The Journal of Hospital Infection - Supplement 1

ID: 4490

Comparison of the QuantiFERON-TB Gold (QFT) and Gold Plus (QFT

Plus) ELISAs and manual and automated QFT Plus for the detection

of latent TB infection

Ngee Keong Tan

, Foziya Malik

, Aine O

’

Callaghan

Carmel Prendergast

, Angela Houston

, Cassie Pope

Timothy Planche

South West London Pathology, St George

’

s University

Hospitals NHS Foundation Trust,

Biomnis Ireland, Three Rock Road,

Sandyford Business Estate, Dublin 18, Ireland,

Infection Care Group, St

George

’

s University Hospitals NHS Foundation Trust

Background:

Latent tuberculosis infection (LTBI) is an asymptomatic

condition which occurs in some individuals after an infection with

Mycobacterium tuberculosis

. The main purpose of diagnosing LTBI is to

consider medical treatment for preventing active TB. QuantiFERON-TB

Gold ELISA (Qiagen, Germany), an interferon-gamma release assay

(IGRA), has been used in our laboratory for LTBI screening since 2014.

In 2015, Qiagen released a new generation IGRA called

“

QFT Plus

”

These assays maybe performed manually or automated on a DS2

analyser (Dynex).

Aim(s)/Objective(s):

This study aims to investigate the agreement

between the QFTand QFT Plus assays. Agreement betweenmanual and

automated methods between two laboratories was also examined.

Method(s):

84 prospectively collected clinical and 14 internal QC

samples were tested manually in parallel between December 2015 and

February 2016 using QFTand QFT Plus according to the manufacturer

’

instructions. Of the 84 clinical samples, 15 positive and 21 negative

samples by manual QFT Plus were tested on a DS2 by Biomnis.

Results:

31/98 samples were positive, 63/98 were negative and 2/98

were indeterminate by both ELISAs. This gives the overall agreement of

98% (

kappa

0.957; 95% CI 0.897

–

1.000). 2 results were not in

agreement, one was low positive and the other was low mitogen.

14/15 samples were positive and 21/21 were negative by both manual

and automated methods. This gives the overall agreement of 97%

(

kappa

0.942; 95%CI 0.831

–

1.000). 1 positive was not reproduced due

to the presence of clots.

Discussion and/or Conclusion(s):

Excellent agreement was demon-

strated between the QFT and QFT-Plus ELISAs, and between manual

and automated methods.

ID: 4497

Serodiagnostic markers as predictors for tuberculosis diagnostic

and treatment outcome

Dolapo Awoniyi

, Ralf Baumann

, Novel Chegou

, Belinda Kriel

Ruschca Jacobs

, Jayne Sutherland

, Harriet Mayanja-Kizza

Tom Ottenhoff

, Desta Kassa

, Martin Kidd

, Gerhard Walzl

Stellenbosch University,

Institute for Occupational and Social Medicine,

Aachen University of Technology, 52074 Aachen, Germany;

Stellenbosch

Univrsity, Cape Town, South Africa;

Vaccines and Immunity Theme,

Medical Research Council, Gambia;

Department of Medicine, Makerere

University, Kampala, Uganda;

Department of Infectious Diseases, Leiden

University Medical Centre, Leiden, The Netherlands;

Ethiopian Health

and Nutrition Research Institute, Addis Ababa, Ethiopia;

Centre for

Statistical Analysis, Stellenbosch University,

Stellenbosch University,

Cape Town, South Africa

Background:

Successful control of tuberculosis is not only dependent

on timely and accurate diagnosis but also on efficacious treatment

monitoring, which currently relies largely on month 2 and 5 sputum

culture status.

Aim(s)/Objective(s):

To evaluate the potential of serodiagnostic

markers for TB diagnosis and as candidates for monitoring the

response to TB treatment.

Method(s):

We evaluated the sensitivity and specificity of plasma

immunoglobulin IgA, IgG and/or IgM against 8 mycobacterium protein

antigens (ESAT-6, Tpx, LAM, PstS1, AlaDH, MPT64, 16 kDa and 19 kDa)

and 2 antigen combinations (TUB, TB-LTBI) of 21 LTBI controls, 21

healthy controls and 21 active TB patients at baseline. 19 TB cases were

followed up at the end of anti-TB treatment at month 6.

