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Diagnosing ventilator-associated pneumonia in pediatric intensive care
American Journal of Infection Control xxx (2015) 1-4
Contents lists available at ScienceDirect
American Journal of Infection Control
American Journal of Infection Control
journal homepage: www.ajicjournal.org
Brief report
Diagnosing ventilator-associated pneumonia in pediatric intensive care Elias Iosifidis MD, MSc, PhD a, Stella Stabouli MD, PhD b, Anastasia Tsolaki MD, MSc b, Vaios Sigounas MD c, Emilia-Barbara Panagiotidou RN b, Maria Sdougka MD, PhD b, Emmanuel Roilides MD, PhD a, * a b c
Infectious Diseases Unit, 3rd Department of Pediatrics, Aristotle University School of Medicine, Hippokration Hospital, Thessaloniki, Greece Pediatric Intensive Care Unit, Hippokration Hospital, Thessaloniki, Greece Radiology Department, Hippokration Hospital, Thessaloniki, Greece
Key Words: Health careeassociated infection Radiology Pediatric intensive care Pneumonia Mechanical ventilation Chest radiograph
The Centers for Disease Control and Prevention’s criteria were applied by independent investigators for ventilator-associated pneumonia (VAP) diagnosis in critically ill children and compared with tracheal aspirate cultures (TACs). In addition, correlation between antibiotic use, VAP incidence, and epidemiology of TACs was investigated. A modest agreement (k ¼ 0.41) was found on radiologic findings between 2 investigators. VAP incidence was 7.7 episodes per 1,000 ventilator days, but positive TACs were the most significant factor for driving high antimicrobial usage in the pediatric intensive care unit. Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Until now, the Centers for Disease Control and Prevention’s (CDC’s) algorithm for ventilator-associated pneumonia (VAP) diagnosis has been widely acceptable and used for surveillance purposes in children.1,2 Although this algorithm has recently been updated, there are significant difficulties, including the requirement of radiographic findings.2-4 We aimed to apply the CDC’s criteria for VAP diagnosis in critically ill children, evaluate chest radiographs by 2 independent investigators, and compare the results to the yield of tracheal aspirate cultures (TACs). Secondary aims included the relationship among antibiotic use, VAP incidence, and epidemiology of TACs. METHODS A retrospective study was conducted in an 8-bed pediatric intensive care unit (PICU) in Hippokration Hospital between January and December 2011.
* Address correspondence to Emmanuel Roilides, MD, PhD, 3rd Department of Pediatrics, Hippokration Hospital, Konstantinoupoleos 49, GR-546 42 Thessaloniki, Greece. E-mail address: [email protected] (E. Roilides). Previous Presentation: Preliminary results of this study were presented at the 53rd Interscience Conference of Antimicrobial Agents and Chemotherapy; September 10-13, 2013; Denver, CO. Funding/Support: This study was supported by a 2011-2013 European Society for Pediatric Infectious Diseases fellowship to E.I. Conflicts of interest: None to report.
