OBJECTIVES: To evaluate two enrichment broths for methicillin-resistant Staphylococcus aureus (MRSA) detection and compare results with direct plating. METHODS: Swabs from 1224 patients were re-analysed for MRSA in a central laboratory (Münster) using six methods. Swabs were suspended in 0.5 mL of non-selective enrichment broth (NB) and vortexed. Aliquots of 100 microL were inoculated on/into: (I) ChromID MRSA agar; (II) Columbia sheep blood (5\%) agar (BA) and ChromID MRSA; (III, IV) NB incubated overnight followed by plating on BA and ChromID MRSA; and (V, VI) a semi-selective broth containing cefoxitin and aztreonam (TSB-SSI) incubated overnight followed by plating on BA and ChromID MRSA. In III-VI, 100 microL of the enriched broth was plated on each agar. RESULTS: The combined MRSA-positive rate was 21.5\%. MRSA isolates detected by each method were: TSB-SSI, n = 223; NB, n = 205; BA and ChromID MRSA, n = 203; ChromID MRSA alone, n = 183. TSB-SSI detected more positive throat samples than the comparators and significantly reduced methicillin-susceptible S. aureus (MSSA) growth. The maximum sensitivity obtained was only 85\%, possibly due to the study design using pre-used swabs and dilution of swab material. For 997 samples, results from Münster were compared with initial results. Peripheral laboratories identified 172 MRSA compared with Münster where 186, 186 and 204 MRSA were found for direct plating, NB and TSB-SSI broth, respectively. CONCLUSIONS: TSB-SSI was superior to both NB and direct plating on ChromID MRSA and BA. Despite re-using swabs for the study, we showed that routine diagnostic screening could be significantly improved, using a semi-selective enrichment broth.
%0 Journal Article
%1 baecher_semi-selective_2010
%A Böcher, S
%A Middendorf, B
%A Westh, H
%A Mellmann, A
%A Becker, K
%A Skov, R
%A Friedrich, A W
%D 2010
%J The Journal of Antimicrobial Chemotherapy
%K Bacteriological Culture Humans, Infections Mass Media, Screening, Sensitivity Specificity, Staphylococcal Staphylococcus Techniques, and aureus, {Methicillin-Resistant}
%N 4
%P 717--720
%R 10.1093/jac/dkq001
%T Semi-selective broth improves screening for methicillin-resistant Staphylococcus aureus
%U http://www.ncbi.nlm.nih.gov/pubmed/20130023
%V 65
%X OBJECTIVES: To evaluate two enrichment broths for methicillin-resistant Staphylococcus aureus (MRSA) detection and compare results with direct plating. METHODS: Swabs from 1224 patients were re-analysed for MRSA in a central laboratory (Münster) using six methods. Swabs were suspended in 0.5 mL of non-selective enrichment broth (NB) and vortexed. Aliquots of 100 microL were inoculated on/into: (I) ChromID MRSA agar; (II) Columbia sheep blood (5\%) agar (BA) and ChromID MRSA; (III, IV) NB incubated overnight followed by plating on BA and ChromID MRSA; and (V, VI) a semi-selective broth containing cefoxitin and aztreonam (TSB-SSI) incubated overnight followed by plating on BA and ChromID MRSA. In III-VI, 100 microL of the enriched broth was plated on each agar. RESULTS: The combined MRSA-positive rate was 21.5\%. MRSA isolates detected by each method were: TSB-SSI, n = 223; NB, n = 205; BA and ChromID MRSA, n = 203; ChromID MRSA alone, n = 183. TSB-SSI detected more positive throat samples than the comparators and significantly reduced methicillin-susceptible S. aureus (MSSA) growth. The maximum sensitivity obtained was only 85\%, possibly due to the study design using pre-used swabs and dilution of swab material. For 997 samples, results from Münster were compared with initial results. Peripheral laboratories identified 172 MRSA compared with Münster where 186, 186 and 204 MRSA were found for direct plating, NB and TSB-SSI broth, respectively. CONCLUSIONS: TSB-SSI was superior to both NB and direct plating on ChromID MRSA and BA. Despite re-using swabs for the study, we showed that routine diagnostic screening could be significantly improved, using a semi-selective enrichment broth.
@article{baecher_semi-selective_2010,
abstract = {{OBJECTIVES:} To evaluate two enrichment broths for methicillin-resistant Staphylococcus aureus {(MRSA)} detection and compare results with direct plating. {METHODS:} Swabs from 1224 patients were re-analysed for {MRSA} in a central laboratory {(Münster)} using six methods. Swabs were suspended in 0.5 {mL} of non-selective enrichment broth {(NB)} and vortexed. Aliquots of 100 {microL} were inoculated on/into: {(I)} {ChromID} {MRSA} agar; {(II)} Columbia sheep blood (5\%) agar {(BA)} and {ChromID} {MRSA;} {(III,} {IV)} {NB} incubated overnight followed by plating on {BA} and {ChromID} {MRSA;} and {(V,} {VI)} a semi-selective broth containing cefoxitin and aztreonam {(TSB-SSI)} incubated overnight followed by plating on {BA} and {ChromID} {MRSA.} In {III-VI,} 100 {microL} of the enriched broth was plated on each agar. {RESULTS:} The combined {MRSA-positive} rate was 21.5\%. {MRSA} isolates detected by each method were: {TSB-SSI,} n = 223; {NB,} n = 205; {BA} and {ChromID} {MRSA,} n = 203; {ChromID} {MRSA} alone, n = 183. {TSB-SSI} detected more positive throat samples than the comparators and significantly reduced methicillin-susceptible S. aureus {(MSSA)} growth. The maximum sensitivity obtained was only 85\%, possibly due to the study design using pre-used swabs and dilution of swab material. For 997 samples, results from Münster were compared with initial results. Peripheral laboratories identified 172 {MRSA} compared with Münster where 186, 186 and 204 {MRSA} were found for direct plating, {NB} and {TSB-SSI} broth, respectively. {CONCLUSIONS:} {TSB-SSI} was superior to both {NB} and direct plating on {ChromID} {MRSA} and {BA.} Despite re-using swabs for the study, we showed that routine diagnostic screening could be significantly improved, using a semi-selective enrichment broth.},
added-at = {2011-03-11T10:05:34.000+0100},
author = {Böcher, S and Middendorf, B and Westh, H and Mellmann, A and Becker, K and Skov, R and Friedrich, A W},
biburl = {https://www.bibsonomy.org/bibtex/213824ddff6b196671da5c0f662c139cd/jelias},
doi = {10.1093/jac/dkq001},
interhash = {6e6255e0e1da97940b294e2927b1b0ee},
intrahash = {13824ddff6b196671da5c0f662c139cd},
issn = {1460-2091},
journal = {The Journal of Antimicrobial Chemotherapy},
keywords = {Bacteriological Culture Humans, Infections Mass Media, Screening, Sensitivity Specificity, Staphylococcal Staphylococcus Techniques, and aureus, {Methicillin-Resistant}},
month = apr,
note = {{PMID:} 20130023},
number = 4,
pages = {717--720},
timestamp = {2011-03-11T10:05:58.000+0100},
title = {Semi-selective broth improves screening for methicillin-resistant Staphylococcus aureus},
url = {http://www.ncbi.nlm.nih.gov/pubmed/20130023},
volume = 65,
year = 2010
}