Oral beta-lactam antimicrobials are not routinely tested against Streptococcus pneumoniae due to presumed susceptibility based upon penicillin minimum inhibitory concentration (MIC) testing. ...Currently, Clinical and Laboratory Standards Institute provides comments to use penicillin MIC less than or equai to0.06 to predict oral cephalosporin susceptibility. However, no guidance is provided when cefotaxime MIC is known, leading to uncertainty with interpretation. The purpose of this study was to evaluate cefotaxime and penicillin MICs and their respective correlation to oral beta-lactam categorical susceptibility patterns. 249 S. pneumoniae isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF) and then tested by broth microdilution method to penicillin, cefotaxime, amoxicillin, cefdinir, cefpodoxime, and cefuroxime. Using Clinical and Laboratory Standards Institute (CLSI) non-meningitis breakpoints for cefotaxime, 240/249 isolates were classified as susceptible. Of the cefotaxime susceptible isolates, 23% of the isolates are misrepresented as cefdinir susceptible. Amoxicillin correlated well with penicillin MIC breakpoints with only 1 discordant isolate out of 249. The correlation between amoxicillin and penicillin creates a very reliable predictor to determine categorical susceptibility. However oral cephalosporins were not well predicted by either penicillin or cefotaxime leading to the possible risk of treatment failures. Caution should be used when transitioning to oral cephalosporins in cefotaxime susceptible isolates, especially with higher cefotaxime MICs.
Rapid identification of pathogens in normally sterile body fluid (NSBF) is essential for appropriate patient management, specifically antimicrobial therapy. Limited sensitivity and increased time to ...detection of traditional culture prompted us to evaluate additional testing to contribute to the diagnosis of infection. The purpose of this study was to evaluate the GenMark Dx ePlex Blood Culture Identification (BCID) Panels on positive body fluids inoculated into blood culture bottles for the detection of microorganisms. A total of 88 positive body fluids from blood culture bottles were analyzed using a Gram-Positive, Gram-Negative, and/or Fungal pathogen BCID Panel based on the Gram stain result. Each result was compared to routine culture performed from the positive bottle. When using culture as a reference standard, we found the ePlex multiplex panel performed with a positive percent agreement of 96.5% and a negative percent agreement of 99.8%. The use of multiplex PCR may be a useful supplement to routine culture for NSBF in blood culture bottles.
The identification of pathogens in normally sterile body fluid (NSBF) is performed using routine culture, the current gold standard. Limitations of this method include sensitivity and increased turnaround times which could potentially delay vital patient care, especially antimicrobial therapy. Adaptations of NSBF in blood culture bottles prompted us to consider the utility of additional methods to bridge the gap in diagnostic challenges for these life-threatening infections. Multiplex molecular panels have been manufactured for use with multiple specimen types including blood, cerebral spinal fluid, stool, and respiratory. Therefore, the purpose of this study was to evaluate the off-label use of ePlex Blood Culture Identification Panels on positive body fluids grown in blood culture bottles for the detection of microorganisms for research purposes.
Multi-drug resistant (MDR) Acinetobacter baumannii (Ab) and Acinetobacter spp. present monumental global health challenges. These organisms represent model Gram-negative pathogens with known ...antibiotic resistance and biofilm-forming properties. Herein, a novel, nontoxic biocide, AB569, consisting of acidified nitrite (A-NO2-) and ethylenediaminetetraacetic acid (EDTA), demonstrated bactericidal activity against all Ab and Acinetobacter spp. strains, respectively. Average fractional inhibitory concentrations (FICs) of 0.25 mM EDTA plus 4 mM A-NO2- were observed across several clinical reference and multiple combat wound isolates from the Iraq/Afghanistan wars. Importantly, toxicity testing on human dermal fibroblasts (HDFa) revealed an upper toxicity limit of 3 mM EDTA plus 64 mM A-NO2-, and thus are in the therapeutic range for effective Ab and Acinetobacter spp. treatment. Following treatment of Ab strain ATCC 19606 with AB569, quantitative PCR analysis of selected genes products to be responsive to AB569 revealed up-regulation of iron regulated genes involved in siderophore production, siderophore biosynthesis non-ribosomal peptide synthetase module (SBNRPSM), and siderophore biosynthesis protein monooxygenase (SBPM) when compared to untreated organisms. Taken together, treating Ab infections with AB569 at inhibitory concentrations reveals the potential clinical application of preventing Ab from gaining an early growth advantage during infection followed by extensive bactericidal activity upon subsequent exposures.
The aim was to assess the potential advantage of combined genotypic testing with phenotypic antimicrobial susceptibility testing (AST) to detect AmpC β-lactamases (AmpC) and extended-spectrum ...β-lactamases (ESBL) producing Enterobacteriaceae isolated from blood cultures in a pediatric population.
All first-time Enterobacteriaceae isolates recovered from blood cultures of pediatric patients at the Cincinnati Children's Hospital Medical Center between January 2017 and December 2018 were evaluated. The Check-MDR CT103XL β-lactamase assay was used to determine the presence of AmpC and ESBL, while AST was performed using the VITEK 2 platform. Phenotypic ESBL resistance was defined by resistance to either ceftriaxone or ceftazidime using Clinical and Laboratory Standards Institute breakpoints, while combined cefoxitin resistance with ceftriaxone or ceftazidime resistance was used to detect AmpCs (as per European Committee on Antimicrobial Susceptibility Testing standards).
