Staphylococcus aureus Infecting and Colonizing Experimental Animals, Macaques, in a Research Animal Facility

Abstract

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) infections on the skin and soft tissues of experimental macaques in the vivarium of The Rockefeller University, New York, triggered this observational and interventional study. We screened 14 macaques in the colony (samples from head, nares, and rectum) and their housing (40 environmental surfaces) four times in 1 year, for S. aureus colonization or contamination, while implementing enhanced decolonization and decontamination procedures. A total of 114 isolates of S. aureus were recovered and characterized (antibiograms, spa typing, multilocus sequence typing, pulsed-field gel electrophoresis [PFGE], mecA, Panton-Valentine Leukocidin, and arginine catabolic mobile element). Based on these results, six strains of S. aureus were identified: two MRSA strains (t16708/ST3862/PFGE-A, t16709/ST3862/PFGE-C) and one methicillin-sensitive S. aureus (t8397/ST3884/PFGE-D) were characterized for the first time in this study; strains belonging to spa types t189 and t4167 have been identified in primates in previous studies. None of these strains was common to the neighboring New York City human community. Thus, it seems probable that the animals were already colonized upon arrival to the University. We suggest screening primates for S. aureus carriage upon arrival to University vivaria and possible implementation of extensive decolonization procedures before any surgical interventions.

Keywords: MRSA; veterinary infections.

FIG. 1.

Staphylococcus aureus colonization of the 14 macaques located in three different rooms, at the four sampling times. Each letter represents one macaque. Gray lines separate cages. Note that some animals are caged in pairs (A and D, B and E, C and F, L and N). Some animals were moved to different rooms during the study in an attempt to control bacterial spread (M was moved from room #2 to room #1; then A, C, D, F, G, and J from room #1 to room #3). A star by the letter designating each macaque means that the animal was wearing a transcranial implant at the moment of sampling. Each geometric shape corresponds to one strain of S. aureus detected at each time, in each animal. An “X” means no S. aureus was detected on a particular animal at a particular screening time; circle: MA-I (t189/ST188/PFGE-A/mecA⁻); triangle: MA-II (t4167/ST3862/PFGE-B/mecA⁺); pentagon: MA-III (t4167/ST3862/PFGE-C/mecA⁺); hexagon: MA-IV (t16708/ST3862/PFGE-C/mecA⁺); heptagon: MA-V (t16709/ST3862/PFGE-C/mecA⁺); and square: MA-VI (t8397/ST3884/PFGE-D/mecA⁻). Animals marked with two shapes carried two strains of S. aureus at the corresponding screening. PFGE, pulsed-field gel electrophoresis.

FIG. 2.

The six different PFGE profiles detected among the S. aureus isolates in this study. MA-I to MA-VI are the names of the six S. aureus strains observed in this study. A–D represent the four different PFGE profiles observed for them. MA-I and MA-VI are methicillin-sensitive S. aureus, while MA-II through MA-V are methicillin-resistant S. aureus. On the side of the figure, the kilobases correspond to each band in the ladder.