Development and validation of a next-generation sequencing assay with open-access analysis software for detecting resistance-associated mutations in CMV.

Cytomegalovirus (CMV) resistance testing by targeted next-generation sequencing (NGS) allows for the simultaneous analysis of multiple genes. We developed and validated an amplicon-based Ion Torrent NGS assay to detect CMV resistance mutations in UL27, UL54, UL56, and UL97 and compared the results to standard Sanger sequencing. NGS primers were designed to generate 83 overlapping amplicons of four CMV genes (~10 kb encompassing 138 mutation sites). An open-access software plugin was developed to perform read alignment, call variants, and interpret drug resistance. Plasmids were tested to determine NGS error rate and minor variant limit of detection. NGS limit of detection was determined using the CMV WHO International Standard and quantified clinical specimens. Reproducibility was also assessed. After establishing quality control metrics, 185 patient specimens previously tested using Sanger were reanalyzed by NGS. The NGS assay had a low error rate (<0.05%) and high accuracy (95%) for detecting CMV-associated resistance mutations present at ≥5% in contrived mixed populations. Mutation sites were reproducibly sequenced with 40× coverage when plasma viral loads were ≥2.6 log IU/mL. NGS detected the same resistance-associated mutations identified by Sanger in 68/69 (98.6%) specimens. In 16 specimens, NGS detected 18 resistance mutations that Sanger failed to detect; 14 were low-frequency variants (<20%), and six would have changed the drug resistance interpretation. The NGS assay showed excellent agreement with Sanger and generated high-quality sequence from low viral load specimens. Additionally, the higher resolution and analytic sensitivity of NGS potentially enables earlier detection of antiviral resistance.

HIV-1 Drug Resistance Assay Using Ion Torrent Next Generation Sequencing and On-Instrument End-to-End Analysis Software.

HIV-1 antiretroviral therapy management requires sequencing the protease, reverse transcriptase, and integrase portions of the HIV-1 pol gene. Most resistance testing is performed with Sanger sequencing, which has limited ability to detect minor variants. Next generation sequencing (NGS) platforms enable variant detection at frequencies as low as 1% allowing for earlier detection of resistance and modification of therapy. Implementation of NGS assays in the clinical laboratory is hindered by complicated assay design, cumbersome wet bench procedures, and the complexity of data analysis and bioinformatics. We developed a complete NGS protocol and companion analysis and reporting pipeline using AmpliSeq multiplex PCR, Ion Torrent S5 XL sequencing, and Stanford's HIVdb resistance algorithm. Implemented as a Torrent Suite software plugin, the pipeline runs automatically after sequencing. An optimum variant frequency threshold of 10% was determined by comparing Sanger sequences of archived samples from ViroSeq testing, resulting in a sensitivity of 98.2% and specificity of 99.0%. The majority (91%) of drug resistance mutations were detected by both Sanger and NGS, with 1.7% only by Sanger and 7.3% only by NGS. Variant calls were highly reproducible and there was no cross-reactivity to VZV, HBV, CMV, EBV, and HCV. The limit of detection was 500 copies/mL. The NGS assay performance was comparable to ViroSeq Sanger sequencing and has several advantages, including a publicly available end-to-end analysis and reporting plugin. The assay provides a straightforward path for implementation of NGS for HIV drug resistance testing in the laboratory setting without additional investment in bioinformatics infrastructure and resources.

Mycobacterium grossiae sp. nov., a rapidly growing, scotochromogenic species isolated from human clinical respiratory and blood culture specimens.