A stepwise approach was used according to the CDC’s definition for VAP in children (Fig 1).3 First, radiologic criteria were assessed by 2 investigators (intensivist [S.S.] and radiologist [V.S.]) blinded to symptoms and signs when reviewing radiographs. According to the practice of the PICU, radiographs were taken on admission, daily thereafter, and additionally only if there was clinical change that needed further evaluation in the same day. Chest computed tomography was not evaluated to avoid inconsistency. Predefined criteria were used for evaluating intra- and interobserver variability. If there was agreement between the 2 investigators, no further evaluation was required. If disagreement was found, a second blinded assessment was made by the radiologist. In the case that there was high intraobserver agreement, only the radiologist’s assessment was used (because of professional experience). Second, patients with radiologic criteria fulfilled during the first step were assessed for clinical criteria (A.T. and E.R.). Pathogens isolated from TACs were monitored by a fifth investigator (E.I.) among all ventilated inpatients, including those diagnosed with documented pneumonia and those without VAP (Fig 1). TACs were collected on admission and thereafter routinely twice weekly or on suspicion of pneumonia. All patients were allocated in 3 groups according to the previous criteria: children with VAP (confirmed VAP), children with positive TACs but without VAP (possible ventilator-associated tracheitis [pVAT]),5 and children without VAP or pVAT (control group) (Fig 1). The characteristics of the children in the 3 groups recorded were
0196-6553/$36.00 - Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2015.01.004
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E. Iosifidis et al. / American Journal of Infection Control xxx (2015) 1-4
Fig 1. Flow diagram. Stepwise approach for VAP diagnosis (1st part) and patient allocation according to VAP diagnosis and tracheal aspirate culture results (2nd part). CDC, Centers for Disease Control and Prevention; INV1, author S.S.; INV2, author V.S.; INV3, author A.T.; INV4, author E.R.; INV5, E.I.; p. VAT, possible ventilator-associated tracheitis; VAP, ventilatorassociated pneumonia; VAT, ventilator-associated tracheitis.
demographics (age, sex), underlying disease, reasons for PICU admission, Pediatric Risk of Mortality III (PRISM III score), number of ventilator days, antimicrobial therapy (and modifications because of possible VAP), and length of PICU stay. The annual incidence of VAP was calculated by dividing the number of defined VAP episodes by the total ventilator days. The monthly rates of antimicrobial drug consumption were calculated by the method of days of therapy per 100 bed days.6 In TACs, pathogens were distinguished from commensals, and a positive result was considered only if >104 colony forming units/ mL and 25 neutrophils per low power field (100) were found. Identification and susceptibility were conducted by VITEK 2 (Biomérieux, Marcy l’Etoile, France). Monthly incidence and prevalence of pathogens were calculated. We calculated agreement using the k score, and the correlation was calculated using the Spearman correlation coefficient with SPSS version 17.0 (SPSS, Chicago, IL). The study was approved by the institutional ethics committee without a need for informed consent because of the retrospective design.
RESULTS A total of 127 children were admitted, with a median PRISM III score of 8 (range, 3-35). Among them, 119 (94%) received mechanical ventilation, with a median of 7 ventilator days per patient (range, 1-183 days). Among the 119 patients, radiologic criteria were fulfilled in 30 and 18 children according to the intensivist (S.S.) and radiologist (V.S.), respectively. The interobserver agreement was modest (k score ¼ 0.41). The results of the second blinded assessment on selective patients by the radiologist (V.S.) showed 100% intraobserver agreement, and further assessment relied on his report.
Among the 18 children with radiologic criteria fulfilled by the radiologist (7/18 fulfilled criteria by the intensivist), 13 (11% of patients) had at least 3 signs and symptoms or laboratory abnormalities. The median number of days before the onset of VAP in these patients was 6 (range, 3-40). Thirteen patients had confirmed VAP (11% of patients that received mechanical ventilation). Eight of them had positive TACs (Acinetobacter baumannii: n ¼ 4; Pseudomonas aeruginosa: n ¼ 4). Among 106 patients not meeting VAP criteria, 26 (22%) had positive TACs (pVAT). Among them, 62% had a new antimicrobial agent started based on the TAC. Furthermore, 80 patients (67%) had no VAP or pVAT (control group) (Table 1). The VAP incidence was 7.7 episodes per 1,000 ventilator days. The most common pathogens isolated from the TACs were P aeruginosa (55%) and A baumannii (31%). Other pathogens found were Stenotrophomonas maltophilia (7%), Enterobacteriaceae spp (5%), and Staphylococcus aureus (2%). Resistance rates of P aeruginosa and A baumannii to piperacillin-tazobactam were 13% and 94%, resistance rates to ciprofloxacin were 47% and 97%, resistance rates to imipenem were 42% and 77%, resistance rates to meropenem were 66% and 10%, and resistance rates to gentamicin were 7% and 65%, respectively. There was a continuous high flow of new cases with TACs positive for P aeruginosa or A baumannii during the whole study period except in May and June (Fig 2, panel A). During this 2month interval, antimicrobial consumption significantly dropped. Moreover, consumption of antimicrobial agents correlated with the incidence of positive TACs. However, only 11% of patients had confirmed VAP, whereas 29% of them had positive TACs. Antimicrobial consumption is depicted in panel B of Figure 2. Consumption of antipseudomonal agents constituted >50% of total antimicrobial utilization.
