LETTER TO THE EDITORS
Procalcitonin An Emerging Prognostic Factor of Bacterial Coinfection in Infants With Acute Bronchiolitis?
To the Editors: e have read the recently published article entitled “Procalcitonin (PCT) to predict bacterial coinfection in infants with acute bronchiolitis: a preliminary analysis” by Laham et al1 with great interest. They aimed to investigate whether PCT had an association with bacterial coinfection in infants with acute bronchiolitis. They concluded that elevated PCT levels may assist clinicians in determining the presence of bacterial coinfection at admission in infants with acute bronchiolitis. We would like to thank the authors for their valuable contribution. Procalcitonin, consisting of a 116amino acid propeptide of calcitonin, is synthesized by the parafollicular C cells of the thyroid.2 It is also involved in calcium homeostasis.2 Several studies have demonstrated that PCT levels increase in patients who have bacterial infections, unlike in patients with viral infections, and this marker serves to distinguish bacterial infections from viral infective agents.3 Additionally, PCT is a useful guide for clinicians to make decisions about initiation or duration of antibiotic treatment.3 Bronchiolitis, which is a common lower respiratory tract infection in infants, usually affects children younger than 2 years. Respiratory syncytial virus is the most common cause of bronchiolitis and lower respiratory tract infection in infants.4 These infections may be severe and even life-threatening in selected high-risk populations, such as preterm infants with or without chronic lung disease and children with congenital heart disease.4 First, this was a retrospective review where only patients who had a diagnosis of bronchiolitis and had a PCT level sent were included. The authors should have
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stated that this was a potential area for selection bias because PCT levels may have been sent on patients with highest suspicion of serious bacterial infection. At the least, they should have included total numbers of patients with bronchiolitis during the study period for comparison. Second, it would have been relevant if the authors would have included some severity of illness score (e.g., physiologic stability index and/or pediatric risk of mortality) so that comparisons could have been made between groups. It would also have been helpful to include which patients had indwelling hardware (i.e., tracheostomy) and other preexisting conditions which may predispose them to bacterial illness. In addition, the authors could have differentiate between patients who were newly admitted to the PICU with bronchiolitis and those who might have been in the midst of a longer admission for another reason and developed bronchiolitis in house. Third, PCT is affected by a variety of infectious agents. For this reason, detailed microbiological evaluation is crucial. A previous study by Charles et al demonstrated that PCT levels were found to be higher in gram-negative than gram-positive agents.5 The authors could have evaluated their cases according to the infectious agents in this study. In addition, the authors classified 6 patients as having “bacterial”-based infection on chest x-ray without organism identified. They should have stated in the methods how this was defined in a more rigorous manner. It is not clear that these are truly “bacterial cases.” One option would be to include a subanalysis with these patients excluded. Lastly, PCT levels can be raised via nonbacterial causes, such as massive stress, severe multiorgan dysfunction and surgeries. In these situations, after the elevation of PCT levels, a rapid decline is observed in the follow-up measurements.6 Conversely, PCT can have false-negative values, especially in the early course of an infection.6 In this context, repeated measurements of PCT are crucial and should always be performed. Therefore, it would have been more accurate if the authors had mentioned these conditions as limitations.
In conclusion, further studies are needed to determine the associations between PCT and bacterial coinfections in infants with acute bronchiolitis. We think that PCT should be considered along with other inflammatory markers (e.g., C-reactive protein, erythrocyte sedimentation rate, presepsin) to provide the required information about the inflammatory status of the patient. Ergenekon Karagöz, MD Department of Infectious Diseases and Clinical Microbiology
Bayhan Bektore, MD Department of Medical Microbiology
Alpaslan Tanoglu, MD Department of Internal Medicine Gastroenterology GATA Haydarpasa Training Hospital Istanbul, Turkey [email protected]
DISCLOSURE The authors declare no conflict of interest. REFERENCES 1. Laham JL, Breheny PJ, Gardner BM, et al. Procalcitonin to predict bacterial coinfection in infants with acute bronchiolitis: a preliminary analysis. Pediatr Emerg Care. 2014;30:11–15. 2. Uzun G, Solmazgul E, Curuksulu H, et al. Procalcitonin as a diagnostic aid in diabetic foot infections. Tohoku J Exp Med. 2007;213: 305–312. 3. Choi HJ. Procalcitonin in diagnosis of post-operative bacterial meningitis: a promising but limited role. Infect Chemother. 2013;45: 346–348. 4. Manzoni P, Paes B, Resch B, et al. High risk for RSV bronchiolitis in late preterms and selected infants affected by rare disorders: a dilemma of specific prevention. Early Hum Dev. 2012;88:34–41. 5. Charles PE, Ladoire S, Aho S, et al. Serum procalcitonin elevation in critically ill patients at the onset of bacteremia caused by either gram negative or gram positive bacteria. BMC Infect Dis. 2008;8:38. 6. Schuetz P, Christ-Crain M, Müller B. Procalcitonin and other biomarkers to improve assessment and antibiotic stewardship in infections—hope for hype? Swiss Med Wkly. 2009;139:318–326.
