EUCAST Research Articles

Evaluation of the European Committee on Antimicrobial Susceptibility Testing Guidelines for Rapid Antimicrobial Susceptibility Testing of Bacillus anthracis-, Yersinia pestis- and Francisella tularensis-Positive Blood Cultures.

Rapid determination of bacterial antibiotic susceptibility is important for proper treatment of infections. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) has recently published guidelines for rapid antimicrobial susceptibility testing (RAST) performed directly from positive blood culture vials. These guidelines, however, were only published for a limited number of common pathogenic bacteria. In this study, we evaluated the applicability of these guidelines to three Tier 1 bioterror agents (Bacillus anthracis, Yersinia pestis and Francisella tularensis) that require prompt antibiotic treatment to mitigate morbidity and mortality. We used spiked-in human blood incubated in a BACTEC™ FX40 system to determine the proper conditions for RAST using disc-diffusion and Etest assays. We found that reliable disc-diffusion inhibition diameters and Etest MIC values could be obtained in remarkably short times. Compared to the EUCAST-recommended disc-diffusion assays that will require adjusted clinical breakpoint tables, Etest-based RAST was advantageous, as the obtained MIC values were similar to the standard MIC values, enabling the use of established category breakpoint tables. Our results demonstrate the promising applicability of the EUCAST RAST for B. anthracis-, Y. pestis- or F. tularensis-positive blood cultures, which can lead to shorter diagnostics and prompt antibiotic treatment of these dangerous pathogens.

Antimicrobial Photodynamic Inactivation Affects the Antibiotic Susceptibility of Enterococcus spp. Clinical Isolates in Biofilm and Planktonic Cultures.

Enterococcus faecium and Enterococcus faecalis are opportunistic pathogens that can cause a vast variety of nosocomial infections. Moreover, E. faecium belongs to the group of ESKAPE microbes, which are the main cause of hospital-acquired infections and are especially difficult to treat because of their resistance to many antibiotics. Antimicrobial photodynamic inactivation (aPDI) represents an alternative to overcome multidrug resistance problems. This process requires the simultaneous presence of oxygen, visible light, and photosensitizing compounds. In this work, aPDI was used to resensitize Enterococcus spp. isolates to antibiotics. Antibiotic susceptibility testing according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations was combined with synergy testing methods recommended by the American Society for Microbiology. Two clinical isolates, E. faecalis and E. faecium, were treated with a combination of aPDI utilizing rose bengal (RB) or fullerene (FL) derivative as photosensitizers, antimicrobial blue light (aBL), and 10 recommended antibiotics. aPDI appeared to significantly impact the survival rate of both isolates, while aBL had no significant effect. The synergy testing results differed between strains and utilized methods. Synergy was observed for RB aPDI in combination with gentamycin, ciprofloxacin and daptomycin against E. faecalis. For E. faecium, synergy was observed between RB aPDI and gentamycin or ciprofloxacin, while for RB aPDI with vancomycin or daptomycin, antagonism was observed. A combination of FL aPDI gives a synergistic effect against E. faecalis only with imipenem. Postantibiotic effect tests for E. faecium demonstrated that this isolate exposed to aPDI in combination with gentamycin, streptomycin, tigecycline, doxycycline, or daptomycin exhibits delayed growth in comparison to untreated bacteria. The results of synergy testing confirmed the effectiveness of aPDI in resensitization of the bacteria to antibiotics, which presents great potential in the treatment of infections caused by multidrug-resistant strains.

Azole Resistance in Clinical and Environmental Aspergillus Isolates from the French West Indies (Martinique).

