Visualization of Mycobacterium avium in Crohn's tissue by oil-immersion microscopy

Studies seeking Mycobacterium avium subsp. paratuberculosis in Crohn's disease by PCR have generated inconsistent findings. As an alternative, microscopy offers a number of advantages, including direct visualization of organisms in tissue. Experimental infections have demonstrated that M. avium organisms can be seen by both acid-fast staining and species-specific in situ hybridization, but because they are smaller than M. tuberculosis, oil-immersion microscopy (x 1,000 magnification) is needed. We performed a blinded search for M. avium in paraffin-embedded surgical resections from Crohn's and control subjects at two centres. Specimens were coded and subjected to acid-fast staining and ribosomal RNA in situ hybridization for M. avium rRNA. Agreement between these two methods was good (42/52 patients, kappa=0.60) and similar results were observed for patients from two centers. Together, both methods provided positive results in 10 of 17 Crohn's subjects (59%, 95% CI: 36-78), contrasting with only 5 of 35 control subjects (Odds ratio for Crohn's vs. controls=8.6, p=0.002). M. avium organisms had an intracellular localization within inflammatory lesions, but were often observed as lone organisms outside of granulomas. Using two assays in two settings, presence of M. avium organisms was strongly associated with Crohn's disease.     

Extensive genomic polymorphism within Mycobacterium avium

We have initiated comparative genomic analysis of Mycobacterium avium subspecies by DNA microarray, uncovering 14 large sequence polymorphisms (LSPs) comprising over 700 kb that distinguish M. avium subsp. avium from M. avium subsp. paratuberculosis. Genes predicted to encode metabolic pathways were overrepresented in the LSPs, and analysis revealed a polymorphism within the mycobactin biosynthesis operon that potentially explains the in vitro mycobactin dependence of M. avium subsp. paratuberculosis.     

Postpartum depression and infant feeding practices in a low income urban settlement in Nairobi-Kenya

Background

Postpartum depression can compromise caregiving activities, including infant feeding practices, resulting in child malnutrition. The purpose of this study was to examine the effects of postpartum depression on infant feeding practices and malnutrition among women in an urban low income settlement in Nairobi-Kenya. We conducted a cross-sectional study based in Kariobangi North Health Centre in Nairobi County. The study sample included 200 mother-infant pairs visiting the Maternal and Child Health clinics for infant immunization at 6–14 weeks postpartum. We assessed postpartum depression using the Edinburgh Postpartum Depression Scale. Infant feeding practices were assessed based on World Health Organization infant and young child feeding guidelines. Nutritional status (weight for age) was ascertained using infants’ growth monitoring card (percentiles and z-score). We conducted logistic regression analyses to determine the relative odds of non-exclusive breast feeding and infant underweight among mothers with postpartum depression.

Results

The prevalence of PPD was 13.0% (95% CI 8.3–17.7%). Taking into account differences in socioeconomic status of depressed and non-depressed mothers, non-depressed mothers had a 6.14 (95% CI 2.45–13.36) times higher odds of practicing exclusive breastfeeding than mothers who were depressed. Mothers with PPD had a 4.40 (95% CI 1.91–11.93) time higher odds of having an underweight infant than mothers without depression.

Conclusions

This study contributes towards filling the knowledge gap regarding the adverse effects of postpartum depression on infant health in sub-Saharan Africa. We recommend more research on PPD using longitudinal designs to establish temporal ordering of these important public health problems and development of community-based interventions to address post-partum depression.

     

Visualization of Mycobacterium avium in Crohn's tissue by oil-immersion microscopy

Studies seeking Mycobacterium avium subsp. paratuberculosis in Crohn's disease by PCR have generated inconsistent findings. As an alternative, microscopy offers a number of advantages, including direct visualization of organisms in tissue. Experimental infections have demonstrated that M. avium organisms can be seen by both acid-fast staining and species-specific in situ hybridization, but because they are smaller than M. tuberculosis, oil-immersion microscopy (×1000 magnification) is needed. We performed a blinded search for M. avium in paraffin-embedded surgical resections from Crohn's and control subjects at two centres. Specimens were coded and subjected to acid-fast staining and ribosomal RNA in situ hybridization for M. avium rRNA. Agreement between these two methods was good (42/52 patients, κ = 0.60) and similar results were observed for patients from two centers. Together, both methods provided positive results in 10 of 17 Crohn's subjects (59%, 95% CI: 36–78), contrasting with only 5 of 35 control subjects (Odds ratio for Crohn's vs. controls = 8.6, p = 0.002). M. avium organisms had an intracellular localization within inflammatory lesions, but were often observed as lone organisms outside of granulomas. Using two assays in two settings, presence of M. avium organisms was strongly associated with Crohn's disease.     

A 20-Gene Set Predictive of Progression to Severe Dengue

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