Efficient processing of MRSA screening specimens by a modified inoculation protocol

  • Philipp Thelen
  • Kirsten Hornberg
  • Axel HamprechtEmail author
Original Article


Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of healthcare-associated infections and mortality, and therefore constitutes a serious cost factor in public health. Culture-based MRSA screening is a crucial part of MRSA-infection prevention and control strategies in the hospital setting. Manual inoculation of screening swabs onto culture plates still constitutes the major part of the technicians’ workload in laboratories. We present a modified inoculation protocol that comprises direct inoculation of specimen onto a chromogenic MRSA-selective agar plate without further streaking for isolation. This study aims to evaluate the impact of this inoculation protocol on technicians’ workload and the downstream workflow in our laboratory. Batches of 50 specimens were processed by different technicians and the hands-on time was compared between the standard and modified inoculation protocol. To assess the impact on downstream processing, a retrospective analysis of the rate of subcultures and turnaround time (TAT) of specimens yielding putative MRSA colonies from 9 months before (n = 1548) and after (n = 1267) the protocol change was carried out based on laboratory information system (LIS) data. The implementation of the modified protocol significantly reduced technicians’ hands-on time needed for inoculation by 26.5% without altering the overall turnaround time of surveillance cultures or causing higher costs for extra plates needed for subcultures. Our modified inoculation protocol offers a cost-effective and easy to implement procedure for MRSA surveillance cultures which significantly decreases technicians’ workload and does not impede the downstream workflow. It therefore increases the capacity of laboratory technicians’ to execute more demanding tasks.


MRSA Screening Inoculation Turnaround time 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflicts of interest.

Supplementary material

10096_2018_3319_MOESM1_ESM.pdf (280 kb)
Online Resource 1 (PDF 280 kb)


