Background - The PHE Public Health Laboratory, Birmingham at Heartlands hospital has an annual turn-over in excess of 750,000 specimens, 41,000 of which are processed using real-time PCR in the molecular section. In 2017, due to the age of existing instrumentation, the laboratory began a programme of replacement. Methods - During 2017-19 the entire molecular service was replaced with a new high-throughput automated Roche FLOW system, consisting of a primary sample handler (PSU), two MagNA Pure 96 instruments, a PCR set-up unit (PSU), three 384-well LightCycler 480 II instruments and overarching FLOW software responsible for automated data handling, specimen tracking and workflow between the instruments. Results - The bulk of the in-house developed assay repertoire, representing 34 viral, bacterial and fungal targets was re-optimised in 19 multiplexes. These were fully validated against existing molecular tests and were introduced into routine diagnostic service in June 2018. The FLOW software was successfully interfaced with the LIMS system, allowing rapid two-way communication of test requests and results. Over the following ten months, the service was expanded with an additional seven targets. The new system and assays were audited by UKAS in April 2019 and achieved accreditation to ISO:15189:2012 in August 2019. Conclusion – The Roche FLOW system was successfully validated and introduced into routine diagnostic service and now offers significant improvements in assay performance, sample throughput and turnaround time. Details of the validation process, post-implementation modifications, trouble-shooting and lessons learnt will be of value to other diagnostic laboratories considering the introduction of this technology.

The Xpert Carba-R (Cepheid) is a polymerase chain reaction (PCR) assay for detection and differentiation of five common carbapenemase genes. If used according to manufacturer's instructions, bacterial isolates tested must be cultured on blood or MacConkey agar. This study confirms that the assay performs well against a diverse panel of bacterial isolates with known carbapenemase genes. It also demonstrates that the assay performs well using three solid agar culture media that have not been recommended by the PCR assay's manufacturer: CLED (cystine-, lactose-, and electrolyte-deficient), ChromID CARBA-SMART, and a nutrient slope. By testing isolates directly from any of these media, delays in laboratory reporting can be avoided.

Patient mortality is significantly reduced by rapid identification of bacteria from sterile sites. MALDI-TOF can identify bacteria directly from positive blood cultures and multiple sample preparation methods are available. We evaluated three sample preparation methods and two MALDI-TOF score cut-off values. Positive blood culture bottles with organisms present in Gram stains were prospectively analysed by MALDI-TOF. Three lysis reagents (Saponin, SDS, and SepsiTyper lysis bufer) were applied to each positive culture followed by centrifugation, washing and protein extraction steps. Methods were compared using the McNemar test and 16S rDNA sequencing was used to assess discordant results.

Background Faster identification of bacterial isolates from blood cultures can enable earlier clinical intervention for patients with sepsis. We evaluated the clinical impact of direct identification of micro-organisms from positive blood cultures using MALDI-ToF. Method Positive blood cultures with organisms seen on Gram stain were included over a four week period. For each patient case, comparison was made between the clinical advice given on day one with only a Gram stain result, and the follow up advice given on day two with the benefit of organism identification. Culture results were then compared with direct MALDI-ToF identification. Results For 73 of 115 cases (63.5%), direct organism identification was obtained by MALDI-ToF. Of those 73, 70 (95.5%) had a result concordant with that of the plate culture. In 28 of the 115 cases (24.3%) direct MALDI-ToF identification on day one would have had a clear clinical benefit. In 11 cases it would have helped to identify the potential source of bacteraemia. In 11 cases it would have indicated a different antibiotic regimen on day one, with five patients receiving appropriate antibiotics 24 hours earlier. For 14 cases the blood culture isolate could have been designated as unlikely to be clinically significant. Conclusion We have demonstrated that organism identification on day one of blood culture positivity can have a direct clinical impact. Faster identification using MALDI-ToF assists the clinician in assessing the significance of a blood culture isolate on day one. It can allow earlier appropriate choice of antimicrobial agent, even in the absence of susceptibility testing, and help narrow down the potential source of infection providing a focus for further investigation in a more timely way than conventional techniques alone.