Overall, there were 170 isolates. Genotypically, 21 (12.4%) had AmpC and 18 (10.6%) had ESBL genes detected. Phenotypically, 11 (6.5%) isolates were AmpC and 26 (15.3%) were ESBL producing organisms. Genotypic testing identified an additional 14 AmpC and two ESBL isolates that failed to meet phenotypic criteria.
Using combined genotypic and phenotypic methods to detect AmpC and ESBL producing organisms increased the identification of resistant organism and provided potentially clinical relevant data to guide the treatment of resistant organisms.
Abstract The Check-MDR CT103XL beta-lactamase assay was validated for use in the clinical microbiology laboratory using two CDC-FDA Antimicrobial Resistant Isolate Bank panels (133 gram-negative ...bacilli known beta-lactamase genes). The CT103XL detected most reported resistance genes (123 of 136 genes) and additionally identified several resistance genes not reported by the CDC. Discrepant results were confirmed via whole genome sequencing.
Background. Diagnosis of Trichomonas vaginalis (TV) infection is limited by imperfect testing methods. Newer tests, such as rapid antigen and nucleic acid amplification tests, are often compared with ...culture, which is not widely used but is more sensitive than wet mount. We assessed the sensitivity and specificity of 4 tests for the identification of TV using 3 statistical approaches. Methods. Sexually active adolescent women aged 14–21 years (n = 330) were recruited from a teen health center and emergency department. Vaginal swabs were tested for TV using wet mount, culture (InPouch TV; Biomed Diagnostics), rapid antigen testing (OSOM TV; Genzyme Diagnostics), and transcription-mediated amplification testing (TMA; APTIMA TV analyte specific reagents; Gen-Probe). Results. TV was detected in 61 participants (18.5%). Compared with a composite reference standard (i.e., any TV test with positive results), the sensitivities of wet mount, culture, rapid antigen testing, and TMA were 50.8%, 75.4%, 82%, and 98.4%, respectively. Using latent class analysis, the sensitivity of wet mount (56%) was significantly lower than that of other tests, and the sensitivities of culture and rapid antigen testing were similar (83% and 90%, respectively); specificity was 100% for each of these 3 methods. TMA had a sensitivity of 98.2% and a specificity of 98%. Tests performed equally well regardless of whether the participant had bleeding or other infections. The sensitivities of the rapid antigen test and TMA were comparable (92.5% and 97.5%, respectively) in women who had vaginal symptoms. Conclusions. Wet mount alone is insufficient for the reliable diagnosis of TV infection in women. TMA and rapid antigen tests are highly sensitive and specific, and both are superior to wet mount. Rapid antigen testing is equivalent to culture, and it compares favorably with the sensitivity of TMA for the detection of TV.
Total-Fix, Cary-Blair, and Para-Pak SVT parasite transport systems were compared to 10% formalin with the BD MAX Enteric Parasite Panel, using clinical and contrived samples to determine ...comparability and limits of detection. The three transport systems have equal or superior limits of detection for all pathogens tested compared to 10% formalin.
•BD MAX™ Enteric Parasite Panel is a molecular test designed to detect Giardia lamblia, Cryptosporidium species, and Entamoeba histolytica.•Specimen requirements are fresh stool or stool fixed in 10% formalin, a hazardous risk for laboratories.•Alternate stool transport systems were tested with BD MAX™ Enteric Parasite Panel for comparability to 10% formalin.•Three alternate transport systems tested (Cary-Blair, Total Fix™, and Meridian Bioscience SVT™) may offer some advantages in safety and limits of detection.
Streptococcus constellatus and Streptococcus intermedius in subgingival dental plaque biofilms may contribute to forms of periodontitis that resist treatment with conventional mechanical root ...debridement/surgical procedures and may additionally participate in some extraoral infections. Because systemic antibiotics are often used in these clinical situations, and little is known of the antibiotic susceptibility of subgingival isolates of these two bacterial species, this study determined the in vitro susceptibility to six antibiotics of fresh S. constellatus and S. intermedius clinical isolates from human periodontitis lesions.
A total of 33 S. constellatus and 17 S. intermedius subgingival strains, each recovered from separate patients with severe chronic periodontitis (n = 50) before treatment, were subjected to antibiotic gradient strip susceptibility testing with amoxicillin, azithromycin, clindamycin, ciprofloxacin, and doxycycline on blood-supplemented Mueller-Hinton agar and to the inhibitory effects of metronidazole at 16 mg/L in an enriched Brucella blood agar dilution assay. Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing interpretative standards were used to assess the results.
Clindamycin was the most active antibiotic against S. constellatus (minimum inhibitory concentration at 90% MIC90 0.25 mg/L), and amoxicillin was most active against S. intermedius (MIC90 0.125 mg/L). A total of 30% of the S. constellatus and S. intermedius clinical isolates were resistant in vitro to doxycycline, 98% were only intermediate in susceptibility to ciprofloxacin, and 90% were resistant to metronidazole at 16 mg/L.
Subgingival S. constellatus and S. intermedius exhibited variable antibiotic susceptibility profiles, potentially complicating empirical selection of periodontitis antibiotic therapy in patients who are species positive.
PDF
