Heterosexual transmission of community-acquired MRSA

Evidence has emerged of heterosexual transmission of community-acquired MRSA (methicillin-resistant Staphylococcus aureus. In the February 1^st edition of Clinical Infectious Diseases investigators from New York provide detailed information on three heterosexual couples where there was evidence of sexual transmission of MRSA and also provide details of a prospective, community-based study involving individuals who had been diagnosed with community-acquired MRSA that found that the pubic region was the site of infection in 3% of cases.

There have been reports of community-acquired MRSA in sports team members, military recruits, and children using daycare centres. There is also evidence of sexual transmission among HIV-positive gay men, but there have previously been no reports of heterosexual transmission of the infection.

Between 2004 and 2006, individuals with positive cultures for MRSA in New York were asked to participate in a study to determine the prevalence of community-acquired MRSA. Sociodemographic and medical details was obtained from patients along with information about potential community-acquired MRSA risk factors. Individuals were had a nasal sample obtained and were asked to perform genital samples which were cultured for Staphylococcus aureus.

There were three instances of heterosexual transmission of community-acquired MRSA. In each instance, sexual partners reported a history of recurrent community-acquired MRSA infection, involving the pubic, vaginal or perineal region.

The first case involved a woman who reported a history of “pimples” in the groin at a time when she was sexually active with five men, including her husband. All her partners, expect her husband had used condoms. She recalled that her husband and another partner had had similar “pimples” in the region of the groin. The woman shaved her pubic region and had been diagnosed with genital herpes shortly after her genital cultures tested positive for community-acquired MRSA. The investigators also record that community-acquired MRSA was transmitted to the woman’s daughter.

The second case involved a woman who presented to an emergency room with buttock abscesses that required draining which had tested positive for MRSA. Two months later, her husband developed a generalised rash and “boils” which had positive culture results for community-acquired MRSA. At the same time, the woman had groin abscesses which again tested positive for community-acquired MRSA. The couple had remained sexually active during the period of community-acquired MRSA infection.

The third case involved a woman who reported three instances of MRSA over a three-month period after visiting her boyfriend who was in a military unit that was experiencing an MRSA outbreak. The boyfriend had abscesses on his face and groin, and the patient has abscesses on her legs, groin and buttocks. These tested positive for community-acquired MRSA. Notably, this patient also shaved her pubic region.

A total of 114 individuals participated in the investigators prospective study. In ten instances, the primary site of community-acquired MRSA was the pubic region.

A total of 32 women agreed to provide self-administered pubic or vaginal swabs. Of these, eight (25%) tested positive for MRSA.

“Community-associated MRSA can be regarded as a sexually transmitted disease”, write the investigators.

A study presented at the International AIDS Conference in 2006 found that pubic shaving was associated with community-acquired MRSA in HIV-positive gay men, and the investigators note that two of the case reports they described also involved public shaving. Recent infection with syphilis was also a risk-factor identified in HIV-positive gay men, and the results of the study involving heterosexuals also suggests a possible role for concurrent sexually transmitted infections.

“Our study suggests that colonization of the genital area and heterosexual activity among adult members of an infected household may lead to recurrent infection within the household and may turn individual households into major potential reservoirs of infection in the rest of the community.”