Reliability of phenotypic tests for identification of Acinetobacter species

Gerner‐Smidt, Peter; Tjernberg, Ingela; Ursing, Jan

doi:10.1128/jcm.29.2.277-282.1991

Cited by 289 publications

(155 citation statements)

References 18 publications

(23 reference statements)

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“…Willcox probability scores (Willcox et al 1973) were calculated and an identification accepted if ¼ 0AE99. A modal likelihood score, as the modal likelihood fraction (Dybowski and Franklin 1968) was calculated by pibwin as a measure of the goodnessof-fit for a most likely identification (Gerner-Smidt et al 1991;Bryant 2000); a satisfactory match was indicated when the modal likelihood score was ¼ 0AE01.…”

Section: Probabilistic Identificationmentioning

confidence: 99%

Changes to the phenotypic profile of Vibrio harveyi when infected with the Vibrio harveyi myovirus-like (VHML) bacteriophage

Vidgen

Carson²,

Higgins³

et al. 2006

J Appl Microbiol

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Aims: To determine if infection of Vibrio harveyi with the V. harveyi myovirus‐like (VHML) bacteriophage causes a change to the phenotypic profile of this species. Methods and Results: Using 46 biochemical and metabolic tests, phenotypic profiles for noninfected V. harveyi and VHML infected V. harveyi were developed. Comparison of the infected and bacteriophage‐infected strains of V. harveyi 645, 20 and 45 were found to have different test results for d‐gluconate utilization, γ‐glutamyl transpeptidase and sulfatase activity, respectively. Using probabilistic identification, VHML infected and noninfected strains were identified as V. harveyi and had similar Willcox probability scores though the modal likelihood scores were reduced for VHML infected strains. One VHML infected strain, 642b, was misidentified as V. campbellii by phenotyping but not by PCR. It would appear that the phenotype of V. harveyi strains infected with VHML, are sufficiently altered that they occur at the margins of the known range of strain variation for V. harveyi. Conclusion: Infection of V. harveyi with VHML causes the phenotypic profile of the bacterium to change. This change reduces the modal likelihood score resulting in a poorer level of assurance for an identification of V. harveyi, especially in the natural host, strain 642. The bacteriophage VHML integrates into different sites in different strains of V. harveyi. Significance and Impact of the Study: The identification of V. harveyi as the causative agent of mortality in aquatic organisms is predominantly achieved through phenotyping. Since bacteriophages alter virulence in V. harveyi, understanding the effect they have on phenotype is important.

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Section: Probabilistic Identificationmentioning

confidence: 99%

Changes to the phenotypic profile of Vibrio harveyi when infected with the Vibrio harveyi myovirus-like (VHML) bacteriophage

Vidgen

Carson²,

Higgins³

et al. 2006

J Appl Microbiol

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“…Due to the high level of genotypic and phenotypic similarity among Acinetobacter calcoaceticus, A. baumannii, Acinetobacter genomic species 13TU and Acinetobacter genomic species 3, they are grouped together as the A. calcoaceticus-A. baumannii (Ac-Ab) complex [25].…”

Section: Discussionmentioning

confidence: 99%

Real-Time Fluorescence Loop Mediated Isothermal Amplification for the Detection of Acinetobacter baumannii