Pediatric Emergency Care • Volume 30, Number 12, December 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Procalcitonin An Emerging Prognostic Factor of Bacterial Coinfection in Infants With Acute Bronchiolitis?
To the Editors: e have read the recently published article entitled “Procalcitonin (PCT) to predict bacterial coinfection in infants with acute bronchiolitis: a preliminary analysis” by Laham et al1 with great interest. They aimed to investigate whether PCT had an association with bacterial coinfection in infants with acute bronchiolitis. They concluded that elevated PCT levels may assist clinicians in determining the presence of bacterial coinfection at admission in infants with acute bronchiolitis. We would like to thank the authors for their valuable contribution. Procalcitonin, consisting of a 116amino acid propeptide of calcitonin, is synthesized by the parafollicular C cells of the thyroid.2 It is also involved in calcium homeostasis.2 Several studies have demonstrated that PCT levels increase in patients who have bacterial infections, unlike in patients with viral infections, and this marker serves to distinguish bacterial infections from viral infective agents.3 Additionally, PCT is a useful guide for clinicians to make decisions about initiation or duration of antibiotic treatment.3 Bronchiolitis, which is a common lower respiratory tract infection in infants, usually affects children younger than 2 years. Respiratory syncytial virus is the most common cause of bronchiolitis and lower respiratory tract infection in infants.4 These infections may be severe and even life-threatening in selected high-risk populations, such as preterm infants with or without chronic lung disease and children with congenital heart disease.4 First, this was a retrospective review where only patients who had a diagnosis of bronchiolitis and had a PCT level sent were included. The authors should have
W
e8
www.pec-online.com
stated that this was a potential area for selection bias because PCT levels may have been sent on patients with highest suspicion of serious bacterial infection. At the least, they should have included total numbers of patients with bronchiolitis during the study period for comparison. Second, it would have been relevant if the authors would have included some severity of illness score (e.g., physiologic stability index and/or pediatric risk of mortality) so that comparisons could have been made between groups. It would also have been helpful to include which patients had indwelling hardware (i.e., tracheostomy) and other preexisting conditions which may predispose them to bacterial illness. In addition, the authors could have differentiate between patients who were newly admitted to the PICU with bronchiolitis and those who might have been in the midst of a longer admission for another reason and developed bronchiolitis in house. Third, PCT is affected by a variety of infectious agents. For this reason, detailed microbiological evaluation is crucial. A previous study by Charles et al demonstrated that PCT levels were found to be higher in gram-negative than gram-positive agents.5 The authors could have evaluated their cases according to the infectious agents in this study. In addition, the authors classified 6 patients as having “bacterial”-based infection on chest x-ray without organism identified. They should have stated in the methods how this was defined in a more rigorous manner. It is not clear that these are truly “bacterial cases.” One option would be to include a subanalysis with these patients excluded. Lastly, PCT levels can be raised via nonbacterial causes, such as massive stress, severe multiorgan dysfunction and surgeries. In these situations, after the elevation of PCT levels, a rapid decline is observed in the follow-up measurements.6 Conversely, PCT can have false-negative values, especially in the early course of an infection.6 In this context, repeated measurements of PCT are crucial and should always be performed. Therefore, it would have been more accurate if the authors had mentioned these conditions as limitations.
In conclusion, further studies are needed to determine the associations between PCT and bacterial coinfections in infants with acute bronchiolitis. We think that PCT should be considered along with other inflammatory markers (e.g., C-reactive protein, erythrocyte sedimentation rate, presepsin) to provide the required information about the inflammatory status of the patient. Ergenekon Karagöz, MD Department of Infectious Diseases and Clinical Microbiology
Bayhan Bektore, MD Department of Medical Microbiology
Alpaslan Tanoglu, MD Department of Internal Medicine Gastroenterology GATA Haydarpasa Training Hospital Istanbul, Turkey [email protected]
DISCLOSURE The authors declare no conflict of interest. REFERENCES 1. Laham JL, Breheny PJ, Gardner BM, et al. Procalcitonin to predict bacterial coinfection in infants with acute bronchiolitis: a preliminary analysis. Pediatr Emerg Care. 2014;30:11–15. 2. Uzun G, Solmazgul E, Curuksulu H, et al. Procalcitonin as a diagnostic aid in diabetic foot infections. Tohoku J Exp Med. 2007;213: 305–312. 3. Choi HJ. Procalcitonin in diagnosis of post-operative bacterial meningitis: a promising but limited role. Infect Chemother. 2013;45: 346–348. 4. Manzoni P, Paes B, Resch B, et al. High risk for RSV bronchiolitis in late preterms and selected infants affected by rare disorders: a dilemma of specific prevention. Early Hum Dev. 2012;88:34–41. 5. Charles PE, Ladoire S, Aho S, et al. Serum procalcitonin elevation in critically ill patients at the onset of bacteremia caused by either gram negative or gram positive bacteria. BMC Infect Dis. 2008;8:38. 6. Schuetz P, Christ-Crain M, Müller B. Procalcitonin and other biomarkers to improve assessment and antibiotic stewardship in infections—hope for hype? Swiss Med Wkly. 2009;139:318–326.
Pediatric Emergency Care • Volume 30, Number 12, December 2014
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
