scholarly journals Comparing the Yield of Staphylococcus aureus Recovery with Static versus Agitated Broth Incubation

2018 ◽  
Vol 2018 ◽  
pp. 1-3
Author(s):  
Carol E. Muenks ◽  
Patrick G. Hogan ◽  
Carey-Ann D. Burnham ◽  
Stephanie A. Fritz
Keyword(s):  
Staphylococcus Aureus ◽  
Enrichment Culture ◽  
Culture Method ◽  
Ambient Air ◽  
Built Environments ◽  
Culture Methods ◽  
Semiquantitative Assessment ◽  
Direct Plating ◽  
Static Conditions ◽  
Broth Enrichment

Given the lack of standardization of methodologies for microbial recovery from built environments, we sought to compare the yield of Staphylococcus aureus with a broth enrichment method when incubated in agitated versus static conditions. Five unique strains of S. aureus at five different concentrations were cultured to compare direct plating, agitated broth enrichment, and static broth enrichment culture methods. All samples were incubated at 35° in ambient air. The lowest concentration recovered across three replicates and five strains did not differ between culture methods (Fisher’s exact test, p=0.50); notably, recovery of S. aureus was equivalent between static and agitated broth incubation. When broth enrichment was used (both static and agitated), the burden of S. aureus growth was higher (by semiquantitative assessment of 4-quadrant streaking) compared to the direct plating culture method. Optimizing strategies for microbial recovery is essential, particularly in areas of lower biomass, given the paucity of research concerning microbial communities of built environments. The results of this study, in conjunction with other experiments investigating microbiomes of built environments, can help inform protocols for standardizing culturing methods within built environments.

Iron Supplementation to Enhance the Recovery of Salmonella enteritidis from Pools of Egg Contents

1995 ◽  
Vol 58 (3) ◽  
pp. 268-272 ◽  
Author(s):  
RICHARD K. GAST ◽  
PETER S. HOLT
Keyword(s):  
Salmonella Enteritidis ◽  
Iron Supplementation ◽  
Enrichment Culture ◽  
Low Cost ◽  
Iron Availability ◽  
Initial Number ◽  
Culture Methods ◽  
Direct Plating ◽  
Efficient Detection ◽  
Broth Enrichment

Direct-plating culture methods have been proposed for use in programs to test eggs for contamination by Salmonella enteritidis (SE) because of their speed and low cost, but direct plating has previously been observed to detect SE less frequently than more elaborate broth-enrichment culture methods. The present study used experimentally inoculated pools of egg contents to assess the comparative sensitivities of direct-plating and broth-enrichment culturing for detecting SE, to evaluate the ability of iron supplementation to increase the multiplication of SE during incubation of egg pools, and to determine whether iron supplementation could enhance the ability of direct plating to detect SE in egg pools that initially contained very few SE cells. Efficient detection of SE in egg pools was found to require an approximately 10,000-fold higher level of SE for direct plating than for broth-enrichment culturing. Iron supplementation of contaminated egg pools significantly (P < 0.005) increased the resulting final level of SE after 1 day of incubation at 37°C. Iron supplementation also significantly (P < 0.005) increased the percentage of 10-egg pools, initially inoculated with fewer than 10 SE cells each, that were identified as contaminated by direct plating after the pools had been incubated for 1 day at 37°C. Increasing the iron availability in incubating egg pools, therefore, increased the probability that a small initial number of SE cells would grow quickly to levels likely to be detected by direct plating.

scholarly journals Multicenter Diagnostic Accuracy Evaluation of the Luminex Aries Real-Time PCR Assay for Group B Streptococcus Detection in Lim Broth-Enriched Samples

2018 ◽  
Vol 56 (8) ◽  
Author(s):  
D. R. Hernandez ◽  
D. M. Wolk ◽  
K. L. Walker ◽  
S. Young ◽  
R. Dunn ◽  
...  
Keyword(s):  
Clinical Performance ◽  
Enrichment Culture ◽  
Culture Method ◽  
Nucleic Acid Amplification ◽  
Accuracy Evaluation ◽  
Culture Methods ◽  
Assay Sensitivity ◽  
Content Type ◽  
Group B ◽  
Positive Agreement

