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| 2. |
- Göransson, J., et al.
(författare)
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Performance of a System for Rapid Phenotypic Antimicrobial Susceptibility Testing of Gram-Negative Bacteria Directly from Positive Blood Culture Bottles
- 2023
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 61:3
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Tidskriftsartikel (refereegranskat)abstract
- The rapid administration of optimal antimicrobial treatment is paramount for the treatment of bloodstream infections (BSIs), and rapid antimicrobial susceptibility testing (AST) results are essential. Q-linea has developed the ASTar system, a rapid phenotypic AST device. Here, we report the performance of the ASTar BC G- (Gram-negative) kit when assessed according to the ISO 20776-2:2007 standard for performance evaluation of in vitro diagnostic AST devices. The evaluated ASTar BC G- kit uses a broad panel of 23 antimicrobials for the treatment of BSIs caused by Gram-negative fastidious and nonfastidious bacteria across a range of 6 to 14 2-fold dilutions, including cefoxitin as a screening agent for AmpC-producing Enterobacterales. The ASTar system processes blood culture samples to generate data on MICs and susceptible, intermediate, or resistant (SIR) category. The automated protocol includes concentration determination and concentration adjustment to enable a controlled inoculum, followed by broth microdilution (BMD) and microscopy performed continuously to generate MIC values within approximately 6 h once the test is run on the ASTar system. The performance of the ASTar system was assessed against the ISO 20776-2:2007 standard BMD reference method. Testing was performed across three sites, with results from 412 contrived blood cultures and 74 fresh clinical blood cultures. The ASTar system was also tested for reproducibility, with triplicate testing of 11 strains. The accuracy study comprised 8,650 data points of bacterium-antimicrobial tests. The ASTar system demonstrated an overall essential agreement (EA) of 95.8% (8,283/8,650) and a categorical agreement (CA) of 97.6% (8,433/8,639) compared to the reference BMD method. The overall rate of major discrepancies (MDs) was 0.9% (62/6,845), and that of very major discrepancies (VMDs) was 2.4% (30/1,239). This study shows that the ASTar system delivers reproducible results with overall EA and CA of >95%.
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| 3. |
- Hilmarsdóttir, Ingibjörg, et al.
(författare)
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Prevalence of Mycoplasma genitalium and antibiotic resistance-associated mutations in an Icelandic STI population, and comparison of the S-DiaMGTV and Aptima Mycoplasma genitalium assays for diagnosis
- 2020
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 58:9
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Mycoplasma genitalium (MG) is prevalent among attendees in sexually transmitted infections (STI) clinics and therapy is hampered by rapidly rising levels of resistance to azithromycin and moxifloxacin. In this study we evaluated, for the first time in Iceland, the prevalence of MG and azithromycin and moxifloxacin resistance-associated mutations, and assessed the diagnostic performance of the CE/IVD-marked S-DiaMGTV (Diagenode Diagnostics) versus the US FDA/CE/IVD-approved Aptima MG (AMG; Hologic) for MG detection.Methods: From October 2018 to January 2019, urine and vaginal swabs were provided by male and female attendees at Iceland's only STI clinic. Specimens were tested with S-DiaMGTV and AMG, and resistance-associated mutations were determined by 23S rRNA gene and parC sequencing. Demographic and clinical data were collected from patient records.Results: MG prevalence was 9.3% overall; 7.7% (38/491) among male and 10.9% (53/487) among female participants. Azithromycin and moxifloxacin resistance-associated mutations were found in 57.0% (45/79) and 0.0% (0/80) of evaluable specimens, respectively. Sensitivity was 72.5% and 100%, and specificity was 99.9% and 100% for S-DiaMGTV and AMG, respectively. No association was found between MG and symptoms of urethritis in men.Conclusions: Prevalence rates for MG and azithromycin resistance-associated genes in Iceland are among the highest reported in Europe. The significantly higher sensitivity of AMG over that of S-DiaMGTV can have important clinical implications. More information is urgently needed to clarify the significance of false-negative results obtained with S-DiaMGTV and other similarly performing, widely used real-time PCR methods for diagnosis and management of this sexually transmitted infection.
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| 4. |
- Koser, Claudio U., et al.
