A disseminated Lactobacillus rhamnosus GG ATCC 53103 infection was suspected in a 6 day-old newborn with intrauterine growth restriction (IUGR) symptoms, treated empirically with antibiotics and given L. rhamnosus GG with the aim of preventing antibiotic-associated gastrointestinal complications. The level of C-reactive protein on day 5 compared with day 2 was increased in spite of negative urine and cerebrospinal fluid cultures. The blood sampled on day 6 was found to be positive for lactobacilli, and the isolate was pre-identified as L. rhamnosus or Lactobacillus casei on day 11. The strain identity was then verified as L. rhamnosus GG through PCR and 16S rRNA sequencing. Genotyping with the rep-PCR and AFLP methods confirmed the 100% genetic similarity for both the strain isolated from patient blood and the probiotic product. The newborn became touch-sensitive, cried a lot, had worsening laboratory test results, and increased inflammation parameters, but no fever was observed. After a further 9 days of antibiotic therapy, blood cultures became negative, and laboratory tests improved on day 25. The patient was discharged from the hospital after 27 days. IUGR with a possible link to L. rhamnosus GG bacteraemia might be a new potential risk group, beside patients with organ failure, immunocompromised status and dysfunctional gut barrier mechanisms, for which safe use of probiotics needs careful attention. Universally accepted or improved guidelines for the safer administration of probiotics in risk groups are urgently needed. This report should not discourage the use of probiotics, but should highlight the need for their careful use in IUGR patients.
Only three Corynebacterium species are known to produce a lethal exotoxin called diphtheria toxin. These are C. diphtheriae, C. ulcerans and C. pseudotuberculosis. The diphtheria toxin gene (tox) is carried in a family of closely related corynebacteriophages and therefore the toxin can be produced only through lysogenisation, in which the corynephage encoding tox is stably inserted into the chromosome. However, ‘nontoxigenic tox gene-bearing’ (NTTB) strains, which are genotypically tox-positive but do not express the protein, have been described. The emergence of NTTB strains was first observed during the 1990s diphtheria epidemic in Eastern Europe and nowadays such isolates have been detected in many countries in the world. Recently, novel species of Corynebacterium genus have been described which might have the potential of producing the diphtheria toxin due to the possession of the diphtheria toxin gene but it has not produced toxin in laboratory tests. The circulation of NTTB strains could be related to the increased risk for diphtheria disease arising from the risk of re-emerging toxin expression. The article presents the mechanism of diphtheria toxin expression and action, recently described novel species of NTTB corynebacteria as well as the taxonomic changes within the C. diphtheriae group.
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