ISSN: 0971-9032

Current Pediatric Research

International Journal of Pediatrics


Concerning laboratory diagnostics for primary spinal infections in pediatric population.

Concerning laboratory diagnostics for primary spinal infections in pediatric population.

Giacomo De Marco, Oscar Vazquez, Blaise Cochard, Silvia Valisena, Christina Steiger, Romain Dayer, Dimitri Ceroni*

1Department of Pediatric, Orthopedics Geneva University Hospital, Switzerland

Corresponding Author:
Dimitri Ceroni
Department of Pediatric Orthopedics, Geneva University Hospital, Switzerland
E-mail: dimitri.ceroni@hcuge.ch

Received: 04 December, 2023, Manuscript No. AAJCP-23-121948; Editor assigned: 06 December, 2023, Pre QC No. AAJCP-23-121948 (PQ); Reviewed: 20 December, 2023, QC No. AAJCP-23-121948; Revised: 27 December, 2023, Manuscript No. AAJCP-23-121948(R); Published: 03 January, 2024, DOI:10.35841/0971-9032.27.07.1185-1189.

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Abstract

Spinal Infections (SI) include a large variety of conditions that may affect the vertebral body, the intervertebral disk, the adjacent paraspinal tissues, and even the content of the medullary canal. In the pediatric population, SI is rarely restricted to one compartment, since they have the natural tendency to spread, targeting therefore several structures of the vertebral column [1]. In order to fully understand any spinal infection, it remains fundamental to identify the causative pathogen and to know the recipient characteristics? according to patient?s age, immunization status and medical history. Given the heterogeneity of this condition, a classification based on patient?s age helps the clinician to differentiate between 3 main clinical forms of pediatric SI

Description

Spinal Infections (SI) include a large variety of conditions that may affect the vertebral body, the intervertebral disk, the adjacent paraspinal tissues, and even the content of the medullary canal. In the pediatric population, SI is rarely restricted to one compartment, since they have the natural tendency to spread, targeting therefore several structures of the vertebral column [1]. In order to fully understand any spinal infection, it remains fundamental to identify the causative pathogen and to know the recipient characteristics’ according to patient’s age, immunization status and medical history. Given the heterogeneity of this condition, a classification based on patient’s age helps the clinician to differentiate between 3 main clinical forms of pediatric SI [2-9].

The neonate form affects infants less than 6 months old and represents the most severe and rare manifestation of the disease [2,4]. Prematurity accounts for the most important risk factor in this specific age group moreover in patients with a long Intensive Care Unit (ICU) history and several invasive procedures [10]. Staphylococcus aureus and gram negative bacteria are the most relevant pathogens responsible for SI in this group, often presenting with septicemia and multiple infectious foci [11].

The infantile form concerns children from 6 to 48 months old, representing up to 80% of all cases of pediatric spondylodiscitis. Often the disease appears when the weak immunity system of the child takes over the maternally inherited immunity. Some studies in this age group have suggested that Kingella kingae (K. kingae) is the prevalent microorganism responsible for spinal infections [2-4,6].

Finally, the form of PSI affecting children above 4 years old, is more prone to affect vertebral bodies causing osteomyelitis due to S. aureus, often leading to high fever and rapid degeneration of patient’s general status [8,9].

Laboratory tests in SI often provide non-specific information, since they are usually normal or slightly elevated [2-4,12-14]. Increase in WBC count above 12,000 per mm3 is rare, accounting only for 35%-40% of all cases, in addition to that 60%-65% of the patients with SI have been reported to have normal or near-normal CRP levels [2-4,13,15].

ESR (abnormal values in >80% cases) and Platelet Count (abnormal values in 50%-60% of cases appear to be the most sensitive and reliable markers of inflammation in this specific group of patients according to most recent literature [2-4,6-16]. Caution is then required when interpreting blood tests results as these parameters can vary according to the causative germ and patient’s age.

Obtaining bacteriological samples in SI could be even more challenging as opposite to others osteoarticular infections such as septic arthritis. Blood cultures in pediatric SI are characterized by a high percentage of negative results, ranging from 88%-100% [12-14,17,18]. This high rate of negative blood cultures could be explained by the high frequency of PSI in children under 4 years old. It is in-fact recognized that in this age group, infections seem to be mainly caused by K. kingae, a fastidious bacillus difficult to isolate in blood [3,19,20-25]. In addition to that, biopsy and/or needle aspiration are still matter of debate when talking about pathogen isolation in the pediatric population. Indication for invasive procedures, is currently not well established and even considered heretical by most of the authors [2,3,7]. Even though some authors evoke the obtention of a spinal specimen by closed percutaneous or open surgical biopsy, a critical review of the literature shows that the success rates for a needle aspiration and/or an open biopsy to identify causative organisms ranges from 0%-63% in pediatric spondylodiscitis [2,6,18,26-28]. Here again, cultures could stay silent because of the involvement of K. kingae in 80% of SI among patients between 6 months and 4 years of age.

Nowadays, the advent of Nucleic Acid Amplification Assays (NAAAs) has made spectacular progresses to detect pathogens on samples, and continues to improve both in terms of efficiency and specificity [28-30]. The crucial contribution of these diagnostic tools has drastically improved the treatment of infectious diseases in children, as is already the case in adult SI. Despite this, indication for biopsy and/or needle aspiration in pediatric population remains rare and should be reserved only in case of medical treatment failure.

However, the improvement of NAAAs can promote identification of causative pathogens by their indirect recognition without recurring to invasive investigations. On that point, it has already been proven that an oropharyngeal swab Polymerase Chain Reaction (PCR) test could detect the K. kingae Repeats in ToXin (RTX) gene in almost 90% of the toddlers with confirmed spondylodiscitis [3]. This strong evidence comes from previous studies suggesting that K. kingae DNA can be found in the oropharynx of children with osteoarticular infections. Thus indicating that a pharyngeal swab could prove K. kingae as responsible for spinal infections in a specific pediatric population ranging from 6 months to 4 years old when found positive in oral cultures [3,4].

Moreover recent advances in Next Generation Sequencing (NGS) resulted in the advent of very efficient methods to identify microorganisms. Metagenomic NGS (mNGS) is based on high-performance DNA sequencing technologies; this new technique can arbitrarily amplify and detect all the pathogens present in a clinical sample. This new technology, already being used in clinical practice, could be established indirectly on plasma samples (Plasma mNGS) in a recent future as many authors advocate. When mNGS is performed in plasma (known as “liquid biopsy”), the method detects not only pathogens in the bloodstream but also those responsible for focal infections. On that point, an interesting multicenter study performed mNGS in plasma and detected K. kingae in 10 young children (median age: 16.5 months, range: 10–23 months) with spondylodiscitis [31]. The blood cultures were negative in all patients, but the detection of K. kingae by mNGS in plasma could establish the diagnosis without biopsy. These promising results make mNGS a novel and promising versatile tool expected to drastically change bacteriological investigations in a near future especially in pediatric SI.

References