Higher rates of cefiderocol resistance among NDM producing Klebsiella bloodstream isolates applying EUCAST over CLSI breakpoints.

BACKGROUND: Cefiderocol is generally active against carbapenem-resistant Klebsiella spp. (CRK) with higher MICs against metallo-beta-lactamase producers. There is a variation in cefiderocol interpretive criteria determined by EUCAST and CLSI. Our objective was to test CRK isolates against cefiderocol and compare cefiderocol susceptibilities using EUCAST and CLSI interpretive criteria. METHODS: A unique collection (n = 254) of mainly OXA-48-like- or NDM-producing CRK bloodstream isolates were tested against cefiderocol with disc diffusion (Mast Diagnostics, UK). Beta-lactam resistance genes and multilocus sequence types were identified using bioinformatics analyses on complete bacterial genomes. RESULTS: Median cefiderocol inhibition zone diameter was 24 mm (interquartile range [IQR] 24-26 mm) for all isolates and 18 mm (IQR 15-21 mm) for NDM producers. We observed significant variability between cefiderocol susceptibilities using EUCAST and CLSI breakpoints, such that 26% and 2% of all isolates, and 81% and 12% of the NDM producers were resistant to cefiderocol using EUCAST and CLSI interpretive criteria, respectively. CONCLUSIONS: Cefiderocol resistance rates among NDM producers are high using EUCAST criteria. Breakpoint variability may have significant implications on patient outcomes. Until more clinical outcome data are available, we suggest using EUCAST interpretive criteria for cefiderocol susceptibility testing.

[Comparison of the Multiplex Real Time Polymerase Chain Reaction Method Directly from Whole Blood and from Blood Culture Bottle with the Conventional Method for the Etiological Diagnosis in Patients with Pre-Diagnosis of Sepsis]. / Sepsis Ön Tanili Hastalarda Tam Kandan ve Kan Kültür Sisesinden Multipleks Gerçek Zamanli Polimeraz Zincir Reaksiyonu ile Hizli Etken Tayininin Konvansiyonel Yöntemlerle Karsilastirilmasi.

In this study, it was aimed to evaluate the use of multiplex real time polymerase chain reaction (RtPCR) method, directly from whole blood and blood culture bottles of intensive care unit patients with a pre-diagnosis of sepsis for the determination of the causative agent by comparing it with the conventional method. The study was carried out prospectively between November 2019 and August 2020. Ninety patients hospitalized with a pre-diagnosis of sepsis were included in the study. Samples were collected simultaneously with aseptic technique as whole blood and at least two sets of blood cultures. Blood culture bottles were monitored by the BACT/ALERT 3D (bioMerieux, France) instrument. Blood culture bottles were studied both by Sepsis Pathogens Panel Kit v1 (Anatolia, Turkey) using the multiplex Rt-PCR and with the conventional culture methods. The duration of detection and reporting of the multiplex Rt-PCR methods were compared with the conventional method. In this study, a total of 90 whole blood samples and 280 blood culture bottles were collected from the patients. It was found that 73 (81%) patients had already been administered antibiotic treatment at the time of blood sampling. Conventional blood culture was accepted as the gold standard in the diagnosis of sepsis. Rt-PCR performed from blood culture bottles was found to have a sensitivity of 89.58%; specificity of 57.14%; positive predictive value of 70.49%; negative predictive value of 82.76% and accuracy of 74.44% (p= 0.019). On the basis of the bacterial species, the sensitivity of the Rt-PCR method was determined to be between 66.7-100% and the specificity was between 86.6-100%. The Rt-PCR performed from whole blood, was found to have a sensitivity of 11.67% and a specificity of 96.67%; positive predictive value of 87.50%; negative predictive value of 35.37% and accuracy of 40% (p= 1.684). In this study, the duration of reporting of blood culture results was in average 116:50 hours, that of PCR from blood culture bottles was 80:57 hours, and that of PCR from whole blood samples was 15:38 hours (p<0.001). It was determined that the PCR from whole blood shortened the reporting time by an average of 101:12 hours (approximately four days), and that the PCR from blood culture bottles shortened the reporting time by an average of 35:53 hours (1.5 days) compared to the conventional method. In this study, the results determined by the Sepsis Pathogens Panel Kit v1 (Anatolia, Turkey) performed from blood culture bottles were superior compared to the conventional method. It has been determined that improvement is required for the usage of the sepsis kit directly from whole blood. On the other hand, considering the species detected by the blood culture method and not by the assay, the species range detected by the multiplex assay panel needs to be improved.

