Implementation of the EUCAST rapid antimicrobial susceptibility test (RAST) for carbapenemase/ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates, and its effect on mortality.

OBJECTIVES: With the rise in antimicrobial resistance, there is a growing demand for rapid antimicrobial susceptibility testing (RAST). In this study, we applied the EUCAST RAST method to ESBL/carbapenemase-producing Escherichia coli and Klebsiella pneumoniae isolates without using advanced identification systems and analysed the effect of this method on mortality rates Also the clinical impact of this method on patients infected with these bacteria and its effect on mortality rates were investigated. METHODS: RAST was used for clinical blood cultures containing carbapenemase/ESBL-producing E. coli and K. pneumoniae without advanced identification systems (e.g. MALDI TOF), with preliminary identification by simple diagnostic tests (predicted RAST, or p-RAST), and its categorical agreement was investigated. The impact of the method on mortality was analysed by comparing the clinical data of patients whose blood cultures were subject to p-RAST (p-RAST group, n = 49) and those who were not subject to p-RAST (non-RAST group, n = 145). RESULTS: p-RAST results were analysed based on 539 antibiotic-bacteria combinations. Total error rates at 4, 6 and 8 h of incubation were 2.9%, 3.9% and 3.8%, respectively. In the p-RAST group, patients who did not receive appropriate antibiotics (29/45, 59.1%) were switched to appropriate treatment within 8 h at the latest. In contrast, in the non-RAST group, treatment of patients who received inappropriate antibiotics (79/145, 54.5%) could be changed after at least 24 h. Mortality rates were lower in the p-RAST group than in the non-RAST group (28.6% versus 51.7%, P = 0.005). CONCLUSIONS: p-RAST can be used safely in hospital laboratories with high rates of antimicrobial resistance and can reduce mortality rates by shortening the transition time to appropriate treatment.

Secondary Infections in Critical Patients with COVID-19 Associated ARDS in the ICU: Frequency, Microbiologic Characteristics and Risk Factors.

OBJECTIVE:  To determine frequency, microbiologic characteristics and risks of secondary infections in patients with Coronavirus disease 2019 (COVID-19) associated acute respiratory distress syndrome (ARDS). STUDY DESIGN: An Observational study. PLACE AND DURATION OF STUDY:  COVID-19 intensive care unit (ICU), University of Health Sciences, Diskapi Yildirim Beyazit Research and Training Hospital, Turkey, from July 2020 to January 2021. METHODOLOGY: Demographic data of the COVID-19 patients with ARDS, was collected with reference to (age, gender), comorbidities, illness scores, ICU management modalities, hospital, and ICU stay durations and ICU outcomes. Secondary infections [bloodstream infection (BSI), possible lower respiratory tract infection (pLRTI) or urinary tract infections (UTI)], microbiologic pathogens, and resistant patterns were recorded. RESULTS:  A total of 205 COVID-19-related ARDS patients were included in this study. Out of them, 61 (29.8%) were diagnosed with secondary infection, 27 (13.1%) had at least one BSI, 20 (9.8%) had at least one pLRTI, and 34 (16.6%) had at least one UTI. Gram-negative pathogens were the most common cause of secondary infections (66/91, 72.5%). Klebsiella spp for BSI (10/19, 52.6%), Acinetobacter baumannii for pLRTI (10/18, 55.6%), and Escherichia coli for UTI (29/40, 72.5%) were the main causative agents. Among all Gram-negative bacteria, Carbapenem resistant was 62.1% (41/66) and extended-spectrum beta-lactamases positivity was 22.7% (15/66). At multivariable analysis, application of mechanical ventilation (MV) longer than 48 h, central catheterisation longer than 72 h, ICU stay longer than 10 days, and the time from hospitalisation to admission to the ICU longer than 48 h were associated with secondary infections. CONCLUSION: Patients with COVID-19 associated ARDS had a high rate of secondary infections. In order to reduce secondary infection in these patients, MV duration and ICU stay should be shortened and invasive catheters should be removed as soon as possible. KEY WORDS: SARS-CoV-2, COVID-19, Acute respiratory distress syndrome, Secondary infections.

