Challenging scenarios in nontuberculous mycobacterial infection in cystic fibrosis

This review summarizes the discussion of a session held during the 2018 North American Cystic Fibrosis (CF) Conference titled “Challenging Cases in Nontuberculous Mycobacterial (NTM) Management.” In this session, a multidisciplinary panel of NTM experts discussed clinical challenges related to the management of NTM infection in people with CF in which decision‐making falls outside of the Cystic Fibrosis Foundation/European Cystic Fibrosis Society NTM guidelines. Topics discussed included managing newly acquired NTM infection, selecting and monitoring treatment regimens, determining treatment endpoints, and caring for patients after NTM treatment.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153589/1/ppul24604_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153589/2/ppul24604.pd

Newborn Screening for Cystic Fibrosis: A Qualitative Study of Successes and Challenges from Universal Screening in the United States

Cystic fibrosis (CF) newborn screening (NBS) was universally adopted in 2009 in the United States. Variations in NBS practices between states may impact the timing of diagnosis and intervention. Quantitative metrics can provide insight into NBS programs (NBSP), but the nuances cannot be elucidated without additional feedback from programs. This study was designed to determine facilitators and barriers to timely diagnosis and intervention following NBS for CF. The median age at the first CF event for infants with CF within each state was used to define early and late states (n = 15 per group); multiple CF centers were invited in states with more than two CF centers. Thirty states were eligible, and 61 NBSP and CF centers were invited to participate in structured interviews to determine facilitators and barriers. Once saturation of themes was reached, no other interviews were conducted. Forty-five interviews were conducted (n = 16 early CF center, n = 12 late CF center, n = 11 early NBSP, and n = 6 late NBSP). Most interviewees reported good communication between CF centers and NBSP. Communication between primary care providers (PCPs) and families was identified as a challenge, leading to delays in referral and subsequent diagnosis. The misperception of low clinical risk in infants from racial and ethnic minority groups was a barrier to early diagnostic evaluation for all groups. NBSP and CF centers have strong relationships. Early diagnosis may be facilitated through more engagement with PCPs. Quality improvement initiatives should focus on continuing strong partnerships between CF centers and NBS programs, improving education, communication strategies, and partnerships with PCPs, and improving CF NBS timeliness and accuracy

Mycobacterium abscessus induces a limited pattern of neutrophil activation that promotes pathogen survival.

Mycobacterium abscessus is a rapidly growing mycobacterium increasingly detected in the neutrophil-rich environment of inflamed tissues, including the cystic fibrosis airway. Studies of the immune reaction to M. abscessus have focused primarily on macrophages and epithelial cells, but little is known regarding the neutrophil response despite the predominantly neutrophillic inflammation typical of these infections. In the current study, human neutrophils released less superoxide anion in response to M. abscessus than to Staphylococcus aureus, a pathogen that shares common sites of infection. Exposure to M. abscessus induced neutrophil-specific chemokine and proinflammatory cytokine genes. Although secretion of these protein products was confirmed, the quantity of cytokines released, and both the number and level of gene induction, was reduced compared to S. aureus. Neutrophils mediated killing of M. abscessus, but phagocytosis was reduced when compared to S. aureus, and extracellular DNA was detected in response to both bacteria, consistent with extracellular trap formation. In addition, M. abscessus did not alter cell death compared to unstimulated cells, while S. aureus enhanced necrosis and inhibited apoptosis. However, neutrophils augment M. abscessus biofilm formation. The response of neutrophils to M. abscessus suggests that the mycobacterium exploits neutrophil-rich settings to promote its survival and that the overall neutrophil response was reduced compared to S. aureus. These studies add to our understanding of M. abscessus virulence and suggest potential targets of therapy

ATS Core Curriculum 2021. Pediatric Pulmonary Medicine: Pulmonary Infections.

The following is a concise review of the Pediatric Pulmonary Medicine Core reviewing pediatric pulmonary infections, diagnostic assays, and imaging techniques presented at the 2021 American Thoracic Society Core Curriculum. Molecular methods have revolutionized microbiology. We highlight the need to collect appropriate samples for detection of specific pathogens or for panels and understand the limitations of the assays. Considerable progress has been made in imaging modalities for detecting pediatric pulmonary infections. Specifically, lung ultrasound and lung magnetic resonance imaging are promising radiation-free diagnostic tools, with results comparable with their radiation-exposing counterparts, for the evaluation and management of pulmonary infections. Clinicians caring for children with pulmonary disease should ensure that patients at risk for nontuberculous mycobacteria disease are identified and receive appropriate nontuberculous mycobacteria screening, monitoring, and treatment. Children with coronavirus disease (COVID-19) typically present with mild symptoms, but some may develop severe disease. Treatment is mainly supportive care, and most patients make a full recovery. Anticipatory guidance and appropriate counseling from pediatricians on social distancing and diagnostic testing remain vital to curbing the pandemic. The pediatric immunocompromised patient is at risk for invasive and opportunistic pulmonary infections. Prompt recognition of predisposing risk factors, combined with knowledge of clinical characteristics of microbial pathogens, can assist in the diagnosis and treatment of specific bacterial, viral, or fungal diseases

