Objective:

To systematically compare bacterial pathogen profiles in acute rhinosinusitis (ARS) and chronic rhinosinusitis (CRS).

Approach:

• Data sources and searches: Following PRISMA guidelines, investigators searched PubMed, Web of Science, and the Cochrane Library for studies published from January 1, 1980, through May 31, 2024.
• Study selection and analysis: The review included 57 studies—16 involving ARS and 41 involving CRS—that reported culture-based bacteriologic data from appropriately collected sinonasal specimens. Pathogen prevalence was estimated using random-effects meta-analysis.

Key Findings:

• ARS was defined as rhinosinusitis lasting less than 4 weeks, whereas CRS was defined as persistent sinonasal inflammation and symptoms lasting at least 12 weeks.
• In ARS, the most prevalent isolates were methicillin-susceptible *Staphylococcus aureus* (MSSA; 20.5%), coagulase-negative staphylococci (16.9%), *Streptococcus pneumoniae* (16.3%), viridans group streptococci (13.0%), and *Haemophilus influenzae* (12.2%).
• In CRS, coagulase-negative staphylococci were most prevalent (24.3%), followed by MSSA (22.5%), viridans group streptococci (12.1%), *H influenzae* (11.9%), and *S pneumoniae* (9.4%).
• MSSA was the single most prevalent ARS isolate, surpassing traditional respiratory pathogens. Staphylococcal species predominated in CRS, which had broader polymicrobial flora and a lower prevalence of *S pneumoniae*.

Interpretation:

ARS and CRS have markedly different bacterial profiles, supporting condition-specific management and antibiotic strategies rather than extrapolating treatment approaches between the 2 conditions.

Limitations:

• Included studies varied substantially in patient characteristics, geographic region, sampling methods, infection types, and study methodology.
• Key outcomes showed very high statistical heterogeneity, and some pooled estimates had wide 95% CIs.
• Restriction to English-language publications and exclusion of gray and unpublished literature may have introduced language, selection, reporting, or publication bias.

Conclusion:

Distinct pathogen distributions in ARS and CRS support more targeted, condition-specific empiric antibiotic therapy and reinforce the importance of antimicrobial stewardship.