A previously undescribed, rapidly growing, scotochromogenic species of the genus Mycobacterium (represented by strains PB739T and GK) was isolated from two clinical sources - the sputum of a 76-year-old patient with severe chronic obstructive pulmonary disease, history of tuberculosis exposure and Mycobacterium avium complex isolated years prior; and the blood of a 15-year-old male with B-cell acute lymphoblastic leukaemia status post bone marrow transplant. The isolates grew as dark orange colonies at 25-37 °C after 5 days, sharing features in common with other closely related species. Analysis of the complete 16S rRNA gene sequence (1492 bp) of strain PB739T demonstrated that the isolate shared 98.8 % relatedness with Mycobacterium wolinskyi. Partial 429 bp hsp65 and 744 bp rpoB region V sequence analyses revealed that the sequences of the novel isolate shared 94.8 and 92.1 % similarity with those of Mycobacterium neoaurum and Mycobacterium aurum, respectively. Biochemical profiling, antimicrobial susceptibility testing, HPLC/gas-liquid chromatography analyses and multilocus sequence typing support the taxonomic status of these isolates (PB739T and GK) as representatives of a novel species. Both isolates were susceptible to the Clinical and Laboratory Standards Institute recommended antimicrobials for susceptibility testing of rapidly growing mycobacteria including amikacin, ciprofloxacin, moxifloxacin, doxycycline/minocycline, imipenem, linezolid, clarithromycin and trimethropin/sulfamethoxazole. Both isolates PB739T and GK showed intermediate susceptibility to cefoxitin. We propose the name Mycobacterium grossiae sp. nov. for this novel species and have deposited the type strain in the DSMZ and CIP culture collections. The type strain is PB739T (=DSM 104744T=CIP 111318T).

Human Bocavirus Capsid Messenger RNA Detection in Children With Pneumonia.

Background: The role of human bocavirus (HBoV) in respiratory illness is uncertain. HBoV genomic DNA is frequently detected in both ill and healthy children. We hypothesized that spliced viral capsid messenger RNA (mRNA) produced during active replication might be a better marker for acute infection. Methods: As part of the Etiology of Pneumonia in the Community (EPIC) study, children aged <18 years who were hospitalized with community-acquired pneumonia (CAP) and children asymptomatic at the time of elective outpatient surgery (controls) were enrolled. Nasopharyngeal/oropharyngeal specimens were tested for HBoV mRNA and genomic DNA by quantitative polymerase chain reaction. Results: HBoV DNA was detected in 10.4% of 1295 patients with CAP and 7.5% of 721 controls (odds ratio [OR], 1.4 [95% confidence interval {CI}, 1.0-2.0]); HBoV mRNA was detected in 2.1% and 0.4%, respectively (OR, 5.1 [95% CI, 1.6-26]). When adjusted for age, enrollment month, and detection of other respiratory viruses, HBoV mRNA detection (adjusted OR, 7.6 [95% CI, 1.5-38.4]) but not DNA (adjusted OR, 1.2 [95% CI, .6-2.4]) was associated with CAP. Among children with no other pathogens detected, HBoV mRNA (OR, 9.6 [95% CI, 1.9-82]) was strongly associated with CAP. Conclusions: Detection of HBoV mRNA but not DNA was associated with CAP, supporting a pathogenic role for HBoV in CAP. HBoV mRNA could be a useful target for diagnostic testing.

Viral Pathogen Detection by Metagenomics and Pan-Viral Group Polymerase Chain Reaction in Children With Pneumonia Lacking Identifiable Etiology.

Background: Community-acquired pneumonia (CAP) is a leading cause of pediatric hospitalization. Pathogen identification fails in approximately 20% of children but is critical for optimal treatment and prevention of hospital-acquired infections. We used two broad-spectrum detection strategies to identify pathogens in test-negative children with CAP and asymptomatic controls. Methods: Nasopharyngeal/oropharyngeal (NP/OP) swabs from 70 children <5 years with CAP of unknown etiology and 90 asymptomatic controls were tested by next-generation sequencing (RNA-seq) and pan viral group (PVG) PCR for 19 viral families. Association of viruses with CAP was assessed by adjusted odds ratios (aOR) and 95% confidence intervals controlling for season and age group. Results: RNA-seq/PVG PCR detected previously missed, putative pathogens in 34% of patients. Putative viral pathogens included human parainfluenza virus 4 (aOR 9.3, P = .12), human bocavirus (aOR 9.1, P < .01), Coxsackieviruses (aOR 5.1, P = .09), rhinovirus A (aOR 3.5, P = .34), and rhinovirus C (aOR 2.9, P = .57). RNA-seq was more sensitive for RNA viruses whereas PVG PCR detected more DNA viruses. Conclusions: RNA-seq and PVG PCR identified additional viruses, some known to be pathogenic, in NP/OP specimens from one-third of children hospitalized with CAP without a previously identified etiology. Both broad-range methods could be useful tools in future epidemiologic and diagnostic studies.

