children Case Report Pediatric Septic Arthritis of the Knee Due to a Multi-Sensitive Streptococcus pyogenes Strain Responsive to Clindamycin—A Case Report Giada Maria Di Pietro 1,* , Irene Maria Borzani 2, Sebastiano Aleo 3 , Samantha Bosis 3, Paola Marchisio 1 and Claudia Tagliabue 3 1 Department of Pathophysiology and Transplantation, University of Milan, 20122 Milan, Italy; [email protected] 2 Radiology Unit, Pediatric Division, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy; [email protected] 3 Paediatric Highly Intensive Care Unit, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, 20122 Milan, Italy; [email protected] (S.A.); [email protected] (S.B.); [email protected] (C.T.) * Correspondence: [email protected] Abstract: Septic arthritis is an inflammatory process usually generated by a bacterial infection. The knee is one of the most frequently involved joints. The etiology varies depending on age, and hematogenous spread remains the primary cause in children. Herein, we report a case of a previously healthy three-year-old female who was referred to our institution for acute swelling of her right knee. After a clinical and radiological diagnosis of septic arthritis, an empirical treatment with a combination of cefotaxime and clindamycin was initiated. The isolation of a multi-sensitive Streptococcus pyogenes strain from the joint’s effusion prompted the discontinuation of clindamycin Citation: Di Pietro, G.M.; Borzani, and the usage of cefotaxime alone. One week later, an ultrasound was executed due to worsening in I.M.; Aleo, S.; Bosis, S.; Marchisio, P.; Tagliabue, C. Pediatric Septic Arthritis the patient’s clinical conditions, and an organized corpuscular intra-articular effusion with diffuse of the Knee Due to a Multi-Sensitive synovial thickening was revealed. Cefotaxime was therefore replaced with clindamycin, which Streptococcus pyogenes Strain Responsive improved the symptoms. Despite the antibiotic sensitivity test having revealed a microorganism with to Clindamycin—A Case Report. sensitivity to both cephalosporin and clindamycin, clinical resistance to cefotaxime was encountered Children 2021, 8, 189. https:// and a shift in the antimicrobial treatment was necessary to ensure a full recovery. This case study doi.org/10.3390/children8030189 confirms that an antibiotic regimen based solely on a susceptibility test may be ineffective for such cases. Academic Editor: Teresa Giani Keywords: septic arthritis; Streptococcus pyogenes; clindamycin; children Received: 28 December 2020 Accepted: 1 March 2021 Published: 3 March 2021 1. Introduction Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in Septic arthritis (SA) is an inflammatory process generated by a bacterial or fungal published maps and institutional affil- infection. The incidence of SA in children ranges from 1 to 20 cases per 100,000 chil- iations. dren depending on the geographic region, with developing countries having the highest numbers [1,2]. SA occurs most commonly in young children, especially males. Several risk factors have been identified, such as prematurity, umbilical artery catheterization, presence of cen- tral venous catheters, and history of preceding trauma [3–5]. The incidence is increased by Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. the presence of bacteremia or concomitant osteomyelitis in immunocompromised patients This article is an open access article and those with sickle cell disease [3–5]. The hip and knee are the most commonly involved distributed under the terms and joints, and irreversible damage may occur if not promptly diagnosed and treated [6]. conditions of the Creative Commons Microorganisms can enter the joint space by hematogenous spread, direct inoculation Attribution (CC BY) license (https:// during procedures, such as arthrocentesis or intra-articular corticosteroid injection, or creativecommons.org/licenses/by/ extension of a contiguous focus of infection due to open fractures or traumatic injuries [7]. 4.0/). Hematogenous infections remain the primary cause of SA in children [8]. Children 2021, 8, 189. https://doi.org/10.3390/children8030189 https://www.mdpi.com/journal/children Children 2021, 8, x FOR PEER REVIEW 2 of 8 tion during procedures, such as arthrocentesis or intra-articular corticosteroid injection, Children 2021, 8, 189 2 of 7 or extension of a contiguous focus of infection due to open fractures or traumatic injuries [7]. Hematogenous infections remain the primary cause of SA in children [8]. Looking at the current literature, a recent review states that pathogens from blood Lookingand at synovial the current fluid literature, cultures a recentare isolated review in states 34–82% that pathogensof