Breast milk as a source for acquisition of cytomegalovirus (HCMV) in a premature infant with sepsis syndrome: Detection by real-time PCR

New short-term heat inactivation method of cytomegalovirus (CMV) in breast milk: impact on CMV inactivation, CMV antibodies and enzyme activities

OBJECTIVES

Breast milk (BM) is the primary source of cytomegalovirus (CMV) transmission to premature infants with potentially harmful consequences. We therefore wanted to evaluate temperature and duration of short-term BM pasteurisation with respect to CMV inactivation, effect on CMV-IgG antibodies and BM enzyme activities.

METHODS

116 artificially CMV-spiked BM and 15 wild-type virus-infected samples were subjected for 5 s to different temperatures (55°C-72°C). CMV-IE-1 expression in fibroblast nuclei was assessed using the milk whey fraction in short-term microculture. BM lipase and alkaline phosphatase (AP) activities and CMV binding using CMV-recomLine immunoblotting and neutralising antibodies using epithelial target cells were analysed before and after heating.

RESULTS

A minimum of 5 s above 60°C was necessary for CMV inactivation in both CMV-AD-169 spiked and wild-type infected BM. Lipase was very heat sensitive (activities of 54% at 55°C, 5% at 60°C and 2% at 65°C). AP showed activities of 77%, 88% and 10%, respectively. CMV-p150 IgG antibodies were mostly preserved at 62°C for 5 s.

CONCLUSION

Our results show that short-term pasteurisation of BM at 62°C for 5 s might be efficient for CMV inactivation and reduces loss of enzyme activities, as well as CMV binding, and functional CMV antibodies.

HIV, HCMV and mycobacterial antibody levels: a cross-sectional study in a rural Ugandan cohort

OBJECTIVES

A growing evidence base implicates human cytomegalovirus (HCMV) as a risk factor for TB disease. We investigated total IgG and mycobacteria-specific antibodies in a cross-sectional study nested within a rural Ugandan General Population Cohort (GPC), in relation to HIV infection and the magnitude of HCMV IgG response.

METHODS

Sera from 2189 individuals (including 27 sputum-positive TB cases) were analysed for antibodies against mycobacteria (Ag85A, PPD, LAM, ESAT6/CFP10) and HCMV, tetanus toxoid (TT) and total IgG.

RESULTS

Anti-mycobacterial antibodies increased with age until approximately 20 years, when they plateaued. Higher HCMV exposure (measured by IgG) was associated with lower levels of some anti-mycobacterial antibodies, but no increase in total IgG. HIV infection was associated with a decrease in all anti-mycobacterial antibodies measured and with an increase in total IgG.

CONCLUSIONS

The increase in anti-mycobacterial antibodies with age suggests increasing exposure to non-tuberculous mycobacteria (NTM), and to M.tb itself. HIV infection is associated with decreased levels of all mycobacterial antibodies studied here, and high levels of HCMV IgG are associated with decreased levels of some mycobacterial antibodies. These findings point towards the importance of humoral immune responses in HIV/TB co-infection and highlight a possible role of HCMV as a risk factor for TB disease.

Quantitative monitoring of HCMV DNAlactia in human milk by real time PCR assay: Implementation of internal control contributes to standardization and quality control

For cytomegalovirus screening of breastfeeding mothers of preterm infants under risk, we present a rapid, quantitative real-time PCR protocol using the hybridization format of the viral gB target region. For quantification, we used an external gB fragment cloned into a vector system. For standardization, we created an internal control-plasmid by site-directed mutagenesis with an exchange of 9 nucleotides. Spiked with internal control, patient wildtype amplicons could be discriminated from internal controls by hybridization probes using two-channel fluorescence detection. Potential bias of formerly reported false nucleotide sequence data of gB-hybridization probes was excluded. Using this approach, we could demonstrate excellent analytical performance and high reproducibility of HCMV detection during lactation. This assay shows very good correlation with a commercial quantitative HCMV DNA PCR and may help to identify rapidly HCMV shedding mothers of very low birth weight preterm infants to prevent HCMV transmission. On the other hand, negative DNA amplification results allow feeding of milk samples of seropositive mothers to their preterm infants under risk (<30 weeks of gestational age, <1000g birth weight) during the onset and late stage of HCMV shedding during lactation.