Comparison of ceftazidime-avibactam susceptibility testing methods against OXA-48-like carrying Klebsiella blood stream isolates.

Ceftazidime-avibactam exhibits good in vitro activity against carbapenem resistant Klebsiella carrying OXA-48-like enzymes. We tested two hundred unique carbapenem resistant Klebsiella blood stream isolates (71% with single OXA-48-like carbapenemases, including OXA-48, n = 62; OXA-232, n = 57; OXA-244, n = 17; OXA-181, n = 5) that were collected as part of a multicentre study against ceftazidime-avibactam using Etest (bioMérieux, Marcyl'Étoile, France), 10/4 µg disc (Thermo Fisher) and Sensititre Gram Negative EURGNCOL Plates (Lyophilized panels, Sensititre, Thermo Fisher) with the aim of comparing the performances of the Etest and disc to that of Sensititre. Ceftazidime-avibactam MIC50/90 was 2/>16 mg/L for the entire collection and was 2/4 mg/L for single OXA-48-like producers. Categorical and essential agreements between the Etest and Sensititre were 100% and 97%, respectively. Categorical agreement between the disc and Sensititre was 100%. Etest and 10/4 µg discs are suitable alternatives to Sensititre for ceftazidime-avibactam sensitivity testing for OXA-48-like producers.

Characteristics and outcomes of carbapenemase harbouring carbapenem-resistant Klebsiella spp. bloodstream infections: a multicentre prospective cohort study in an OXA-48 endemic setting.

A prospective, multicentre observational cohort study of carbapenem-resistant Klebsiella spp. (CRK) bloodstream infections was conducted in Turkey from June 2018 to June 2019. One hundred eighty-seven patients were recruited. Single OXA-48-like carbapenemases predominated (75%), followed by OXA-48-like/NDM coproducers (16%). OXA-232 constituted 31% of all OXA-48-like carbapenemases and was mainly carried on ST2096. Thirty-day mortality was 44% overall and 51% for ST2096. In the multivariate cox regression analysis, SOFA score and immunosuppression were significant predictors of 30-day mortality and ST2096 had a non-significant effect. All OXA-48-like producers remained susceptible to ceftazidime-avibactam.

High prevalence of ArmA-16S rRNA methyltransferase among aminoglycoside-resistant Klebsiella pneumoniae bloodstream isolates.

Introduction. Aminoglycosides are used for the treatment of carbapenemase-producing Klebsiella pneumoniae (CPK) infections. 16S rRNA methyltransferases (RMTs) confer resistance to all aminoglycosides and are often cocarried with NDM.Hypothesis/Gap Statement. There is a dart of studies looking at the aminoglycoside resistance mechanisms for invasive CPK isolates, particularly in OXA-48 endemic settings.Aim. We aimed to determine the prevalence of RMTs and their association with beta lactamases and MLSTs amongst aminoglycoside-resistant CPK bloodstream isolates in an OXA-48 endemic setting.Methodology. CPK isolates (n=181), collected as part of a multicentre cohort study, were tested for amikacin, gentamicin and tobramycin susceptibility using custom-made sensititre plates (GN2XF, Thermo Fisher Scientific). All isolates were previously subjected to whole-genome sequencing. Carbapenemases, RMTs, MLSTs and plasmid incompatibility groups were detected on the assembled genomes.Results. Of the 181 isolates, 109(60 %) were resistant to all three aminoglycosides, and 96 of 109(88 %) aminoglycoside-resistant isolates carried an RMT (85 ArmA, 10 RmtC, 4 RmtF1; three isolates cocarried ArmA and RmtC). Main clonal types associated with ArmA were ST2096 (49/85, 58 %) and ST14 (24/85, 28 %), harbouring mainly OXA-232 and OXA-48 +NDM, respectively. RmtC was cocarried with NDM (5/10) on ST395, and NDM +OXA-48 or NDM +KPC (4/10) on ST14, ST15 and ST16. All RMT producers also carried CTX-M-15, and the majority cocarried SHV-106, TEM-150 and multiple other antibiotic resistance genes. The majority of the isolates harboured a combination of IncFIB, IncH and IncL/M type plasmids. Non-NDM producing isolates remained susceptible to ceftazidime-avibactam.Conclusion. Aminoglycoside resistance amongst CPK bloodstream isolates is extremely common and mainly driven by clonal spread of ArmA carried on ST2096 and ST14, associated with OXA-232 and OXA48 +NDM carriage, respectively.

