Effects of seasonal changes in temperature and humidity on incidence of necrotizing soft tissue infections in Halifax, Canada, 2001-2015

Necrotizing fasciitis: an update on epidemiology, diagnostic methods, and treatment

PURPOSE OF REVIEW

The aim of this review is to discuss the latest evidence of epidemiology, diagnostic methods, and treatment of necrotizing soft tissue infections (NSTIs) with a particular focus on necrotizing fasciitis (NF).

RECENT FINDINGS

NSTIs have been historically referred to as NF but encompass a broader range of infections, with variable rates ranging from 0.86 to 32.64 per 100 000 person-years, influenced by factors such as climate and seasonal variations. They have diverse microbiological profiles categorized into different types based on the involved pathogens, including polymicrobial or monomicrobial infections caused by organisms such as group A streptococcus (GAS), Staphylococcus aureus , some Gram-negative pathogens, and filamentous fungi following trauma and natural disasters. Diagnosis relies on clinical symptoms and signs, laboratory markers, and imaging. However, the gold standard for diagnosis remains intraoperative tissue culture. Treatment involves repeated surgical debridement of necrotic tissues in addition to intravenous antibiotics. Adjuvant therapies with intravenous immunoglobulin (IVIG) and hyperbaric oxygen therapy (HBOT) might have a role. Soft tissue reconstruction may be necessary following surgery.

SUMMARY

Prompt diagnosis and proper medical and surgical management of NSTI will improve outcomes.

Regional Variations in Microbiology and Outcomes of Necrotizing Soft Tissue Infections: A Systematic Review and Meta-Analysis

Background: Frequency, microbiology, and outcomes of necrotizing soft tissue infections (NSTIs) could vary across the United States because of differences in locoregional and environmental factors. We synthesized the literature from across the regions of the United States on NSTIs in a systematic review/meta-analysis. Methods: PubMed, ProQuest, Scopus, and Web of Science databases were systematically searched and screened. DerSimonian-Laird random-effects meta-analyses were performed using 'meta' package in R to determine pooled prevalences. Meta-regression analyses examined moderator effects of risk factors. Results: Twenty-seven studies (2,242 total patients) were included. Pooled prevalences of polymicrobial and monomicrobial infections were 52.2% and 39.9%, respectively. The prevalence of monomicrobial NSTIs increased over the last two decades (p = 0.018), whereas polymicrobial infections declined (p = 0.003). Meta-regression analysis showed that most polymicrobial NSTIs were Fournier gangrene (p < 0.001), whereas monomicrobial NSTIs mostly affected extremities (p < 0.001). Staphylococcus aureus was the most common organism isolated (predominantly in the South), followed by Bacteroides spp. (predominately in the East) and Streptococcus pyogenes. Methicillin-resistant Staphylococcus aureus (MRSA) accounted for 11.9% of NSTIs, mainly in the South. The overall mortality rate was 17.8% and declined over last two decades (p < 0.001), with the lowest rate reported in the last decade at 13% without any regional differences. Conclusions: Advancement in the management of NSTIs may have contributed to the observed decline in NSTI-related mortality in the United States. However, the proportion of monomicrobial NSTIs seems to be increasing, possibly because of increased comorbidities affecting extremities. Causative organisms varied by region. Multi-center observational studies are warranted to confirm our observations.

Global patterns of necrotizing soft tissue infections: A systematic review and meta-analysis

BACKGROUND

Frequency, microbiology, and outcomes of necrotizing soft tissue infections vary based on locoregional and environmental factors; however, there has been no global survey of these patterns. We performed a systematic review/meta-analysis on published reports of necrotizing soft tissue infections from across the globe.

METHODS

Peer-reviewed empirical studies examining rates of polymicrobial and monomicrobial necrotizing soft tissue infections with microbial isolation and overall mortality rate were extracted along with geographic location using PubMed, Scopus, ProQuest, and Web of Science. Random-effects meta-analyses and sensitivity analyses were performed, adjusting for publication bias. Meta-regression analyses examined moderator effects of risk factors.

RESULTS

One hundred and five studies (8,718 total patients) were included. Pooled prevalence of polymicrobial and monomicrobial infections were 53% and 37.9%, respectively. Truncal necrotizing soft tissue infections were commonly polymicrobial (P < .001), whereas monomicrobial infections prevailed in extremities (P = .008). Global prevalence of monomicrobial necrotizing soft tissue infections was observed to increase by 1.1% annually (P = .003). Staphylococcus aureus was the most common organism globally and in North America, Asia, the Middle East, and Africa, followed by Streptococcus pyogenes and Escherichia coli. Methicillin-resistant S. aureus accounted for 16% of necrotizing soft tissue infections globally. Overall mortality was 23.1%, observed to decline globally over the last decade (P = .020). No regional differences were noted for mortality.

CONCLUSION

Although polymicrobial infections remain predominant worldwide, the incidence of monomicrobial infections is increasing. The observed decline in necrotizing soft tissue infection-related mortality is encouraging and may reflect advances in management, despite major variations in available healthcare resources globally.

Temporal and seasonal trends of hospitalization and mortality associated with necrotizing fasciitis: A retrospective study of 12 years (2002-2013)

Background: Necrotizing fasciitis (NF) is a rare but aggressive infection that affects the superficial fascia and progressively destroys the tissue between the skin and underlying muscles. It is a surgical emergency with significant morbidity and mortality. This study aimed to explore the temporal and seasonal trends in NF infection in Qatar. Methods: A total of 327 patients diagnosed with NF, aged ≥ 18 years, and admitted to the Hamad General Hospital, Qatar, in 2002-2013 were retrospectively reviewed. The hospitalization and mortality rates in the general population in Qatar and the case fatality rate (CFR) were calculated for each year. The patients were grouped into summer, autumn, winter, and spring admissions based on their admission dates. Seasonality was studied by comparing the characteristics, bacteriological status, and outcomes of the patients admitted in different seasons. Results: The hospitalization rate of NF in Qatar was 2.9 per 100,000 population; in the study duration, this rate decreased from 2.8 to 1.6 per 100,000 population in 2002 and 2013, respectively. The mortality rate among NF cases increased from 1.9 to 3.6 per million population, and the CFR increased from 6.7 to 23 per 100 admissions in the same duration. No temporal trends in the hospitalization and mortality rates or CFR were evident in the study duration. Polybacterial infections were higher in autumn than in other seasons. Monobacterial Gram-positive infections were higher in spring than in other seasons, and monobacterial Gram-negative infections were higher in summer than in other seasons (p = 0.02). However, seasonality was not evident after further analysis in terms of species, severity, complications, length of hospital stays, and CFR in patients with NF. Conclusion: No clear trend or seasonality was observed in terms of outcomes; however, seasonality in NF-causing bacteria was evident, as polybacterial infections were significantly higher in autumn than in other seasons, whereas monobacterial infections were more frequent in spring and summer than in other seasons. However, the severity of infections, length of hospital stay, and mortality did not significantly vary. Further microbiological studies are needed to obtain confirmatory data regarding the temporal and seasonal trends of NF.