Results:

The top single serodiagnostic markers are anti-16 kDa IgA,

anti-MPT64 IgA, anti-LAM IgG and anti-TB-LTBI IgG. IgA response

to MPT64 best discriminated active TB from non TB (QFT +ve and

QFT

–

ve) with both sensitivity and specificity of 95%. Anti-16 kDa IgA

had the best sensitivity of 95% and specificity of 90% for differentiating

active TB from latently infected individuals. There was a further

improved performance when marker combinations were used, with

accuracy exceeding 95%. Anti-LAM and anti-TB-LTBI had low baseline

IgG while there were high baseline responses in anti-TUB IgG, anti-

16 kDa IgA and anti-16 kDa IgM after successful completion of anti-TB

treatment.

Discussion and/or Conclusion(s):

This result shows the potential of a

multi-serodiagnostic marker in differentiating active TB from non TB.

Furthermore, we have shown that some serological markers could be

useful for monitoring TB treatment response.

ID: 4559

Evaluation of the Unyvero P55 Pneumonia Cartridge for the

identification of respiratory pathogens and resistance genes in

broncho-alveolar lavage fluids

Naomi Gadsby

, Martin McHugh

, Stephen Hamilton

Laura MacKenzie

, David Griffith

, Kate Templeton

NHS Lothian,

NHS Lothian/Univeristy of Edinburgh

Background:

Faster respiratory pathogen detection and antibiotic

resistance identification is important in critical care due to the severity

of illness, significant prior antibiotic exposure and infection control

implications. The Unyvero P55 Pneumonia Cartridge (Curetis AG)

rapid molecular assay detects 38 bacterial pathogens and antibiotic

resistance genes.

Aim(s)/Objective(s):

To evaluate the performance of the Unyvero P55

Pneumonia Cartridge test on broncho-alveolar lavage (BAL) fluids from

patients in Critical Care, compared to routine microbiological culture

and in-house molecular assays.

Method(s):

75 BAL fluids from patients admitted to the Royal

Infirmary of Edinburgh Intensive Care Unit between Jan 2013 and

Sept 2015 were tested using routine microbiological culture methods.

Residual specimens were stored at

−

80°C for retrospective anon-

ymised molecular testing by the Unyvero test and a range of in-house

real-time PCRs.

Results:

At least one bacterial species was isolated by routine culture

in 49 (65%) cases. Unyvero and in-house assay results were both

concordant with culture in 56% instances. Additional organisms were

detected by Unyvero test and in-house assay in 21% and 25% instances

respectively. Cultured organisms were not detected by the Unyvero

test and in-house assay in 27% and 22% instances respectively.

Antibiotic resistance genes were detected in 26 instances by the

Unyvero assay, these matched the antibiogram in 53% cases where the

relevant sensitivity was known.

Discussion and/or Conclusion(s):

Molecular testing identified a

number of respiratory pathogens in this patient cohort that were not

grown in culture. Improvements in panel coverage and detection

sensitivity are required to increase the utility of these assays in the

critical care setting.

ID: 4713

Matrix assisted laser desorption-ionisation time-of-flight mass

spectrometry (MALDI-TOF MS) for the identification of

Neisseria

gonorrhoeae

Ruaridh Buchanan

, Heather Dolphin

, David Ball

, Jayshree Dave

Barts Health NHS Trust,

Barts Health NHS Trust/Public Health England

Background:

Neisseria gonorrhoeae

is the second most common

sexually transmitted pathogen in the UK. Increasing levels of anti-

microbial resistance make accurate identification of this organismvital

clinically and epidemiologically. Current PHE guidance stipulates the

need for dual identification to increase accuracy, partly due to the

psycho-social and medico-legal consequences of incorrect identifica-

tion, but also because there has been no large series examining the

Abstracts of FIS/HIS 2016

–

Poster Presentations / Journal of Hospital Infection 94S1 (2016) S24

–

S134

S74