(författare)
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On the Consequences of Poorly Defined Breakpoints for Rifampin Susceptibility Testing of Mycobacterium tuberculosis Complex
- 2021
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Ingår i: Journal of Clinical Microbiology. - : AMER SOC MICROBIOLOGY. - 0095-1137 .- 1098-660X. ; 59:4
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In a recent report of a systematic review of critical concentrations (CCs), the World Health Organization (WHO) lowered the rifampin (RIF) CC for antimicrobial susceptibility testing (AST) of the Mycobacterium tuberculosis complex using Middlebrook 7H10 medium and the Bactec Mycobacterial Growth Indicator Tube (MGIT) 960 system from 1 to 0.5mg/ ml. The previous RIF CC for 7H10 had been in use for over half a century. Because it had served as the de facto reference standard, it contributed to the endorsement of inappropriately high CCs for other AST methods, including the U.S. Food and Drug Administration (FDA)-approved MGIT system. Moreover, this resulted in confusion about the interpretation of seven borderline resistance mutations in rpoB (i.e., L430P, D435Y, H445L, H445N, H445S, L452P, and I491F). In this issue of the Journal of Clinical Microbiology, Shea et al. (J Clin Microbiol 59:e01885-20, 2021, https://doi.org/10.1128/JCM.01885-20) provide evidence that the CC endorsed by the Clinical and Laboratory Standards Institute for the Sensititre MYCOTB system, which is not FDA approved but is CE-IVD marked in the European Union, is likely also too high. These findings underscore the importance of calibrating AST methods against a rigorously defined reference standard, as recently proposed by the European Committee on Antimicrobial Susceptibility Testing, as well as the value of routine next-generation sequencing for investigating discordant AST results.
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| 5. |
- Larsson, Anna, et al.
(författare)
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Single-site sampling versus multi-site sampling for blood cultures; A retrospective clinical study
- 2022
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 60:2
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Tidskriftsartikel (refereegranskat)abstract
- Objectives The performance of blood cultures (BC) relies on optimal sampling. Sepsis guidelines do not specify which sampling protocol to use, but recommend two sets of BC bottles, each set containing one aerobic and one anaerobic bottle. For the single-site sampling (SSS) protocol, only one venipuncture is performed for all four bottles. The predominating multi-site sampling (MSS) protocol implies that BC bottles are collected from two separate venipuncture sites. The aim of this study was to compare SSS and MSS. Primary outcomes were number of BC sets collected, sample volume and diagnostic performance. Methods This was a retrospective clinical study comparing BC results in an emergency department before and after changing the sampling protocol to SSS from MSS. All BC samples were incubated in the BacT/ALERT BC system. Results The analysis included 5,248 patients before and 5,364 patients after the implementation of SSS. There was a significantly higher proportion of positive BCs sampled with SSS compared to MSS, 1,049/5,364 (19.56%) and 932/5,248 (17.76%) respectively (P=0.018). This difference was due to a higher proportion of solitary BC sets (two BC bottles) in MSS. Analyzing only patients with the recommended four BC bottles, there was no difference in positivity. SSS had a higher proportion of BC bottles with the recommended sample volumes of 8-12 ml than MSS (P<0.001). Conclusions Changing the sampling protocol to SSS from MSS resulted in higher positivity rates, higher sample volume and fewer solitary BC sets. These advantages of SSS should be considered in future sepsis guidelines.
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| 6. |
- Odeberg, Görel, et al.
(författare)
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Infection or Contamination with Rothia, Kocuria, Arthrobacter and Pseudoglutamicibacter — a Retrospective Observational Study of Non-Micrococcus Micrococcaceae in the Clinic
- 2023
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 1098-660X .- 0095-1137. ; 61:4, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Rothia, Kocuria, Arthrobacter, and Pseudoglutamicibacter are bacterial species within the family Micrococcaeae. Knowledge of human infections due to these bacteria is limited. This study aimed to examine features of infections caused by non-Micrococcus Micrococcaeae (NMM). Findings of NMM from blood cultures and other sterile cultures from 2012 to 2021 were identified from the records of the Department of Clinical Microbiology in Region Skåne, Lund, Sweden. Medical records were retrospectively reviewed. True infection was defined as having signs of infection, no other more likely pathogen, and no other focal infection, together with two positive blood cultures or one positive blood culture and an intravascular device. A total of 197 patients with findings of NMM in blood cultures were included. Among adult patients with bacteremia, 29 patients (22%) were considered to have a true infection. Adults with true infection were significantly more likely to have malignancy (69%), leukopenia (62%), and treatment with chemotherapeutics (66%) compared to patients with contaminated samples (24%, 3%, and 8%, respectively) (P
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| 7. |
- Salado-Rasmussen, Kirsten, et al.
