Cefazolin treatment failure has been observed in high-inoculum infections caused by methicillin-susceptible Staphylococcus aureus (MSSA) with a cefazolin inoculum effect (CIE). However, data on the characteristics and risk factors for the acquisition of CIE-positive MSSA infection are scarce. CIE positivity was measured as an MIC ≥ 16 μg/ml with a high inoculum (∼5 × 107 CFU/ml). The blaZ gene type was assessed through sequence analysis. The clinical characteristics and risk factors for the acquisition of CIE-positive MSSA infection were assessed. The association between the antimicrobial susceptibility profile and CIE positivity was evaluated. A total of 303 MSSA bacteraemia cases and their corresponding isolates were collected from ten hospitals: 61 (20.1 %) isolates showed a positive CIE; 254 (83.8 %) were positive for the blaZ gene. No significant association was found between CIE positivity and the site of infection. Metastatic cancer (aOR 2.86, 95 % CI, 1.10–7.48) and recent (≤1 month) close contact with a chronically ill patient (aOR 4.69, 95 % CI, 1.76–12.50) were identified as significant risk factors for CIE-positive MSSA infection through multivariate analyses. Resistances to clindamycin (OR 3.55, 95 % CI, 1.62–7.80) and erythromycin (OR 5.00, 95 % CI, 2.50–9.99) were associated with CIE positivity, presenting high specificity (92.9 %) and a negative predictive value (82.3 %). CIE-positive MSSA constituted approximately one-fifth of MSSA bacteraemia cases. Although CIE positivity was not clinically discernible, CIE positivity was associated with clindamycin or erythromycin susceptibility. Therefore, our findings suggest that cefazolin can be used in the treatment of high-inoculum MSSA infection if the isolates are susceptible to clindamycin or erythromycin.
|Number of pages||10|
|Journal||European Journal of Clinical Microbiology and Infectious Diseases|
|Publication status||Published - 2017 Feb 1|
Bibliographical noteFunding Information:
This work was supported by a Biomedical Research Institute Grant (2015–05) of Pusan National Hospital.
The isolates and clinical information were obtained from a previous prospective cohort study, ‘Establishment of Network for Clinical Research of Staphylococcus aureus Infection’, which was supported by a grant from the National Strategic Coordinating Center for Clinical Research (Grant No. HI10C2020). The study consecutively collected all S. aureus blood isolates between September 2013 and March 2015 at ten general hospitals across South Korea (Supplement ). Only the first bloodstream isolate collected from each patient was included. Demographic data and clinical information were collected. Informed consent was obtained or waived according to the recommendations from each Institutional Review Board (IRB). The isolation of S. aureus and antimicrobial susceptibility tests were performed in the clinical microbiology laboratory of each participating hospital using an automated system. The prospective cohort study had been approved by the IRB at each participating hospital, and the protocol used in this study (IRB No. E-2016032) was approved by the IRB at Pusan National University Hospital.
Clinical MSSA isolates were collected from the prospective cohort study ‘Establishment of Network for Clinical Research of Staphylococcus aureus Infection’, which was supported by Grant No. HI10C2020 from the National Strategic Coordinating Center for Clinical Research.
© 2016, Springer-Verlag Berlin Heidelberg.
All Science Journal Classification (ASJC) codes
- Microbiology (medical)
- Infectious Diseases