The issue of serious bacterial illness in children is an ongoing debate and new articles are emerging that help shed some light on the topic. This journal club will review lab tests that are better indicators of serious bacterial illness, how to reduce the rate of blood culture contaminants, the significance of the clinical examination for the diagnosis of meningitis and whether or not a routine lumbar puncture is necessary in children less than 18 months of age with a first time, simple febrile seizure.
After evaluating this article, participants will be able to:
1. Incorporate strategies into practice for the appropriate assessment of laboratory data in febrile infants.
2. Develop strategies to reduce the false positive rate of blood cultures.
3. Develop strategies to avoid the misdiagnosis of meningitis.
Q. Can newborns who present with fever for less than 12 hours of duration and have normal initial laboratory findings still be at risk for serious bacterial illness
A. In this study, there were 5 neonates who had initially normal lab findings who had subsequent serious bacterial illness. In addition, the authors conclude that C-reactive protein and Absolute Neutrophil Counts ( ANC) are better indicators than a peripheral white blood cell count.
Citation: Bressan, Silvia MD; Andreola, Barbara MD; Cattelan, Francesca MD etal. Predicting Severe Bacterial Infections in Well-Appearing Febrile Neonates: Laboratory Markers Accuracy and Duration of Fever. Pediatr Infect Dis J 2010;29: 227–232
Objectives: To assess the diagnostic accuracy of white blood cell count (WBC), absolute neutrophil count (ANC), and C-reactive protein (CRP) in detecting severe bacterial infections (SBI) in well-appearing neonates with early onset fever without source (FWS) and in relation to fever duration.
Methods: An observational study was conducted on previously healthy neonates 7 to 28 days of age, consecutively hospitalized for FWS from less than 12 hours to a tertiary care Pediatric Emergency Department, over a 4-year period. Laboratory markers were obtained upon admission in all patients and repeated 6 to 12 hours from admission in those with normal values on initial determination. Sensitivity, specificity, positive and negative likelihood ratios, and receiver operating characteristic analysis were carried out for primary and repeated laboratory examinations.
Results: Ninety-nine patients were finally studied. SBI was documented in 25 (25.3%) neonates. Areas under receiver operating characteristic curves were 0.78 (95% CI, 0.69–0.86) for CRP, 0.77 (95% CI, 0.67–0.85) for ANC and 0.59 (95% CI, 0.49–0.69) for WBC. Sixty-two patients presented normal laboratory markers on initial determination. Of these, 58 successfully underwent repeated blood examination at >12 hours from fever onset. Five of them had an SBI. The area under curve calculated for repeated laboratory tests showed better values, respectively of 0.99 (95% CI, 0.92–1) for CRP, 0.85 (95% CI, 0.73–0.93) for ANC and 0.79 (95% CI, 0.66–0.88) for WBC.
Conclusions: In well-appearing neonates with early onset FWS, laboratory markers are more accurate and reliable predictors of SBI when performed after >12 hours of fever duration. ANC and especially CRP resulted better markers than the traditionally recommended WBC
Commentary: This is an interesting concept as we commonly see newborns presenting with fever without source prior to 12 hours of fever. While more studies are necessary to fine tune our evaluation and management in the fragile neonatal age group, it may be prudent to repeat laboratory evaluation after admission in those patients who were initially evaluated prior to 12 hours of symptom onset.
Q. Should blood cultures be drawn from a separate site rather than being obtained while starting an intravenous line?
A. In this study, a phlebotomty policy change which required a separate blood draw for blood cultures significantly reduced the contamination rate.
Citation: Weddle, Gina MSN, RN, CPNP; Jackson, Mary Anne MD; Selvarangan, Rangaraj BVSc, PhD, D(ABMM).Culture Contamination in a Pediatric Emergency Department. Pediatric Emergency Care: March 2011 - Volume 27 - Issue 3 - pp 179-181
Background: Blood cultures (BCs) are used to diagnose bacteremia in febrile children. False-positive BCs increase costs because of further testing, longer hospital stays, and unnecessary antibiotic therapy. Data from a study at our hospital showed the emergency department consistently exceeded established guidelines of 2% to 4%. A phlebotomy policy change was made whereby BC had to be obtained by a second venipuncture and no longer obtained during insertion of intravenous catheters.
Methods: A descriptive study compared preintervention and postintervention blood culture contamination (BCC) rates. A BC was considered contaminated if a single culture grew coagulase-negative staphylococci, diphtheroids, Micrococcus spp, Bacillus spp, or viridans group streptococci. Patients with indwelling central lines or who grew pathogenic bacteria were excluded.
Results: Preintervention BCC was 120 (6.7% [SD, 2.3%]) of 1796. Postintervention BCC was 29 (2.3%, [SD, 0.8]) of 1229 with odds ratio of 2.96 (confidence interval, 1.96-4.57; P = 0.001). The most common contaminant was coagulase-negative staphylococcus, 21 (72%) of 120, followed by viridans streptococcus, 3 (10%) of 29, which was not significantly different between intervention periods. Before intervention, 44 patients were called back to the emergency department, and 25 were admitted because of BCC. After intervention, a total of 9 patients were called back, and 5 were admitted. The decrease in unnecessary hospitalization was statistically significant (P < 0.05).
Conclusions: The new policy significantly reduced BCC rates, thereby decreasing unnecessary testing and hospitalizations. Coagulase-negative staphylococci and viridans streptococci remain the most common BC contaminants. Further research should focus on additional interventions to reduce BCC.
Commentary: This is an extremely interesting article and deserves further study. It is common place particularly in children to obtain a blood culture while inserting an IV. Even though the site is prepped appropriately, the bottom line is that the access site is palpated more times with IV placement than with a single blood draw, so the conclusion makes sense. In this era of infection control, identification of your sites contamination rates and a trial of this policy may be warranted.