(författare)
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Clinical Importance of Superior Sensitivity of the Aptima TMA-Based Assays for Mycoplasma genitalium Detection
- 2022
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 60:4
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Tidskriftsartikel (refereegranskat)abstract
- Mycoplasma genitalium (MG) is a common cause of nongonococcal cervicitis and urethritis. We investigated the demographic and clinical characteristics of patients tested in Denmark with the Conformité Européenne (CE)/in vitro diagnostics (IVD) Aptima Mycoplasma genitalium assay (CE/IVD AMG; Hologic) and examined the clinical significance of the higher sensitivity of the TMA-based MG assays. From March to June 2016, urogenital and extragenital specimens from consecutive attendees at a sexually transmitted infection clinic in Copenhagen, Denmark were tested with the CE/IVD AMG assay (TMA-based), the research-use-only MG Alt TMA-1 assay (Hologic), a laboratory-developed TaqMan mgpB quantitative real-time PCR (qPCR), and the Aptima Combo 2 (CT/NG; Hologic). Demographic characteristics and clinical symptoms were collected from the patient records. There were 1,245 patients included in the study. The MG prevalence among female subjects was 9.4%, and the MG prevalence among male subjects was 8.7%. Compared to the TMA-based assays, the sensitivity of the PCR-based MG assay was 64.52%, and 55 specimens from 48 individuals were missed in the mgpB qPCR. Of these, 26 individuals (54.2%) were symptomatic, whereas, among 64 individuals with concordant results, 30 individuals (46.9%) were symptomatic; no statistically significant difference was found between the groups (P = 0.567). The improved sensitivity of the TMA-based assays resulted in diagnoses of more patients with clinically relevant symptoms for which antibiotic treatment is indicated. However, approximately half of the MG-infected patients reported no symptoms, and future research is needed to investigate the pros and cons of diagnosing and treating MG in asymptomatic subjects.
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| 8. |
- Strålin, Kristoffer, et al.
(författare)
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Performance of PCR/electrospray ionization-mass spectrometry on whole blood for detection of bloodstream microorganisms in patients with suspected sepsis
- 2020
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 58:9, s. e01860-19
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Tidskriftsartikel (refereegranskat)abstract
- Blood culture (BC) often fails to detect bloodstream microorganisms in sepsis. However, molecular diagnostics hold great potential. The molecular method PCR/electrospray ionization-mass spectrometry (PCR/ESI-MS) can detect DNA from hundreds of different microorganisms in whole blood. The aim of the present study was to evaluate the performance of this method in a multicenter study including 16 teaching hospitals in the USA (n=13) and Europe (n=3). First, on 2,754 contrived whole blood samples, with or without spiked microorganisms, PCR/ESI-MS produced 99.1% true positive and 97.2% true negative results. Secondly, among 1,460 patients with suspected sepsis (sepsis-2 definition), BC and PCR/ESI-MS on whole blood were positive in 14.6% and 25.6% of cases, respectively, with the following result combinations: BC+/PCR/ESI-MS-, 4.3%; BC+/PCR/ESI-MS+, 10.3%; BC-/PCR/ESI-MS+, 15.3%; and BC-/PCR/ESI-MS-, 70.1%. Compared with BC, PCR/ESI-MS showed the following sensitivities (coagulase-negative staphylococci not included): Gram-positive bacteria, 58%; Gram-negative bacteria, 78%; and Candida species, 83%. The specificities were > 94% for all individual species. Patients treated with prior antimicrobial medications (n=603) had significantly increased PCR/ESI-MS positivity rates compared with patients without prior antimicrobial treatment, 31% vs 22% (p<0.0001), with pronounced differences for Gram-negative bacteria and Candida species. In conclusion, PCR/ESI-MS showed excellent performance on contrived samples. On clinical samples, it showed high specificities, moderately high sensitivities for Gram-negative bacteria and Candida species, and elevated positivity rates during antimicrobial treatment. These promising results encourage further development of molecular diagnostics on whole blood for detection of bloodstream microorganisms in sepsis.