  1. 1.
    Köck R, Becker K, Cookson B, Gemert-Pijnen JE, van Harbarth S, Kluytmans J, Mielke M, Peters G, Skov RL, Struelens MJ, Tacconelli E, Witte W, Friedrich AW (2014) Systematic literature analysis and review of targeted preventive measures to limit healthcare-associated infections by meticillin-resistant Staphylococcus aureus. Eurosurveillance 19:20860. CrossRefPubMedGoogle Scholar
  2. 2.
    Wolkewitz M, Frank U, Philips G, Schumacher M, Davey P, BURDEN Study Group (2011) Mortality associated with in-hospital bacteraemia caused by Staphylococcus aureus: a multistate analysis with follow-up beyond hospital discharge. J Antimicrob Chemother 66:381–386. CrossRefPubMedGoogle Scholar
  3. 3.
    Kalenic S, Cookson B, Gallagher R, Popp W, Asensio-Vegas A, Assadian O, Blok A, Brusaferro S, Eastaway A, Elstrom P, Schreinerova MG, Hartemann P, Iversen BRG, Jans B, Jul-Jorgensen A, Koller W, Kramer A, Laugesen D, Licker M, Mannerquist K, Nussbaum B, Parneix P, Ruiter T de Jensen ET, Ummels L, Zastrow K-D (2010) Comparison of recommendations in national/regional guidelines for prevention and control of MRSA in thirteen European countries. Int J Infect Control 6:
  4. 4.
    Harbarth S, Hawkey PM, Tenover F, Stefani S, Pantosti A, Struelens MJ (2011) Update on screening and clinical diagnosis of meticillin-resistant Staphylococcus aureus (MRSA). Int J Antimicrob Agents 37:110–117. CrossRefPubMedGoogle Scholar
  5. 5.
    Huang SS, Septimus E, Kleinman K, Moody J, Hickok J, Avery TR, Lankiewicz J, Gombosev A, Terpstra L, Hartford F, Hayden MK, Jernigan JA, Weinstein RA, Fraser VJ, Haffenreffer K, Cui E, Kaganov RE, Lolans K, Perlin JB, Platt R, CDC Prevention Epicenters Program, AHRQ DECIDE Network and Healthcare-Associated Infections Program (2013) Targeted versus universal decolonization to prevent ICU infection. N Engl J Med 368:2255–2265. CrossRefPubMedGoogle Scholar
  6. 6.
    Huang SS, Septimus E, Avery TR, Lee GM, Hickok J, Weinstein RA, Moody J, Hayden MK, Perlin JB, Platt R, Ray GT (2014) Cost savings of universal decolonization to prevent intensive care unit infection: implications of the REDUCE MRSA trial. Infect Control Hosp Epidemiol 35(Suppl 3):S23–S31. CrossRefPubMedGoogle Scholar
  7. 7.
    Lagacé-Wiens PRS, Alfa MJ, Manickam K, Harding GKM (2008) Reductions in workload and reporting time by use of methicillin-resistant Staphylococcus aureus screening with MRSA select medium compared to mannitol-salt medium supplemented with oxacillin. J Clin Microbiol 46:1174–1177. CrossRefPubMedPubMedCentralGoogle Scholar
  8. 8.
    BBL™ CHROMagar™ MRSA II [package insert on the Internet]. Sparks (USA): Becton, Dickinson and Company, 2017 [cited 2017 December 17]. Available from:
  9. 9.
    Spectra™ MRSA [package insert on the Internet]. Lenexa (USA): Thermo Fisher Scientific, 2013 [Cited 2018 January 19]. Avalable from:
  10. 10.
    Nonhoff C, Denis O, Brenner A, Buidin P, Legros N, Thiroux C, Dramaix M, Struelens MJ (2009) Comparison of three chromogenic media and enrichment broth media for the detection of methicillin-resistant Staphylococcus aureus from mucocutaneous screening specimens : comparison of MRSA chromogenic media. Eur J Clin Microbiol Infect Dis Off Publ Eur Soc Clin Microbiol 28:363–369. CrossRefGoogle Scholar
  11. 11.
    Böcher S, Smyth R, Kahlmeter G, Kerremans J, Vos MC, Skov R (2008) Evaluation of four selective agars and two enrichment broths in screening for methicillin-resistant Staphylococcus aureus. J Clin Microbiol 46:3136–3138. CrossRefPubMedPubMedCentralGoogle Scholar
  12. 12.
    Huebner N-O, Dittmann K, Henck V, Wegner C, Kramer A, Action Group Infection Prevention (AGIP) (2016) Epidemiology of multidrug resistant bacterial organisms and Clostridium difficile in German hospitals in 2014: results from a nationwide one-day point prevalence of 329 German hospitals. BMC Infect Dis 16:467. CrossRefPubMedPubMedCentralGoogle Scholar
  13. 13.
    Van Eldere J (2005) Changing needs, opportunities and constraints for the 21st century microbiology laboratory. Clin Microbiol Infect 11:15–18. CrossRefPubMedGoogle Scholar
  14. 14.
    Public Health England. (2017). Inoculation of culture media for bacteriology. UK Standards for Microbiology Investigations. Q 5 issue 2. https://ww Accessed 19 Jan 2018
  15. 15.
    Siegel JD, Rhinehart E, Jackson M, Chiarello L (2007) Management of multidrug-resistant organisms in health care settings, 2006. Am J Infect Control 35:S165–S193. CrossRefPubMedGoogle Scholar
  16. 16.
    Warnke P, Harnack T, Ottl P, Kundt G, Podbielski A (2014) Nasal screening for Staphylococcus aureus—daily routine with improvement potentials. PLoS One 9:e89667. CrossRefPubMedPubMedCentralGoogle Scholar
  17. 17.
    Warnke P, Frickmann H, Ottl P, Podbielski A (2014) Nasal screening for MRSA: different swabs—different results! PLoS One 9:e111627. CrossRefPubMedPubMedCentralGoogle Scholar
  18. 18.
    Froment P, Marchandin H, Vande Perre P, Lamy B (2014) Automated versus manual sample inoculations in routine clinical microbiology: a performance evaluation of the fully automated InoqulA instrument. J Clin Microbiol 52:796–802. CrossRefPubMedPubMedCentralGoogle Scholar
  19. 19.
    Croxatto A, Dijkstra K, Prod’hom G, Greub G (2015) Comparison of inoculation with the InoqulA and WASP automated systems with manual inoculation. J Clin Microbiol 53:2298–2307. CrossRefPubMedPubMedCentralGoogle Scholar
  20. 20.
    Malhotra-Kumar S, Abrahantes JC, Sabiiti W, Lammens C, Vercauteren G, Ieven M, Molenberghs G, Aerts M, Goossens H, Team on behalf of the MWS (2010) Evaluation of chromogenic media for detection of methicillin-resistant Staphylococcus aureus. J Clin Microbiol 48:1040–1046. CrossRefPubMedPubMedCentralGoogle Scholar
  21. 21.
    Warnke P, Warning L, Podbielski A (2014) Some are more equal—a comparative study on swab uptake and release of bacterial suspensions. PLoS One 9:e102215. CrossRefPubMedPubMedCentralGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Institute for Medical Microbiology, Immunology and HygieneUniversity of CologneCologneGermany
  2. 2.German Centre for Infection Research (DZIF), Partner Site Bonn-CologneCologneGermany

Personalised recommendations