Study Examines Staph Colonization of Military Service Members in U.S., Afghanistan

Staphylococcus aureus [methicillin-resistant and methicillin-susceptible (MRSA/MSSA)] is a leading cause of infections in military personnel, but there are limited data regarding baseline colonization of individuals while deployed. Vento et al. (2013) conducted a pilot study to screen non-deployed and deployed healthy military service members for MRSA/MSSA colonization at various anatomic sites and assessed isolates for molecular differences.

Colonization point-prevalence of 101 military personnel in the US and 100 in Afghanistan was determined by swabbing 7 anatomic sites. US-based individuals had received no antibiotics within 30 days, and Afghanistan-deployed personnel were taking doxycycline for malaria prophylaxis. Isolates underwent identification and testing for antimicrobial resistance, virulence factors, and pulsed-field type (PFT).

Four individuals in the U.S. (four isolates -- three oropharynx, one perirectal) and four in Afghanistan (six isolates -- two oropharynx, two nare, one hand, one foot) were colonized with MRSA. Among U.S.-based personnel, three had USA300 (1 PVL+) and one USA700.

Among Afghanistan-based personnel, one had USA300 (PVL+), one USA800 and two USA1000. MSSA was present in 40 (71 isolates-25 oropharynx, 15 nare) of the U.S.-based and 32 (65 isolates -- 16 oropharynx, 24 nare) of the Afghanistan-based individuals. 56 (79%) US and 41 (63%) Afghanistan-based individuals had MSSA isolates recovered from extra-nare sites.

The most common MSSA PFTs were USA200 (9 isolates) in the U.S. and USA800 (seven isolates) in Afghanistan. MRSA/MSSA isolates were susceptible to doxycycline in all but three personnel (one U.S., two Afghanistan; all were MSSA isolates that carried tetM).

The researchers conclude that MRSA and MSSA colonization of military personnel was not associated with deployment status or doxycycline exposure. Higher S. aureus oropharynx colonization rates were observed and may warrant changes in decolonization practices. Their research was published in BMC Infectious Diseases.

Reference: Vento TJ, Calvano TP, et al. Staphylococcus aureus colonization of healthy military service members in the United States and Afghanistan. BMC Infectious Diseases 2013, 13:325 doi:10.1186/1471-2334-13-325