Journal Club presentation. Infectious Diseases rotation (R2). Clinical Microbiology Residency Program KFHU-Alkhobar

1. Procalcitonin as a diagnostic
biomarker of sepsis: A tertiary care
centre experience
Clinical Microbiology Resident.
King Fahd Hospital of the University.
Teaching Assistant, Department of Microbiology, Imam Abdulrahman Bin
Faisal University, Dammam, Saudi Arabia.
Abdullatif Sami Al Rashed

3. Outline
• Introduction
– Sepsis definitions
– Sepsis epidemiology
– Procalcitonin test and pathophysiology
• Aim of the study
• Material and Methods
• Results
• Conclusion
• Critical Appraisal
• References

4. INTRODUCTION

5. Introduction
Sepsis is a heterogeneous infectious disease associated with
high rates of morbidity and mortality.
A global incidence of 31.5 million cases per year has been
reported in a recent meta-analysis. (1)
Despite of its association with high morbidity and mortality,
sepsis remains a very difficult condition to diagnose.

6. Definition of Sepsis
• The definitions of sepsis and septic shock have
rapidly evolved since the early 1990s. (2)
• The systemic inflammatory response
syndrome (SIRS) is no longer included in the
definition since it is not always caused by
infection.
SIRS is considered a clinical syndrome that is a form
of dysregulated inflammation. It is defined as two
or more abnormalities in temperature, heart rate,
respiration, or white blood cell count

7. Definition of Sepsis
• In 2016, sepsis definitions were updated by
the national societies including the Society of
Critical Care Medicine (SCCM) and the
European Society of Intensive Care Medicine
(ESICM). (3)
• However, such definitions are still
NOT diagnostic of sepsis since they do not
comprehensively include specific criteria for
the identification of infection.

8. Early Sepsis
• The 2016 SCCM/ESICM task force have
described an assessment score for patients
outside the intensive care unit as a way to
facilitate the identification of patients
potentially at risk of dying from sepsis.
• This score is a modified version of the
Sequential (Sepsis-related) Organ Failure
Assessment score (SOFA) called the quickSOFA
(qSOFA) score.

9. A score ≥2 is associated with poor outcomes due to sepsis.
Singer M, Deutschman CS, Seymour CW, Shankar-Hari M, Annane D, Bauer M, Bellomo R, Bernard GR, Chiche JD, Coopersmith CM, Hotchkiss
RS. The third international consensus definitions for sepsis and septic shock (Sepsis-3). Jama. 2016 Feb 23;315(8):801-10.

10. Sepsis
• A 2016 SCCM/ESICM task force has defined sepsis as life-
threatening organ dysfunction caused by a dysregulated host
response to infection (Sepsis-3).
Organ dysfunction
• is defined by the 2016 SCCM/ESICM task force as an
increase of ≥2 points in the SOFA score.
Infection
• There are no clear guidelines to help the clinician identify the
presence of infection or to link an identified organism with
sepsis.
• For this component of the diagnosis, the clinician is reliant
upon clinical suspicion derived from the signs and symptoms
of infection as well as supporting radiologic and microbiologic

11. Singer M, Deutschman CS, Seymour CW, Shankar-Hari M, Annane D, Bauer M, Bellomo R, Bernard GR,
Chiche JD, Coopersmith CM, Hotchkiss RS. The third international consensus definitions for sepsis and
septic shock (Sepsis-3). Jama. 2016 Feb 23;315(8):801-10.

12. Septic shock
• Septic shock is defined as:
– Sepsis that has circulatory, cellular, and metabolic
abnormalities that are associated with a greater
risk of mortality than sepsis alone.
• Clinically, this includes patients who fulfill the
criteria for sepsis who:
– despite adequate fluid resuscitation, require
vasopressors to maintain a mean arterial pressure
(MAP) ≥65 mmHg and have a lactate >2 mmol/L
(>18 mg/dL).

13. Introduction
• In light of these reasons, a dire need has been
felt to search for rapid and reliable biomarkers
of sepsis.
• A biomarker with high sensitivity and negative
predictive value (NPV), which can exclude
suspected sepsis early could be a very useful
addition to the diagnostic evaluation for
management of sepsis.