The emergence of azole resistant Aspergillus spp., especially Aspergillus fumigatus, has been described in several countries around the world with varying prevalence depending on the country. To our knowledge, azole resistance in Aspergillus spp. has not been reported in the West Indies yet. In this study, we investigated the antifungal susceptibility of clinical and environmental isolates of Aspergillus spp. from Martinique, and the potential resistance mechanisms associated with mutations in cyp51A gene. Overall, 208 Aspergillus isolates were recovered from clinical samples (n = 45) and environmental soil samples (n = 163). They were screened for resistance to azole drugs using selective culture media. The Minimum Inhibitory Concentrations (MIC) towards voriconazole, itraconazole, posaconazole and isavuconazole, as shown by the resistant isolates, were determined using the European Committee on Antimicrobial Susceptibility Testing (EUCAST) microdilution broth method. Eight isolates (A. fumigatus, n = 6 and A. terreus, n = 2) had high MIC for at least one azole drug. The sequencing of cyp51A gene revealed the mutations G54R and TR34/L98H in two A. fumigatus clinical isolates. Our study showed for the first time the presence of azole resistance in A. fumigatus and A. terreus isolates in the French West Indies.

The Antibiotic Susceptibilities of Methicilline-Resistant Staphylococcus aureus Strains Isolated From Various Clinical Samples

Objective: In this study, it was aimed to determine the in vitro susceptibilities of Methicillin-Resistant Staphylococcus aureus (MRSA) strains to fluoroquinolone, linezolid, tigecycline, and quinupristin/dalfopristin as well as the macrolide-lincosamide-streptogramin B (MLSB) resistance phenotype.
 Materials and Methods: A total of 94 MRSA strains isolated from various clinical samples in our hospital laboratory between January 2020 and September 2020 were included. The in-vitro susceptibilities of MRSA strains against fluoroquinolone, linezolid, tigecycline, and quinupristin/dalfopristin were determined by Kirby-Bauer disc diffusion assay according to The European Committee on Antimicrobial Susceptibility Testing (EUCAST). The E test assay was used for evaluation of tigecycline susceptibility. The D-zone test was performed with erythromycin (15 μg) and clindamycin (2 μg) discs to determine the MLSB resistance. Besides, bacterial identification, antibiotic susceptibility tests including methicillin resistance and MLSB phenotype determination were performed by using VITEK 2 Gram-positive diagnostic kits (Bio-Mérieux/France).
 Results: Results: Among 94 MRSA strains included, resistance rates to ciprofloxacin, moxifloxacin, tigecycline, and quinupristin/dalfopristin were found as 71% (67 isolates) 64% (60 isolates), 17% (16 isolates), and 2% (2 isolates), respectively. Resistance was not detected for linezolid. A total of 36 (49%) isolates showed cMLSB resistance phenotype, while 18(19%) had iMLSB resistance. The methicillin susceptibility (MS) phenotype – strains resistant to erythromycin and susceptible to clindamycin- was not detected.
 Conclusion: Very little resistance was found to linezolid, quinupristin/dalfopristin and tigecycline. Therefore, these antibiotics may be beneficial for the proper treatment of infections caused by MLSB-resistant isolates.

Rethinking Manure Application: Increase in Multidrug-Resistant Enterococcus spp. in Agricultural Soil Following Chicken Litter Application.

The current study investigated the impact of chicken litter application on the abundance of multidrug-resistant Enterococcus spp. in agricultural soil. Soil samples were collected from five different strategic places on a sugarcane farm before and after manure application for four months. Chicken litter samples were also collected. Enterococci were enumerated using the Enterolert®/Quanti-Tray 2000® system and confirm and differentiated into species using real-time PCR. The antibiotic susceptibility profile of the isolates was determined using the disk diffusion method following the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. The overall mean bacterial count was significantly higher (p < 0.05) in manure-amended soil (3.87 × 107 MPN/g) than unamended soil (2.89 × 107 MPN/g). Eight hundred and thirty-five enterococci (680 from soil and 155 from litter) were isolated, with E. casseliflavus being the most prevalent species (469; 56.2%) and E. gallinarum being the least (16; 1.2%). Approximately 56% of all the isolates were resistant to at least one antibiotic tested, with the highest resistance observed against tetracycline (33%) and the lowest against chloramphenicol (0.1%); 17% of E. faecium were resistant to quinupristin-dalfopristin. Additionally, 27.9% (130/466) of the isolates were multidrug-resistant, with litter-amended soil harbouring more multidrug-resistant (MDR) isolates (67.7%; 88/130) than unamended soil (10.0%; 13/130). All isolates were susceptible to tigecycline, linezolid and gentamicin. About 7% of the isolates had a multiple antimicrobial resistance index > 0.2, indicative of high antibiotic exposure. Although organic fertilizers are regarded as eco-friendly compared to chemical fertilizers for improving soil fertility, the application of untreated animal manure could promote the accumulation of antibiotics and their residues and antibiotic-resistant bacteria in the soil, creating an environmental reservoir of antimicrobial resistance, with potential human and environmental health risks.