E. Iosifidis et al. / American Journal of Infection Control xxx (2015) 1-4
3
Table 1 Demographic and clinical characteristics of children on mechanical ventilation
Demographic and clinical characteristics
Confirmed VAP (n ¼ 13)
Age (mo), median (range) Sex (% female) Underlying disease (%), medical/surgical LOS (d), median (range) Total ventilator days, median (range) PRISM III (score), median (range)
15 (2-144) 58 83/27 19 (2-209) 18 (2-183) 7 (0-20)
pVAT (n ¼ 26)
Control (without VAP or pVAT) (n ¼ 80)
VAP versus control
pVAT versus control
42 (3-156) 28 68/32 17 (2-90) 17 (1-90) 10 (2-20)
36 (1-204) 51 56/44 5 (1-124) 5 (1-124) 8 (0-35)
NS NS .04 <.0001 <.0001 NS
NS .046 NS .0024 .0024 NS
NOTE. Children with VAP were compared with children without evidence of VAP or even pVAT. Children with ventilator-associated tracheitis were compared with children without evidence of VAP or pVAT. Control, children without ventilator-associated pneumonia or possible ventilator-associated pneumonia; LOS, length of stay; NS, not significant; pVAT, children with possible ventilator-associated tracheitis; VAP, ventilator-associated pneumonia.
Fig 2. Monthly incidence of ventilated children with positive tracheal aspirate cultures (TAC) (A) and monthly antimicrobial consumption rates (B). Other pathogens include Stenotrophomonas maltophilia, Staphylococcus aureus, and Enterobacteriaceae (Escherichia coli and Klebsiella pneumoniae).
DISCUSSION In this study, we used the currently proposed CDC’s criteria for the diagnosis of VAP in children. We found that there was a modest interobserver agreement when interpreting radiologic findings. Second, a high antibiotic usage was detected that was mostly driven by the high rates of positive TACs and not by the diagnosis of VAP. Prolonged mechanical ventilation and length of stay were found both in patients with VAP and patients with pVAT. Common VAP pathogens, including P aeruginosa, were characterized by high resistance. The development of a clear and uniformly accepted VAP surveillance definition is still challenging in children.7,8 Since 2013, a new term, ventilator-associated event, has been applied by the CDC for surveillance in adults. In 2015 this definition was updated.7,9 However, the VAP definition is still used in children3; therefore, we used the same algorithm. Radiologic criteria are currently used in the diagnosis of VAP in children.3 However, evaluation of pediatric chest radiographs remains difficult especially in the case of consolidation and atelectasis.3,8 In this study, only a modest agreement was found between the radiologist and intensivist. Interobserver agreement for the
CDC’s criteria to classify infections in critically ill adults was assessed in a prospective cohort in The Netherlands.10 The lowest agreement was found in cases of VAP. Moreover, a low degree of agreement was found in ventilated adults made by 3 infection control personnel and 1 physician.4 In most cases, we found that TAC positivity resulted in modification of antimicrobial treatment at the patient level and a rise of total antimicrobial use in the PICU. A study conducted in adults showed that routine TACs could be useful in choosing appropriate empirical treatment of VAP.11 However, a prospective study conducted in intubated children found that positive TACs lack specificity for VAP diagnosis.2 Although P aeruginosa was the predominant pathogen followed by A baumannii, S aureus was infrequently isolated as in most studies in Greece. By comparison, a review of pediatric VAP studies found that the prevalence of P aeruginosa and S aureus in TACs and bronchoalveolar lavage ranged between 2.6% and 57% and 11.8% and 38%, respectively.1 In our study, high antimicrobial use was found, and most antimicrobials were used for the treatment of pVAT. In the Comparative Pediatric Critical Illness Stress-Induced Immune Suppression study, a more sensitive definition for VAP diagnosis resulted in high total
