Evaluation of a modified protocol that decreases the turnaround time of positive blood cultures

  • Renuka Anegundi Department of Microbiology, Kasturba Medical College, Manipal, Karnataka, India
  • Raghavendra Dheerendra Kulkarni Department of Microbiology, SDM College of Medical Sciences and Hospital, Dharwad, Karnataka, India
  • Satish S Patil Department of Microbiology, SS Institute of Medical Sciences and Research Centre, Davangere, Karnataka, India
  • Vidyavathi B Chitharagi Department of Microbiology, JSS Medical College, Mysore, Karnataka, India
  • Ganavalli Subramanya Ajantha Department of Microbiology, SDM College of Medical Sciences and Hospital, Dharwad, Karnataka, India
Keywords: Modified protocol, Automated blood culture, Neonatal septicemia

Abstract

Background and Objectives: Neonatal septicemia can be rapidly fatal if not treated promptly. A speedy laboratory diagnosis would improve the outcome. The BacT/ALERT 3D system (bioMerieux, Durham, North Carolina) is currently being used for laboratory diagnosis of blood stream infections. In the present study, a modified protocol was employed in which the broth was subcultured into two nutrient broth tubes and these tubes were used for biochemical tests and antimicrobial susceptibility testing to decrease the turnaround time. Materials and Methods: A prospective study was conducted in the Department of Microbiology, SDM College of Medical Sciences and Hospital, Dharwad from October 2010 to July 2012 after receiving clearance from the institutional ethics committee. Automated blood cultures of 250 neonates admitted to the Neonatal Intensive Care Unit (NICU), clinically diagnosed to have septicemia, were performed using BacT/ALERT 3D. Bottles flagged positive within 72 hours of loading were processed for identification and antibiotic susceptibility testing using a modified protocol. The results were assessed for time saved in reporting in comparison with standard protocol. Student’s t test was used for statistical analysis. Results: Of the 250 cases studied, 117 cases yielded a positive blood culture giving a yield of 46.8%. The number of cases yielding monomicrobial growth were 73, which were included for further analysis. Of the remaining samples, 133 did not show growth, 11 were polymicrobial while 33 samples were flagged positive after 72 hours. Candida spp. grew in 34 cases, Gram negative bacilli grew in 28 cases and Gram positive cocci grew in 11 cases. In four cases, 66 hours were saved, 60 and 54 hours were saved in 18 cases each, 48 hours were saved in 27 cases, and 24 hours were saved in 6 cases. Methicillin resistant Staphylococcus aureus and Klebsiella pneumoniae were the most common isolates among Gram positive cocci and Gram negative bacilli, respectively, while C. guilliermondii was the most common Candida isolate. All Gram positive isolates were susceptible to vancomycin and linezolid. Most of the Gram negative isolates were susceptible to imipenem. Conclusion: This method can be employed in peripheral laboratory settings where there is no complete automation. Modification in processing blood culture can provide speedy identification and sensitivity report in blood stream infections. Time saved in reporting would play a crucial role in improving morbidity and mortality rates in neonatal septicemia.

References

Vergnano S, Sharland M, Kazembe P, Mwansambo C, Heath PT. Neonatal sepsis: an international perspective. Arch Dis Child Fetal Neonatal Ed 2005; 90: 220-4.

World Health Organization. Make Every Mother and Child Count. Chapter 5: Newborns: no longer going unnoticed. The World Health Report: Geneva; 2005.

Wattala C, Raveendrana R, Goela N, Oberoia JK, Rao BK. Ecology of blood stream infection and antibiotic resistance in intensive care unit at a tertiary care hospital in North India. Braz J Infect dis 2014; 18(3): 245–51.

PHE. Polymicrobial bacteraemia and fungaemia in England, Wales and Northern Ireland: 2013. Health Protection Report [serial online] 2014; 8(48).

Parikh HR, De AS, Baveja SM. Comparison of the Lysis Centrifugation Method with the Conventional Blood Culture Method in Cases of Sepsis in a Tertiary Care Hospital. J Lab Physicians 2012; 4(2): 89–93.

Wilson CB, Nizet V, Maldonado Y, Remington JS, Klein JO (2016). Remington and Klien’s Infectious diseases of Fetus and Newborn Infant. 8thed. Philadelphia: Saunders Elsevier.

Buttery JP. Blood cultures in newborns and children: optimising an everyday test. Arch Dis Child Fetal Neonatal Ed 2002; 87: 25–8.

Kumar Y, Qunibi M, Neal TJ, Yoxall CW. Time to positivity of neonatal blood cultures. Arch Dis Child Fetal Neonatal Ed 2001; 85: 182–6.

Janjindamai W, Phetpisal S. Time to positivity of blood culture in newborn infants. Southeast Asian J Trop Med Public Health 2006; 37(1): 171-6.

Forbes BA, Sahm DF, Weissfeld AS (2007). Bailey and Scott’s Diagnostic Microbiology. 12th ed. St. Louis: Mosby Elsevier.

Performance Standards for Antimicrobial Disk Susceptibility Tests, M100-S24. Clinical and Laboratory Standards Institute. Pennsylvania, USA; 2014 Jan; 34(1).

Jardine L, Davies MW, Faoagali J. Incubation time required for neonatal blood cultures to become positive. J Paediatr Child Health 2006; 42: 797–802.

Ganatra HA, Stoll BJ, Zaidi AKM. International Perspective on Early-Onset Neonatal Sepsis. Clin Perinatol 2010; 37: 501-23.

Guerti K, Devos H, Leven MM, Mahieu LM. Time to positivity of neonatal blood cultures: fast and furious? Journal of Medical Microbiology 2011; 60: 446–53.

Opota O, Croxatto A, Prod’hom G, Greub G. Blood culture-based diagnosis of bacteraemia: state of the art. Clin Microbiol Infect 2015; 21(4): 313–22.

Machen A, Drake T, Wang YF. Same Day Identification and Full Panel Antimicrobial Susceptibility Testing of Bacteria from Positive Blood Culture Bottles Made Possible by a Combined Lysis-Filtration Method with MALDI-TOF VITEK Mass Spectrometry and the VITEK 2 System. PLoS ONE 9(2): e87870.doi:10.1371/journal.pone.0087870.

Prod’hom G, Durussel D and Greub G. A simple blood-culture bacterial pellet preparation for faster accurate direct bacterial identification and antibiotic susceptibility testing with the VITEK 2 system. Journal of Medical Microbiology 2013; 62: 773–7.

Chapin KC, Musgnug MC. Direct Susceptibility Testing of Positive Blood Cultures by Using Sensititre Broth Microdilution Plates. Journal of Clinical Microbiology 2003; 41(10): 4751-4.

Published
2018-11-23
How to Cite
1.
Anegundi R, Kulkarni R, Patil S, Chitharagi V, Ajantha G. Evaluation of a modified protocol that decreases the turnaround time of positive blood cultures. IJM. 10(5):281-6.
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Original Article(s)