Triazole-Resistance in Environmental Aspergillus fumigatus in Latin American and African Countries.

Triazole-resistance has been reported increasingly in Aspergillus fumigatus. An international expert team proposed to avoid triazole monotherapy for the initial treatment of invasive aspergillosis in regions with >10% environmental-resistance, but this prevalence is largely unknown for most American and African countries. Here, we screened 584 environmental samples (soil) from urban and rural locations in Mexico, Paraguay, and Peru in Latin America and Benin and Nigeria in Africa for triazole-resistant A. fumigatus. Samples were screened using triazole-containing agars and confirmed as triazole-resistant by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth dilution reference method. Isolates were further characterized by cyp51A sequencing and short-tandem repeat typing. Fungicide presence in samples was likewise determined. Among A. fumigatus positive samples, triazole-resistance was detected in 6.9% (7/102) of samples in Mexico, 8.3% (3/36) in Paraguay, 9.8% (6/61) in Peru, 2.2% (1/46) in Nigeria, and none in Benin. Cyp51A gene mutations were present in most of the triazole-resistant isolates (88%; 15/17). The environmentally-associated mutations TR34/L98H and TR46/Y121F/T289A were prevalent in Mexico and Peru, and isolates harboring these mutations were closely related. For the first time, triazole-resistant A. fumigatus was found in environmental samples in Mexico, Paraguay, Peru, and Nigeria with a prevalence of 7–10% in the Latin American countries. Our findings emphasize the need to establish triazole-resistance surveillance programs in these countries.

Faecal carriage of extended-spectrum beta-lactamase-producing Enterobacteriaceae in healthy volunteers and hospitalized patients in Ouagadougou, Burkina Faso: prevalence, resistance profile, and associated risk factors

Background: Extended spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) are a serious challenge to patients’ treatment. The aim of this study is to determine the prevalence of ESBL-PE, investigate the associated resistance, and analyze the associated risk factors for acquisition of ESBL-PE.Methodology: A cross-sectional study was conducted on healthy volunteers and inpatients. After obtaining informed consent, rectal swabs were collected from each participant for isolation of Enterobacteriaceae on Hektoen enteric agar containing 4µg/L cefotaxime. The Enterobacteriaceae isolates were identified using biochemical tests and ESBL production was confirmed by the double-disc synergy test of amoxicillin and clavulanic acid. Antibiotic susceptibility test of each isolate was done by the disc diffusion method and interpreted using the recommendations of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) clinical breakpoints version 5.0.Results: During the study period, prevalence of faecal ESBL-PE among the study participants was 54.5% (103/189); 53.5% among healthy volunteers and 55.7% among inpatients (p=0.87). The major ESBL-PE isolates was Escherichia coli (71%) followed by Klebsiella pneumoniae (16%). The isolates in hospitalized patients were resistant to norfloxacin (84.2%), cotrimoxazole (89.5%), and gentamicin (7.0%). The isolates from healthy volunteers were resistant to norfloxacin (86.2%), cotrimoxazole (82.8%), and gentamicin (1.7%).Gender, age, and previous antibiotic use were not significantly associated with carriage of ESBL-PE (p=0.51).Conclusion: The high prevalence of ESBL-PE in this study is worrying. There is an urgent need to develop measures to monitor and limit the spread of these multidrug-resistant organisms in healthcare facilities and the community in Burkina Faso.&#x0D; Keywords: faecal carriage, ESBL-PE, healthy volunteers, inpatients, Burkina Faso

