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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Trends in Antibiotic Susceptibility in Staphylococcus aureus in Boston, Massachusetts, from 2000 to 2014
Sanjat Kanjilal1,2, Mohamad R Abdul Sater3, Maile Thayer3
1Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts, USA skanjilal@bwh.harvard.edu ygrad@hsph.harvard.edu.
Abstract:
The rate of infection by methicillin-resistant Staphylococcus aureus (MRSA) has declined over the past decade, but it is unclear whether this represents a decline in S. aureus infections overall. To evaluate the trends in the annual rates of infection by S. aureus subtypes and mean antibiotic resistance, we conducted a 15-year retrospective observational study at two tertiary care institutions in Boston, MA, of 31,753 adult inpatients with S. aureus isolated from clinical specimens. We inferred the gain and loss of methicillin resistance through genome sequencing of 180 isolates from 2016. The annual rates of infection by S. aureus declined from 2003 to 2014 by 4.2% (2.7% to 5.6%), attributable to an annual decline in MRSA of 10.9% (9.3% to 12.6%). Penicillin-susceptible S. aureus (PSSA) increased by 6.1% (4.2% to 8.1%) annually, and rates of methicillin-susceptible penicillin-resistant S. aureus (MSSA) did not change. Resistance in S. aureus decreased from 2000 to 2014 by 0.8 antibiotics (0.7 to 0.8). Within common MRSA clonal complexes, 3/14 MSSA and 2/21 PSSA isolates arose from the loss of resistance-conferring genes. Overall, in two tertiary care institutions in Boston, MA, a decline in S. aureus infections has been accompanied by a shift toward increased antibiotic susceptibility. The rise in PSSA makes penicillin an increasingly viable treatment option.
Insights
Infections from Staphylococcus aureus, including MRSA, have decreased. This trend is linked to increased antibiotic susceptibility, making penicillin a more effective treatment option for S. aureus infections.
Area of Science:
- Infectious Diseases
- Microbiology
- Genomics
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) infections have declined, prompting an investigation into overall Staphylococcus aureus (S. aureus) infection trends.
- Understanding shifts in S. aureus subtypes and antibiotic resistance is crucial for public health strategies.
Purpose of the Study:
- To evaluate trends in annual S. aureus infection rates, including subtypes and antibiotic resistance, over a 15-year period.
- To analyze the genetic basis for resistance changes in S. aureus isolates.
Main Methods:
- A 15-year retrospective observational study of 31,753 adult inpatients at two tertiary care institutions in Boston, MA.
- Genome sequencing of 180 S. aureus isolates from 2016 to infer resistance gene dynamics.
- Analysis of annual infection rates for S. aureus, MRSA, penicillin-susceptible S. aureus (PSSA), and methicillin-susceptible penicillin-resistant S. aureus (MSSA).
Main Results:
- Overall S. aureus infection rates declined by 4.2% annually from 2003 to 2014, primarily due to a 10.9% annual decline in MRSA.
- Penicillin-susceptible S. aureus (PSSA) rates increased by 6.1% annually, while methicillin-susceptible penicillin-resistant S. aureus (MSSA) rates remained stable.
- A decrease in the average number of antibiotics to which S. aureus was resistant was observed, with some MSSA and PSSA isolates showing loss of resistance genes.
Conclusions:
- S. aureus infections have declined in Boston tertiary care institutions, marked by a significant decrease in MRSA and an increase in PSSA.
- The observed shift towards increased antibiotic susceptibility in S. aureus suggests penicillin is becoming a more viable treatment option.
- Genetic analysis revealed instances of resistance gene loss contributing to the observed increase in antibiotic susceptibility.
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