SUMMARYIn spring 2009 a new strain of influenza A(H1N1) emerged and caused a worldwide pandemic. This study utilized a large collection of respiratory specimens from suspected cases of influenza A(H1N1) in the UK West Midlands during the pandemic in order to investigate which other respiratory viruses were circulating and whether they played any role in the increased hospitalization rates seen during that period. Study specimens were selected from community and hospitalized patients positive and negative for influenza A(H1N1) and tested by PCR for other respiratory viruses. A number of infections diagnosed as influenza during the summer influenza outbreak were found to be due to other virus infections (most commonly rhinovirus). No statistically significant difference was found between the rates of respiratory virus co-infection with H1N1 in patients from community or hospital locations suggesting underlying factors were likely to be more significant than viral co-infections in determining severity of influenza A(H1N1) disease.

Acute viral respiratory infections are the most common infections in humans. Co-infection with different respiratory viruses is well documented but not necessarily well understood. The aim of this study was to utilise laboratory data from the winter season following the 2009 influenza A(H1N1) outbreak to investigate rates of respiratory virus co-infections, virus prevalence in different age groups and temporal variations in virus detection. The Health Protection Agency Public Health Laboratory (HPA PHL) Birmingham, UK, routinely uses polymerase chain reaction (PCR) to detect common respiratory viruses. The results from specimens received for respiratory virus investigations from late September 2009 to April 2010 were analysed. A total of 4,821 specimen results were analysed. Of these, 323 (13.2 %) had co-detections of two viruses, 22 (0.9 %) had three viruses and four (0.2 %) had four viruses. Reciprocal patterns of positive or negative associations between different virus pairs were found. Statistical analysis confirmed the significance of negative associations between influenza A and human metapneumovirus (HMPV), and influenza A and rhinovirus. Positive associations between parainfluenza with rhinovirus, rhinovirus with respiratory syncytial virus (RSV) and adenovirus with rhinovirus, parainfluenza and RSV were also significant. Age and temporal distributions of the different viruses were typical. This study found that the co-detection of different respiratory viruses is not random and most associations are reciprocal, either positively or negatively. The pandemic strain of influenza A(H1N1) was notable in that it was the least likely to be co-detected with another respiratory virus.

ABSTRACT PCR ribotyping is currently used in many countries for epidemiological investigation to track transmission and to identify emerging variants of Clostridium difficile. Although PCR ribotyping differentiates over 300 types, it is not always sufficiently discriminatory for epidemiological investigations particularly for common ribotypes, e.g., ribotypes 027, 106, and 017. Multilocus variable-number tandem-repeat analysis (MLVA) is a highly discriminatory molecular subtyping method that has been applied to a number of bacterial species for high-level subtyping. Two MLVA typing schemes for C. difficile have been previously published, each utilizing seven variable-number tandem-repeat (VNTR) loci on the genome with four loci common to both schemes. Although these schemes are good genotyping methods with the ability to discriminate between isolates, they do not identify the ribotype. We show here that increasing the number of VNTR loci to 15, creating the extended MLVA (eMLVA) scheme, we have successfully subtyped all clinically significant ribotypes while still clustering isolates in concordance with PCR ribotyping. The eMLVA scheme developed here provides insight into the genetic diversity of the C. difficile population at both global and cross-infection clusters in patient levels, with the possibility of replacing PCR ribotyping.

We investigated whether multilocus variable-number tandem-repeat analysis (MLVA) typing could identify different subtypes of Clostridium difficile ribotype 027 within the same feces specimen. Five of 39 specimens yielded at least one isolate with an MLVA profile different (more than five summed tandem repeat differences) from that of other isolates in the same specimen, thereby potentially obscuring epidemiological links between C. difficile infection cases.