Low-bacterial diet in children undergoing HSCT: concept, key principles and unresolved issues

Summary

Conditioning regimens before HSCT inevitably lead to immunosupression. Under these conditions, the probability of infections complicating the post-transplant period and negatively affecting the patient’s recovery increases dramatically. Therefore, during neutropenia it is required to protect the patient from the possibility of infection. Lungs and gastrointestinal tract are the key gates of infection: because of the "openness", the vital importance of these systems, the complexity of anti-microbial therapy and huge area of their inner surface. Our aim was to compare different studies in the field.

Objects and methods

As early as in 1960s, the first outlined recommendations on the diet of neutropenia patients were developed (Reimer 1966). Subsequently, the diet under the terms "neutropenic" and "low-microbial" (LMD) became stably included in the guidelines for the support in oncology and hematology. Strict methods of long-term food processing (thermal, hyperbaric, radiation, canning) were used (Aker 1983). The main goal was achieved, but there was a high monotony and taste properties, thus dictating a need for "softening" the regime, and composition of the diet (Preisler 1970). The emergence of a low-bacterial diet (LBD) modified by inclusion of raw, well-washed fruits and vegetables. The effectiveness of LMD, in terms of reducing the risk of infection, begins to be seriously challenged with the 90s.

Results

Foreign experience (Ziegler 1992, Smith 2000, French 2001, Wilson 2002, Moody 2006, Van Thiel 2007, Gardner 2008, Stecher 2008, Trifilio 2012) shows that:
• There exist many LMD modifications;
• A diet including raw fruits and vegetables is psychologically better tolerated by patients whereas "sterile" LMD is an additional "burden";
• No significant differences were found between LMD classic and soft LBD, with respect to duration and presence of infectious complications in patients with neutropenia, including after HSCT;
• There is a reverse effect of "decontamination": invasion of opportunistic and pathogenic microflora of the intestinal surface with a decrease in the number and activity of gut microflora is faster and more aggressive. In Russia, there are logical inconsistencies with LMD. On the one hand, there is too long cooking. The dishes prepared in this way become tasteless and less useful;
• Limitations for heat-treated nuts, dried fruits and honey. There is no basis for such exceptions in the literature, except for general suggestions and "for any case" concepts;
• Prohibition of fresh vegetables, raw fruits (especially, citrus). At present, there is no clear evidence for exclusion of raw fruits in patients after HSCT (Trifilio 2012). On the other hand, the following products are allowed: marmalade, chocolate, cakes and packed non-yeasted bread, bananas, ice cream sorbet. In addition, there is no clear understanding of the principles of low microbial regimen, why LMD is needed, when it is needed and when it should be cancelled;
• There is lack of coherence and universality of dietary approaches, even within one clinic, e.g., usage of LMD for patients being outside the transplantation box, and especially at home.

Conclusions

1. LMD prepared by certain rules of treatment, storage and delivery of food, was developed as an additional way to prevent infection.
2. The diet, generally, has low taste properties and high monotony, thus hard to consume it.
3. The researchers conclude that LMD for patients undergoing HSCT is advisable, but with the inclusion of fresh fruits and vegetables. Rigid restrictions may have the opposite effect.
4. There is no universal diet for children after HSCT.
5. Current LMD is imperfect and not always justified, it is necessary to review and unify it on the basis of logical positions of evidence-based medicine, individual approaches, and harm-benefit ratio.

Keywords

Hematopoietic stem cell transplantation, children, nutrition, neutropenic diet, low-bacterial diet.