Antimicrobial resistance profiles of Enterobacter cloacae and Klebsiella aerogenes a tertiary hospital in Turkey: A five-years study

Objective: Enterobacter cloacae and Klebsiella aerogenes species have multiple drug resistance and antibiotic resistance is a growing problem regarding to treating infections.&#x0D; Objective: The aim of this study was to determine and evaluate the antimicrobial resistance profiles of E. cloacae and K. aerogenes isolated from various clinical samples in our laboratory, retrospectively.&#x0D; Material and Methods: Totally 223 patients who applied to Karabuk University Training and Research Hospital microbiology laboratory between October2016-December2020 were included in this study. Conventional methods and automated systems were used for the identification and antibiotic susceptibilities of strains. Antibiotic susceptibility results were evaluated as per the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines.&#x0D; Results: Total of 223 clinical samples (urine 68.6%, blood 12.6%, endotracheal aspirate 7.2%, wound 4.9%, sputum 3.6%, bronchoalveolar lavage fluid 2.7%, and ear fluid 0.4%) obtained from 223 patients; 119 (53%) females and 104 (47%) females, were analysed. The identified species were E. cloacae (132 strains, 59.2%) and K. aerogenes (91 strains, 40.8%). The Enterobacter cloacae and Klebsiella aerogenes positivity was detected as 30(13.4%) and 20(9.0%) in the samples. The highest resistance was found against cefixime at a rate of 60%; the lowest resistance was against amikacin, meropenem and imipenem ranged between 3% and 4% in both E. cloacae and K. aerogenes strains.&#x0D; Conclusions: Amikacin, imipenem and meropenem were the most effective antibiotics against E. cloacae and K. aerogenes. We may prefer TMP-SMX and ciprofloxacin, as oral antibiotic agents in the treatment of E. cloacae/K. aerogenes infections. Amikacin, gentamicin and carbapenems may be the first choice for parenteral antibiotics therapy

Morpholinium-based ionic liquids show antimicrobial activity against clinical isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a multi-drug resistant (MDR) pathogen. It is classified by WHO as one of the most life-threatening pathogens causing nosocomial infections. Some of its clinical isolates and their subpopulations show high persistence to many antibiotics that are recommended by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Thus, there is a need for non-traditional classes of antibiotics to fight the increasing threat of MDR P. aeruginosa. Ionic liquids (IL) are one such promising class of novel antibiotics. We selected four strains of P. aeruginosa and studied the growth inhibition and other effects of 12 different ILs. We used the well-characterized P. aeruginosa PAO1 (ATCC 15692) as model strain and compared it to three other isolates from chronic lung infection (LES B58), skin burn infection (UCBPP-PA14) and keratitis infection (39016), respectively. The ILs consisted of either 4,4-didecylmorpholinium [Dec2Mor]+ or 4-decyl-4-ethylmorpholinium [DecEtMor]+ cations combined with different anions. We found that the ILs with 4,4-didecylmorpholinium [Dec2Mor]+ cations most effectively inhibited bacterial growth as well as reduced strain fitness and virulence factor production. Our results indicate that these ILs could be used to treat P. aeruginosa infections.

Interpreting Burkholderia pseudomallei disc diffusion susceptibility test results by the EUCAST method

Interpreting Burkholderia pseudomallei disc diffusion susceptibility test results by the EUCAST method

Organization of antibiotic stewardship in Europe: the way to go.