ABSTRACT The vertical transmission of group B Streptococcus (GBS) strains causing neonatal sepsis is one of the leading reasons for neonatal mortality worldwide. The gold standard for GBS detection is enriched culture with or without the aid of chromogenic agars. Given the high risk for morbidity and mortality in this population, high assay sensitivity is required to prevent the personal and economic costs of GBS disease. Nucleic acid amplification tests (NAATs) allow for objective determination of GBS colonization with a sensitivity and a specificity higher than those of traditional culture methods. In this study, we determined the analytical and clinical performance of the Aries GBS assay compared to those of the enrichment culture method, biochemical identification, and the NAATs used at the study sites. Remnant Lim broth samples were used to perform the Aries assay and reference testing. Upon first testing using enriched culture as the reference standard, the Aries GBS assay identified GBS with a 96.1% sensitivity (95% confidence interval [CI], 91.2 to 98.7%) and a 91.4% specificity (95% CI, 88.8 to 93.6%). The test performed with 100% positive agreement (95% CI, 83.2 to 100%) compared to the results of the BD Max GBS assay and 98.0% positive agreement (95% CI, 89.2 to 99.9%) compared to the results of the Cepheid Xpert GBS LB test. Repeatability and reproducibility were maintained in intra- and interlaboratory testing, regardless of the instrument, module, or user who performed the test. The Aries GBS assay can be set up in less than 5 min and produces results in 2 h. The easy setup, with minimal hands-on time, and high assay sensitivity and specificity make this a useful testing option for GBS screening in prepartum women.

The Use of a Selective Staphylococcal Broth v Direct Plating for the Recovery of Staphylococcus aureus

1988 ◽  
Vol 9 (5) ◽  
pp. 204-205 ◽  
Author(s):  
R.L. Sautter ◽  
W.J. Brown ◽  
L.H. Mattman
Keyword(s):  
Staphylococcus Aureus ◽  
Infection Control ◽  
Agar Plate ◽  
Culture Methods ◽  
Direct Plating ◽  
Two Cultures ◽  
Culture Techniques ◽  
Sheep Blood ◽  
Surveillance Cultures

AbstractNine hundred seventy-two cultures taken from the external nares and the vaginal vestibules of 54 women for the isolation of Staphylococcus aureus were studied. The swabs were plated directly to a trypticase soy agar plate containing 5% sheep blood and were then placed into a selective staphylococcal broth. Both culture methods were compared for the ability to recover S aureus.Twenty percent (26/131) and 66% (38/58) of the S aureus-positive cultures taken from the nares and vagina respectively were cultured from the selective broth only. We believe that a selective staphylococcal broth should be used in addition to routine culture techniques to isolate S aureus from infection control surveillance cultures.

scholarly journals Probing the dissonance among the diagnostic outputs of multiple approaches used for detection of Methicillin-resistant Staphylococcus aureus (MRSA)

2020 ◽  
Author(s):  
Ujjwal Ranjan Dahiya ◽  
Arnab Sikidar ◽  
Priyanka Sharma ◽  
Chitra Rawat ◽  
Benu Dhawan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Culture Method ◽  
Nucleic Acid Amplification ◽  
Detection Methods ◽  
Diagnostic Efficiency ◽  
Coagulase Negative Staphylococci ◽  
Culture Methods ◽  
Methicillin Resistant ◽  
Conventional Culture

