Do bed bugs spread MRSA? Study findings support hypothesis
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Key takeaways:
- Studies showed that bed bugs could acquire MRSA both externally on the cuticle surface as well as internally when feeding.
- Bed bugs were able to transmit MRSA to an uncontaminated membrane feeder.
Through the first experimental evidence of its kind, researchers determined that bed bugs can contract MRSA through contact with or feeding through a surface contaminated with the bacteria, although this does not necessarily mean they can spread the infection to humans.
“Although a wide range of hematophagous arthropods that feed on humans are established vectors of infectious disease agents, bed bugs have never been conclusively demonstrated to act as a vector of any human pathogen in nature,” Andrea L. Herrera, postdoctoral researcher of basic biomedical sciences at the University of South Dakota, and colleagues wrote.
“However, the involvement of bed bugs in the transmission of various pathogens has generated controversy and debate within the field of vector-borne infectious diseases for decades,” the researchers wrote.
They added that there is particular debate surrounding bed bugs and pathogen transmission specifically regarding bed bugs and MRSA.
To assess the amount of viable MRSA present on and inside bed bugs over a period of 7 days, the researchers performed three separate trials during which bed bugs were exposed to MRSA by taking a blood meal through a contaminated feeding membrane.
According to the study, control bed bugs from laboratory colonies, as well as the blood and untreated collagen membranes used to feed them, were free of MRSA. On 0, 3, and 7 days after exposure, the researchers individually analyzed four bed bugs per replicate for the presence of MRSA by using dilution plating.
The study demonstrated that immediately after feeding, all 12 bed bugs tested across three independent biological replicates acquired MRSA on the cuticle surface, with significantly more MRSA detected on the surface of the bed bugs on 0 days after exposure (2.13 × 102 colony forming units [CFU]/insect) compared with 3 days after exposure (19 CFU/insect) or 7 days after exposure (2 CFU/insect).
In contrast, however, the study showed that significantly more MRSA was detected internally 3 days after exposure (2.98 × 102 CFU/insect) compared with day 0 (less than 1 CFU/insect) or 7 days after exposure (6 CFU/insect), which the authors wrote indicated “proliferation of MRSA within the bed bugs following its ingestion.” According to the study, MRSA remained viable on the bed bug surface for up to 3 days after exposure in two of the trials and 7 days after exposure in one trial and within the bed bugs 3 days after exposure in all three trials and 7 days after exposure in one of the trials.
The study also showed that bed bugs were able to transmit MRSA to an uncontaminated membrane feeder in two out of three trials.
In the first trial, 10 bed bugs previously fed on a contaminated membrane deposited 459 CFU of MRSA/cm2 on the sterile membrane when taking a second blood meal, although no MRSA was detected in the blood within the feeding capsule.
In the second, 153 CFU of MRSA/cm2 was left by the bed bugs on the sterile membrane, and 12 CFU/mL were present in the blood within the feeding capsule.
“These results do not prove that bed bugs are relevant vectors of MRSA in nature,” the authors wrote. “However, when considered together the detection of MRSA in field-collected bed bugs and clinical reports associating bed bugs with Staphylococcus infections, they provide support for the hypothesis that bed bugs may contribute to the transmission of MRSA in some settings.”
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