Characterization of human breast milk leukocytes and their potential role in cytomegalovirus transmission to newborns

BACKGROUND

Breast milk is the primary source of cytomegalovirus (CMV) transmission to newborns and premature infants. The role of cell-free milk whey in virus transmission is well understood, yet the knowledge about the role of milk cells in this process is scarce.

OBJECTIVE

To preliminarily characterize different breast milk cell types during various stages of lactation to evaluate their potential role in the transmission of CMV.

MATERIALS AND METHODS

Breast milk cells of 18 lactating and 3 CMV-seropositive mothers of preterm infants were isolated and characterized for expression of myeloid markers by flow cytometry. In parallel, cytospin preparations were stained with α-naphthyl acetate esterase to identify milk macrophages and describe the dynamic changes of the macrophage-granulocyte population during lactation. The influence of different time points of lactation was analyzed by FACS analysis of double-stained (CD15/CD66b) milk cells. To characterize CMV target cells in breast milk, we enriched CD14+ cells by MACS (Miltenyi) and monitored cell fractions using CMV IEEx4 nested PCR and pp67 CMV RNA by NASBA.

RESULTS

Virolactia, viral DNAlactia, and viral pp67 late mRNA could be detected in breast milk cells only in defined time periods. Granulocytes and macrophages demonstrated an inverse dynamic with neutrophils predominating in the early stages (<30 days postpartum) and macrophages in later stages (>60 days postpartum) of lactation. Enrichment of CD14-positive cells resulted in viral DNA and pp67 late mRNA detection.

CONCLUSIONS

Granulocytes and monocytes/macrophages are the predominating cell populations in breast milk with changing frequencies during early lactation. These results demonstrate that CD14-positive breast milk cells seem to be one of the target cells for CMV in breast milk.

Ultrasound confirmation of endotracheal tube position in neonates

BACKGROUND

The placement of the endotracheal tube (ETT) in neonates is a challenging procedure that currently requires timely confirmation of tip placement by radiographic imaging.

OBJECTIVE

We sought to determine if bedside ultrasound (US) could demonstrate ETT tip location in preterm and term newborns and offer a quick alternative method of ETT positioning.

METHODS

We conducted a prospective pilot study of 30 newborns admitted to the UC San Diego Medical Center who had their ETT placement confirmed by chest radiographs. After a radiograph, each infant had a US exam with a 13-MHz linear transducer on a portable US machine. To assist localization, gentle longitudinal movement of the ETT of less than 0.5 cm was performed. Measurements from the tip of the ETT tip to the carina were made on chest radiograph and midsagittal US images.

RESULTS

Study infants had a mean gestational age of 30.2 ± 4.9 (SD) weeks and mean birth weight of 1,595.2 ± 862 g. US images were taken a mean 2.9 ± 2.2 h after radiographs. Data from 2 infants were excluded for poor radiograph image quality and extreme outlier values. The ETT was visualized by US in all newborns examined. We observed a good correlation between ETT tip-to-carina distance on US and radiograph (r(2) = 0.68) with minimal bias. Each study took less than 5 min to obtain without any clinical deterioration.

CONCLUSIONS

Bedside US can visualize the anatomic position of the ETT position in preterm and term infants but further validation is required before routine clinical implementation.

Transmission of cytomegalovirus via breast milk in extremely premature infants

OBJECTIVE

We prospectively evaluated the rate of postnatal cytomegalovirus (CMV) transmission through breast milk in extremely premature infants to address the impact of CMV infection on preterm infants during lactation.

STUDY DESIGN

A total of 25 mothers and 27 infants (two sets of twins) with birth weights <1000 g and/or gestational ages <28 weeks were enrolled in the study. They were mostly fed frozen-thawed breast milk. Breast milk, serum and urine samples were collected every 2 weeks and screened for CMV infection using the real-time polymerase chain reaction.

RESULT

All of the 21 CMV-seropositive mothers had detectable CMV DNA in their breast milk, with a peak at 4 to 6 weeks postpartum. CMV infection was confirmed in only one infant (4.3%) who displayed almost no clinical symptoms.