[Evaluation of EUCAST Direct Rapid Antimicrobial Susceptibility Test Method in Blood Culture Bottles with Positive Signal]. / Pozitif Sinyal Veren Kan Kültürü Siselerinde EUCAST Dogrudan Hizli Antimikrobiyal Duyarlilik Testi Yönteminin Degerlendirilmesi.

Early reporting of the antibiotic susceptibility testing (AST) results is essential for the survival of sepsis patients. In 2019, European Committee on Antimicrobial Susceptibility Testing (EUCAST) published a proposal to detect antimicrobial susceptibility from positive blood culture bottles with a rapid antimicrobial susceptibility test (RAST) method in a maximum of eight hours. In this study, it was aimed to evaluate the EUCAST RAST method in blood culture bottles that resulted with positive signal in BacT/ALERT (bioMérieux, France) blood culture system and that showed gram-negative bacteria with single morphology with Gram stain. The study was conducted prospectively between April 2019 and November 2019. Ninety blood culture bottles that we detected single gram negative bacteria morphology by Gram stain were tested according to the EUCAST RAST method, The isolates obtained from the blood culture bottles were studied with the EUCAST disk diffusion method and the Vitek 2 Compact (bioMerieux, France) automated system. The results obtained with RAST were compared with the results of these methods. The turn around time of the RAST method was recorded. Categorical agreement of the RAST method with conventional methods and the very major error rates were determined. Of the 14 isolates not yet covered by the EUCAST HADT method, 12 were determined to be other Enterobacterales members and two as other non-fermentatives. Two isolates were detected with the same morphological characteristics in Gram stain of the blood culture bottle and the same antibiotic susceptibility profile, but with different identification results. These sixteen isolates were excluded from the study. In this study the susceptibility of 74 isolates were determined according to the EUCAST breakpoint tables, of which 31 were Klebsiella pneumoniae, 35 were Escherichia coli, four were Acinetobacter baumannii and four were Pseudomonas aeruginosa. According to the evaluation periods of EUCAST RAST; the susceptibility profile was reported for nine (12%) of E.coli at four hours, eight (11%) at six hours, 18 (24%) at eight hours; three (4%) of K.pneumoniae at four hours, 16 (21%) at six hours, 12 (16%) at eight hours; three of P.aeruginosa (4%) at six hours, one (1%) at eight hours; two of A.baumannii (2%) at six hours and two (2%) at eight hours. The categorical aggrement of the RAST method was 91.8% with the automated system and 96.8% with the disc diffusion method. Very major errors of RAST method compared to the automated system were detected for piperacillin-tazobactam (17.7%), ceftazidime (11.6%) and meropenem (5.6%); and when compared to the disc diffusion method, for cefotaxime (5.7%) and meropenem (6.7%). Our results have shown that EUCAST RAST method can practicaly be performed in routine laboratories to report early results with a low cost. Because of the very major errors it is necessary to confirm the results with the standard methods.

Pan-resistant Acinetobacter baumannii mediastinitis treated successfully with tigecycline: a case report.

BACKGROUND: Mediastinitis due to Acinetobacter baumannii is rare. METHODS: We report a case of mediastinitis caused by pan-resistant A. baumannii in a patient with multiple comorbidities who underwent cardiopulmonary bypass and we also present a literature review. RESULTS: Successful treatment consisted of surgical debridement plus drainage, and tigecycline administration for three weeks. CONCLUSION: Surgical source control along with effective antibiotics is essential in the treatment of mediastinitis. Tigecycline has the potential to be an option for pan-resistant A. baumannii mediastinitis.