Implementation of the EUCAST rapid antimicrobial susceptibility test (RAST) directly from positive blood culture bottles without the advanced identification systems.

OBJECTIVES: EUCAST published its recommendations for rapid antimicrobial susceptibility tests (RASTs) directly from positive signal blood culture (BC) bottles. The objective of the present study was to investigate the accuracy and applicability of the predicted RAST (p-RAST) method without using automated identification systems, and the effects of the results obtained with this method on the treatment decision of the clinician. METHODS: The RAST procedure was applied to positive BC samples between November 2020 and June 2021. The categorical results of the method were obtained by comparing the p-RAST results obtained at 4, 6 and 8 h of incubation according to predicted bacterial species with conventional methods and standard disc diffusion results. The effects of these results on the treatment decision of the clinician were evaluated retrospectively. The actual categorical results of the EUCAST RAST [standard RAST (s-RAST)] method were identified. RESULTS: The p-RAST and s-RAST results were analysed according to 145 and 111 isolates, respectively. The p-RAST total error rates were 3.0%, 3.1% and 2.8% at 4, 6 and 8 h of incubation, respectively, and the s-RAST total error rates were determined as 2.7%, 3.3% and 3.2%, respectively. With p-RAST's results, it was observed that effective escalation was performed in the antimicrobial treatment for 45 patients, and effective de-escalation could be performed in 32 patients, but it was recommended not to perform de-escalation. CONCLUSIONS: Even in a microbiology laboratory with limited facilities, reliable antimicrobial susceptibility test results can be obtained in a short time with the p-RAST method without using automated systems and antimicrobial choice can be guided in a shorter time.

Role of serological rapid antibody test in the management of possible COVID-19 cases.

BACKGROUND: Although the detection of viral particles by reverse transcription polymerase chain reaction (RT-PCR) is the gold standard diagnostic test for coronavirus disease 2019 (COVID-19), the false-negative results constitute a big challenge. AIM: To examine a group of patients diagnosed and treated as possible COVID-19 pneumonia whose multiple nasopharyngeal swab samples were negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by RT-PCR but then serological immunoglobulin M/immunoglobulin G (IgM/IgG) antibody against SARS-CoV-2 were detected by rapid antibody test. METHODS: Eighty possible COVID-19 patients who had at least two negative consecutive COVID-19 RT-PCR test and were subjected to serological rapid antibody test were evaluated in this study. RESULTS: The specific serological total IgM/IgG antibody against SARS-CoV-2 was detected in twenty-two patients. The mean age of this patient group was 63.2± 13.1-years-old with a male/female ratio of 11/11. Cough was the most common symptom (90.9%). The most common presenting chest computed tomography findings were bilateral ground glass opacities (77.2%) and alveolar consolidations (50.1%). The mean duration of time from appearance of first symptoms to hospital admission, to hospital admission, to treatment duration and to serological positivity were 8.6 d, 11.2 d, 7.9 d, and 24 d, respectively. Compared with reference laboratory values, serologically positive patients have shown increased levels of acute phase reactants, such as C-reactive protein, ferritin, and procalcitonin and higher inflammatory markers, such as erythrocyte sedimentation rate, lactate dehydrogenase enzyme, and fibrin end-products, such as D-dimer. A left shift on white blood cell differential was observed with increased neutrophil counts and decreased lymphocytes. CONCLUSION: Our study demonstrated the feasibility of a COVID-19 diagnosis based on rapid antibody test in the cases of patients whose RT-PCR samples were negative. Detection of antibodies against SARS-CoV-2 with rapid antibody test should be included in the diagnostic algorithm in patients with possible COVID-19 pneumonia.