffered from peripartum thrombophlebitis and from anorexia nervosa (BMI 8.8 kg/m²). In contrast, men with Leuconostoc spp. in the blood culture had severe, limiting underlying diseases. While the two women survived, five of the seven blood-culture-positive men died. Overall, our results show that Leuconostoc spp. is mainly acquired in outpatient settings, but men are at a higher risk of acquisition. Colonized men over the age of 60 with severe underlying diseases have a high risk of systemic infection with a fatal outcome.

Keywords: Leuconostoc lactis; Leuconostoc mesenteroides; albumin; anorexia nervosa; food production; inflammation markers; probiotic; review article; starter culture.

Figure 1

Male and female patients from whose materials Leuconostoc spp. were detected. (A) Age of patients. (B) Time interval between hospitalization and collection of patient samples from which Leuconostoc spp. were detected.

Figure 2

Serum concentration of leukocytes (A), C-reactive protein (CRP) (B), and procalcitonin (PCT) (C) in a female anorexia nervosa patient suffering from a Leuconostoc spp. infection.

Figure 3

Albumin and C-reactive Protein (CRP) concentration in the serum of a female anorexia nervosa patient suffering from Leuconostoc spp. infection. Dotted line: lower limit of the normal value range of albumin.