82 / 150
Discussion and/or Conclusion(s):
Overall sensitivity of the RenDx
Fungiplex test was lower than previously reported and may relate
to low copy-number candidaemias or retrospective PCR testing.
Furthermore, the sample size is small, leading to uncertainty in
these accuracy metrics. Further diagnostic accuracy assessment is
required to guide optimal adoption of this test into routine NHS
practice.
ID: 4932
Impact of changes in the diagnostics of Pneumocystis jirovecii (PJP)
helping outbreak identification and management
Milind Khare, Deborah Gnanarajah, Wijitha Weerakoon,
Rebecca Turner.
Royal Derby Hospital
Background:
Immunofluorescence was a gold standard for the
diagnosis of PJP infections. PCR became available for various samples
like broncho-alveolar lavage (BAL), sputum, throat swab and EDTA
blood. It is still difficult to differentiate between colonisation and
disease.
Aim(s)/Objective(s):
To evaluate impact of changes in diagnostics for
PJP in a teaching hospital.
Method(s):
PJ PCR was introduced as available investigation for
diagnosis in 2009. 2009 to 2012, Immunofluorescencewas still offered
for BAL. From 2012 onwards only PCR was offered as investigation for
PJP.
Results:
In 2012, 29 patients were positive for PJ PCR of which 11
were definite, 7 probable, 5 possible and 6 colonised cases. Some of
this positivity might be due to change in diagnostics. In 2013 total of
only 7 patients had positive PCR, no definite infection, 1 probable, 3
possible and 3 colonised. In 2014 total positives went up to 27 with
14 definite, 4 possible and 9 colonised. Outbreak was declared as 5
patients had PJP positive from the same unit at the same time. Air,
inlet and outlet filters, environmental sampling & genotyping
were initiated. In 2015 22 were positive with 11 definite, 3
probable, 1 possible and 7 colonised. In 2016 only 4 definite cases
identified so far.
Discussion and/or Conclusion(s):
PJP can be a coloniser and
sometimes difficult to differentiate from an infection. Clinical features
and HRCT guides diagnosis. Cycle times may be helpful. Blood PCR
although not validated, is a useful practical tool.
Availability of PCR and genotyping was helpful in the recognition and
management of outbreak.
ID: 4951
Comparison of 4 multiplex real-time PCR assays for the detection
of viral pathogens in respiratory specimens
Helen Kirk-Granger, Christopher Holmes, Julian Tang.
University
Hospitals of Leicester NHS Trust
Background:
Multiplex real-time PCR has become the test of choice
for the detection of multiple respiratory viruses in clinical specimens.
Several commercial assays are available, and a head-to-head compari-
son of multiple assays/platforms assists the final selection for
diagnostic service provision.
Aim(s)/Objective(s):
Comparison of 4 real-time PCR assays: the
Argene multi-well system (Biomerieux), Respiratory pathogens 21
assay (Fast-track Diagnostics
–
FTD21), and twoversions of an in-house
multiplex real-time PCR assay (
‘
standard
’
and
‘
extended
’
).
Method(s):
1.
Comparison of the relative analytical sensitivity and inter/intra
assay variations of each assay by testing a panel of known positive
samples for: influenza A/B, RSV, parainfluenza 1
–
4, adenovirus,
human metapneumovirus, coronavirus & rhinovirus
2.
Determination of clinical sensitivity, specificity, positive and
negative predictive values for each viral target by testing a
blinded panel of respiratory samples (n = 81). Consensus results
were defined as those with the highest inter-assay concordance
for each target.
Results:
For the known positives, the FTD21 kit was the most
sensitive, giving the lowest Cts for 79% of samples tested (22/28),
though it gave the lowest relative performance (based on concord-
ance) of 80%. The
‘
extended
’
in-house assay had the highest
concordance, 98%, compared to 90% for the
‘
standard
’
in-house and
Argene assays.