SummaryIt is more than two decades ago that a European Union conference on “The Microbial Threat” hosted by the Danish Government in Copenhagen in September 1998 issued recommendations to encourage good practice in the use of antimicrobial agents and reduce inappropriate prescribing. Essential components of those recommendations were antimicrobial teams in hospitals and the use of feedback to prescribers as well as educational activities. Two decades later, important surveillance systems on both antimicrobial resistance as well as on antibiotic consumption are functioning at the European level and in most European countries; European Committee on Antimicrobial Susceptibility Testing (EUCAST) has thoroughly re-evaluated, standardized and harmonized antibiotic susceptibility testing and breakpoints; there have been educational activities in many countries; and stewardship teams are now included in many guidelines and policy papers and recommendations. Yet, antimicrobial resistance problems in Europe have shifted from methicillin-resistant Staphylococus aureus (MRSA) to vancomycin-resistent Enterococcus faecium (VRE) and to multidrug-resistant gramnegative bacteria, while antibiotic consumption volumes, trends and patterns across countries do not show major and highly significant improvements. The way to go further is to recognize that better prescribing comes at a cost and requires investment in expert personnel, practice guideline drafting, and implementation aids, and, secondly, the setting of clear goals and quantitative targets for prescribing quality.

In-vitro pharmacokinetic/pharmacodynamic model data suggest a potential role of new formulations of posaconazole against Candida krusei but not Candida glabrata infections

Posaconazole exhibits in-vitro activity against Candida glabrata and Candida krusei. Epidemiological cut-off values set by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) and the Clinical and Laboratory Standards Institute (CLSI) are 1/1 and 0.5/0.5 mg/L, respectively, but clinical breakpoints have not been established to date. This study explored the pharmacodynamics (PD) of posaconazole in a validated one-compartment in-vitro pharmacokinetic (PK)/PD model, and determined the probability of PK/PD target attainment (PTA) for the available formulations. Five C. glabrata and three C. krusei isolates with posaconazole minimum inhibitory concentrations (MICs) of 0.06-2 and 0.03-0.25 mg/L, respectively, were tested in the PK/PD model simulating different time-concentration profiles of posaconazole. The exposure-effect relationship fAUC0-24/MIC was described for EUCAST/CLSI methods, and PTA was calculated in order to determine PK/PD susceptibility breakpoints for oral solution (400 mg q12h), and intravenous (i.v.)/tablet formulations (300 mg q24h). Fungicidal activity (~2log kill) was found against the most susceptible C. glabrata isolate alone, and against all three C. krusei isolates. The corresponding EUCAST/CLSI PK/PD targets (fAUC0-24/MIC) were 102/79 for C. glabrata and 12/8 for C. krusei. Mean PTA was high (>95%) for C. glabrata isolates with EUCAST/CLSI MICs ≤0.03/≤0.03 mg/L for oral solution and ≤0.125/≤0.125 mg/L for i.v. and tablet formulations for the wild-type population. For C. krusei isolates, mean PTA was high (>95%) for EUCAST/CLSI MICs ≤0.25/≤0.5 mg/L for oral solution and ≤1/≤2 mg/L for i.v. and tablet formulations for the wild-type population. The use of posaconazole to treat C. glabrata infections is questionable. Intravenous and tablet formulations may be therapeutic options for the treatment of C. krusei infections, and oral exposure can be optimized with therapeutic drug monitoring (trough levels >0.6-0.9 mg/L).

Susceptibility of Clinical Enterobacterales Isolates With Common and Rare Carbapenemases to Mecillinam.