Taxonomer: an interactive metagenomics analysis portal for universal pathogen detection and host mRNA expression profiling.

BACKGROUND: High-throughput sequencing enables unbiased profiling of microbial communities, universal pathogen detection, and host response to infectious diseases. However, computation times and algorithmic inaccuracies have hindered adoption. RESULTS: We present Taxonomer, an ultrafast, web-tool for comprehensive metagenomics data analysis and interactive results visualization. Taxonomer is unique in providing integrated nucleotide and protein-based classification and simultaneous host messenger RNA (mRNA) transcript profiling. Using real-world case-studies, we show that Taxonomer detects previously unrecognized infections and reveals antiviral host mRNA expression profiles. To facilitate data-sharing across geographic distances in outbreak settings, Taxonomer is publicly available through a web-based user interface. CONCLUSIONS: Taxonomer enables rapid, accurate, and interactive analyses of metagenomics data on personal computers and mobile devices.

Unbiased Detection of Respiratory Viruses by Use of RNA Sequencing-Based Metagenomics: a Systematic Comparison to a Commercial PCR Panel.

Current infectious disease molecular tests are largely pathogen specific, requiring test selection based on the patient's symptoms. For many syndromes caused by a large number of viral, bacterial, or fungal pathogens, such as respiratory tract infections, this necessitates large panels of tests and has limited yield. In contrast, next-generation sequencing-based metagenomics can be used for unbiased detection of any expected or unexpected pathogen. However, barriers for its diagnostic implementation include incomplete understanding of analytical performance and complexity of sequence data analysis. We compared detection of known respiratory virus-positive (n= 42) and unselected (n= 67) pediatric nasopharyngeal swabs using an RNA sequencing (RNA-seq)-based metagenomics approach and Taxonomer, an ultrarapid, interactive, web-based metagenomics data analysis tool, with an FDA-cleared respiratory virus panel (RVP; GenMark eSensor). Untargeted metagenomics detected 86% of known respiratory virus infections, and additional PCR testing confirmed RVP results for only 2 (33%) of the discordant samples. In unselected samples, untargeted metagenomics had excellent agreement with the RVP (93%). In addition, untargeted metagenomics detected an additional 12 viruses that were either not targeted by the RVP or missed due to highly divergent genome sequences. Normalized viral read counts for untargeted metagenomics correlated with viral burden determined by quantitative PCR and showed high intrarun and interrun reproducibility. Partial or full-length viral genome sequences were generated in 86% of RNA-seq-positive samples, allowing assessment of antiviral resistance, strain-level typing, and phylogenetic relatedness. Overall, untargeted metagenomics had high agreement with a sensitive RVP, detected viruses not targeted by the RVP, and yielded epidemiologically and clinically valuable sequence information.

The Suspected Infected Prosthetic Joint: Clinical Acumen and Added Value of Laboratory Investigations.

Consensus definitions have emerged for the discrimination between infected and uninfected prosthetic joints but diagnostic uncertainty often occurs. We examined the accuracy of orthopaedic surgeons' assessments to diagnose the infected prosthetic hip or knee and elucidated the added value of laboratory parameters. A prospective cohort study of patients undergoing revision arthroplasty of hip or knee was conducted over a one-year period. Orthopaedic surgeons' determinations prior to arthroplasty were recorded. A reference diagnostic standard was determined retrospectively by independent review from 3 infectious diseases physicians. Patients were followed up to 12 months. For 198 patients enrolled, 228 surgical encounters (110 knee, 118 hip) were classified by independent reviewers as 176 uninfected and 52 infected. Orthopaedic surgeons' preoperative diagnoses of infection had high diagnostic accuracy (sensitivity 89%, specificity 99%, PPV 98%, NPV 97%). Addition of intraoperative findings and histopathology improved their diagnostic accuracy. Addition of culture and PCR results improved sensitivity of diagnostic determinations but not specificity. We provide evidence that clinical acumen has high diagnostic accuracy using routine preoperative parameters. Histopathology from intraoperative specimens would improve surgeons' diagnostic accuracy but culture and PCR from intraoperative specimens could create greater diagnostic uncertainty. This study is critical to further our understanding of the added value, if any, of laboratory testing to support clinical decision making for the suspected infected joint and allow us to identify diagnostic gaps for emerging technologies to fill that will improve our ability to diagnose the infected prosthetic joint.

