Predictors for successful PBSC collection on the fourth day of G‐CSF‐induced mobilization in allogeneic stem cell donors

Peripheral blood stem cells (PBSCs) used for allogeneic transplantation are collected by apheresis after pre‐treatment of donors with G‐CSF. Using modern apheresis devices stem cells can be collected more efficiently. It was studied whether collection on the 4th instead of the 5th day after initiation of G‐CSF treatment might be feasible. Stem cell yields that could have been collected on day 4 were calculated in two cohorts treated with 10 µg/kg G‐CSF once daily (n = 106, cohort I) or 5 µg/kg twice daily schedule (n = 85, cohort II). Harvests were predicted using the median collection efficiency (CE) of the apheresis machine and regarded successful when > 5.0 x10⁶ CD34^+/kg recipient body weight. Successful harvests at day 4 could have been obtained in only 22.6% and 41.2% of donors in cohort I and II respectively, while the expected successful collections on day 5 were 55.7% and 76.5%. Individual donor factors that correlated with a successful harvest on day 4 were weight, BMI, age, ratio donor/recipient weight and total G‐CSF dose in cohort I, whereas ratio donor/recipient weight was the only significant predictor in cohort II. Donor weight, BMI and total G‐CSF dose correlated positively with CD34⁺ values in the blood on day 4 in all donors. However, donor characteristics were not able to be used as strong predictors in daily practice. In conclusion, PBSC collection on day 4 will not result in a successful harvest in most stem cell donors, however using a twice daily G‐CSF scheme increases the yield.     

The SMART‐COP score performs well for pneumonia risk stratification in Australia’s Tropical Northern Territory: a prospective cohort study

Objective To prospectively compare a modified pneumonia severity scoring system, SMARTACOP, with other severity scores in patients presenting with pneumonia to the emergency department (ED) of a tertiary referral hospital in tropical Australia. Methods We conducted a prospective observational study of adult patients presenting with radiologically confirmed pneumonia over a 12‐month period. The sensitivity of risk stratification scores were assessed against the need for intensive respiratory or vasopressor support (IRVS). Results There were 367 ED attendances for pneumonia of whom 77.1% were admitted to hospital, 10% required intensive respiratory or vasopressor support and 2.8% died. Mean age was 50.0 years, 52% were men and 59% were Indigenous. The sensitivity of a SMART‐COP score ≥3, a SMARTACOP score ≥3 and a pneumonia severity index (PSI) class ≥3 for predicting IRVS was 97%, 97% and 78% respectively. Conclusions We found no significant advantage of the SMARTACOP over the SMART‐COP score for the prediction of intensive respiratory or vasopressor support, but both scores significantly outperformed PSI. The SMART‐COP score should replace the PSI in tropical Australia and should be assessed in other tropical areas for pneumonia risk stratification in emergency departments.     

Biogeography of Burkholderia pseudomallei in the Torres Strait Islands of Northern Australia

It has been hypothesized that biogeographical boundaries are a feature of Burkholderia pseudomallei ecology, and they impact the epidemiology of melioidosis on a global scale. This study examined the relatedness of B. pseudomallei sourced from islands in the Torres Strait of Northern Australia to determine if the geography of isolated island communities is a determinant of the organisms'' dispersal. Environmental sampling on Badu Island in the Near Western Island cluster recovered a single clone. An additional 32 clinical isolates from the region were sourced. Isolates were characterized using multilocus sequence typing and a multiplex PCR targeting the flagellum gene cluster. Gene cluster analysis determined that 69% of the isolates from the region encoded the ancestral Burkholderia thailandensis-like flagellum and chemotaxis gene cluster, a proportion significantly lower than that reported from mainland Australia and consistent with observations of isolates from southern Papua New Guinea. A goodness-of-fit test indicated that there was geographic localization of sequence types throughout the archipelago, with the exception of Thursday Island, the economic and cultural hub of the region. Sequence types common to mainland Australia and Papua New Guinea were identified. These findings demonstrate for the first time an environmental reservoir for B. pseudomallei in the Torres Strait, and multilocus sequence typing suggests that the organism is not randomly distributed throughout this region and that seawater may provide a barrier to dispersal of the organism. Moreover, these findings support an anthropogenic dispersal hypothesis for the spread of B. pseudomallei throughout this region.     

Overlapping Functionality of the Pht Proteins in Zinc Homeostasis of Streptococcus pneumoniae

Streptococcus pneumoniae is a globally significant pathogen that causes a range of diseases, including pneumonia, sepsis, meningitis, and otitis media. Its ability to cause disease depends upon the acquisition of nutrients from its environment, including transition metal ions such as zinc. The pneumococcus employs a number of surface proteins to achieve this, among which are four highly similar polyhistidine triad (Pht) proteins. It has previously been established that these proteins collectively aid in the delivery of zinc to the ABC transporter substrate-binding protein AdcAII. Here we have investigated the contribution of each individual Pht protein to pneumococcal zinc homeostasis by analyzing mutant strains expressing only one of the four pht genes. Under conditions of low zinc availability, each of these mutants showed superior growth and zinc accumulation profiles relative to a mutant strain lacking all four genes, indicating that any of the four Pht proteins are able to facilitate delivery of zinc to AdcAII. However, optimal growth and zinc accumulation in vitro and pneumococcal survival and proliferation in vivo required production of all four Pht proteins, indicating that, despite their overlapping functionality, the proteins are not dispensable without incurring a fitness cost. We also show that surface-attached forms of the Pht proteins are required for zinc recruitment and that they do not contribute to defense against extracellular zinc stress.