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E. Iosifidis et al. / American Journal of Infection Control xxx (2015) 1-4
antimicrobial utilization, with patients receiving at least 1 antimicrobial agent for >80% of their PICU stay.12 In conclusion, diagnosis of VAP in mechanically ventilated children using the currently available CDC’s definition results in several limitations, including radiologic diagnostic variance and discordance between the CDC’s definition and yield of TACs driving antimicrobial utilization for VAP. Therefore, there is a need for a better definition of VAP in children. Acknowledgment The dedication of the personnel of the PICU for the care of the patients studied is highly acknowledged. References 1. Venkatachalam V, Hendley JO, Willson DF. The diagnostic dilemma of ventilator-associated pneumonia in critically ill children. Pediatr Crit Care Med 2011;12:286-96. 2. Willson DF, Conaway M, Kelly R, Hendley JO. The lack of specificity of tracheal aspirates in the diagnosis of pulmonary infection in intubated children. Pediatr Crit Care Med 2014;15:299-305. 3. CDC. Pneumonia (ventilator-associated [VAP] and non-ventilator-associated pneumonia [PNEU]) event. 2015. Available from: http://www.cdc.gov/nhsn/ PDFs/pscManual/6pscVAPcurrent.pdf. Accessed January 2, 2015.
4. Klompas M. Interobserver variability in ventilator-associated pneumonia surveillance. Am J Infect Control 2010;38:237-9. 5. Tamma PD, Turnbull AE, Milstone AM, Lehmann CU, Sydnor ER, Cosgrove SE. Ventilator-associated tracheitis in children: does antibiotic duration matter? Clin Infect Dis 2011;52:1324-31. 6. Polk RE, Hohmann SF, Medvedev S, Ibrahim O. Benchmarking risk-adjusted adult antibacterial drug use in 70 US academic medical center hospitals. Clin Infect Dis 2011;53:1100-10. 7. Magill SS, Klompas M, Balk R, Burns SM, Deutschman CS, Diekema D, et al. Developing a new, national approach to surveillance for ventilator-associated events: executive summary. Clin Infect Dis 2013;57: 1742-6. 8. Bradley JS. Considerations unique to pediatrics for clinical trial design in hospital-acquired pneumonia and ventilator-associated pneumonia. Clin Infect Dis 2010;51(Suppl 1):S136-43. 9. CDC. Ventilator-associated event (VAE). 2015. Available from: http://www.cdc. gov/nhsn/pdfs/pscManual/10-VAE_FINAL.pdf. Accessed January 2, 2015. 10. Klein Klouwenberg PM, Ong DS, Bos LD, de Beer FM, van Hooijdonk RT, Huson MA, et al. Interobserver agreement of Centers for Disease Control and Prevention criteria for classifying infections in critically ill patients. Crit Care Med 2013;41:2373-8. 11. Luna CM, Sarquis S, Niederman MS, Sosa FA, Otaola M, Bailleau N, et al. Is a strategy based on routine endotracheal cultures the best way to prescribe antibiotics in ventilator-associated pneumonia? Chest 2013;144: 63-71. 12. Carcillo JA, Dean JM, Holubkov R, Berger J, Meert KL, Anand KJ, et al. The randomized comparative pediatric critical illness stress-induced immune suppression (CRISIS) prevention trial. Pediatr Crit Care Med 2012;13: 165-73.