cases [4]; from thus, blood in approximately and synovial fluid18–70% cultures of cases, are isolated no organisms in 34–82% can of casesbe identified [4]; thus, [9,10]. in approximately One factor 18–70%contributing of to cul- cases, no organismsture-negative can beSA identified is Kingella [9, 10kingae]. One bacterial factor contributing arthritis, which to culture-negative is difficult to SAculture with is Kingella kingaestandardbacterial laboratory arthritis, culture which techniques is difficult [11]. to culture with standard laboratory culture techniquesThe [ 11etiology]. varies depending upon age, immunization status of the patient, and The etiologygeographic varies region. depending Among upon children age, immunizationbetween three statusmonths of theof age patient, and five and years old, geographicStaphylococcus region. Among aureus children is the betweenmost common three monthscause of of SA age in and children, five years with old, the methicil- Staphylococcuslin-resistant aureus is Staphylococcus the most common aureus cause (MRSA) of SA being in children, responsible with for the an methicillin- increasing portion of resistant Staphylococcusthese infections aureus [12].(MRSA) The other being microorganisms responsible forresponsible an increasing for SA portion are Kingella of kingae, these infectionsStreptococcus [12]. The pyogenes other, microorganismsStreptococcus pneumoniae, responsible and for Haemophilus SA are Kingella influenzae kingae type, B (Hib), Streptococcuswhich pyogenes is especially, Streptococcus common pneumoniae, in areas withand lowHaemophilus Hib immunization influenzae typerates B[13,14]. (Hib), which is especiallyHerein, common we report in areas the with case low of Hiba patient immunization with SA rates of the [13 ,knee14]. induced by a mul- Herein,ti-sensitive we report Streptococcus the case of pyogenes a patient, not with responsive SA of the to knee cefotaxime induced but by successfully a multi- treated sensitive Streptococcuswith clindamycin. pyogenes , not responsive to cefotaxime but successfully treated with clindamycin. 2. Case Report 2. Case Report A previously healthy three-year-old female was referred to our emergency room for A previously healthy three-year-old female was referred to our emergency room for an acute swelling of her right knee associated with limping and no history of trauma. The an acute swelling of her right knee associated with limping and no history of trauma. The parents reported high fever, malaise, and pharyngodynia, which all started four days parents reported high fever, malaise, and pharyngodynia, which all started four days prior. prior. Antibiotic therapy with amoxicillin/clavulanic acid was started two days before Antibiotic therapy with amoxicillin/clavulanic acid was started two days before admission due to a positiveadmission rapid due strep to a test. positive The girlrapid appeared strep test. in goodThe girl general appeared conditions, in good with general a condi- temperaturetions, of 37.3 with◦ C,a temperature a heart rate of 13037.3 beats/minute,°C, a heart rate and of 130 oxygen beats/minute, saturation and of 98%.oxygen satura- The physicaltion examination of 98%. The showed physical edema examination and hyperemia showed ofedema the tonsils and hyperemia and pharynx, of the no tonsils and palpable lymphadenopathies,pharynx, no palpable swelling, lymphadenopathies, pain, tenderness, swelling, and limited pain, mobility tenderness, of the and right limited mo- knee. All otherbility joints of the were right normal. knee. All The other blood joints tests were showed normal. a C-reactive The blood protein tests (CRP) showed of 21 a C-reactive mg/dL (normalprotein value (CRP) <0.5 of mg/dL),21 mg/dL an (nor erythrocytemal value sedimentation <0.5 mg/dL), an rate er (ESR)ythrocyte of 80 sedimentation mm/h, rate a white blood(ESR) cell of count 80 mm/h, (WBC) a white of 9250/mmc, blood cell with count 49.4% (WBC) neutrophils, of 9250/mmc, 43% lymphocytes,with 49.4% neutrophils, and a mild43% increase lymphocytes, in liver transaminase. and a mild increase A blood in cultureliver transaminase. and a nasopharyngeal A blood culture swab and a na- tested negative.sopharyngeal swab tested negative. To excludeTo the exclude possible the presence possible of presence fractures, of anfractures, X-ray was an X-ray performed was performed of the knee, of the knee, which, otherwhich, than other showing than showing a mild swelling a mild swelling of the soft of the tissues soft tissues in the rightin the knee,right knee, was was neg- negative (rulingative (ruling out signs out of signs early of bone early involvement). bone involvement). A knee A ultrasound knee ultrasound