Microbiology without culture - is the future? Professor Brian Duerden Inspector of Microbiology and Infection Control, Department of Health
Historical perspective 1850 – 1900 – 1850 s: Pasteur; liquid culture – 1870 -80 s Koch: solid media – 1894 Gram’s stain 1900 – 1980 – Serotyping; phage typing – DNA discovered 1980 s Biochemical analyses – – – Metabolic products (GLC) Proteins – whole cell; cell wall (SDS-PAGE) Whole cell (pyrolysis) All needed culture first
1990 s – age of immediacy! Rapid tests Same day results Short turnaround times Immediate answers Point of care (POC) testing And automation; computerisation ………non-culture methods
Methods Molecular detection – nucleic acid – Probes – PCR Antigen detection. . . who does the tests? where are they done?
Why are we doing the tests? Cost? Diagnosis – Guide treatment Antibiotic or not? Which? eg. Gp. A streptococcus – Start infection prevention and control action – Take public health actions Screening for carriage/colonisation – Infection control & public health actions – Prophylaxis (eg. Gp. B streptococcus) Speed is of the essence
How urgent are the answers? Primary care – While the patient is there? – Organisation? STDs – GUM clinics; strong history – Now in pharmacies? ? ? Public health – TB – Days not hours Healthcare Associated Infections (HCAI) – Treatment; isolation; infection control action
NB. Primary culture then non-culture? Identify organisms in primary cultures – Rapid non-culture methods – Probes; PCR; r. RNA – Resistance genes How vital? – Blood cultures – Early CORRECT antibiotic improves survival – But will clinicians change antibiotic?
MRSA screening DH requirement – all admissions to be screened before or on admission – All elective admissions by March 2009 Includes day cases Not ophthalmic day cases; not maternity – All admissions asap, at latest by March 2011 Methods – conventional culture; rapid; automated? – Needs clinical organisation; ability to take action – Laboratory? Point of admission? Pre-admission clinic?
C. difficile diagnosis DH target – 30% reduction by 2010 -11 – Baseline 2007 -8: c. 60, 000 – SHA and PCT targets based on population Standardised to 8. 4 cases per 10, 000 as target – Acute trust targets within PCT packages Standardised to admissions Surveillance figures depend upon accurate diagnosis Infection control actions depend upon rapid results in all healthcare settings Methods: toxin detection (A+B); +/- antigen?
Norovirus Major cause of ward closure Respond to clinical diagnosis – Isolation; cohorting; closed to admissions – Staff restrictions (cohorting) – Cleaning and disinfection Quick confirmation needed to reassure actions Not every case needs testing
Pandemic (or seasonal) flu? Primary care – Confirm diagnosis for antiviral use? Current policy – Diagnose on clinical grounds when flu known to be circulating – Keep infected patients away from GP surgeries
Cautionary tales Loss of epidemiological and surveillance data Antimicrobial susceptibility data? POC – whose responsibility Quality and standards Serendipity
Loss of data Antimicrobial susceptibility – Few non-culture tests Epidemiology – Typing Can it be done on non-culture testing? Most needs the isolate Surveillance – POC – loss of data Unless systems linked to reporting systems
POC testing Who does it? – What training? Who assesses competence? – Who manages them? Equipment maintenance – Who is responsible? QC and QA? Links to the laboratory Reporting system? Accreditation?
Quality issues Quality control – Records; links to laboratories EQA – NEQAS programmes? Accreditation – CPA; UKAS
Current developments POC Accreditation – Pathology modernisation project – Working with UKAS Benchmarking – Primary care use of Pathology services – Keele team – Microbiology pilots soon – ? ? ? Impact of POC; rapid results
Serendipity What could be causing that? I would not have thought of that? We don’t have a DNA probe for that! Where is experience, ‘nose’, knowledge? With non-culture tests ……. . you only find what you know you are looking for
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