Comparison of the Precision Obtained in Counting Viable Bacteria by the Spiral Plate Maker, the Droplette and the Miles &amp; Misra Methods

Hedges, A. J.; Shannon, R. D.; Hobbs, Ryan P.

doi:10.1111/j.1365-2672.1978.tb04198.x

Cited by 44 publications

(14 citation statements)

References 7 publications

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“…80,122 Spiral plating, which was used by the research laboratory in this study and involves a much larger inoculum (50 µl) over an entire 9-cm agar plate, is a more accurate method of quantifying bacterial counts and allows easy differentiation of mixed cultures. 126 Enhanced diagnostic performance might also be achieved through improvements in procedures for sample collection and transport.…”

Section: Results In Context With Other Studiesmentioning

confidence: 99%

“…They performed the microbiological cultures and interpreted results using standardised processes, which included spiral plating, a more accurate method of quantifying bacterial counts and differentiating mixed cultures. 126 We prospectively collected cost data, allowing us to model cost-effectiveness. Our statistical techniques are well described, and the clinical rules we produced have clinical face validity, and should be easy use in everyday general practice.…”

Section: Strengthsmentioning

confidence: 99%

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The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness

Hay

Birnie²,

Busby³

et al. 2016

Health Technol Assess

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BackgroundIt is not clear which young children presenting acutely unwell to primary care should be investigated for urinary tract infection (UTI) and whether or not dipstick testing should be used to inform antibiotic treatment.ObjectivesTo develop algorithms to accurately identify pre-school children in whom urine should be obtained; assess whether or not dipstick urinalysis provides additional diagnostic information; and model algorithm cost-effectiveness.DesignMulticentre, prospective diagnostic cohort study.Setting and participantsChildren < 5 years old presenting to primary care with an acute illness and/or new urinary symptoms.MethodsOne hundred and seven clinical characteristics (index tests) were recorded from the child’s past medical history, symptoms, physical examination signs and urine dipstick test. Prior to dipstick results clinician opinion of UTI likelihood (‘clinical diagnosis’) and urine sampling and treatment intentions (‘clinical judgement’) were recorded. All index tests were measured blind to the reference standard, defined as a pure or predominant uropathogen cultured at ≥ 105colony-forming units (CFU)/ml in a single research laboratory. Urine was collected by clean catch (preferred) or nappy pad. Index tests were sequentially evaluated in two groups, stratified by urine collection method: parent-reported symptoms with clinician-reported signs, and urine dipstick results. Diagnostic accuracy was quantified using area under receiver operating characteristic curve (AUROC) with 95% confidence interval (CI) and bootstrap-validated AUROC, and compared with the ‘clinician diagnosis’ AUROC. Decision-analytic models were used to identify optimal urine sampling strategy compared with ‘clinical judgement’.ResultsA total of 7163 children were recruited, of whom 50% were female and 49% were < 2 years old. Culture results were available for 5017 (70%); 2740 children provided clean-catch samples, 94% of whom were ≥ 2 years old, with 2.2% meeting the UTI definition. Among these, ‘clinical diagnosis’ correctly identified 46.6% of positive cultures, with 94.7% specificity and an AUROC of 0.77 (95% CI 0.71 to 0.83). Four symptoms, three signs and three dipstick results were independently associated with UTI with an AUROC (95% CI; bootstrap-validated AUROC) of 0.89 (0.85 to 0.95; validated 0.88) for symptoms and signs, increasing to 0.93 (0.90 to 0.97; validated 0.90) with dipstick results. Nappy pad samples were provided from the other 2277 children, of whom 82% were < 2 years old and 1.3% met the UTI definition. ‘Clinical diagnosis’ correctly identified 13.3% positive cultures, with 98.5% specificity and an AUROC of 0.63 (95% CI 0.53 to 0.72). Four symptoms and two dipstick results were independently associated with UTI, with an AUROC of 0.81 (0.72 to 0.90; validated 0.78) for symptoms, increasing to 0.87 (0.80 to 0.94; validated 0.82) with the dipstick findings. A high specificity threshold for the clean-catch model was more accurate and less costly than, and as effective as, clinical judgement. The additional diagnostic utility of dipstick testing was offset by its costs. The cost-effectiveness of the nappy pad model was not clear-cut.ConclusionsClinicians should prioritise the use of clean-catch sampling as symptoms and signs can cost-effectively improve the identification of UTI in young children where clean catch is possible. Dipstick testing can improve targeting of antibiotic treatment, but at a higher cost than waiting for a laboratory result. Future research is needed to distinguish pathogens from contaminants, assess the impact of the clean-catch algorithm on patient outcomes, and the cost-effectiveness of presumptive versus dipstick versus laboratory-guided antibiotic treatment.FundingThe National Institute for Health Research Health Technology Assessment programme.

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Section: Results In Context With Other Studiesmentioning

confidence: 99%

Section: Strengthsmentioning

confidence: 99%

The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness

Hay

Birnie²,

Busby³

et al. 2016

Health Technol Assess

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show abstract

“…Previous comparison between methods of enumeration of micro-organisms have been carried out under strictly controlled conditions on pure cultures of bacteria, spore suspensions, or relatively small numbers of food samples (Jarvis, Lach & Wood, 1977;Hedges, Shannon & Hobbs, 1978;Kramer & Gilbert, 1978, Kramer, Kendall & Gilbert, 1979. These workers showed a good correlation between the methods tested.…”

Section: Discussionmentioning

confidence: 99%

The microbiology of selected retail food products with an evaluation of viable counting methods

Greenwood

Coetzee²,

Ford

et al. 1984

J. Hyg.

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SUMMARYIn an inter-laboratory survey, the pour plate, surface spread, agar.droplet and spiral plate methods were used in parallel with the surface drop method for enumeration of micro-organisms in foods. Good agreement was obtained between all surface methods of enumeration, but there was poor agreement between molten agar methods and the surface drop method.A total of 1143 samples of food that were ready for consumption at the point of retail sale were examined. Eight types of food products were chosen: meat pasties, sausage rolls, real-cream slices, synthetic-cream slices, mayonnaise-based coleslaws, faggots, pates and continental sausages. The results ofthis survey suggest that the upper limit for an acceptable viable count should vary according to the food product. Salmonellae were not isolated on any occasion. Potentially harmful organisms were not isolated at levels expected to constitute a public health hazard.

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“…Culturable organism enumeration was by the spiral plating technique described by Hedges, Shannon, and Hobbs (1978). Liquid samples of the spore containing liquid were applied to standard nutrient agar plates with a spiral platter (model 4000, Spiral Biotech Inc. Bethesda, MD).…”

Section: Culturable Spore Assaymentioning

confidence: 99%

An approach towards characterizing a reference sampler for culturable biological particle measurement

Spence

Duncan

2005

Journal of Aerosol Science

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Comparison of the Precision Obtained in Counting Viable Bacteria by the Spiral Plate Maker, the Droplette and the Miles & Misra Methods

Cited by 44 publications

References 7 publications

The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness

The Diagnosis of Urinary Tract infection in Young children (DUTY): a diagnostic prospective observational study to derive and validate a clinical algorithm for the diagnosis of urinary tract infection in children presenting to primary care with an acute illness

The microbiology of selected retail food products with an evaluation of viable counting methods

An approach towards characterizing a reference sampler for culturable biological particle measurement

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