ABSTRACT
This study aimed to assess the performance of the MALDI-TOF MS short incubation method for bacterial identification at short-term incubation times to improve the reporting of blood cultures. MALDI-TOF MS analysis was conducted at intervals of 2, 4, and 6 hours during the development of microbial biomass on solid media until successful identification was achieved, with a final assessment at 24 hours for conventional identification. Species-level identification rates at the 2nd, 4th, 6th, and 24th hours were 57.5%, 83.6%, 93.1%, and 93.1% for Gram-negative bacilli; 12.5%, 42.7%, 76.1%, 97.8% for Gram-positive cocci and 0%, 11.8%, 17.6%, 58.8% for Gram-positive bacilli, respectively. The species-level identification rate was 76.5% for all monomicrobial cultures at the 6th hour. Our results have led us to implement this method into our routine laboratory workflow, and we have started to report rapid identification results for Gram-negative bacteria on the day of blood culture positivity.
ABSTRACT
Objective: The rise of antibiotic-resistant organisms necessitates the implementation of rapid identification (ID) and antibiotic susceptibility testing (AST) methods for patient management. We aimed to analyze how rapid ID and AST reporting influenced clinicians' treatment decisions. Materials and Methods: Bacteria were identified directly from positive blood cultures (BC) using serum separator tubes and MALDI-TOF MS. EUCAST rapid antibiotic susceptibility testing (RAST) method was performed for AST. The impact of rapid ID and AST reports on clinician treatment decisions was evaluated through clinical documentation. The appropriateness of antimicrobial therapy and interventions was assessed according to institutional antimicrobial prescribing guidelines, AST results, and clinical data. Results: A total of 128 BC bottles from 86 patients underwent processing. The rapid ID method was successful in 105 (82.1%) bottles obtained from 76 patients. The rapid ID results were reviewed by the Infectious Diseases Team on the same day for 55 (72.4%) of the 76 patients. Following the evaluation, new treatments or interventions were recommended for 28 (36.8%) patients. RAST results were available for 24 patients. The susceptibility profile of seven patients was assessed by the Infectious Diseases Team on the same day. Antimicrobial treatment was escalated in four cases, and de-escalation was made in two based on RAST results. If all rapid results had been assessed, adjustments could have been made for eight (10.5%) and eleven (14.5%) more patients, according to ID and RAST results, respectively. Conclusion: Implementation of rapid ID and AST may contribute to patient management. Although rapid reporting was made, some results were not evaluated by the clinician on the same day, indicating that communication between the clinician and the laboratory needs to be strengthened.
ABSTRACT
It is well-established that Infectious Diseases consultation (IDC) enhances the prognosis of bloodstream infections. However, it is unclear if adoption of an institutional sepsis protocol would lead to any further improvement in a setting where IDC and infectious diseases approval (IDA) - available throughout 7 days/24 hours -are mandatory for administering broad spectrum antibiotics. We aimed to evaluate the influence of the institutional sepsis protocol developed by Department of Infectious Diseases and Clinical Microbiology on the selection of appropriate empirical antibiotics by IDC through focusing on patients who had bloodstream infections caused by Extended-spectrum ß-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae, which poses a therapeutic challenge. One hundred and fifty-three adult patients (58 patients in the pre-protocol period and 95 patients in the post-protocol period), who received empirical antibiotic treatment for ESBL-producing E. coli and K. pneumoniae, in whom at least one systemic antibiotic was started either on the day blood cultures were drawn or not later than 24 hours were included in the study, retrospectively. The primary outcome was whether the empirical treatment regimen included a carbapenem that was accepted as the appropriate treatment based on the results of the MERINO trial. Secondary outcomes included empirical treatment based on pre-defined risk factors suggesting multidrug resistance (MDR), 30-day inpatient mortality, and appropriate antibacterial treatment according to antimicrobial susceptibility test (AST) results. The median age (Interquartile range) was 61 (48-70.5) years and 76 (49.7%) out of 153 patients were male. The patients in the post-protocol period were older compared to the pre-protocol period (54 years vs 64 years, p = 0.045). The Charlson Comorbidity Index was higher during the post-protocol period compared to the pre-protocol period (4 vs 5, p=0.038). At least one risk factor for MDR bacteria infection was present in 147 (96.1%) of the 153 patients. While the rate of risk factors for MDR bacteria infections did not differ significantly between the pre-protocol and post-protocol periods, the post-protocol period showed a significantly higher level of appropriate antibiotic treatment according to the presence of MDR risk factors compared to the pre-protocol period (44.8% vs 64.2%, p=0.019). There was a significant increase in the use of carbapenems in the post-protocol period compared to the pre-protocol period (34.5% vs. 56.8%, p=0.007). When the subgroup of patients who were likely to have infection caused by ESBL-producing bacteria is taken into consideration, the carbapenem use was more frequent in the post-protocol period (37.8% vs 68.9%, p=0.002). The rate of appropriate empirical treatment according to AST was not statistically different between pre-protocol and post-protocol period. The 30-day mortality rates were similar in both periods (24.1% vs 31.5, p=0.33). However, the rate of susceptibility to piperacillin-tazobactam was statistically higher in the pre-protocol period (82.6% vs 46.2%, p=0.016) when 39.7% of the patients received piperacillin-tazobactam as the empirical treatment. This study highlights the significance of using a structured protocol to attain appropriate empirical treatment for patients suspected of sepsis, even in a setting where IDC is readily available.
