Nocardiosis in Quebec,Canada, 1988–2008

Nocardia is an uncommon pathogen, but immunosuppression, its main risk factor, is becoming more frequent. We aimed to evaluate changes in the annual incidence of nocardiosis and in the susceptibility profile of its aetiological agents. Demographic data were analysed for all isolates of Nocardia forwarded to the provincial public health laboratory of Quebec, Canada during the last two decades. Population incidence could be measured from 1997 onwards. Resistance patterns were analysed for those isolates selected for in vitro susceptibility testing. Throughout Quebec, 575 incident cases were identified between 1997 and 2008. The annual incidence of Nocardia infection/colonization increased from 0.33 (1997–1998) to 0.87 (2007–2008) per 100 000 inhabitants (p 0.001). In a small subset of patients for whom detailed clinical information was available, 59% of isolates corresponded to genuine infections. Nocardia farcinica predominated in specimens representing invasive infections (blood, brain, lung or pleural aspirates). Isolates were often non‐susceptible to several antimicrobials, with the exception of amikacin and linezolid. Overall, 43% of 157 isolates were non‐susceptible to trimethoprim–sulphamethoxazole. In conclusion, Nocardia infection/colonization remains rare. However, from 1997–1998, a progressive increase in incidence was noted in the province of Quebec. In regions such as ours, where a substantial proportion of invasive isolates are non‐susceptible in vitro to trimethoprim–sulphamethoxazole, the latter may no longer be the empirical treatment of choice in immunosuppressed and severely ill patients with nocardiosis.     

Microbes,metabolites, and the gut–lung axis

The microbiota plays an essential role in the education, development, and function of the immune system, both locally and systemically. Emerging experimental and epidemiological evidence highlights a crucial cross-talk between the intestinal microbiota and the lungs, termed the ‘gut–lung axis’. Changes in the constituents of the gut microbiome, through either diet, disease or medical interventions (such as antibiotics) is linked with altered immune responses and homeostasis in the airways. The importance of the gut–lung axis has become more evident following the identification of several gut microbe-derived components and metabolites, such as short-chain fatty acids (SCFAs), as key mediators for setting the tone of the immune system. Recent studies have supported a role for SCFAs in influencing hematopoietic precursors in the bone marrow—a major site of innate and adaptive immune cell development. Here, we review the current understanding of host–microbe cross-talk along the gut–lung axis. We highlight the importance of SCFAs in shaping and promoting bone marrow hematopoiesis to resolve airway inflammation and to support a healthy homeostasis.     

Amphibian immunity–stress,disease, and climate change

Like all other vertebrate groups, amphibian responses to the environment are mediated through the brain (hypothalamic)-pituitary-adrenal/interrenal (HPA/I) axis and the sympathetic nervous system. Amphibians are facing historically unprecedented environmental stress due to climate change that will involve unpredictable temperature and rainfall regimes and possible nutritional deficits due to extremes of temperature and drought. At the same time, amphibians in all parts of the world are experiencing unprecedented declines due to the emerging diseases, chytridiomycosis (caused by Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans) and ranavirus diseases due to viruses of the genus Ranavirus in the family Iridoviridae. Other pathogens and parasites also afflict amphibians, but here I will limit myself to a review of recent literature linking stress and these emerging diseases (chytridiomycosis and ranavirus disease) in order to better predict how environmental stressors and disease will affect global amphibian populations.     

Professor Peter Alexander, 1922–93

Obituary

Professor Peter Alexander, 1922–93     

Reginald Henry Whitehouse, 1911–1987

The hypothesis of a dominant or major seasonal factor that produces the winter peak of menarche found in European girls was tested using several Caucasian and Mongolian samples from the northern hemisphere and two Chilean samples. Present results do not support such a hypothesis. The month at menarche of Chilean girls did not show the expected winter peak; February, a winter month in Europe, showed a deep trough in most samples. Instead, several Mongolian and Caucasian samples from the northern hemisphere clustered according to their ethnic origin rather than to the expected northern hemisphere yearly distribution of photoperiods and temperatures. Other non-seasonal factors seem to explain much better the periodicity of the monthly incidence of menarche. A phylogenetic factor (imprinting) is proposed to explain peaks seen in December and January for Caucasian, Mongolian, Finnish and Chilean samples living in the northern and southern hemispheres. Ontogenetic factors are proposed to explain the highly significant coincidence between the month of menarche and the month of birth, and the modulation of the phylogenetic imprinting by months at which gestation occurred in relation to menarche. The Finnish and Chilean samples, which can be considered mixed Caucasian and Mongolian, showed an intermediate pattern between the Caucasian and Mongolian groups.