Q. Can we rely on physical examination findings alone to diagnose meningitis in children?
A. Classic findings of meningitis are not always present and therefore should not be the sole determinants of the need for lumbar puncture.
Citation: Amarilyo, G; Alper, A ; Ben-Tov,A etal. Diagnostic Accuracy of Clinical Symptoms and Signs in Children With
Meningitis. Pediatric Emergency Care;March 2011 - Volume 27 - Issue 3 - pp 196-199
Background: The diagnostic accuracy of the classic symptoms and signs of meningitis in infants and children has not been established.
Methods: All children aged 2 months to 16 years with clinically suspected meningitis were eligible for this prospective cohort study at 2 large medical centers between February 2006 and October 2007. Exclusion criteria were severe chronic disease, severe immune deficiency, or idiopathic intracranial hypertension. The emergency department physician obtained information on clinical symptoms and signs and cerebrospinal fluid analysis. Meningitis was defined as white blood cell count of 6 or higher per microliter of cerebrospinal fluid.
Results: A total of 108 patients with suspected meningitis were enrolled. Meningitis was diagnosed in 58 patients (53.7%; 6 bacterial and 52 aseptic). Sensitivity and specificity were 76% and 53% for headache (among the verbal patients) and 71% and 62% for vomiting, respectively. Photophobia was highly specific (88%) but had low sensitivity (28%). Clinical examination revealed nuchal rigidity (in patients without open fontanel) in 32 (65%) of the patients with meningitis and in 10 (33%) of the patients without meningitis. Brudzinski and Kernig signs were present in 51% and 27% of the patients with meningitis, respectively, and had relatively high positive predictive values (81% and 77%, respectively). Bulging fontanel in patients with open fontanel was present in 50% of the patients with meningitis but had a positive predictive value of only 38%.
Conclusions: Classic clinical diagnostic signs have limited value in establishing the diagnosis of meningitis in children and should not be the sole determinants for referral to further diagnostic testing and lumbar puncture
Commentary: This study confirms the difficulty in diagnosing meningitis in children who do not have the classic signs of meningitis. In addition, it is important to not rely on the peripheral white blood cell counts to assist with the diagnosis of meningitis. Bonsu et al found that patients with meningitis classically had normal WBC counts and practitioners would have missed the majority of cases of true bacterial meningitis had they relied on this lab test as a marker of serious bacterial illness. (Ann Emerg Med. 2003 Feb;41(2):206-14)
Q. Do we need to perform a spinal tap in infants less than 18 months of age who experience a simple febrile seizure
A. The AAP has revised its 1996 Practice Parameter. The Annals of Emergency Medicine 2003 had refuted the routine performance of lumbar punctures in well appearing infants but the AAP just revised its guidelines.
Citation: American Academy of Pediatrics. Febrile Seizures: Guideline for the Neurodiagnostic Evaluation of the Child With a Simple Febrile Seizure. PEDIATRICS Volume 127, Number 2, February 2011
Objective: To formulate evidence-based recommendations for health care professionals about the diagnosis and evaluation of a simple febrile seizure through 60 months of age and to revise the practice guideline published by the American Academy of Pediatrics (AAP) in 1996.
Methods: This review included search and analysis of the medical literature published since the last version of the guideline. Physicians with expertise and experience in the fields of neurology and epilepsy, pediatrics, epidemiology, and research methodologies constituted a subcommittee of the AAP Steering Committee on Quality Improvement and
Management. The steering committee and other groups within the AAP and organizations outside the AAP reviewed the guideline. The subcommittee member who reviewed the literature for the 1996 AAP practice guidelines searched for articles published since the last guideline through 2009, supplemented by articles submitted by other committee members in infants and young children 6.
Results: Results from the literature search were provided to the subcommittee members for review. Interventions of direct interest included lumbar puncture, electroencephalography, blood studies, and neuroimaging. Multiple issues were raised and discussed iteratively until consensus was reached about recommendations. The strength of evidence supporting each recommendation and the strength of the recommendation were assessed by the committee member most experienced in informatics and epidemiology and graded according to AAP policy.
Conclusions: Clinicians evaluating infants or young children after a simple febrile seizure should direct their attention toward identifying the cause of the child’s fever. Meningitis should be considered in the differential diagnosis for any febrile child, and lumbar puncture should be performed if there are clinical signs or symptoms of concern. For any infant between 6 and 12 months of age who presents with a seizure and fever, a lumbar puncture is an option when the child is considered deficient in Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae immunizations (ie, has not received scheduled immunizations as recommended), or when immunization status cannot be determined, because of an increased risk of bacterial meningitis. A lumbar puncture is an option for children who are pretreated with antibiotics. In general, a simple febrile seizure does not usually require further evaluation, specifically electroencephalography, blood studies, or neuroimaging.
Commentary: It is nice to see that the AAP has finally revised the 1996 Practice guideline on the indications for routine lumbar puncture in infants less than one year of age who experience a simple febrile seizures. The Emergency Medicine literature was ahead of the game and in 2003, the guidelines were questioned in an outstanding article by Warden C etal in the Annals of Emergency Medicine (Ann Emerg Med. 2003;41:215-222) and lumbar punctures were recommended for children under 18 months of age with a simple febrile seizure for clear indications that none of us would miss:
- a history of irritability, decreased feeding, or lethargy;
- an abnormal appearance or mental status findings on initial observation of the child (after the postictal period);
- any physical signs of meningitis, such as a bulging fontanelle, Kernig or Brudzinski signs, photophobia, or severe headache;
- any complex features
- any slow postictal clearing of mentation; or
- pretreatment with antibiotics.