Mycobacterium franklinii sp. nov., a species closely related to members of the Mycobacterium chelonae-Mycobacterium abscessus group.

Two isolates from water, D16Q19 and D16R27, were shown to be highly similar in their 16S rRNA, 16S-23S internal transcribed spacer (ITS), hsp65 and rpoB gene sequences to 'Mycobacterium franklinii' DSM 45524, described in 2011 but with the name not validly published. They are all nonpigmented rapid growers and are related phenotypically and genetically to the Mycobacterium chelonae-Mycobacterium abscessus group. Extensive characterization by phenotypic analysis, biochemical tests, drug susceptibility testing, PCR restriction enzyme analysis of the hsp65 gene and ITS, DNA sequencing of housekeeping genes and DNA-DNA hybridization demonstrated that 'M. franklinii' DSM 45524, D16Q19 and D16R27 belong to a single species that is separated from other members of the M. chelonae-M. abscessus group. On the basis of these results we propose the formal recognition of Mycobacterium franklinii sp. nov. Strain DSM 45524(T) ( = ATCC BAA-2149(T)) is the type strain.

Sequencing-based genotyping of mixed human papillomavirus infections by use of RipSeq software.

Sequencing-based pathogen identification directly from clinical specimens requires time-consuming interpretation, especially with mixed chromatograms when multiple microorganisms are detected. We assessed RipSeq Mixed software for human papillomavirus (HPV) genotyping by comparison to the linear array HPV genotyping assay. RipSeq Mixed provided rapid, sequencing-based HPV typing for single-type infections and coinfections with 2 types.

Isolation and identification of Kroppenstedtia eburnea isolates from multiple patient samples.

No clinical isolates have been reported for the recently described thermoactinomycete Kroppenstedtia eburnea. Between 2006 and 2011, we obtained 14 clinical isolates from patients in 9 U.S. states. Here we report growth characteristics, 16S rRNA gene sequencing, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry-based identification, and antimicrobial susceptibility profiles of this recently described organism.

A systematic approach for discovering novel, clinically relevant bacteria.

Sequencing of the 16S rRNA gene (16S) is a reference method for bacterial identification. Its expanded use has led to increased recognition of novel bacterial species. In most clinical laboratories, novel species are infrequently encountered, and their pathogenic potential is often difficult to assess. We reviewed partial 16S sequences from >26,000 clinical isolates, analyzed during February 2006-June 2010, and identified 673 that have <99% sequence identity with valid reference sequences and are thus possibly novel species. Of these 673 isolates, 111 may represent novel genera (<95% identity). Isolates from 95 novel taxa were recovered from multiple patients, indicating possible clinical relevance. Most repeatedly encountered novel taxa belonged to the genera Nocardia (14 novel taxa, 42 isolates) and Actinomyces (12 novel taxa, 52 isolates). This systematic approach for recognition of novel species with potential diagnostic or therapeutic relevance provides a basis for epidemiologic surveys and improvement of sequence databases and may lead to identification of new clinical entities.

Dual priming oligonucleotides for broad-range amplification of the bacterial 16S rRNA gene directly from human clinical specimens.

