Staphylococcus aureus (MSSA) and MRSA (CC398) isolated from post-mortem samples from pigs

Area of Science:

• Veterinary Pathology
• Microbiology
• Antimicrobial Resistance

Background:

• Livestock-associated Methicillin-resistant Staphylococcus aureus (LA-MRSA) is commonly found in healthy pigs.
• Reports linking LA-MRSA to pathological lesions in pigs are scarce.
• The study investigates the prevalence and characteristics of S. aureus, including MRSA, in porcine pathological samples.

Purpose of the Study:

• To determine the frequency of S. aureus isolation from post-mortem pig samples.
• To quantify the proportion of methicillin-resistant S. aureus (MRSA) among S. aureus isolates.
• To analyze the temporal distribution of S. aureus and MRSA over a six-year period.

Main Methods:

• Analysis of S. aureus and MRSA isolates from pathological lesions and aborted fetuses submitted for post-mortem examination.
• Data collection from 2003 to October 2008 at the Animal Health Service in The Netherlands.
• Antimicrobial susceptibility testing of isolated S. aureus strains.

Main Results:

• S. aureus (MSSA and MRSA) was isolated from approximately 0.5% of pigs examined.
• LA-MRSA CC398 was identified in 18 cases, primarily in (peri)arthritis and internal organs suggesting septicaemia.
• Antimicrobial resistance increased post-2004, with LA-MRSA emerging in 2005 and subsequent years; all isolates were susceptible to Trimethoprim/Sulfamethoxazole.

Conclusions:

• S. aureus, including LA-MRSA CC398, is present in pathological lesions in pigs.
• LA-MRSA appears to be an emerging pathogen in pigs with pathological conditions.
• Resistance to antimicrobials is a growing concern, though Trimethoprim/Sulfamethoxazole remains effective.