Contents lists available at ScienceDirect
American Journal of Infection Control
American Journal of Infection Control
journal homepage: www.ajicjournal.org
Brief report
Diagnosing ventilator-associated pneumonia in pediatric intensive care Elias Iosifidis MD, MSc, PhD a, Stella Stabouli MD, PhD b, Anastasia Tsolaki MD, MSc b, Vaios Sigounas MD c, Emilia-Barbara Panagiotidou RN b, Maria Sdougka MD, PhD b, Emmanuel Roilides MD, PhD a, * a b c
Infectious Diseases Unit, 3rd Department of Pediatrics, Aristotle University School of Medicine, Hippokration Hospital, Thessaloniki, Greece Pediatric Intensive Care Unit, Hippokration Hospital, Thessaloniki, Greece Radiology Department, Hippokration Hospital, Thessaloniki, Greece
Key Words: Health careeassociated infection Radiology Pediatric intensive care Pneumonia Mechanical ventilation Chest radiograph
The Centers for Disease Control and Prevention’s criteria were applied by independent investigators for ventilator-associated pneumonia (VAP) diagnosis in critically ill children and compared with tracheal aspirate cultures (TACs). In addition, correlation between antibiotic use, VAP incidence, and epidemiology of TACs was investigated. A modest agreement (k ¼ 0.41) was found on radiologic findings between 2 investigators. VAP incidence was 7.7 episodes per 1,000 ventilator days, but positive TACs were the most significant factor for driving high antimicrobial usage in the pediatric intensive care unit. Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
Until now, the Centers for Disease Control and Prevention’s (CDC’s) algorithm for ventilator-associated pneumonia (VAP) diagnosis has been widely acceptable and used for surveillance purposes in children.1,2 Although this algorithm has recently been updated, there are significant difficulties, including the requirement of radiographic findings.2-4 We aimed to apply the CDC’s criteria for VAP diagnosis in critically ill children, evaluate chest radiographs by 2 independent investigators, and compare the results to the yield of tracheal aspirate cultures (TACs). Secondary aims included the relationship among antibiotic use, VAP incidence, and epidemiology of TACs. METHODS A retrospective study was conducted in an 8-bed pediatric intensive care unit (PICU) in Hippokration Hospital between January and December 2011.
* Address correspondence to Emmanuel Roilides, MD, PhD, 3rd Department of Pediatrics, Hippokration Hospital, Konstantinoupoleos 49, GR-546 42 Thessaloniki, Greece. E-mail address: [email protected] (E. Roilides). Previous Presentation: Preliminary results of this study were presented at the 53rd Interscience Conference of Antimicrobial Agents and Chemotherapy; September 10-13, 2013; Denver, CO. Funding/Support: This study was supported by a 2011-2013 European Society for Pediatric Infectious Diseases fellowship to E.I. Conflicts of interest: None to report.
