Reappearance and treatment of penicillin-susceptible Staphylococcus aureus in a tertiary medical centre.
OBJECTIVE
The purpose of this study was to describe trends in the prevalence and treatment patterns of penicillin-susceptible Staphylococcus aureus (SA) infections.


METHODS
This was a cross-sectional study of MSSA isolates from blood cultures at a tertiary-care centre between 1 January 2003 and 31 December 2012. All blood cultures positive for MSSA drawn during the study period were used to calculate the prevalence of penicillin-susceptible SA. Repeat cultures were excluded if they were isolated within 6 weeks of the index culture. The analysis was then restricted to inpatient blood cultures to assess treatment patterns. Antibiotics administered 48-96 h after the culture were analysed.


RESULTS
A total of 446 blood cultures positive for MSSA were included in the analysis. There was a distinct trend showing an increase in the percentage of penicillin-susceptible SA over 10 years from 13.2% (95% CI 4.1%-22.3%) in 2003 to 32.4% (95% CI 17.3%-47.5%) in 2012 (P trend <0.001). During the study period, penicillin use for penicillin-susceptible SA bacteraemia increased from 0.0% in 2003-04 to 50.0% in 2011-12 (P trend = 0.007).


CONCLUSIONS
Over a decade, there was an ∼3-fold increase in penicillin susceptibility among MSSA blood cultures at a large tertiary-care facility. Although treatment with penicillin increased over the study period, only 50% of penicillin-susceptible SA was treated with penicillin in the final study period. This study suggests that while susceptibility to penicillin appears to be returning in SA, the use of penicillin for penicillin-susceptible SA bacteraemia is low.
Department of Internal Medicine, Baystate Medical Center, Springfield, MA, USA Department of Pediatrics, Baystate Medical Center, Springfield, MA, USA matthew.chabot@baystatehealth.org.
Matthew R
MR
Chabot
Department of Internal Medicine, Baystate Medical Center, Springfield, MA, USA.
Mihaela S
MS
Stefan
Department of Epidemiology & Biostatistics, Baystate Medical Center, Springfield, MA, USA.
Jennifer
J
Friderici
Department of Infectious Diseases, Baystate Medical Center, Springfield, MA, USA.
Jennifer
J
Schimmel
Department of Internal Medicine, Baystate Medical Center, Springfield, MA, USA Department of Pediatrics, Baystate Medical Center, Springfield, MA, USA.
Julius
J
Larioza
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D016470:Bacteremia / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D003428:Cross Infection / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010406:Penicillins / Q000494:pharmacology* / Q000627:therapeutic use; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D062606:Tertiary Care Centers
D000900:Anti-Bacterial Agents; D010406:Penicillins