Purpose: To investigate the susceptibility of carbapenemase-producing Enterobacterales (CPE) to mecillinam based on the recently updated European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints for uncomplicated Urinary Tract Infection (uUTI).Methods: The challenge collection consisted of 105 molecularly characterized Enterobacterales [Klebsiella spp. (N = 49), Escherichia coli (N = 30), Enterobacter cloacae (n = 13), Citrobacter freundii (N = 9), Proteus mirabilis (N = 3), and Raoultella ornithinolytica (N = 1)]. Isolates produced OXA-48 (N = 18), OXA-48-like (N = 18), VIM (N = 22), NDM (N = 22), KPC (N = 12), IMI (N = 9), IMP (N = 6), GES (N = 1), OXA-58 (N = 2) or combinations thereof (N = 5). MICs of carbapenems were determined by agar gradient diffusion (AGD). MICs of mecillinam were assessed by agar dilution (reference method) and compared to disk diffusion (DD) and AGD.Results: Overall 23/105 CPE (21.9%) were susceptible to mecillinam. Susceptibility was observed in E. coli (N = 12), E. cloacae (N = 7), and Klebsiella pneumoniae (N = 4) producing IMI, OXA-48, OXA-48-like, and NDM-1 carbapenemases. MIC50 for mecillinam in all isolates was 128 mg/L while MIC50 for meropenem was 8 mg/L. Lower MICs for mecillinam were found in IMI (MIC50 8 mg/L) and OXA-48-like (MIC50 16 mg/L) producers. The comparison of the different susceptibility methods showed very major errors of 12.2% with AGD and 8.5% with disk diffusion when compared to the reference method.Conclusion: Mecillinam susceptibility was restricted to isolates producing IMI-, OXA-48-like, and NDM-1 carbapenemases and was documented despite high carbapenem MICs in some isolates. Mecillinam could be a promising oral antimicrobial in uUTI caused by E. coli and E. cloacae isolates carrying IMI- and OXA-48-like carbapenemases; however, susceptibility testing by AGD and disk diffusion remains problematic.

Establishment of sentinel surveillance of human clinical campylobacteriosis in Ireland.

The aim of this work was the establishment of a national laboratory sentinel surveillance service for human clinical Campylobacter in Ireland. This included detailed genomic molecular epidemiology of Campylobacter for 2019. For February-December 2019, 24 clinical microbiology laboratories in Ireland submitted all PCR/culture-positive clinical Campylobacter spp. specimens to Public Health Laboratory (PHL) Dublin oneweek out of every four. Antimicrobial susceptibility testing (AST) according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria was carried out for Campylobacter spp. isolates for ciprofloxacin, tetracycline and erythromycin. Batch whole genome sequencing (WGS) was carried out on cultures and analysis was performed to determine species, genotype, identify antimicrobial resistance (AMR) and virulence determinants and identify clusters. A total of 75 isolates and 366 PCR-positive stools were received, and 277 isolates recovered (55.7% recovery from stools). Of 257 isolates characterized by WGS, 86.4% (n=222) were Campylobacter jejuni, 11.7% (n=30) Campylobacter coli and 1.9% (n=5) Campylobacter lari. There were 20 clonal complexes with ST-21 clonal complex most prevalent at 26.8% (n=69). 50.5% (n=140) of isolates were susceptible to all three antimicrobials tested. 39.3% (n=109) isolates were ciprofloxacin resistant, 26.3% (n=73) tetracycline resistant and two isolates erythromycin resistant. Congruence between phenotypic and genotypic AST was observed. There was 95.9% and 95.6% sensitivity and specificity for WGS to predict ciprofloxacin sensitivity and 98.6% and 99.5% sensitivity and specificity for WGS to predict tetracycline sensitivity. Virulence factors flaA, racR, ciaB and cdtB were detected in all isolates. WGS identified 31 potential clusters for public health alert. This sentinel surveillance of human campylobacteriosis in Ireland establishes the basis for a national reference service. Linking with other partners in a 'One Health' framework will help us better understand sources of infection to reduce disease burden and the threat of AMR.

Evaluation of a Phenotypic Algorithm to Direct Carbapenemase Testing in Pseudomonas aeruginosa: Validation in a Multicenter German Cohort.

Pseudomonas aeruginosa remains a prominent nosocomial pathogen. Detection of carbapenemase-producing P. aeruginosa is vital to dictate antimicrobial therapy and infection control measures. A pragmatic, minimum inhibitory concentration-based algorithm using imipenem AND meropenem-resistant plus ceftazidime-, cefepime-, and piperacillin/tazobactam-nonsusceptible criterion was derived to guide carbapenemase testing in P. aeruginosa. This study was an assessment of the algorithm's test performance in a cohort of 985 nonduplicate P. aeruginosa isolates collected from 20 German medical laboratories. Susceptibility data were assessed in the algorithm using both Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) interpretations. Sensitivity and specificity were calculated to evaluate algorithm test performance. The original algorithm criteria resulted in high specificity (95-97%) using both CLSI and EUCAST criteria; however, it failed to capture five carbapenemase-harboring isolates testing piperacillin/tazobactam susceptibility (CLSI/EUCAST). Two carbapenemase-producing isolates were also meropenem susceptible per EUCAST. A modified algorithm utilizing imipenem OR meropenem-resistant plus ceftazidime and cefepime nonsusceptible, improved the sensitivity of the criteria without significantly compromising specificity (CLSI sensitivity/specificity: 96%/94% and EUCAST sensitivity/specificity: 96%/95%). Application of the modified algorithm criteria resulted in high sensitivity and specificity using both CLSI and EUCAST interpretations in a large cohort of clinical P. aeruginosa. Utilization of this algorithm can improve the efficiency of carbapenemase testing in the clinical laboratory.