A stepwise approach was used according to the CDC’s definition for VAP in children (Fig 1).3 First, radiologic criteria were assessed by 2 investigators (intensivist [S.S.] and radiologist [V.S.]) blinded to symptoms and signs when reviewing radiographs. According to the practice of the PICU, radiographs were taken on admission, daily thereafter, and additionally only if there was clinical change that needed further evaluation in the same day. Chest computed tomography was not evaluated to avoid inconsistency. Predefined criteria were used for evaluating intra- and interobserver variability. If there was agreement between the 2 investigators, no further evaluation was required. If disagreement was found, a second blinded assessment was made by the radiologist. In the case that there was high intraobserver agreement, only the radiologist’s assessment was used (because of professional experience). Second, patients with radiologic criteria fulfilled during the first step were assessed for clinical criteria (A.T. and E.R.). Pathogens isolated from TACs were monitored by a fifth investigator (E.I.) among all ventilated inpatients, including those diagnosed with documented pneumonia and those without VAP (Fig 1). TACs were collected on admission and thereafter routinely twice weekly or on suspicion of pneumonia. All patients were allocated in 3 groups according to the previous criteria: children with VAP (confirmed VAP), children with positive TACs but without VAP (possible ventilator-associated tracheitis [pVAT]),5 and children without VAP or pVAT (control group) (Fig 1). The characteristics of the children in the 3 groups recorded were
0196-6553/$36.00 - Copyright Ó 2015 by the Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajic.2015.01.004
2
E. Iosifidis et al. / American Journal of Infection Control xxx (2015) 1-4
Fig 1. Flow diagram. Stepwise approach for VAP diagnosis (1st part) and patient allocation according to VAP diagnosis and tracheal aspirate culture results (2nd part). CDC, Centers for Disease Control and Prevention; INV1, author S.S.; INV2, author V.S.; INV3, author A.T.; INV4, author E.R.; INV5, E.I.; p. VAT, possible ventilator-associated tracheitis; VAP, ventilatorassociated pneumonia; VAT, ventilator-associated tracheitis.
demographics (age, sex), underlying disease, reasons for PICU admission, Pediatric Risk of Mortality III (PRISM III score), number of ventilator days, antimicrobial therapy (and modifications because of possible VAP), and length of PICU stay. The annual incidence of VAP was calculated by dividing the number of defined VAP episodes by the total ventilator days. The monthly rates of antimicrobial drug consumption were calculated by the method of days of therapy per 100 bed days.6 In TACs, pathogens were distinguished from commensals, and a positive result was considered only if >104 colony forming units/ mL and 25 neutrophils per low power field (100) were found. Identification and susceptibility were conducted by VITEK 2 (Biomérieux, Marcy l’Etoile, France). Monthly incidence and prevalence of pathogens were calculated. We calculated agreement using the k score, and the correlation was calculated using the Spearman correlation coefficient with SPSS version 17.0 (SPSS, Chicago, IL). The study was approved by the institutional ethics committee without a need for informed consent because of the retrospective design.
RESULTS A total of 127 children were admitted, with a median PRISM III score of 8 (range, 3-35). Among them, 119 (94%) received mechanical ventilation, with a median of 7 ventilator days per patient (range, 1-183 days). Among the 119 patients, radiologic criteria were fulfilled in 30 and 18 children according to the intensivist (S.S.) and radiologist (V.S.), respectively. The interobserver agreement was modest (k score ¼ 0.41). The results of the second blinded assessment on selective patients by the radiologist (V.S.) showed 100% intraobserver agreement, and further assessment relied on his report.
Among the 18 children with radiologic criteria fulfilled by the radiologist (7/18 fulfilled criteria by the intensivist), 13 (11% of patients) had at least 3 signs and symptoms or laboratory abnormalities. The median number of days before the onset of VAP in these patients was 6 (range, 3-40). Thirteen patients had confirmed VAP (11% of patients that received mechanical ventilation). Eight of them had positive TACs (Acinetobacter baumannii: n ¼ 4; Pseudomonas aeruginosa: n ¼ 4). Among 106 patients not meeting VAP criteria, 26 (22%) had positive TACs (pVAT). Among them, 62% had a new antimicrobial agent started based on the TAC. Furthermore, 80 patients (67%) had no VAP or pVAT (control group) (Table 1). The VAP incidence was 7.7 episodes per 1,000 ventilator days. The most common pathogens isolated from the TACs were P aeruginosa (55%) and A baumannii (31%). Other pathogens found were Stenotrophomonas maltophilia (7%), Enterobacteriaceae spp (5%), and Staphylococcus aureus (2%). Resistance rates of P aeruginosa and A baumannii to piperacillin-tazobactam were 13% and 94%, resistance rates to ciprofloxacin were 47% and 97%, resistance rates to imipenem were 42% and 77%, resistance rates to meropenem were 66% and 10%, and resistance rates to gentamicin were 7% and 65%, respectively. There was a continuous high flow of new cases with TACs positive for P aeruginosa or A baumannii during the whole study period except in May and June (Fig 2, panel A). During this 2month interval, antimicrobial consumption significantly dropped. Moreover, consumption of antimicrobial agents correlated with the incidence of positive TACs. However, only 11% of patients had confirmed VAP, whereas 29% of them had positive TACs. Antimicrobial consumption is depicted in panel B of Figure 2. Consumption of antipseudomonal agents constituted >50% of total antimicrobial utilization.