CONCLUSION

At our institutes, we mainly use frozen-thawed breast milk. We found low CMV transmission rates even in extremely premature infants, and the CMV-positive infant did not develop serious symptoms.

Transmission of cytomegalovirus via breast milk to the prematurely born infant: a systematic review

To analyse current data on transmission of human cytomegalovirus (HCMV) via breast milk with subsequent symptomatic HCMV infection of the preterm infant and to report on long-term follow-up, a systematic literature review was performed using EMBASE, MEDLINE and CINAHL (January 1966 to December 2008) Studies were included for analysis if congenital HCMV infection was excluded and transmission via breast milk was either confirmed or strongly suspected. Twenty-six studies were included for analysis. Maternal HCMV-IgG-positivity was reported to be in the range 51.6-100% (median 81.6%), HCMV-IgG detection in breast milk in the range 67-97.2% (median 80%) and HCMV-positivity of the infants in the range 5.7-58.6%. Symptomatic HCMV disease occurred in 0-34.5% (median 3.7%) and severe sepsis-like syndrome in 0-13.8% (median 0.7%). Data on long-term outcome of preterm infants with symptomatic HCMV infection revealed a low risk for mild neurological and cognitive sequelae, without hearing impairment. Recommendations for high-risk preterm infants diverged markedly. The current data report low rates of symptomatic disease after transmission of HCMV via breast milk to the preterm infant without evidence of certain long-term sequelae. The results of our review do not support a general approach, either by avoidance or pasteurization of breast milk, in high-risk preterm infants.

[Review and guidelines on the prevention, diagnosis and treatment of post-natal cytomegalovirus infection]

Postnatal cytomegalovirus (CMV) infection in the newborn can occur from exposure to maternal cervical secretions during birth, ingestion of breast milk, transfusion of blood products or transmission by body fluids of infected people. Breast milk is the main source of infection, given the high rate of CMV-positive mothers excreting CMV in milk. Freezing reduces the risk of CMV transmission by breastfeeding, although it does not eliminate it completely. Pasteurisation prevents such transmission, but it can alter the immunological properties of breast milk. Postnatal CMV infection is usually asymptomatic, as it normally results from viral reactivation in the mother, and the neonate is born with protective antibodies. However, in the very low birth weight premature infant the amount of transferred antibodies is smaller and a symptomatic infection can occur. Symptomatic post-natal CMV infection in the newborn typically causes hepatitis, neutropenia, thrombocytopenia or sepsis-like syndrome. Pneumonitis and enteritis are less common, but very characteristic. Diagnosis is based on urine virus detection at the time of onset of symptoms. Postnatal CMV infection in the newborn generally resolves spontaneously without antiviral treatment. Ganciclovir should be reserved for severe cases. Unlike congenital CMV disease, post-natal CMV infection in the preterm infant does not seem to be associated with hearing loss or abnormal neuro-development in long term follow-up.

Cytomegalovirus transmission to preterm infants during lactation

Breastfeeding has a major impact on HCMV epidemiology. The incidence of postnatal HCMV reactivation during lactation equals the maternal seroprevalence. Infectious virus, viral DNA and RNA can be isolated easily from cell and fat-free milk whey. Early onset of viral DNAlactia and virolactia as well as high viral load in milk whey are maternal risk factors for virus transmission. The dynamics of HCMV reactivation can be described by unimodal kinetics with interindividual variation. Virus reactivation during lactation is a self-limiting local process in the absence of systemic HCMV infection. Preterm infants below 1000g birthweight and a gestational age below 30 weeks may be at high risk of acquiring a symptomatic HCMV infection. Several recent studies described low transmission rates and mostly asymptomatically infected neonates using frozen milk. Despite different freeze-storing procedures, HCMV transmissions occurred, and severe HCMV infections were observed. Few data exist on the long-term outcome of postnatally acquired HCMV infection via breast milk. To substantiate the international debate on the use of native or inactivated milk for feeding of preterm infants, additional data are necessary for better identification of mother-infant-pairs at risk for viral transmission and symptomatic infection early after birth.