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| 9. |
- Tesfaye, Fregenet, et al.
(författare)
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Longitudinal Mycobacterium tuberculosis-specific Interferon Gamma responses in Ethiopian HIV-negative women during pregnancy and postpartum
- 2021
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Ingår i: Journal of Clinical Microbiology. - 0095-1137. ; 59:10
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Tidskriftsartikel (refereegranskat)abstract
- Pregnancy may influence cellular immune responses to Mycobacterium tuberculosis. We investigated M. tuberculosis-specific interferon-g responses in women followed longitudinally during pregnancy and postpartum. Interferon-g levels (stimulated by M. tuberculosis antigens [TB1 and TB2] and mitogen included in the QuantiFERON-TB Gold Plus assay) were measured in blood from pregnant HIV-negative women identified from a prospective cohort at Ethiopian antenatal care clinics. Longitudinal comparisons included women without active tuberculosis (TB) with M. tuberculosis-triggered interferon-g responses of $ 0.20 IU/ml, sampled on two and/or three occasions (1st/2nd trimester, 3rd trimester, and 9 months postpartum). Among 2,093 women in the source cohort, 363 met inclusion criteria for longitudinal comparisons of M. tuberculosis-stimulated interferon-g responses. Median M. tuberculosis-triggered interferon-g concentrations were higher at 3rd than those at the 1st/2nd trimester (in 38 women with samples available from these time points; TB1: 2.8 versus 1.6 IU/ml, P = 0.005; TB2: 3.3 versus 2.8 IU/ml, P = 0.03) and postpartum (in 49 women with samples available from these time points; TB1: 3.1 versus 2.2 IU/ml, P = 0.01; TB2: 3.1 versus 2.3 IU/ml, P = 0.03). In contrast, mitogen-stimulated interferon-g levels were lower at 3rd than those at 1st/2nd trimester (in 32 women with samples available from these time points: 21.0 versus 34.9 IU/ml, P = 0.02). Results were similar in 22 women sampled on all 3 occasions. In HIV-negative women, M. tuberculosis-stimulated interferon-g responses were higher during the 3rd trimester than those at earlier stages of pregnancy and postpartum, despite decreased mitogen-triggered responses. These findings suggest increased M. tuberculosis-specific cellular responses due to dynamic changes of latent TB infection during pregnancy.
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| 10. |
- Werinder, Anna, et al.
(författare)
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Whole-Genome Sequencing Evaluation of MALDI-TOF MS as a Species Identification Tool for Streptococcus suis
- 2021
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 59
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus suis is an important bacterial pathogen in pigs that may also cause zoonotic disease in humans. The aim of the study was to evaluate matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identification of S. suis case isolates from diseased pigs and tonsil isolates from healthy pigs and wild boar using sequence analysis methods. Isolates (n = 348) that had been classified as S. suis by MALDI-TOF MS were whole-genome sequenced and investigated using analyses of (i) the 16S rRNA gene, (ii) the recN gene, and (iii) whole-genome average nucleotide identity (ANI). Analysis of the 16S rRNA gene indicated that 82.8% (288 out of 348) of the isolates were S. suis, while recN gene analysis indicated that 75.6% (263 out of 348) were S. suis. ANI analysis classified 44.3% (154 out of 348) as S. suis. In total, 44% (153 out of 348) of the investigated isolates were classified as S. suis by all of the species identification methods employed. The mean MALDI-TOF MS score was significantly higher for the S. suis case isolates than for the tonsil isolates; however, the difference is of limited practical use. The results show that species confirmation beyond MALDI-TOF MS is needed for S. suis isolates. Since the resolution of 16S rRNA gene analysis is too low for Streptococcus spp., ANI analysis with a slightly lowered cutoff of 94% may be used instead of, or in addition to, recN gene analysis. Supplementation of the MALDI-TOF MS reference library with mass spectra from S. orisratti, S. parasuis, S. ruminantium, and additional S. suis serotypes should be considered in order to produce more accurate classifications.
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