Candida parapsilosis Colony Morphotype Forecasts Biofilm Formation of Clinical Isolates.

Candida parapsilosis is a frequent cause of fungal bloodstream infections, especially in critically ill neonates or immunocompromised patients. Due to the formation of biofilms, the use of indwelling catheters and other medical devices increases the risk of infection and complicates treatment, as cells embedded in biofilms display reduced drug susceptibility. Therefore, biofilm formation may be a significant clinical parameter, guiding downstream therapeutic choices. Here, we phenotypically characterized 120 selected isolates out of a prospective collection of 215 clinical C. parapsilosis isolates, determining biofilm formation, major emerging colony morphotype, and antifungal drug susceptibility of the isolates and their biofilms. In our isolate set, increased biofilm formation capacity was independent of body site of isolation and not predictable using standard or modified European Committee on Antimicrobial Susceptibility Testing (EUCAST) drug susceptibility testing protocols. In contrast, biofilm formation was strongly correlated with the appearance of non-smooth colony morphotypes and invasiveness into agar plates. Our data suggest that the observation of non-smooth colony morphotypes in cultures of C. parapsilosis may help as an indicator to consider the initiation of anti-biofilm-active therapy, such as the switch from azole- to echinocandin- or polyene-based strategies, especially in case of infections by potent biofilm-forming strains.

Health vigilance concerning Acinetobacter baumannii bacteremia at the mohammed VI university hospital of oujda (morocco): epidemiological profile and antibiotic resistance

The objective of this work is to determine the epidemiological profile of Acinetobacter b aumannii (A.baumannii ) bacteremia in the microbiology laboratory of CHU Mohammed VI of Oujda and its antibiotic resistance rates. This is a retrospective and descriptive study of 27 months from June 24, 2016to September 19, 2018 including all positive blood cultures processed in the microbiology laboratory in accordance with REMIC (reference in medical microbiology)and EUCAST(European Committee on Antimicrobial Susceptibility Testing). Contaminated blood cultures were excluded. As results we collected 863 positive blood cultures, A. baumannii accounted for 7.41% (n = 64). 67% (n =43) of the strains were isolated from patients hospitalized in intensive care (adults, children and newborns). The two main risk factors described in patients with our series were wearing of intravascular device in 55% (n=35) Immunosuppression in 22% n=14). A. baumannii bacteremia was associated with care in 37.5% (n=24). 75% (n=48) of A. baumannii isolates were resistant to carbapenems. No strain of A. baumannii was resistant to colistin. In light of these results strengthening the control and prevention measures for healthcare associated infections would be the most reliable way to limit the spread of A. baumannii in our establishment.

Culture-Based Antimicrobial Susceptibility Testing for Helicobacter pylori.

Culture-based antimicrobial susceptibility testing is a crucial method for the management of Helicobacter pylori infection . It must follow the European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations for fastidious microaerophilic bacteria, with some possible variation especially for the medium to be used. It is recommended to test six antibiotics by diffusion using strips charged with an antibiotic gradient in order to determine the minimum inhibitory concentrations (MICs). Two of these antibiotics, clarithromycin and levofloxacin, are more important because of frequent resistance which jeopardizes the success of the treatment.