Discussion and/or Conclusion(s):
Although the FTD21 kit appeared to
be the most sensitive assay, this selection needs to be considered
within the context of each individual laboratory
’
s workflow and
staffing numbers. The use of concordance (indicating the lack of a
specific gold standard) can give misleading impressions. Eventually, a
semi-automated platform (AusDiagnostics) was deemed more suit-
able for our laboratory.
ID: 5008
Evaluation of the Xpert MRSA NxG assay and the BD MAX MRSA XT
assay for the detection of mecA+, mecC+ and mecA drop-out
S.
aureus
isolates circulating in Europe
Frederic Laurent
1
, Jason Tasse
2
, William Mouton
2
,
Patricia Martins-Simoes
2
, Jean-Philippe Emond
3
,
Jean-Philippe Rasigade
2
, Olivia Raulin
3
.
1
French National Reference
centre for Staphylococci International Centre for Infectiology Research
(CIRI), INSERM U1111
–
CNRS UMR5308, Université Lyon 1, ENS de Lyon
Hospices Civils de Lyon Institut des Sciences Pharmaceutiques et
biologiques, Université de Lyon France,
2
French National Reference centre
for Staphylococci, International Centre for Infectiology Research (CIRI)
–
INSERM U1111
–
CNRS UMR5308
–
Université Lyon 1
–
ENS de Lyon,
Hospices Civils de Lyon,
3
Laboratoire de bactériologie, Hôpital de
Compiegne, France
Background:
Reports of atypical SCCmec cassettes, novel mec genes,
diverse genetic backgrounds in MRSA strains as well as emergence of
mecA drop-out isolates are increasing.
Aim(s)/Objective(s):
To evaluate the accuracy of the last versions of
Xpert MRSA NxG assay (XpertA) (Cepheid) and BD MAX MRSA XT
assay (BDA) (Becton Dickinson) using a selection of
S. aureus
isolates
circulating in Europe.
Method(s):
114 isolates were included: (i) Group 1: 53 MRSA isolates
(mecA-positive, n = 43; mecC-positive, n = 10, 33 different spa-types)
representing the main clones circulating in Europe; (ii) Group 2: 37
randomly-choosen MRSA isolates harbouring various atypical SCCmec
cassette; (iii) Group 3: 16 randomly-choosen mecA-drop-out MSSA.
All isolates were tested using XpertA and BDA kits according to
manufacturers.
Results:
In Group 1, all isolates were correctly identified as MRSA
except one for XpertA (spa-t045) and three for BDA (spa-t001, spa-
t091, spa-t064). All mecC isolates were detected by both reagents.
In Group 2, 8 isolates (spa-t008, -t030, -t127, -t190, -t1614) using BDA
and 3 isolates (spa-t777, -t1664, -t2505) using XpertA were
misclassified.
In Group 3, all the 26 mecA drop-out isolates (Group 3) were identified
as MSSAwhatever the assay used.
Discussion and/or Conclusion(s):
Xpert MRSA NxG assay showed
a higher accuracy to identify the MRSA isolates tested compared to
BD MAX MRSA XT assay (BDA) with 4 versus 11 misclassifications
respectively, mainly due to MRSA with new or variant SCCmec
cassette. The range of primers targetting SCCmec cassette is likely
more wide and optimised in XpertA kit.
ID: 5011
An assessment of the extent of unnecessary inpatient full-body
(chest, abdomen and pelvis) CT scan examinations
Taufiq Khan
1
, Rashika Fernando
2
, Elizabeth Joekes
2
,
Michael Beadsworth
2
.
1
University of Liverpool,
2
Royal Liverpool and
Broadgreen University Hospitals NHS Trust
Background:
Radiation exposure is a risk factor for malignancy. The
use of diagnostic computed tomography (CT) imaging is increasing
Abstracts of FIS/HIS 2016
–
Poster Presentations / Journal of Hospital Infection 94S1 (2016) S24
–
S134
S77