Killing and phagocytosis of <i>M. abscessus</i>.

<p><b>A</b>, Neutrophil killing of <i>M. abscessus</i>. Neutrophils were incubated with <i>M. abscessus</i> for 2 and 4 hours; surviving bacteria were enumerated and compared to bacterial cfu in the absence of neutrophils for the same time points to obtain percent killing. Data represents mean±SEM of 6 experiments. <b>B</b>, Phagocytosis of <i>M. abscessus</i> by neutrophils. FITC-labeled bacteria were incubated with neutrophils for the indicated times, and the percent of neutrophils with intracellular staining was determined. Data represents mean±SEM of 10 experiments. Two-way ANOVA was performed; *p<0.05 by Bonferroni post-test. <b>C</b>, Extracellular DNA release. Neutrophils were exposed to <i>M. abscessus</i> (Mab) at a MOI of 2 for 4 hours. Data represents mean±SEM; n = 13. <b>D</b>, Extracellular DNA release by neutrophils exposed to <i>S. aureus</i> (Sa) at an MOI of 2 for 2 hours. Data represents mean±SEM; n = 6. Analysis for significance for <b>C</b> and <b>D</b> was determined by a paired, one-tail t test.</p

Hierarchical clustering of cytokine and chemokine genes by <i>M. abscessus</i>.

<p>Neutrophils were stimulated with <i>M. abscessus</i> (Sm; <i>yellow shading</i>), or <i>S. aureus</i> (Sa; <i>red shading</i>) for 2 hours, and gene expression was determined compared to non-stimulated neutrophils (C; <i>blue shading</i>). Tree spacing indicates linkage distance. Highly expressed (<i>red</i>) and low expressed (<i>green</i>) genes are indicated from 4 different neutrophil donors.</p

<i>M. abscessus</i> does not alter neutrophil death pathways.

<p>Neutrophils were incubated with <i>M. abscessus</i> (Mab; <i>closed bars</i>) or <i>S. aureus</i> (Sa; <i>open bars</i>) for 4 hours. <b>A</b>, Necrotic cell death was measured by release of lactate dehydrogenase (LDH). <b>B</b>, Apoptotic cell death was measured by solubilized histone-bound DNA. Only <i>S. aureus</i> significantly changed either necrosis or apoptosis compared to non-stimulated neutrophils. Data represents mean±SEM; n = 6–9; *p<0.05, **p<0.01, †p<0.001 by Bonferroni post-test analysis.</p

<i>M. abscessus</i> biofilm density is enhanced by neutrophils.

<p>Bacteria (<i>hatched bars</i>), neutrophils (<i>open bars</i>), or the combination of bacteria and neutrophils (<i>closed bars</i>) were incubated for 5 days, and biofilm density was assessed by crystal violet staining in response to <b>A</b>, <i>M. abscessus</i>; <b>B</b>, <i>P. aeruginosa</i>. Data represent mean±SEM from 4–9 experiments. *p<0.05; †, p<0.001. Representative biofilm formation in a flow chamber by: <b>C</b>, <i>M. abscessus</i> alone (10×); <b>D</b>, <i>M. abscessus</i> and neutrophils (40×); <b>E</b>, neutrophils alone (40×). Biofilms were stained for live (<i>green</i>) and dead (<i>red</i>) cells.</p

Secretion of chemokines and cytokines.

<p>Neutrophils were stimulated with <i>M. abscessus</i> (Mab; <i>closed bars</i>), or <i>S. aureus</i> (Sa; <i>open bars</i>) for 2 and 4 hours, or left unstimulated (NS; <i>hatched bars</i>) and supernatants were collected. The indicated cytokine and chemokine levels were determined by ELISA. Mean±SEM, n = 7–8; *p<0.05; **p<0.01; †p<0.001 by Bonferroni post-test analysis.</p