Dear Editor

We read with interest the article entitled “Contamination of a milk bank pasteuriser causing a Pseudomonas aeruginosa outbreak in a neonatal intensive care unit” by Gras-Le Guen et al.[1]

This article dealt with clinical features of Pseudomonas infection in neonates after milk contamination. Pseudomonas is a rare pathogen in neonatal populations but the associated mortality and morbidity are huge. Leigh et al. [2] found a mortality rate of 50% in a population of very low birth weight infants with Pseudomonas infections. Gupta et al.[3] found a mortality rate of 23% amongst a cross-section of babies of all birth weights with Pseudomonas infections.

One major complication of Pseudomonas infection which did not arise in the recently reported1 outbreak is Pseudomonas endophthalmitis. The exact incidence of this infection is unknown. However an estimated 75% of cases of endophthalmitis are thought to be due to Pseudomonas infection.[4] Thus any abnormal ophthalmological examination in a sick or septic neonate should raise the possibility of Pseudomonas infection. The clinical manifestations of endophthalmitis include corneal injection, eye discharge and, in severe cases, proptosis, corneal clouding and complete corneal opacification.

A very important and possibly under-recognised association of endophthalmitis is meningitis.[5] The severe morbidity and mortality associated with endophthalmitis is possibly related to the co-existence of meningitis. In one series 6 of 4 patients with Pseudomonas endophthalmitis, 3 died of overwhelming sepsis and 1 suffered enucleation of the affected eye but had no other complications.

In summary, any unwell or septic neonate with an abnormal eye examination merits empiric treatment with antipseudomonal antibiotics. Pseudomonas endophthalmitis is a neonatal and ophthalmological emergency. Endophthalmitis and meningitis co-exist frequently: the presence of one does not preclude the other and the presence of endophthalmitis should prompt a search for meningitis.

References

(1) Gras-Le Guen C, Lepelletier D, Debillon T, Gournay V, Espaze E, Roze J C. Contamination of a milk bank pasteuriser causing a Pseudomonas aeruginosa outbreak in a neonatal intensive care unit. Arch Dis Child Fetal Neonatal Ed 2003;88:F434-F435.

(2) Leigh L, Stoll BJ, Rahman M, McGowan J Jr. Pseudomonas aeruginosa infection in very low birth weight infants: a case-control study. Pediatr Infect Dis J 1995;14(5):367-71.

(3) Gupta AK, Shashi S, Mohan M, Lamba IM, Gupta R. Epidemiology of Pseudomonas aeruginosa in a neonatal intensive care unit. J Trop Paediatr 1993;39(1):32-6.

(4) Lohrer, Belohradsky BH. Bacterial endophthalmitis in neonates. Eur J Pediatr 1987;146:354-9.

(5) Shan SS, Gloor P, Gallagher PG. Bacteraemia, meningitis and brain abscess in a hospitalised infant: complications of Pseudomonas aeruginosa conjunctivitis. J Perinatol 1999;19:462-5.

(6) Boyle EM, Ainsworth JR, Levin AV, Campbell AN, Watkinson M. Arch Dis Child Fetal Neonatal Ed 2001;85(2):F139-40.

Dear Editor

As relatively new milk bank (3 years old) we are constantly on the look out for ways of reducing the risks involved. With the article by Gras -Le Guen et al[1] we thought we might learn some valuable lessons.

However the substance of the article would seem to be that a pasteuriser was being used to thaw frozen milk. The water in the pasteuriser became contaminated by pseudomonas and this pseudomonas was probably transmitted to the neonatal unit on the cover of the milk bottles and became established in a bottle warmer.

It transpires that on this occasion we have nothing to learn. We operate in accordance with the guidelines of the UK milk bank association both for donor milk [2] and mothers own milk.[3] Under these guidelines frozen donor milk is thawed either in a refrigerator over 24 hours or "rapidly .. in running cold or lukewarm water" or for mothers own milk " Frozen milk should ideally be thawed in a fridge … in an emergency the preferred method is to hold the bottle under cold or tepid running water".

We cannot help wondering if the pasteuriser in question was being used as a pasteuriser at the time in question or merely as a milk warmer. The latter is clearly a relatively high risk environment for culture of pseudomonas – warm and moist. A pasteuriser is a much lower risk area – relatively short burst of relatively high temperature followed by periods of draining and drying.

The authors acknowledge the rarity of human milk banks as a source of contamination. Part of the reason, at least in the UK, is undoubtedly the high standards promoted by the UK Human Milk Bank Association. These are currently being updated. Any milk bank that does not have a local supervisory organisation would be well advised to acquire a copy and they could do worse than make them the basis of their working practice.

References

(1) Gras-Le Guen C, Lepelletier D, Debillon T, Gournay V, Espaze E, Roze JC. Contamination of a milk bank pasteuriser causing a Pseudomonas aeruginosa outbreak in a neonatal intensive care unit. Arch Dis Child Fetal Neonatal Ed 2003;88:F434-F435.

(2) Royal College of Paediatrics and Child Health and United Kingdom Association for Milk Banking. Guidelines for the Establishment and Operation of Human Milk Banks in UK, 2nd Edition.

(3) Association for Milk Banking. Guidelines for the collection, storage and handling of breast milk for a mothers own baby in hospital United Kingdom, 2nd Edition, 2001.

Dear Editor

We were concerned to read of the contamination of a pasteuriser in the milk bank in Nantes, Western France. The details of milk banking procedures in the report were sketchy and in particular we were unclear as to why breastmilk was thawed in a pasteuriser.

Guidelines for the Establishment and Operation of Human Milk Banks in the UK have been available since 1994 and a revised (3rd) edition will be available from UKAMB (United Kingdom Association for Milk Banking) in October 2003. These evidence-based guidelines fully describe how human milk can be safely collected, processed and stored. Amongst other things they require donor milk to be tested both prior to and after pasteurisation, and recommend that the milk be thawed either by defrosting slowly in a refrigerator or by the careful use of running water, ensuring the bottle cap remains dry.

The UKAMB website http://www.ukamb.org offers further information about milk banking and how to obtain the Guidelines.