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Published on: September 5, 2013
Changing epidemiology of MRSA-CC398 in Spanish hospitals located in areas with different pig farming densities: a
Allelen Campaña-Burguet1, Javier Latorre-Fernández1, Paula Eguizábal1
1Area de Bioquímica y Biología Molecular, Grupo de Investigación OneHealth-UR, Universidad de La Rioja, Logroño, Spain.
Background:
Livestock-associated (LA)-MRSA of CC398 lineage is related to the pig environment, although it also colonizes/infects humans. Tetracycline resistance (TETR) is a phenotypic marker of LA-MRSA-CC398.
Objectives:
To determine the prevalence and changing epidemiology of LA-MRSA-CC398 in seven Spanish hospitals (H1-H7) located in areas with different pig farming densities (PFDs) (extremely high, very high, medium, and very low: EH/VH/M/VL), and to identify other non-CC398-LA-MRSA clones.
Methods:
MRSA-TETR isolates (n = 165) obtained from hospitals H1-H7 over 6 months in 2023 were characterized with respect to genetic lineages/antimicrobial resistance and virulence/immune evasion cluster of CC398 and non-CC398. Results were compared with a previous multicentre study from 2016.
Results:
We identified 86/165 MRSA-TETR isolates (52.1%) as being MRSA-CC398. A significant difference in MRSA-CC398/MRSA prevalence was detected between hospitals located in EH-PFD areas (H1 and H2, > 25%) and the one in a VL-PFD area (H7, 0%). Prevalences in the range 6.4%-12.2% were found in hospitals in M- and VH-PFD areas (H3-H6). Fourteen spa-types were identified among MRSA-CC398 isolates, with t011/t034 predominating (68.3%), followed by t1451/t1255 (13%). All but two MRSA-CC398 isolates were scn-negative (human adaptation marker). Among the 79 non-CC398-MRSA-TETR isolates, CC5, CC1 and CC8 predominated (45.6%, scn-negative). The prevalences of the scn gene among non-CC398-MRSA-TETR isolates in hospitals of EH-, VH-, M- and VL-PFD areas were 77.8%, 50%, 18.75% and 0%, respectively (significant correlation, P < 0.05). This study shows that MRSA-CC398 isolates are prevalent in hospitals located in EH-PFD areas but absent in the hospital of the VL-PFD area. Moreover, an increase in both PFD and prevalence of MRSA-CC398/MRSA in hospitals H3-H6 was observed in the 2023 study compared with the 2016 study.
Conclusions:
A significant increase and more genetic diversity of predominant lineages of CC398-MRSA-TETR were observed in hospitals located in M- to VH-PFD areas.
Insights
Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) CC398 is more prevalent in Spanish hospitals near high pig farming densities. An increase in LA-MRSA-CC398 prevalence and genetic diversity was observed in medium to very high pig farming density areas.
Area of Science:
- Antimicrobial resistance surveillance
- One Health epidemiology
- Bacterial genomics and evolution
Background:
- Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) CC398 is linked to swine environments and can colonize or infect humans.
- Tetracycline resistance (TETR) serves as a key phenotypic marker for identifying LA-MRSA CC398 strains.
Purpose of the Study:
- To assess the prevalence and epidemiological trends of LA-MRSA CC398 in seven Spanish hospitals.
- To investigate the influence of varying pig farming densities (PFDs) on LA-MRSA CC398 prevalence.
- To identify and characterize non-CC398 LA-MRSA clones circulating in these healthcare settings.
Main Methods:
- Characterization of 165 tetracycline-resistant MRSA (MRSA-TETR) isolates from seven Spanish hospitals over six months in 2023.
- Genetic lineage, antimicrobial resistance, and virulence/immune evasion cluster analysis for both CC398 and non-CC398 strains.
- Comparison of current findings with a previous multicentre study conducted in 2016.
Main Results:
- MRSA-CC398 accounted for 52.1% (86/165) of MRSA-TETR isolates, with significantly higher prevalence in hospitals in extremely high PFD areas (H1, H2) compared to very low PFD areas (H7).
- Hospitals in medium and very high PFD areas (H3-H6) showed MRSA-CC398 prevalences ranging from 6.4% to 12.2%, with an observed increase since 2016.
- Dominant spa-types for MRSA-CC398 were t011/t034 (68.3%), and most isolates were scn-negative, indicating human adaptation. Non-CC398 isolates were predominantly CC5, CC1, and CC8, with a significant correlation between PFD and the presence of the scn gene.
Conclusions:
- LA-MRSA-CC398 is significantly more prevalent in hospitals situated in areas with high pig farming densities.
- An increase in both pig farming density and the prevalence of LA-MRSA CC398/MRSA was noted in hospitals in medium to very high PFD areas between 2016 and 2023.
- Growing genetic diversity among predominant CC398-MRSA-TETR lineages was observed in hospitals located in medium to very high PFD areas.
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