Study on Staphylococcus aureus Colonization and Disease Progression

Overview of Staphylococcus aureus

A recent investigation examined the link between Staphylococcus aureus colonization and the subsequent risk of developing disease in non-hospital settings. Staphylococcus aureus is a bacterial pathogen present in specific anatomical sites of approximately 24% of the population. The term “colonization” refers to the process by which these bacteria settle in a host without causing any immediate harm or disease. Common sites of colonization include the nasal epithelium, perineum, underarm, and various skin areas.

Clinical Implications of S. aureus

S. aureus is classified as an opportunistic microorganism, posing a risk of disease primarily in immunocompromised individuals who were previously asymptomatic carriers. The major clinical manifestations associated with S. aureus infections include skin and soft tissue infections, bacteremia, infective endocarditis, pneumonia, and bone and joint infections. While the progression from S. aureus colonization to disease is well-documented in hospital patients undergoing surgery or dialysis, the relationship in community settings had not been thoroughly studied until now.

Meta-Analysis of Community Acquired Infections

An American study published in the journal BMC Infectious Diseases conducted a comprehensive meta-analysis to assess the prevalent assumption that Staphylococcus aureus colonization serves as a risk factor for symptomatic S. aureus disease in community settings. The authors reviewed articles from 1979 to 2016, focusing on studies involving patients with community-acquired S. aureus infections. Out of 3,477 articles reviewed, only 12 met the eligibility criteria and were included in the meta-analysis, involving a total of 6,988 patients from diverse backgrounds, including HIV-infected individuals, adult and pediatric outpatients, military trainees, and prison inmates.

Findings on Colonization and Disease Risk

The results indicated that individuals colonized with Staphylococcus aureus in the community are at a higher risk of developing S. aureus-related diseases compared to non-colonized individuals. Notably, MRSA colonization was linked to a greater likelihood of disease progression than MSSA colonization, with MRSA prevalence at 6.2% among 5,417 subjects and MSSA prevalence at 26.1% among 912 subjects.

Data Heterogeneity in the Study

The authors noted significant heterogeneity in data across the three subgroups (S. aureus, MRSA, and MSSA). For instance, in eight of the twelve studies, specimens were collected via nasal swabs, while four studies utilized samples from other anatomical sites such as the perineum and throat. Genetic differences among S. aureus strains from various sites could influence their antibiotic susceptibility.

Evaluation Methods and Data Accuracy

The methodology for confirming S. aureus disease varied across studies. Six studies utilized laboratory confirmation through culture or polymerase chain reaction (PCR), while four relied on physician assessments without laboratory testing. Additionally, two studies based disease presence solely on patient chart information, which may impact data accuracy and the reliability of the findings.

Need for Further Research

While this meta-analysis indicates a correlation between Staphylococcus aureus colonization and the risk of symptomatic disease in community settings, the noted data heterogeneity limits comprehensive interpretation. The authors emphasize the need for more rigorous investigations to better quantify the risk of disease progression following colonization in non-hospital environments.

Reference

Kim M W, Greenfield B K, Snyder R E, Steinmaus C M, Riley L W. The association between community-associated Staphylococcus aureus colonization and disease: a meta-analysis. BMC Infectious Diseases 2018; v 18: 1 – 11.