E. Iosifidis et al. / American Journal of Infection Control xxx (2015) 1-4
3
Table 1 Demographic and clinical characteristics of children on mechanical ventilation
Demographic and clinical characteristics
Confirmed VAP (n ¼ 13)
Age (mo), median (range) Sex (% female) Underlying disease (%), medical/surgical LOS (d), median (range) Total ventilator days, median (range) PRISM III (score), median (range)
15 (2-144) 58 83/27 19 (2-209) 18 (2-183) 7 (0-20)
pVAT (n ¼ 26)
Control (without VAP or pVAT) (n ¼ 80)
VAP versus control
pVAT versus control
42 (3-156) 28 68/32 17 (2-90) 17 (1-90) 10 (2-20)
36 (1-204) 51 56/44 5 (1-124) 5 (1-124) 8 (0-35)
NS NS .04 <.0001 <.0001 NS
NS .046 NS .0024 .0024 NS
NOTE. Children with VAP were compared with children without evidence of VAP or even pVAT. Children with ventilator-associated tracheitis were compared with children without evidence of VAP or pVAT. Control, children without ventilator-associated pneumonia or possible ventilator-associated pneumonia; LOS, length of stay; NS, not significant; pVAT, children with possible ventilator-associated tracheitis; VAP, ventilator-associated pneumonia.
Fig 2. Monthly incidence of ventilated children with positive tracheal aspirate cultures (TAC) (A) and monthly antimicrobial consumption rates (B). Other pathogens include Stenotrophomonas maltophilia, Staphylococcus aureus, and Enterobacteriaceae (Escherichia coli and Klebsiella pneumoniae).
DISCUSSION In this study, we used the currently proposed CDC’s criteria for the diagnosis of VAP in children. We found that there was a modest interobserver agreement when interpreting radiologic findings. Second, a high antibiotic usage was detected that was mostly driven by the high rates of positive TACs and not by the diagnosis of VAP. Prolonged mechanical ventilation and length of stay were found both in patients with VAP and patients with pVAT. Common VAP pathogens, including P aeruginosa, were characterized by high resistance. The development of a clear and uniformly accepted VAP surveillance definition is still challenging in children.7,8 Since 2013, a new term, ventilator-associated event, has been applied by the CDC for surveillance in adults. In 2015 this definition was updated.7,9 However, the VAP definition is still used in children3; therefore, we used the same algorithm. Radiologic criteria are currently used in the diagnosis of VAP in children.3 However, evaluation of pediatric chest radiographs remains difficult especially in the case of consolidation and atelectasis.3,8 In this study, only a modest agreement was found between the radiologist and intensivist. Interobserver agreement for the
CDC’s criteria to classify infections in critically ill adults was assessed in a prospective cohort in The Netherlands.10 The lowest agreement was found in cases of VAP. Moreover, a low degree of agreement was found in ventilated adults made by 3 infection control personnel and 1 physician.4 In most cases, we found that TAC positivity resulted in modification of antimicrobial treatment at the patient level and a rise of total antimicrobial use in the PICU. A study conducted in adults showed that routine TACs could be useful in choosing appropriate empirical treatment of VAP.11 However, a prospective study conducted in intubated children found that positive TACs lack specificity for VAP diagnosis.2 Although P aeruginosa was the predominant pathogen followed by A baumannii, S aureus was infrequently isolated as in most studies in Greece. By comparison, a review of pediatric VAP studies found that the prevalence of P aeruginosa and S aureus in TACs and bronchoalveolar lavage ranged between 2.6% and 57% and 11.8% and 38%, respectively.1 In our study, high antimicrobial use was found, and most antimicrobials were used for the treatment of pVAT. In the Comparative Pediatric Critical Illness Stress-Induced Immune Suppression study, a more sensitive definition for VAP diagnosis resulted in high total
