Epidemiology of MRSA CC398 in hospitals located in Spanish regions with different pig-farming densities: a multicentre study

Abstract

Background Tetracycline resistance (TetR) is a marker of livestock-associated MRSA of lineage CC398. Objectives To determine the MRSA CC398 prevalence among TetR-MRSA recovered in Spanish hospitals located in regions with different pig-farming densities, and the influence of pig density as a key risk factor for its acquisition. Methods TetR-MRSA isolates (n = 232) recovered from clinical and epidemiological samples during January–June 2016 in 20 hospitals in 13 regions with different pig-farming densities were analysed. MRSA CC398 identification, detection of spa types, methicillin resistance genes and immune evasion cluster (IEC) genes were performed by PCR/sequencing. Statistical analyses were performed to establish the relationships between MRSA CC398 prevalence and pig density. Results The global MRSA prevalence was 29.7% (6.9% TetR-MRSA/MRSA), with 137 CC398 isolates recovered, representing 4.1% of total MRSA and 59.1% of TetR-MRSA. Among MRSA CC398, 16 different spa types were recorded (t011: 72.3%), and all but two strains were IEC negative. Higher pig-density regions were associated with significant MRSA CC398 increases in hospitals located in adjacent regions (P < 0.001). Linear regression models explained the relationships between MRSA CC398 and pig density (P < 0.001), with an increase of 6.6 MRSA CC398 cases per 100 MRSA per increase of 100 pigs/km2 in a region. Conclusions High pig density leads to a significant increase in MRSA CC398 in hospitals in Spain, and its combination with a high human population could help its dissemination. In Spain, the prevalence of the zoonotic CC398 lineage is closely related to pig-farming density; therefore, specific tools could be implemented in order to detect its dissemination.

Staphylococcus aureus Nasal Colonization in Spanish Children. The COSACO Nationwide Surveillance Study

“…None of the MRSA strains was associated with tetracycline resistance, a marker of livestock-associated MRSA. 31 In addition, no relationship was observed between the presence of pets in the household and MRSA colonization, suggesting that MRSA carriage is not a zoonotic problem among Spanish children.…”

Molecular Epidemiology of Staphylococcus aureus Lineages in Wild Animals in Europe: A Review

“…The frequent detection of this clonal lineage among wild animals leads us to believe that CC398 may have originated from farm animals and has been spreading to the environment. Although being mainly associated with livestock species, CC398 has been isolated in humans in most European countries [157][158][159]. According to Price et al (2012), MRSA CC398 might have evolved from the human strain MSSA CC398, and the jump to livestock might have caused it to acquire resistance to methicillin and tetracycline [160].…”

Human Infection of Methicillin-Susceptible Staphylococcus aureus CC398: A Review

“…The prophage ϕSa3 contains the immune evasion gene cluster (IEC, which facilitates the escape from human immune response) genes sak (coding for a staphylokinase), chp (coding for a chemotaxis inhibitory protein; CHIPS), scn (coding for a complement inhibitor; SCIN), sea (coding for enterotoxin; SEA) and sep (coding for enterotoxin; SEP). However, only a small proportion of the MRSA CC398 isolates retrieved from infected patients contains the ϕSa3-associated IEC [1,7,26,42,66,[83][84][85][86][87]. This suggests that although IEC is not a prerequisite for infections in humans, it plays a crucial role in the adaptation to the human niche.…”