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In children, osteomyelitis is primarily hematogenous in origin and acute in nature. The principal cause of osteomyelitis in children is Staphylococcus aureus, and both the epidemiology and pathogenesis of S. aureus infections, including osteomyelitis, have changed in recent years owing to the emergence of community-associated methicillin-resistant S. aureus. This review focuses on advances in the diagnosis and overall management of acute hematogenous osteomyelitis in children with these changes in mind. [ABSTRACT FROM AUTHOR]

Background: Acute rheumatic fever is infrequently diagnosed in sub-Saharan African countries despite the high prevalence of rheumatic heart disease. We aimed to determine the incidence of acute rheumatic fever in northern and western Uganda., Methods: For our prospective epidemiological study, we established acute rheumatic fever clinics at two regional hospitals in the north (Lira district) and west (Mbarara district) of Uganda and instituted a comprehensive acute rheumatic fever health messaging campaign. Communities and health-care workers were encouraged to refer children aged 3-17 years, with suspected acute rheumatic fever, for a definitive diagnosis using the Jones Criteria. Children were referred if they presented with any of the following: (1) history of fever within the past 48 h in combination with any joint complaint, (2) suspicion of acute rheumatic carditis, or (3) suspicion of chorea. We excluded children with a confirmed alternative diagnosis. We estimated incidence rates among children aged 5-14 years and characterised clinical features of definite and possible acute rheumatic fever cases., Findings: Data were collected between Jan 17, 2018, and Dec 30, 2018, in Lira district and between June 5, 2019, and Feb 28, 2020, in Mbarara district. Of 1075 children referred for evaluation, 410 (38%) met the inclusion criteria; of these, 90 (22%) had definite acute rheumatic fever, 82 (20·0%) had possible acute rheumatic fever, and 24 (6%) had rheumatic heart disease without evidence of acute rheumatic fever. Additionally, 108 (26%) children had confirmed alternative diagnoses and 106 (26%) had an unknown alternative diagnosis. We estimated the incidence of definite acute rheumatic fever among children aged 5-14 years as 25 cases (95% CI 13·7-30·3) per 100 000 person-years in Lira district (north) and 13 cases (7·1-21·0) per 100 000 person-years in Mbarara district (west)., Interpretation: To the best of our knowledge, this is the first population-based study to estimate the incidence of acute rheumatic fever in sub-Saharan Africa. Given the known rheumatic heart disease burden, it is likely that only a proportion of children with acute rheumatic fever were diagnosed. These data dispel the long-held hypothesis that the condition does not exist in sub-Saharan Africa and compel investment in improving prevention, recognition, and diagnosis of acute rheumatic fever., Funding: American Heart Association Children's Strategically Focused Research Network Grant, THRiVE-2, General Electric, and Cincinnati Children's Heart Institute Research Core., Competing Interests: Declaration of interests TP reports grant funding from the National Institute for Health Research (ACF-2016-20-001). All other authors declare no competing interests., (Copyright © 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Background Despite the high burden of rheumatic heart disease in sub-Saharan Africa, diagnosis with acute rheumatic fever (ARF) is exceedingly rare. Here, we report the results of the first prospective epidemiologic survey to diagnose and characterize ARF at the community level in Africa. Methods and Results A cross-sectional study was conducted in Lira, Uganda, to inform the design of a broader epidemiologic survey. Key messages were distributed in the community, and children aged 3 to 17 years were included if they had either (1) fever and joint pain, (2) suspicion of carditis, or (3) suspicion of chorea, with ARF diagnoses made by the 2015 Jones Criteria. Over 6 months, 201 children met criteria for participation, with a median age of 11 years (interquartile range, 6.5) and 103 (51%) female. At final diagnosis, 51 children (25%) had definite ARF, 11 (6%) had possible ARF, 2 (1%) had rheumatic heart disease without evidence of ARF, 78 (39%) had a known alternative diagnosis (10 influenza, 62 malaria, 2 sickle cell crises, 2 typhoid fever, 2 congenital heart disease), and 59 (30%) had an unknown alternative diagnosis. Conclusions ARF persists within rheumatic heart disease-endemic communities in Africa, despite the low rates reported in the literature. Early data collection has enabled refinement of our study design to best capture the incidence of ARF and to answer important questions on community sensitization, healthcare worker and teacher education, and simplified diagnostics for low-resource areas. This study also generated data to support further exploration of the relationship between malaria and ARF diagnosis in rheumatic heart disease/malaria-endemic countries.

Background: We describe the clinical characteristics and epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in children with cystic fibrosis (CF) from the U.S. CF center with the highest MRSA prevalence., Methods: Medical records of children with CF were retrospectively reviewed from 1997-2009. MRSA clinical isolates from 2007-2009 were analyzed by polymerase chain reaction and pulsed field gel electrophoresis., Results: The prevalence of MRSA was 1% in 1997 and 49% in 2009. Fifty-five children (26%) had persistent MRSA infection. Sixty-eight percent of MRSA isolates were hospital-associated (HA) MRSA, of which 52% were pulsed-field type USA 100. Ninety-three percent of HA MRSA isolates were clindamycin resistant. Twelve children acquired MRSA before 1 year of age, 83% of whom were hospitalized prior to acquisition of MRSA. Ten of 11 sibling pairs carried indistinguishable MRSA strains. Children with persistent MRSA were hospitalized more often (P = .01), required inhaled medications more frequently (P = .01), and had higher rates of Pseudomonas aeruginosa coinfection (P < .001)., Conclusion: MRSA prevalence in children with CF is increasing, and most children are infected with HA MRSA. Exposure to health care facilities and gastrointestinal surgeries may facilitate early acquisition of MRSA. Siblings carry indistinguishable MRSA strains, indicating household transmission of MRSA. Children with persistent MRSA had worse pulmonary morbidity. Coinfection with MRSA and P aeruginosa is likely associated with further increased pulmonary morbidity., (Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)

