27-Enterococcus hirae: a zoonotic microorganism in human umbilical cord blood

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Enterococcus hirae: a zoonotic microorganism in human umbilical cord blood

World J Microbiol Biotechnol DOI 10.1007/s11274-013-1537-4

Vincenzo Savini • Tiziana Bonfini • Roberta Marrollo • Angela Valentina Argentieri • Sara Riccioni • Daniela Astolfi • Paolo Fazii • Domenico D’Antonio • Giovanni Gherardi

Abstract 

Enterococcus hirae is rarely collected from man, while it is a common pathogen in mammals and birds. We describe the first isolation of the organism (strain DSM 27815) from human umbilical cord blood (UCB), thus emphasizing the risk of contamination of UCB units for clinical use. In this context, we also highlight the importance of an extensive training of the collecting personnel as to the observance of the disinfection protocol ensuring UCB units sterility.

Discussion 

Bacterial contamination may involve any blood component for transfusion and transplantation, although it is mostly observed with platelets (Fig. ). Since, as a consequence, recipient’s device colonization and/or bacteraemia, even fatal, may occur after transfusion/transplant of contaminated products, blood components must be examined  carefully to ensure their sterility prior to clinical use (Guo et al. ; Savini et al. ). According to current literature, the overall incidence of UCB contamination is 0–48 %. It is mainly due to skin and gut flora (38.4 and 33.9 %, respectively), while environmental contaminants or vaginal saprophyte bacteria are involved to a lesser extent (6.5 and 1.8 %, respectively). A higher rate is finally observed after vaginal delivery (5.4 %) rather than post-caesarian section (1.1 %) (Clark et al. ). A further variable that is associated with a more frequent reporting of UCB contamination is the use of bottles for anaerobes in addition to those designed for organisms growing aerobically, while inoculating paediatric bottles (that only provide aerobic atmosphere and allow to introduce a smaller volume of the final product than those for adults) is associated with a reduced sensitivity when contaminating organisms are anaerobes (Clark et al. ). Again, Clark addressed the role of quality improvement strategies, as well as of training and expertise of personnel as a tool to reduce the contamination risk (Clark et al. ). As E. hirae is a zoonotic pathogen, we presumed the donor acquired colonization from pets. Accordingly, the mother referred past exposure to cats, birds and turtles. Hence, it has been assumed that the organism had colonized her enteric flora thus contaminating the CB unit at the time of delivery, during collection, probably due to a non-thorough disinfection procedure. Nevertheless, the donor was not asked to collect stools for culture, after contamination detection, aiming not to create unjustified alarmism and anxiety. Moreover, transient colonization due to ingestion of E. hirae-contaminated fruit and/or vegetables could not be excluded. This brief communication wants to emphasize the observation of a veterinary organism in the checked product, along with the risk of UCB contamination during delivery. E. hirae may be hard to identify through automated, phenotype-based systems (bioMe´rieux Rapid ID 32 Strep, for instance) that potentially misinterpret it as E. faecium, E. durans or Enterococcus gallinarum (Talarmin et al. ). We obtained unreliable results through API20, but correct identification was provided by both the Vitek2 GP card and the Phoenix. Nevertheless, it is clear that molecular tools are indispensable to confirm identification of uncommonly encountered enterococci. Potential transmission of enterococci to blood component recipients is of worrisome concern, as these pathogens poorly respond to several antibiotic classes and can therefore represent difficult-to-treat agents of disease once ). E. hirae is mostly an animal pathogen and isolation from a UCB unit raises questions about its source(s). Accordingly, we believe that asking informations about contact with animals and country environments might be included in the donors’ anamnesis once zoonotic microorganisms are isolated, to investigate origins of UCB contamination by veterinary bacteria, and elucidate their life cycle, niches, and routes of transmission.