Extensive Genome-Wide Phylogenetic Discordance Is Due to Incomplete Lineage Sorting and Not Ongoing Introgression in a Rapidly Radiated Bryophyte Genus.

The relative importance of introgression for diversification has long been a highly disputed topic in speciation research and remains an open question despite the great attention it has received over the past decade. Gene flow leaves traces in the genome similar to those created by incomplete lineage sorting (ILS), and identification and quantification of gene flow in the presence of ILS is challenging and requires knowledge about the true phylogenetic relationship among the species. We use whole nuclear, plastid, and organellar genomes from 12 species in the rapidly radiated, ecologically diverse, actively hybridizing genus of peatmoss (Sphagnum) to reconstruct the species phylogeny and quantify introgression using a suite of phylogenomic methods. We found extensive phylogenetic discordance among nuclear and organellar phylogenies, as well as across the nuclear genome and the nodes in the species tree, best explained by extensive ILS following the rapid radiation of the genus rather than by postspeciation introgression. Our analyses support the idea of ancient introgression among the ancestral lineages followed by ILS, whereas recent gene flow among the species is highly restricted despite widespread interspecific hybridization known in the group. Our results contribute to phylogenomic understanding of how speciation proceeds in rapidly radiated, actively hybridizing species groups, and demonstrate that employing a combination of diverse phylogenomic methods can facilitate untangling complex phylogenetic patterns created by ILS and introgression.

Safety and effectiveness of a modification of diet in renal disease equation-based potassium replacement protocol.

BACKGROUND: No data exist regarding the safety and effectiveness of a potassium replacement protocol for hospitalized patients when potassium replacement dosing regimens (KRDRs) are adjusted to Modification of Diet in Renal Disease estimation of glomerular filtration rate (MDRD GFR). OBJECTIVE: To evaluate the effectiveness and safety of a potassium replacement protocol in which KRDRs are prescribed based on MDRD GFR and serum potassium deficiency (Kdef). METHODS: Patients prescribed the potassium replacement order set were identified in a retrospective fashion. Serum potassium, prescriber-defined goal serum potassium, and MDRD GFR data were collected for patients who received protocol KRDRs. The KRDR to be administered is selected based on Kdef (goal serum potassium minus measured serum potassium) of 0.1-0.2, 0.3-0.5, or more than 0.5 mEq/L and the patients' MDRD GFR of greater than 70, 40-70, or less than 40 mL/min/1.73 m(2) (any patient undergoing dialysis is included in the <40 mL/min/1.73 m(2) group). Efficacy was evaluated by determining the change in serum potassium level (Delta K) following potassium replacement, the number of KRDRs needed to achieve goal serum potassium, and the milliequivalents of potassium needed to achieve goal serum potassium levels. Safety was assessed by the incidence of serum potassium values greater than 5.0 mEq/L following replacement. RESULTS: One hundred forty-nine patients were evaluated. There were 184 protocol initiations and 257 KRDRs administered to achieve goal serum potassium levels. The DeltaK was 0.50 +/- 0.40 mEq/L (mean +/- SD) following KRDR. The Delta K was similar between MDRD GFR groups. One hundred thirty six (73.9%) protocol initiations required 1 KRDR, and 168 (91.3%) protocol initiations required 1 or 2 KRDRs to achieve goal serum potassium. Patients whose MDRD GFR was 40-70 mL/min/1.73 m(2) were less likely to achieve goal serum potassium value after 1 KRDR (58.2% vs 79.6% >70 group and 84.6% <40 group). This was true regardless of the patient's goal serum potassium. One (0.54%) serum potassium greater than 5.0 mEq/L occurred following a KRDR. CONCLUSIONS: Our potassium replacement protocol based on MDRD GFR and Kdef effectively corrects hypokalemia. Fewer protocol initiations achieved goal serum potassium levels in the group with MDRD GFR 40-70 mL/min/1.73 m(2). Hyperkalemia rarely occurred following KRDR.

Rapid control of an outbreak of Staphylococcus aureus on a neonatal intensive care department using standard infection control practices and nasal mupirocin.

BACKGROUND: Staphylococcus aureus is a common pathogen in neonatal intensive care departments, causing significant morbidity, mortality, and cost. Frequently, S aureus outbreaks may last for months or years. After a cluster of 4 clinically significant S aureus infections in a 7-day period in our 35-bed neonatal intensive care department, we immediately introduced standard outbreak control measures. Unique to our approach was the addition of immediate nasal mupirocin treatment of all staff members and selected patients. METHODS: Patients were screened for S aureus colonization and were cohorted with separate caregivers. S aureus isolates were submitted to a reference laboratory for pulse-field gel electrophoretic typing. Infection control practices were emphasized and education was provided for staff, physicians, and parents of patients. All caregivers and selected patients were treated immediately with nasal mupirocin. Cohorting was maintained until all patients who were colonized or infected were discharged. RESULTS: A total of 5 patients were found to be infected and 4 of 19 patients tested were found to be colonized during the study period. Patients who were infected were successfully treated. Secondary colonization and infection did not occur after implementation of controls. CONCLUSIONS: Rapid and comprehensive implementation of standard outbreak controls along with immediate treatment of direct care staff and patients with nasal mupirocin successfully controlled this outbreak within 4 weeks and no further cases have been noted.