We demonstrate that the purified Staphylococcus aureus extracellular proteases aureolysin, ScpA, SspA, and SspB limit biofilm formation, with aureolysin having the greatest impact. Using protease-deficient derivatives of LAC, we confirmed that this is due to the individual proteases themselves. Purified aureolysin, and to a lesser extent ScpA and SspB, also promoted dispersal of an established biofilm. Mutation of the genes encoding these proteases also only partially restored biofilm formation in an FPR3757 sarA mutant and had little impact on restoring virulence in a murine bacteremia model. In contrast, eliminating the production of all of these proteases fully restored both biofilm formation and virulence in a sarA mutant generated in the closely related USA300 strain LAC. These results confirm an important role for multiple extracellular proteases in S. aureus pathogenesis and the importance of sarA in repressing their production. Moreover, purified aureolysin limited biofilm formation in 14 of 15 methicillin-resistant isolates and 11 of 15 methicillin-susceptible isolates, while dispersin B had little impact in UAMS-1, LAC, or 29 of 30 contemporary isolates of S. aureus. This suggests that the role of sarA and its impact on protease production is important in diverse strains of S. aureus irrespective of their methicillin resistance status., (© 2014 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

On October 27, 2011, the Arkansas Department of Health (ADH) was notified by a northeast Arkansas primary care provider of a cluster of three histoplasmosis cases. On November 4, ADH was notified by a pediatric infectious diseases specialist regarding seven potential cases of pulmonary histoplasmosis associated with a family gathering that included a bonfire that burned bamboo from a grove that had been a red-winged blackbird roost. These reports prompted an outbreak investigation to ensure that the persons involved received appropriate medical care, to identify whether any novel exposures were associated with illness, and to determine whether any factors were associated with hospitalization. The investigation found that, among the 19 attendees at the family gathering, seven were confirmed with histoplasmosis, 11 were probable, and one did not have histoplasmosis.

Background: Secondary skin infection with Staphylococcus aureus is a significant problem in atopic dermatitis (AD) patients., Objective: This study evaluated antimicrobial resistance patterns of S aureus isolates from skin lesions in AD patients and empiric antimicrobial prescribing patterns., Methods: Resistance patterns from positive skin cultures obtained from AD patients in the Allergy/Immunology clinic from May 1, 2006, to December 31, 2008, were compared with all outpatient wound cultures over the same period., Results: Fifty-nine cultures were obtained from 38 AD patients. S aureus was the most common pathogen cultured from AD patients (53/59 cultures). S aureus resistance to clindamycin and methicillin differed significantly between the study group and the outpatient reference population (37.7% vs 9.4% and 45.3% vs 76.4%). Clindamycin was the most commonly prescribed antimicrobial (59%). Overall, 31.4% of organisms showed resistance to the antimicrobial prescribed., Conclusions: Susceptibility profiles of S aureus isolates from AD patients vary significantly from that of the general population.

Recently, cholesterol was identified as a physiologically important nutrient for Mycobacterium tuberculosis survival in chronically infected mice. However, it remained unclear precisely when cholesterol is available to the bacterium and what additional bacterial functions are required for its metabolism. Here, we show that the igr locus, which we previously found to be essential for intracellular growth and virulence of M. tuberculosis, is required for cholesterol metabolism. While igr-deficient strains grow identically to the wild type in the presence of short- and long-chain fatty acids, the growth of these bacteria is completely inhibited in the presence of cholesterol. Interestingly, this mutant is still able to respire under cholesterol-dependent growth inhibition, suggesting that the bacteria can metabolize other carbon sources during cholesterol toxicity. Consistent with this hypothesis, we found that the growth-inhibitory effect of cholesterol in vitro depends on cholesterol import, as mutation of the mce4 sterol uptake system partially suppresses this effect. In addition, the Delta igr mutant growth defect during the early phase of disease is completely suppressed by mutating mce4, implicating cholesterol intoxication as the primary mechanism of attenuation. We conclude that M. tuberculosis metabolizes cholesterol throughout infection.

Few tools exist to assess replication of chronic pathogens during infection. This has been a considerable barrier to understanding latent tuberculosis, and efforts to develop new therapies generally assume that the bacteria are very slowly replicating or nonreplicating during latency. To monitor Mycobacterium tuberculosis replication within hosts, we exploit an unstable plasmid that is lost at a steady, quantifiable rate from dividing cells in the absence of antibiotic selection. By applying a mathematical model, we calculate bacterial growth and death rates during infection of mice. We show that during chronic infection, the cumulative bacterial burden-enumerating total live, dead and removed organisms encountered by the mouse lung-is substantially higher than estimates from colony-forming units. Our data show that M. tuberculosis replicates throughout the course of chronic infection of mice and is restrained by the host immune system. This approach may also shed light on the replication dynamics of other chronic pathogens.

Mycobacterium tuberculosis lives intracellularly, and many facets of its interactions with host cells are not well understood. We screened an M. tuberculosis transposon library for mutants exhibiting reduced ability to kill eukaryotic cells. Four of the mutants identified had insertions in 3 adjacent genes: single insertions in each of 2 acyl-coenzyme A dehydrogenases (fadE) plus 2 unique insertions in a cytochrome P450 homolog. A mutant in which these genes were replaced by allelic exchange was powerfully attenuated in our macrophage viability assay, and there was a striking defect in its ability to grow intracellularly. Interestingly, the difference between wild-type and mutant growth was minimized in activated macrophages. Aerosol infection of mice revealed a lag in growth, delayed dissemination to the spleen, and reduced lung pathology but no difference in persistence. Thus, these genes may be particularly important for events early during infection.