Broad-range amplification and sequencing of the bacterial 16S rRNA gene directly from clinical specimens are offered as a diagnostic service in many laboratories. One major pitfall is primer cross-reactivity with human DNA which will result in mixed chromatograms. Mixed chromatograms will complicate subsequent sequence analysis and impede identification. In SYBR green real-time PCR assays, it can also affect crossing threshold values and consequently the status of a specimen as positive or negative. We evaluated two conventional primer pairs in common use and a new primer pair based on the dual priming oligonucleotide (DPO) principle. Cross-reactivity was observed when both conventional primer pairs were used, resulting in interpretation difficulties. No cross-reactivity was observed using the DPOs even in specimens with a high ratio of human to bacterial DNA. In addition to reducing cross-reactivity, the DPO principle also offers a high degree of flexibility in the design of primers and should be considered for any PCR assay intended for detection and identification of pathogens directly from human clinical specimens.

Internal transcribed spacer region sequence analysis using SmartGene IDNS software for the identification of unusual clinical yeast isolates.

Rapid and accurate identification of clinically important yeasts is essential given their inherent differences in antifungal susceptibility. We implemented nucleic acid sequencing for those species that could not be identified by phenotypic methods. Internal Transcribed Spacer region 1 and 2 (ITS1 and ITS2) sequences were investigated using SmartGene IDNS software, an rDNA sequence database and analysis program for microbial identification (ID). Over a 2.5-year period, 2,938 specimens were evaluated. Most (94%) isolates were fully identified by conventional methods, with Candida species accounting for the majority of them. Of the 169 organisms that required molecular analysis, 79% were identified to species level, 19% to genus and 2% remained unresolved. Sequenced isolates encompassed 33 unique species of which approximately half (52%) were common pathogens with atypical biochemical profiles and the remainder were rarer yeast species. A significant proportion (33%) of sequenced organisms displayed elevated MICs to fluconazole. Our experience supports the use of molecular techniques as an adjunct to conventional methods for the identification of medically important yeasts. Susceptibility testing alone may provide valuable treatment information in situations where phenotypic assessments are inconclusive and molecular or proteomic testing is not readily available.

Mycobacterium chelonae-abscessus complex associated with sinopulmonary disease, Northeastern USA.

Members of the Mycobacterium chelonae-abscessus complex represent Mycobacterium species that cause invasive infections in immunocompetent and immunocompromised hosts. We report the detection of a new pathogen that had been misidentified as M. chelonae with an atypical antimicrobial drug susceptibility profile. The discovery prompted a multicenter investigation of 26 patients. Almost all patients were from the northeastern United States, and most had underlying sinus or pulmonary disease. Infected patients had clinical features similar to those with M. abscessus infections. Taxonomically, the new pathogen shared molecular identity with members of the M. chelonae-abscessus complex. Multilocus DNA target sequencing, DNA-DNA hybridization, and deep multilocus sequencing (43 full-length genes) support a new taxon for these microorganisms. Because most isolates originated in Pennsylvania, we propose the name M. franklinii sp. nov. This investigation underscores the need for accurate identification of Mycobacterium spp. to detect new pathogens implicated in human disease.

Isolation and characterization of "Pseudomonas andersonii" from four cases of pulmonary granulomas and emended species description.

"Pseudomonas andersonii" is a Gram-negative bacillus initially isolated from a granulomatous lung lesion. Novel species status has not been validated for this single strain. We report four additional cases of pulmonary granuloma involving P. andersonii and further characterize the organism. These patients had pulmonary nodules that were surgically resected and which grew P. andersonii on routine culture. Mycobacterium avium complex was concomitantly isolated in two cases, and fungal structures were identified histopathologically in two other cases. The five P. andersonii strains described to date were similar in growth characteristics, biochemical reactions, matrix-assisted laser desorption ionization-time of flight mass spectrometry protein profiles, and susceptibility to antimicrobial agents. Their 16S rRNA genes were 99.9 to 100% identical but less than 95.0% similar to those of all other known bacteria. The gyrA genes of these strains were 99.5 to 100% identical. These shared features illustrate P. andersonii as a unique and distinct bacterium and support the novel species status of the organism.

Mycobacterium neoaurum and Mycobacterium bacteremicum sp. nov. as causes of mycobacteremia.

