Characterising clinical Staphylococcus aureus isolates from the sinuses of patients with chronic rhinosinusitis

The role of Staphylococcus aureus in the pathogenesis of the chronic sinonasal disease chronic rhinosinusitis (CRS), has not been definitively established. Comparative analyses of S. aureus isolates from CRS with those from control participants may offer insight into a possible pathogenic link between this organism and CRS. The intra- and inter-subject S. aureus strain-level diversity in the sinuses of patients with and without CRS were compared in this cross-sectional study. In total, 100 patients (CRS = 64, control = 36) were screened for S. aureus carriage. The overall carriage prevalence of S. aureus in this cohort was 24% (CRS n = 13, control n = 11). Cultured S. aureus isolates from 18 participants were strain-typed using spa gene sequencing. The bacterial community composition of the middle meatus was assessed using amplicon sequencing targeting the V3V4 hypervariable region of the bacterial 16S rRNA gene. S. aureus isolates cultured from patients were grown in co-culture with the commensal bacterium Dolosigranulum pigrum and characterised. All participants harboured a single S. aureus strain and no trend in disease-specific strain-level diversity was observed. Bacterial community analyses revealed a significant negative correlation in the relative abundances of S. aureus and D. pigrum sequences, suggesting an antagonistic interaction between these organisms. Co-cultivation experiments with these bacteria, however, did not confirm this interaction in vitro. We saw no significant associations of CRS disease with S. aureus strain types. The functional role that S. aureus occupies in CRS likely depends on other factors such as variations in gene expression and interactions with other members of the sinus bacterial community.

Sinus bacteriology in patients with cystic fibrosis or primary ciliary dyskinesia: A systematic review

BACKGROUND

A correlation exists between the microbial flora of the upper and lower airways in patients with cystic fibrosis (CF) or with primary ciliary dyskinesia (PCD). The sinuses can function as a bacterial reservoir where gram-negative bacteria adapt to the airways and repeatedly are aspirated to and colonize the lungs according to the theory of the united (unified) airways. Whereas the pattern of bacterial flora in the lower airways has been extensively studied, the upper airways have drawn limited attention.

OBJECTIVE

Our aim was to review the literature that reported bacterial flora in the sinuses and nasal cavities of patients with CF or PCD.

METHODS

A number of medical literature data bases were systematically searched between January 1960 and July 2016. We applied the following inclusion criteria: a minimum of one case of PCD (or Kartagener syndrome) or CF, and microbiology analyses from the nose or paranasal sinuses.

RESULTS

We included 46 studies (1823 patients) from 16 countries. Staphylococcus aureus was found in 30% of the noses and sinuses of patients with CF. Other common bacteria found included Pseudomonas aeruginosa, coagulase negative staphylococci, and Haemophilus influenzae. In PCD, H. influenzae was the most common bacteria (28%), followed by Streptococcus pneumoniae and P. aeruginosa. If studies that included nonsurgical swab and blowing samples were excluded, then P. aeruginosa was the most common bacterium in patients with CF (34%) and in patients with PCD (50%), followed by S. aureus and H. influenza.

CONCLUSION

S. aureus, P. aeruginosa, coagulase negative staphylococci, and H. influenzae dominated in the upper airways of patients with CF. In patients with PCD, H. influenzae, S. pneumoniae, and P. aeruginosa dominated. When studies that included swab and blowing samples were excluded, P. aeruginosa was the most common bacterium in both groups. Direct comparisons among the studies were restricted due to very heterogeneous methods, and a better standardization of procedures and outcomes is needed.

Chronic Rhinosinusitis and the Evolving Understanding of Microbial Ecology in Chronic Inflammatory Mucosal Disease

Chronic rhinosinusitis (CRS) encompasses a heterogeneous group of debilitating chronic inflammatory sinonasal diseases. Despite considerable research, the etiology of CRS remains poorly understood, and debate on potential roles of microbial communities is unresolved. Modern culture-independent (molecular) techniques have vastly improved our understanding of the microbiology of the human body. Recent studies that better capture the full complexity of the microbial communities associated with CRS reintroduce the possible importance of the microbiota either as a direct driver of disease or as being potentially involved in its exacerbation. This review presents a comprehensive discussion of the current understanding of bacterial, fungal, and viral associations with CRS, with a specific focus on the transition to the new perspective offered in recent years by modern technology in microbiological research. Clinical implications of this new perspective, including the role of antimicrobials, are discussed in depth. While principally framed within the context of CRS, this discussion also provides an analogue for reframing our understanding of many similarly complex and poorly understood chronic inflammatory diseases for which roles of microbes have been suggested but specific mechanisms of disease remain unclear. Finally, further technological advancements on the horizon, and current pressing questions for CRS microbiological research, are considered.

Clinical Significance and Pathogenesis of Staphylococcal Small Colony Variants in Persistent Infections

Small colony variants (SCVs) were first described more than 100 years ago for Staphylococcus aureus and various coagulase-negative staphylococci. Two decades ago, an association between chronic staphylococcal infections and the presence of SCVs was observed. Since then, many clinical studies and observations have been published which tie recurrent, persistent staphylococcal infections, including device-associated infections, bone and tissue infections, and airway infections of cystic fibrosis patients, to this special phenotype. By their intracellular lifestyle, SCVs exhibit so-called phenotypic (or functional) resistance beyond the classical resistance mechanisms, and they can often be retrieved from therapy-refractory courses of infection. In this review, the various clinical infections where SCVs can be expected and isolated, diagnostic procedures for optimized species confirmation, and the pathogenesis of SCVs, including defined underlying molecular mechanisms and the phenotype switch phenomenon, are presented. Moreover, relevant animal models and suggested treatment regimens, as well as the requirements for future research areas, are highlighted.

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.