A case of acute septic arthritis of the hip joint caused by Panton-Valentine leukocidin-positive ST772 community-acquired methicillin-resistant Staphylococcus aureus

Arthritis Caused by MRSA CC398 in a Patient without Animal Contact, Japan

Clonal complex 398 methicillin-resistant Staphylococcus aureus (MRSA) is a typical lineage of livestock-associated MRSA. We report a case of intractable arthritis of the shoulder joint caused by a multidrug-resistant Panton-Valentine leukocidin–positive livestock-associated MRSA clonal complex 398 sequence type 1232 clone in a patient in Japan who had no animal contact.

[Antimicrobial Resistance and Infection Control for Gram-positive Bacteria]

Antimicrobial resistance (AMR) is a serious problem worldwide. We searched for the AMR determinants of various bacteria isolated from clinical settings and studied their resistance mechanisms and molecular epidemiology. This review focuses on the AMR of Staphylococcus aureus, a major gram-positive pathogen, which has the ability to acquire resistance to antimicrobials. The resistance factors of S. aureus are frequently found on mobile elements, including plasmids and transposons. We determined the complete DNA sequence of the tetracycline-resistance plasmid and found that the inducible expression of tetK in S. aureus was regulated by a post-transcriptional attenuation mechanism. Furthermore, outbreaks of methicillin-resistant S. aureus (MRSA) in hospitals and communities have led us to study infection controls, including the antiseptic susceptibility evaluation and molecular epidemiology of MRSA. Various antiseptic resistance determinants, such as qacA/B and smr, were identified on plasmids and characterized. We demonstrated that the plasmid-mediated efflux pump QacB variant QacIII confers fluoroquinolone efflux ability to S. aureus. Studies on MRSA epidemiology had shown that community-acquired MRSA (CA-MRSA) was disseminated into hospitals and that an increased use of alcohol-based rubs could reduce the incidence of MRSA infections in such institutions. Additionally, the study of CA-MRSA collected from communities and hospitals showed an increase in Panton-Valentine leucocidin (PVL)-positive CA-MRSA, causing severe skin and soft tissue infections. Moreover, various PVL-positive CA-MRSA clones have disseminated in Japan, whereas the USA300 LV/J clone evolved in that country. Our study provides important information regarding MRSA infection control.