4
E. Iosifidis et al. / American Journal of Infection Control xxx (2015) 1-4
antimicrobial utilization, with patients receiving at least 1 antimicrobial agent for >80% of their PICU stay.12 In conclusion, diagnosis of VAP in mechanically ventilated children using the currently available CDC’s definition results in several limitations, including radiologic diagnostic variance and discordance between the CDC’s definition and yield of TACs driving antimicrobial utilization for VAP. Therefore, there is a need for a better definition of VAP in children. Acknowledgment The dedication of the personnel of the PICU for the care of the patients studied is highly acknowledged. References 1. Venkatachalam V, Hendley JO, Willson DF. The diagnostic dilemma of ventilator-associated pneumonia in critically ill children. Pediatr Crit Care Med 2011;12:286-96. 2. Willson DF, Conaway M, Kelly R, Hendley JO. The lack of specificity of tracheal aspirates in the diagnosis of pulmonary infection in intubated children. Pediatr Crit Care Med 2014;15:299-305. 3. CDC. Pneumonia (ventilator-associated [VAP] and non-ventilator-associated pneumonia [PNEU]) event. 2015. Available from: http://www.cdc.gov/nhsn/ PDFs/pscManual/6pscVAPcurrent.pdf. Accessed January 2, 2015.
4. Klompas M. Interobserver variability in ventilator-associated pneumonia surveillance. Am J Infect Control 2010;38:237-9. 5. Tamma PD, Turnbull AE, Milstone AM, Lehmann CU, Sydnor ER, Cosgrove SE. Ventilator-associated tracheitis in children: does antibiotic duration matter? Clin Infect Dis 2011;52:1324-31. 6. Polk RE, Hohmann SF, Medvedev S, Ibrahim O. Benchmarking risk-adjusted adult antibacterial drug use in 70 US academic medical center hospitals. Clin Infect Dis 2011;53:1100-10. 7. Magill SS, Klompas M, Balk R, Burns SM, Deutschman CS, Diekema D, et al. Developing a new, national approach to surveillance for ventilator-associated events: executive summary. Clin Infect Dis 2013;57: 1742-6. 8. Bradley JS. Considerations unique to pediatrics for clinical trial design in hospital-acquired pneumonia and ventilator-associated pneumonia. Clin Infect Dis 2010;51(Suppl 1):S136-43. 9. CDC. Ventilator-associated event (VAE). 2015. Available from: http://www.cdc. gov/nhsn/pdfs/pscManual/10-VAE_FINAL.pdf. Accessed January 2, 2015. 10. Klein Klouwenberg PM, Ong DS, Bos LD, de Beer FM, van Hooijdonk RT, Huson MA, et al. Interobserver agreement of Centers for Disease Control and Prevention criteria for classifying infections in critically ill patients. Crit Care Med 2013;41:2373-8. 11. Luna CM, Sarquis S, Niederman MS, Sosa FA, Otaola M, Bailleau N, et al. Is a strategy based on routine endotracheal cultures the best way to prescribe antibiotics in ventilator-associated pneumonia? Chest 2013;144: 63-71. 12. Carcillo JA, Dean JM, Holubkov R, Berger J, Meert KL, Anand KJ, et al. The randomized comparative pediatric critical illness stress-induced immune suppression (CRISIS) prevention trial. Pediatr Crit Care Med 2012;13: 165-73.