Methicillin-resistant staphylococcus aureus (MRSA) is an extremely infectious hospital acquired bacterial pathogen often found in post-surgical patients globally. Early detection of such pathogens is a critical requirement to eliminate or reduce the incidence of antimicrobial resistance as well as for effective management of the disease. Despite the development of multiple biochemical, microbiological and nucleic acid amplification techniques (NAATs), conventional culture methods are widely used clinically owing to high variability between the methods, technical skills, and infrastructural needs. Further, multiple reports suggest a significant variation among diagnostic output for MRSA detection. This work attempts to probe the discordance among the diagnostic output of three commonly used methods while trying to understand the underlying cause of variability. MRSA detection on 217 clinical pus isolates was carried out using three different methods namely, conventional culture method, qPCR-based amplification, and a modern LAMP-based detection approach. Also, to confirm the presence of MRSA and distinguish from coagulase-negative staphylococci (CoNS), as well as to investigate the observed differences between qPCR and LAMP outputs, melt curve analysis was performed on discordant samples. LAMP-based MRSA detection was found to be the optimum method. In summary, this study evaluates the diagnostic efficiency of the different detection methods, while probing for possible explanations for the observed differences.

scholarly journals Comparison of Direct Plating and Broth Enrichment Culture for the Detection of Intestinal Colonization by Glycopeptide-Resistant Enterococci among Hospitalized Patients

1999 ◽  
Vol 37 (5) ◽  
pp. 1436-1440 ◽  
Author(s):  
M. Ieven ◽  
E. Vercauteren ◽  
P. Descheemaeker ◽  
F. van Laer ◽  
H. Goossens
Keyword(s):  
Enrichment Culture ◽  
University Hospital ◽  
Detection Methods ◽  
Dialysis Patients ◽  
Cross Sectional ◽  
Direct Plating ◽  
Prevalence Studies ◽  
Rectal Swabs ◽  
Stool Samples ◽  
Broth Enrichment

The results of prevalence studies on glycopeptide-resistant enterococci (GRE) in the intestine may be influenced by the detection methods applied. In most studies different media, different concentrations of antibiotics, and different methods are used, and these differences result in differences in recovery rates. In this cross-sectional study on the carrier state of GRE among patients at the University Hospital Antwerp, Antwerp, Belgium, performed on 21 May 1996, direct plating and broth enrichment were compared by using the same media. Stool samples (n = 213) or rectal swabs (n = 122) were plated directly on Enterococcosel agar (bioMérieux) and after enrichment in Enterococcosel broth. The prevalence of GRE was 12.8%. Direct plating recovered 53.4% of the GRE isolates, and broth enrichment recovered an additional 46.5% of them; in the latter test the isolates were thus present at less than 103 CFU per g of feces. The prevalence of GRE among dialysis patients was higher than among the other patients, but the difference was not significant (P = 0.06), possibly as a result of the small numbers of dialysis patients examined. The GRE species isolated included 19 E. gallinarum (44.2%), 13E. faecium (30.2%), 6 E. faecalis (13.9%), and 5 E. casseliflavus (11.6%) isolates. All E. faecalis and E. faecium strains isolated carried thevanA gene, and E. gallinarum and E. casseliflavus carried the vanC1 and vanC2gene, respectively. The majority of isolates were polyclonal. Our data indicate that the rate of detection of GRE from both stool samples and rectal swabs is significantly increased with enrichment cultures.

scholarly journals Comparison of Culture-Based Methods for Identification of Colonization with Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus in the Context of Cocolonization

2016 ◽  
Vol 54 (7) ◽  
pp. 1907-1911 ◽  
Author(s):  
Meghan F. Davis ◽  
Baofeng Hu ◽  
Karen C. Carroll ◽  
Warren B. Bilker ◽  
Pam Tolomeo ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Screening Methods ◽  
Enrichment Method ◽  
Direct Plating ◽  
Methicillin Resistant ◽  
Content Type ◽  
Broth Enrichment

Two screening methods to detect staphylococcal colonization in humans were compared. Direct plating to CHROMagar (BD Diagnostics) was compared to a broth preenrichment followed by plating to Baird-Parker agar. The broth-enrichment method was comparable to CHROMagar for methicillin-resistantStaphylococcus aureas(MRSA) detection, but the enrichment method was optimum for recovery of coagulase-positiveStaphylococcusspp.

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