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Invasive pulmonary aspergillosis remains a major cause of morbidity and mortality for immunocompromised children, particularly for patients with acute leukaemia and those undergoing haematopoietic stem cell transplantation. Timely diagnosis, using a combination of computed tomography (CT) imaging and microbiological testing, is key to improve prognosis, yet there are inherent challenges in this process. For CT imaging, changes in children are generally less specific than those reported in adults and recent data are limited. Respiratory sampling by either bronchoalveolar lavage or lung biopsy is recommended but is not always feasible in children, and serum biomarkers, including galactomannan, have important limitations. In this review we summarise the current paediatric data on available diagnostic tests for IPA and highlight key emerging diagnostic modalities with potential for future use.

Background Nontuberculous Mycobacterium infections, particularly Mycobacterium abscessus, are increasingly common among patients with cystic fibrosis and chronic bronchiectatic lung diseases. Treatment is challenging due to intrinsic antibiotic resistance. Bacteriophage therapy represents a potentially novel approach. Relatively few active lytic phages are available and there is great variation in phage susceptibilities among M. abscessus isolates, requiring personalized phage identification. Methods Mycobacterium isolates from 200 culture-positive patients with symptomatic disease were screened for phage susceptibilities. One or more lytic phages were identified for 55 isolates. Phages were administered intravenously, by aerosolization, or both to 20 patients on a compassionate use basis and patients were monitored for adverse reactions, clinical and microbiologic responses, the emergence of phage resistance, and phage neutralization in serum, sputum, or bronchoalveolar lavage fluid. Results No adverse reactions attributed to therapy were seen in any patient regardless of the pathogen, phages administered, or the route of delivery. Favorable clinical or microbiological responses were observed in 11 patients. Neutralizing antibodies were identified in serum after initiation of phage delivery intravenously in 8 patients, potentially contributing to lack of treatment response in 4 cases, but were not consistently associated with unfavorable responses in others. Eleven patients were treated with only a single phage, and no phage resistance was observed in any of these. Conclusions Phage treatment of Mycobacterium infections is challenging due to the limited repertoire of therapeutically useful phages, but favorable clinical outcomes in patients lacking any other treatment options support continued development of adjunctive phage therapy for some mycobacterial infections.

Invasive fungal disease (IFD) remains a common and serious complication in children treated for leukaemia. Antifungal prescription in children with leukaemia presents unique challenges, particularly due to variation in IFD risk between and within leukaemia treatment protocols, drug toxicities and interactions between antifungals and chemotherapeutic agents. With recent advances in the understanding of IFD epidemiology and large clinical trials in adults assessing antifungals for IFD treatment and prophylaxis, together with paediatric clinical and pharmacokinetic studies, there is a growing body of data to inform optimal antifungal use in children. A panel of infectious diseases and haematology-oncology clinicians with expertise in IFD management compiled a list of 10 key clinical questions following development of the 2021 Australia and New Zealand Mycology Antifungal Consensus Guidelines. A focused literature review was conducted to explore available evidence and identify gaps in knowledge to direct future research. With the changing epidemiology of IFD globally, the ongoing evolution of paediatric leukaemia treatment and the increasing availability of novel antifungal agents, advocacy for paediatric clinical studies will remain vital to optimize IFD prevention and treatment in children with leukaemia.

Background: Exotoxins are an important virulence factors in Staphylococcus aureus. Clindamycin, a protein synthesis inhibitor antibiotic, is thought to limit exotoxin production and improve outcomes in severe S. aureus infections. However, randomised prospective data to support this is lacking. Methods: An open label, multicenter, randomised controlled trial (RCT) will compare outcome differences in severe S. aureus infection between a standard treatment (flucloxacillin/cefazolin in methicillin-susceptible S. aureus; and vancomycin/daptomycin in methicillin-resistance S. aureus) and a standard treatment plus an additional clindamycin given for 7 days. We will include a minimum of 60 participants (both adult and children) in the pilot study. Participants will be enrolled within 72 hours of an index culture. Severe infections will include septic shock, necrotising pneumonia, or multifocal and non-contiguous skin and soft tissue/osteoarticular infections. Immunosuppressed, moribund, current severe diarrhea or C. difficile infection, pregnant, and those with anaphylaxis to beta-lactams or lincosamides will be excluded. Primary outcomes measure is number of days alive and free (1 or none) of SIRS (Systemic Inflammatory Response Syndrome) within the first 14 days post randomization. Secondary outcomes measure will include all-cause mortality at 14, 42 and 90 days, time to resolution of SIRS, proportion with microbiological treatment failure, and rate of change of C-reactive protein over time. Impacts of inducible clindamycin resistance, strains types, methicillin-susceptibility, and presence of various exotoxins will also be analysed. Discussion: This study will assess the effect of adjunctive clindamycin on patient-centered outcomes in severe, toxin mediated S. aureus infections. The Pilot study will provide feasibility for a much larger RCT. Trial Registration: Australian New Zealand Clinical Trials Registry: ACTRN12617001416381p. Registered 06 October 2017 Keywords: Staphylococcus aureus, exotoxins, prospective studies, clindamycin, leukocidins