14. Procalcitonin
• Procalcitonin (PCT), a polypeptide is one
such biomarker that has demonstrated
highest reliability in the early diagnosis
of sepsis, especially of bacterial etiology.
(4-6)
• PCT is a 116-amino acid residue that was
first explained by Le Moullec et al. in
1984; however, its diagnostic
significance was not recognized until
1993. (7)
• In bacterial sepsis, serum PCT increases
by 100–1000 fold within 4 h after the
onset of systemic infection and peaks at
between 8 and 24 h. (4-6)
The Structure of Procalcitonin

15. Pathophysiology
Normally, physiological conditions result in very low serum
procalcitonin levels (less than 0.05 ng/mL). However, the synthesis
of PCT can be increased (up to 100 to 1000 fold) as a result of
endotoxins and/or cytokines (eg, interleukin (IL)- 6, tumor necrosis
factor (TNF)-alpha, and IL-1b), which act on various tissues.
Later this peptide is transformed into procalcitonin via cleavage of a
25-amino acid signal sequence by endopeptidases. The end product
calcitonin, the 32-amino acid hormone responsible for serum calcium
regulation, is then formed following conversion by the enzyme
prohormone convertase.
Under normal homeostasis, pre-procalcitonin undergoes initial synthesis by
thyroid C cells.

16. Pathophysiology
• The extra-thyroid synthesis of PCT has been
found to occur in the liver, pancreas, kidney,
lung, intestine and within leukocytes;
–However, it has been noticed that the
synthesis of PCT has been shown to be
suppressed within these tissues in the
absence of bacterial infection.

17. Aim of the Study
• They perform this study to investigate the
utility of PCT as a diagnostic marker in sepsis
at a tertiary care hospital in North India.
• They aimed to determine serum PCT levels
and correlate with culture results and further
evaluate sensitivity, specificity, positive
predictive value (PPV), and NPV for PCT to
predict its diagnostic performance.

18. MATERIALS AND METHODS

19. Patient selection and study design
• A prospective observational study on 259
consecutive adult patients who were hospitalized
and treated in Sanjay Gandhi Post Graduate Institute
of Medical Sciences, India with sepsis of bacterial
etiology from September 2016 to October 2017.
• The study population comprised of patients from
different medical wards; various parameters were
recorded to facilitate the calculation of SOFA score.
• Demographic variables, clinical details and other
baseline characteristics of eligible patients were also
documented.

20. Patient selection and study design
• Initially enrolled patients were classified into 3 groups:
• Acute heart failure, hypertensive
cardiomyopathy, acute renal failure, acute
cerebrovascular disease, epilepsy, Crohn’s disease
and neoplastic disease.
Non-infectious
controls (group I).
• Clinical suspicion of infection with
negative culture results.
Group II (culture-
negative sepsis
group):
• Patients with sepsis along with microbiologically
documented source of infection.
• At the time of analysis, group III was further
subdivided into group III(a) Gram positive sepsis and
group III (b) Gram negative sepsis.
Group III (culture-
positive sepsis
group):

21. Patient selection and study design
• The definition of sepsis that has been released
recently by the European Society of Intensive
Care Medicine (ESICM) and Society of Critical
Care Medicine (SCCM) in 2016 has been followed
to define cases of Sepsis. (Sepsis-3)
• Two independent clinicians (also co-authors)
blinded to the diagnosis were involved to confirm
patient inclusion/exclusion into sepsis group. No
discrepancy was found between the two
operators.

22. Patient selection and study design
• Patients with history of:
– Recent surgery or transplant
– Malignancy
– Suspected or documented non-bacterial infections
– Those managed on immunosuppressant agents and
– Patients who were lost to follow-up.
• Additionally, patients were followed up till
discharge or any adverse outcomes happened.
Were excluded from the study

24. Infection identification and diagnostic
criteria
• Infections were clinically diagnosed on the
basis of clinical presentation, laboratory
findings, microbiologic evidence and imaging
studies.
• Type of infections identified:
Abdominal infections
included abdominal
abscesses, peritonitis,
enteritis, pancreatic
and biliary tract
infections.
UTI
Pneumon
ia
Primary
BSI

25. Specimen collection, laboratory
processing and PCT measurement
Also, microbiological investigations were carried out depending on anatomic site of
infection. These included culture of sputum/endotracheal aspirates, pleural or ascitic fluids,
urine, pus and other fluids (abdominal abscesses, peritoneal and biliary infections) as per
treating clinician’s requisition.
Blood culture vials were incubated in the BACTEC automated blood
culture system (BD Biosciences, Maryland, USA) for 5 days.
For the control group, blood was collected only at the
time of admission.
Blood samples for culture and measurement of PCT were drawn
simultaneously from each patient before introduction of antibiotic
therapy and sent to microbiology laboratory for further processing.

26. Specimen collection, laboratory
processing and PCT measurement
PCT estimation in the serum was done using the
commercially available electro chemiluminescense
immunoassay (Elecsys®BRAHMS PCT from Roche
Diagnostics, Berlin, Germany) using a Cobase 411 analyzer.
PCT levels >0.5 ng/ml were taken as clinically significant as per
manufacturer’s instruction.
Values above 100 ng/ml were not delineated further by the
equipment; hence reported as ≥100 ng/ml and all such values
were taken as 100 ng/ml for the purpose of calculations

27. http://labogids.sintmaria.be/sites/default/files/files/ele
csys_brahms_pct_method_sheet_2016-11_v11.pdf

28. Ethical clearance
• The ethics committee of Sanjay Gandhi Post
Graduate Institute of Medical Sciences
(SGPGIMS), Lucknow, Uttar Pradesh
(India)approved the study.
• All procedures involving human participants in
this study were in accordance with the ethical
standards.