Reference isolates of Mycobacterium neoaurum, Mycobacterium aurum, and the nonvalidated species "Mycobacterium lacticola" were the focus of two recent molecular taxonomic studies. On the basis of this grouping, we identified 46 clinical pigmented, rapidly growing mycobacterial isolates. By 16S rRNA gene sequencing, only two major taxa were identified: M. neoaurum and a previously uncharacterized "M. neoaurum-like" group. The M. neoaurum-like group exhibited only 99.7% identity to M. neoaurum by 16S rRNA gene sequencing and 96.5% identity to M. neoaurum by rpoB sequencing and was named M. bacteremicum. No clinical isolates of M. aurum or M. lacticola were identified. Of isolates with known sources, 4/8 (50%) of M. bacteremicum isolates and 22/34 (65%) of M. neoaurum isolates were recovered from blood, and 35% of these were known to be from patients with catheter-related sepsis. MIC and clinical data on these 46 isolates of M. neoaurum and M. bacteremicum along with a review of 16 previously reported cases of infection with the M. neoaurum-M. lacticola group demonstrated that the isolates were highly susceptible to all drugs tested except clarithromycin, and most clinical cases were successfully treated. The clarithromycin resistance suggested the presence of an inducible erm gene reported in other species of rapidly growing mycobacteria. Sequencing studies are currently required to identify these two species. Strain ATCC 25791 (originally submitted as an example of Mycobacterium aurum) is proposed to be the type strain of M. bacteremicum.

Simultaneous sequence analysis of the 16S rRNA and rpoB genes by use of RipSeq software to identify Mycobacterium species.

The 16S rRNA gene is commonly used to identify Mycobacterium spp., but alternative DNA targets can provide better resolution to the species level. We evaluated a novel system that enables simultaneous amplification, sequencing, and analysis of two different DNA targets in a single tube to identify clinical isolates of Mycobacterium spp. For 139 clinical isolates, we found that the 16S rRNA gene alone identified 67 (48%) isolates as single species, 68 (49%) isolates to the complex or group level, and 4 (3%) isolates to the genus level only. The rpoB gene alone identified 117 (84%) isolates as single species, 10 (7%) isolates to the complex or group level, and 12 (8%) isolates to the genus level only. Combining the separate analyses for sequencing of two gene targets, 119 (86%) isolates were identified as single species and 10 (7%) isolates were identified to the complex or group level. Seven (5%) isolates were identified as novel species within established groups, and 3 (2%) were identified to the genus level only. Dual-locus identification identified 110 (79%) isolates as single species and 22 (16%) isolates to the complex or group level. Six (4%) were identified as novel species within established groups, and 1 (1%) was identified to the genus level only. Identifications were more accurate when both the 16S rRNA and rpoB genes were screened, and reliance on a single gene target was suboptimal. RipSeq dual-locus software provides an accurate alternative method for laboratories using two different gene targets for microorganism identification.

Phylogenetic analysis of Mycobacterium aurum and Mycobacterium neoaurum with redescription of M. aurum culture collection strains.

We examined American Type Culture Collection (ATCC) strains of Mycobacterium aurum and Mycobacterium neoaurum by using multilocus DNA target sequencing. Apart from the type strain, all 10 ATCC M. aurum strains examined were classified incorrectly, with most being reclassified as belonging to the M. neoaurum-'Mycobacterium lacticola' relatedness group. All four M. neoaurum strains were tightly clustered, but heterogeneity was observed within the cluster. As a result of the incorrect annotation of the M. aurum strains, two commonly used methods of identification are compromised and two case reports implicating M. aurum as a human pathogen are probably incorrect, with the isolates probably belonging to the M. neoaurum-'M. lacticola' relatedness group. These findings together with a review of isolates identified at two large reference laboratories suggest that M. aurum is not a clinically significant isolate.

Mollicute infections in neonates.

Mollicutes can cause a wide spectrum of disease, especially in neonates. To better define their disease spectrum in the United States, we reviewed the results of >14,000 mollicute isolates, including 1346 from neonates. When mollicute infection is suspected, clinicians should alert laboratories, which will optimize methods of detection.