This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator.
Aim #1. To prospectively determine the prevalence, incidence, and persistence of asymptomatic MRSA colonization among HIV+ MSM in an urban clinic setting. Approximately 20% of general population and 35% of HIV-infected persons are colonized with S. aureus. Although colonization with S. aureus, typically in the anterior nares, is very common, only a small proportion of colonized persons will develop clinical infections. The reasons that HIV+ MSM have been affected of recent MRSA infection outbreaks remain unclear. There is little known about the prevalence of MRSA colonization among HIV+ MSM in the settings of epidemic and endemic MRSA. Since colonization precedes infection, it is important to describe the scope of colonization with S. aureus and MRSA in this population and in locales where outbreaks have been occurring. To address this aim we will perform nasal swabs every 6 months for one year (3 in total) to detect MRSA colonization from a well-described cohort of patients receiving care in two urban HIV clinics in Los Angeles.
Aim #2. To prospectively identify risk factors for MRSA colonization among a well described cohort of HIV-infected patients. Risk factors for MRSA colonization among HIV+ MSM remain unclear. Hypotheses for this outbreak include disease-related (such as HIV-associated immunosuppression), behavioral-related (such as skin to skin contact), and pathogen-related (such as the presence of S. aureus virulence factors). To address this aim we will collect detailed behavioral and clinical information from HIV+ MSM from the above described cohort. Risk factors from this population will be compared to those of 2 groups of controls: HIV+ persons who are not MSM, and HIV+ MSM who are not colonized with MRSA.
Aim #3. To molecularly type colonizing MRSA strains from HIV+ MSM and compare them with MRSA strains clinical infection among HIV+ MSM, and to quantify the persistence of strain colonization in this population. It is unclear if strains that commonly colonize HIV+ MSM are similar to those causing infections. This question has important clinical relevance as interventions to eradicate colonization may need to only target those persons with strains likely to cause disease. To address this aim, we will perform molecular strain typing on MRSA isolates colonizing HIV+ MSM, as described in Aim #1 and compare them to strains causing CA-MRSA infection among hospitalized HIV+ MSM. Additionally, longitudinal surveillance will provide data on the persistence of each colonizing strain over a 12-month period.
Aim #4. To identify virulence factors from MRSA strains colonizing HIV+ MSM and compare these strains to MRSA strains causing clinical infection among HIV+ MSM. The role that most MRSA-produced toxins have in clinical disease remains poorly described. Because toxin production is heterogeneous among S. aureus, comparing production among strains causing colonization and infection will provide important insights as to which factors may be important in for the development of clinical infections. To address this aim, we will characterize virulence factors from a subset of isolates causing colonization and infection to determine which factors may be associated with the development of clinical disease.
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