Wang

Zhou

et al. 2013

PLoS ONE

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BackgroundDetection of Acinetobacter baumannii has been relying primarily on bacterial culture that often fails to return useful results in time. Although DNA-based assays are more sensitive than bacterial culture in detecting the pathogen, the molecular results are often inconsistent and challenged by doubts on false positives, such as those due to system- and environment-derived contaminations. In addition, these molecular tools require expensive laboratory instruments. Therefore, establishing molecular tools for field use require simpler molecular platforms. The loop-mediated isothermal amplification method is relatively simple and can be improved for better use in a routine clinical bacteriology laboratory. A simple and portable device capable of performing both the amplification and detection (by fluorescence) of LAMP in the same platform has been developed in recent years. This method is referred to as real-time loop-mediated isothermal amplification. In this study, we attempted to utilize this method for rapid detection of A. baumannii.Methodology and Significant FindingsSpecies-specific primers were designed to test the utility of this method. Clinical samples of A. baumannii were used to determine the sensitivity and specificity of this system compared to bacterial culture and a polymerase chain reaction method. All positive samples isolated from sputum were confirmed to be the species of Acinetobacter by 16S rRNA gene sequencing. The RealAmp method was found to be simpler and allowed real-time detection of DNA amplification, and could distinguish A. baumannii from Acinetobacter calcoaceticus and Acinetobacter genomic species 3. DNA was extracted by simple boiling method. Compared to bacterial culture, the sensitivity and specificity of RealAmp in detecting A. baumannii was 98.9% and 75.0%, respectively.ConclusionThe RealAmp assay only requires a single unit, and the assay positivity can be verified by visual inspection. Therefore, this assay has great potential of field use as a molecular tool for detection of A. baumannii.

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“…Many species in the Acinetobacter genus, such as Acinetobacter genomospecies 3 and Acinetobacter genomospecies 13, are more recently recognized as important but distinct nosocomial pathogens (Higgins et al 2007). However, detection of these particular organisms is complicated because they are closely related genetically (gyrB) and difficult to differentiate phenotypically (Gerner-Smidt et al 1991;Gerner-Smidt 1992;Yamamoto et al 1998;Higgins et al 2007). Therefore, these unnamed species tend to be grouped with Acinetobacter calcoaceticus in the Ac.…”

Section: Discussionmentioning

confidence: 99%

“…baumannii specificity observed in this assay may or may not prove useful for clinical diagnostics, as treatment may be the same regardless of the Acinetobacter infection. Some researchers have questioned whether there is a need for species identification amongst the Acinetobacter genus (Gerner-Smidt et al 1991). Others argue that it is necessary to distinguish between the Ac.…”

Section: Discussionmentioning

confidence: 99%

Verification of monoplex and multiplex linear-after-the-exponential PCR gene-specific sepsis assays using clinical isolates

et al. 2013

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Aims: To verify monoplex and multiplex gene-specific linear-after-theexponential polymerase chain reaction (LATE-PCR) assays for identifying 17 microbial pathogens (i.e., Klebsiella sp., Acinetobacter baumannii, Staphylococcus aureus, Enterobacter sp., Pseudomonas aeruginosa, coagulase negative staphylococci, Enterococcus sp., Candida sp.) commonly associated with septicaemia using clinical isolates. Methods and Results: Clinical isolates of each target pathogen were collected from the University of California, Davis Medical Center (UCDMC) microbiology laboratory. Five microlitres (ll) of each culture suspension (1 9 10 8 CFU ml À1 ) were added to 20 ll of monoplex mastermix. DNAextracted from clinical isolates was tested in multiplex. Monoplex assays demonstrated 100% sensitivity at this input level, except Enterobacter cloacae (2Á7%), Ac. baumannii (57%) and Ps. aeruginosa (97Á8%). All clinical isolates were positive in multiplex, with the exception of two Ac. baumannii, two Klebsiella oxytoca and two Candida parapsilosis isolates. Conclusions: Sixteen pathogens can be identified by monoplex LATE-PCR assays with sensitivities ! 97Á8%. The multiplex assay demonstrated 91Á4% sensitivity when tested with DNA extracted from 70 different target strains. Significance and Impact of the Study: This study demonstrates the potential of LATE-PCR to serve as an adjunct to culture if the reagents are optimized for sensitivity. Results warrant further testing through analytical and clinical validation of the multiplex assay.

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Reliability of phenotypic tests for identification of Acinetobacter species

Cited by 289 publications

References 18 publications

Changes to the phenotypic profile of Vibrio harveyi when infected with the Vibrio harveyi myovirus-like (VHML) bacteriophage

Changes to the phenotypic profile of Vibrio harveyi when infected with the Vibrio harveyi myovirus-like (VHML) bacteriophage

Real-Time Fluorescence Loop Mediated Isothermal Amplification for the Detection of Acinetobacter baumannii

Verification of monoplex and multiplex linear-after-the-exponential PCR gene-specific sepsis assays using clinical isolates

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