Agarda Dilüsyon ve Deneme Aşamasındaki EUCAST Disk Difüzyon Yöntemi ile Saptanan Bacteroides fragilis Grubu İzolatlarına Ait Antimikrobiyal Duyarlılık Sonuçlarının Karşılaştırılması

Objective: In this study it was aimed to determine the antimicrobial susceptibility of Bacteroides fragilis group (BFG) bacteria using recently developed European Committee on Antimicrobial Susceptibility Testing (EUCAST) disc diffusion method and agar dilution method recommended by Clinical Laboratory Standart Institude (CLSI) for anaerobes and to investigate the agreement of the results of two tests. Method: The antimicrobial susceptibilities of a total of 56 BFG strains isolated from clinical samples and identified by MALDI-TOF MS analysis between January 2017 and December 2018, were tested to ampicillin, ampicillin/sulbactam, cefoxitin, imipenem, clindamycin, tigecycline, moxifloxacin and metronidazole MICs were determined by agar dilution method using sheep blood supplemented Brucella agar and disk diffusion test using host blood supplemented Fastidius Anaerobic Agar (FAA). Results: Six different BFG species consisting mostly strains of Bacteroides fragilis (n=34, 61%) and Bacteroides thetaiotaomicron (n=11, 20%) isolated from various clinical samples such as intraabdominal abscess (n= 24), blood (n=10) and tissue biopsy samples (n=11).were identified. Imipenem and metronidazole were the most effective antimicrobials with 98.2% susceptibility rates, followed by tigecycline, ampicillin/sulbactam, moxifloxacin and clindamycin with susceptibility rates of 89.3%, 66.1%, 57.1% and 46.4%, respectively. Most concordant results were obtained with metronidazole (100%), imipenem (89.8%) and tigecycline (89.8%). Acceptable compliance rates were not found for other antimicrobials. Conclusion: We can say that disc diffusion method is a fast, easy-to-apply, and reliable method used in clinical microbiology laboratories to determine the susceptibility of BFG bacteria to metronidazole, imipenem and tigecycline. However, to evolve a standard method especially for other antimicrobials, the experimental conditions should be optimized with studies dome with greater number of isolates.

Kolistin Duyarlılık Testi İçin Diagnostics Colistin MIC-Strip Testinin Değerlendirilmesi*

Due to the limited number of antimicrobials to be used in the treatment of infections caused by Gram-negative microorganisms with multi-drug resistance recently, old antibiotics such as colistin have started to be preferred frequently. However, some problems are encountered in antibiotic susceptibility tests (disk diffusion, gradient test, automated systems) which are frequently used in the routine laboratory due to the cationic nature of colistin. For this reason, only the broth microdilution test is recommended by European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) for the detection of colistin susceptibility. Since broth microdilution tests are time consuming and inconvenient, tests that can provide fast and reliable colistin susceptibility result is needed in routine laboratories. In this study, it was aimed to evaluate the performance of the commercially produced Diagnostics MIC-COL test (Diagnostics I.n.c, Galanta, Slovakia) for the detection of colistin susceptibility in Klebsiella pneumoniae and Acinetobacter baumannii strains. The strains of K.pneumoniae (n = 22) and A.baumannii (n = 28) isolated from various clinical specimens between 2016 and 2019 in our routine laboratory were included in the study. Colistin minimum inhibitory concentrations (MIC) of the strains were studied with both the reference broth microdilution method and the commercially produced Diagnostics Colistin MIC-COL test. The essential agreement, categorical agreement, major error, and very major error rates of the test were calculated by comparing the obtained results. The essential agreement of the Diagnostics Colistin MIC-Strip test was determined as 84 %, categorical agreement as 98 %, and major error rate as 3.8 %, while no very major error was detected. İt is very important to guide antimicrobial treatment with rapid and reliable detection of colistin susceptibility. The commercial test used in our study is easy to use and not time-consuming. Also, due to its strip from, each isolate can be studied separately. Because of the major error rate being above the expected values, it will be useful to re-evaluate these rates with further studies to be conducted with a larger number of strains with different resistance levels.