29. RESULTS

30. Characteristics of the enrolled subjects

31. Source of infection
• In culture positive sepsis patients,
bloodstream was the major site of
infection(46%) followed by urinary tract (26%)
and respiratory tract (19%).
• The respiratory tract (40%) and abdomen
(33%) were predominant foci of clinically
suspected bacterial infections. (Culture
Negative)

32. PCT differentiation in culture positive
sepsis
• Out of 196 patients, 59% (116) were infected
by Gram-negative bacteria and 41% (80) by
Gram-positive bacteria.
• Thirty positive cultures were polymicrobial
and remaining 166 mono-microbial.

33. PCT differentiation in culture positive
sepsis
• In Gram-negative cultures, Klebsiella
pneumoniae was the most common pathogen
(n = 41, 35.34%) with mean PCT value 25.05 ±
37.48 ng/ml
• Followed by Escherichia coli (n = 25,21.55%)
mean 17.49 ± 26.22 ng/ml and
• Acinetobacter baumanni (n = 21,18.10%)
mean PCT value 14.71 ± 28.99 ng/ml.

34. PCT differentiation in culture positive
sepsis
• Interestingly, Citrobacter freundii was isolated
in only 5 cultures, but mean PCT value 23.38 ±
30.04 ng/ml was higher than that of E. coli
and A. baumanni
• On comparing mean PCT values between
Gram-negative, Gram-positive, and
polymicrobial isolates, Gram-negative
bacterial pathogens had the highest mean PCT
values.

36. Diagnostic performance of PCT
• To estimate the diagnostic performance of
PCT, cut-off value of 1.03 ng/ml and AUC =
0.920 (95% CI = 0.869–0.972) was significant
(P = <0.001) to differentiate culture negative
sepsis from controls with sensitivity 87.30%
and specificity 78.26%

37. Diagnostic performance of PCT
• While PCT cut-off value 2.20 ng/ml and AUC =
0.985, (95%CI = 0.965–1) differentiated
culture positive sepsis from controls with
98.5% sensitivity and 89.13% specificity [(P =
<0.001)

38. Diagnostic performance of PCT
• Differentiation of culture positive sepsis in
comparison with culture negative sepsis found
significant with cut-off 2.58 ng/ml [(AUC =
0.608, 95% CI = 0.512–0.703)] with sensitivity
of 91.33%, but the specificity of this test was
quite low 41.27%.

39. Diagnostic performance of PCT
• Also group III was classified into culture
positive GNB and culture positive GPB
subgroups and found AUC = 0.612 at 3.01
ng/ml cut-off value of PCT with 75%
sensitivity, and 46.34% specificity

41. Conclusion
• PCT can be considered as an effective and elegant
addition to diagnostic algorithm for supporting
clinical decision making, identification of sepsis
and lessen dependence on cultures as well.
• Refined risk stratification and improved patient
outcomes could result from the utilization of PCT
based strategies.
• More multi-centric randomized studies are
needed to confirm the validity of the study
findings.

42. Critical Appraisal

44. Question Yes No Can’t Tell
Was there a clear statement of the aims of the research?
Is a qualitative methodology appropriate?
Was the research design appropriate to address the aims of the
research?
Was the recruitment strategy appropriate to
the aims of the research?
Was the data collected in a way that addressed the
research issue?
Has the relationship between researcher and
participants been adequately considered?
Have ethical issues been taken into consideration?
Was the data analysis sufficiently rigorous?
Is there a clear statement of findings?
Do the results of this study fit with other available evidence?

45. Critical Appraisal Summary
Positive Points Negative Points
Very important topic Sample size?
Clear research question
Study design
Good sample size
Adequate Statistical
analysis
Ethical Approval

46. References
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sepsis and septic shock (Sepsis-3). Jama. 2016 Feb 23;315(8):801-10.
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Antimicrob Chemother 2011;66(Suppl 2):ii33–40, http://dx.doi.org/10.1093/jac/dkq523.
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failure in sepsis. Indian J Clin Biochem 2014;29:93–6,http://dx.doi.org/10.1007/s12291-013-0326-z.
6. Angeletti S, Ciccozzi M, Fogolari M, Spoto S, Lo Presti A, Costantino S, et al.Procalcitonin and MR-
proAdrenomedullin combined score in the diagnosis andprognosis of systemic and localized
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7. Le Moullec JM, Jullienne A, Chenais J, Lasmoles F, Guliana JM, Milhaud G, Moukhtar MS. The
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47. THANK YOU