Three cases of vertebral osteomyelitis caused by Streptococcus dysgalactiae subsp. equisimilis

Group A Streptococcus dysgalactiae subspecies equisimilis vertebral osteomyelitis accompanied by progressive atlantoaxial subluxation: A case report and literature review

RATIONALE

Clinically, vertebral osteomyelitis commonly occurs in immunocompromised individuals, such as people with diabetes, immunosuppression, chronic liver disease, and malignancy. Microbiologically, vertebral osteomyelitis is commonly caused by Staphylococcus aureus; however, Streptococcus dysgalactiae subspecies equisimilis (SDSE) may also potentially cause vertebral osteomyelitis, albeit rarely. Since no case reports have documented the occurrence of SDSE cervical osteomyelitis accompanied by progressive atlantoaxial subluxation, its clinical characteristics remain uncertain. Herein, we report the first case of progressive atlantoaxial subluxation in addition to cervical osteomyelitis due to septic atlantoaxial arthritis caused by SDSE in an immunocompetent individual, and provide a review of the relevant literature.

PATIENT CONCERNS

A 63-year-old man with hypertension but no history of trauma or musculoskeletal disorders presented with worsening neck pain for 1 month without fever. Physical examination revealed neck pain due to neck retroflexion and tenderness with swelling of the upper cervical spine. No neurological deficit was observed. Magnetic resonance imaging revealed low-intensity areas on a T1-weighted image and high-intensity areas on a short tau inversion recovery image at the C2, C5, and C6 vertebral bodies with atlantoaxial subluxation. Two sets of blood culture tests (aerobic and anaerobic) were performed.

DIAGNOSES

The anaerobic blood culture bottle showed the presence of beta-hemolytic pyrrolidonyl arylamidase-negative SDSE expressing Lancefield group A antiserum. Hence, the patient was diagnosed with SDSE cervical osteomyelitis with atlantoaxial subluxation; intensive intravenous ampicillin (2 g every 6 hours) - which is effective against SDSE - was administered.

INTERVENTIONS

Posterior fusion (occipital bone, C4) was performed on day 33 because a follow-up magnetic resonance imaging on day 31 revealed progression of atlantoaxial subluxation with thickened atlantodental soft tissue.

OUTCOMES

The patient's neck pain was completely relieved after treatment with intravenous ampicillin for 6 weeks, followed by oral amoxicillin (1500 mg) daily for an additional 4 weeks. The patient did not experience recurrence or sequelae during the 2-year follow-up period.

LESSONS

SDSE expressing Lancefield group A antiserum can cause afebrile vertebral osteomyelitis and progressive atlantoaxial subluxation due to the occurrence of septic atlantoaxial arthritis in immunocompetent individuals. Spinal instrumentation for vertebral osteomyelitis may be acceptable after 6 weeks of antimicrobial therapy.

Osteomyelitis with abscess associated with acute closed upper humerus fracture in an adult: A case report

A 64-year-old female presented with malaise and fever 11 days after a closed, minimally displaced humerus surgical neck fracture. MR imaging revealed an abscess around the fracture, which is a very rare occurrence in adults. Two open debridements and IV antibiotics eradicated the infection. Reverse total shoulder arthroplasty was eventually performed for fracture nonunion.

Vertebral augmentation-related Clostridium septicum osteomyelitis

We present a case of vertebral osteomyelitis following multiple vertebral augmentations in a patient with an insidious presentation. Vertebral augmentation (kyphoplasty and/or vertebroplasty) is a minimally invasive procedure that has become a fairly common and highly effective method in treating compression fractures. A large majority of patients that undergo this procedure suffer from osteoporosis. Numerous studies have shown that patients who undergo the procedure obtain substantial pain relief and improve functional status, often times to a greater extent than other surgical and nonsurgical management. Although its prevalence is low, infection after vertebral augmentation can be a serious consequence of the procedure. Blood cultures in this case were positive for Clostridium septicum. C septicum is a gram-positive, spore forming bacteria that is part of the normal gut flora in humans and is commonly associated with GI malignancy, necrosis, and inflammation. The patient did not respond to long-term intravenous antibiotics and required vertebral corpectomy and debridement with instrumentation. Vertebral body cultures obtained intraoperatively were positive for C septicum. It was noted historically that the patient had a hemorrhoidectomy 4 weeks prior to her initial fracture presentation. Although the risk of infection after vertebral augmentation is low, it is imperative that careful pre- and postoperative evaluation as well as follow-up is completed in order to prevent catastrophic consequences for patients. In patients with recent gastrointestinal tract manipulation/surgery, appropriate antibiotic prophylaxis should be considered prior to vertebral augmentation procedures.

Diagnosing and treating native spinal and pelvic osteomyelitis in adolescents

STUDY DESIGN

Retrospective case series.

OBJECTIVES

To describe how pediatric patients with spinal and pelvic osteomyelitis are diagnosed and treated and assess the diagnostic value of magnetic resonance imaging (MRI), needle aspiration biopsy (NAB), and blood cultures in this population. Spinal and pelvic osteomyelitis de novo are uncommon in children and minimal literature exists on the subject. Research has shown that NAB and blood cultures have variable diagnostic yield in adult native osteomyelitis. At our institution, there is no standard protocol for diagnosing and treating pediatric spinal and pelvic osteomyelitis de novo.

METHODS

All diagnoses of spinal and pelvic osteomyelitis at a pediatric tertiary care center from 2003 to 2017 were reviewed. Patients aged 0-21 at diagnosis were included. Patients with osteomyelitis resulting from prior spinal operations, wounds, or infections and those with chronic recurrent multifocal osteomyelitis were eliminated. All eligible patients' diagnoses were confirmed by MRI.

RESULTS

29 patients (18 men, 11 women) met the inclusion criteria. The median age at diagnosis was 11 years old (range 1-18). More than half of all cases (17/29, 59%) affected the lumbar spine. The most common symptoms were back pain (20/29, 69%), fever (18/29, 62%), hip pain (11/29, 38%), and leg pain (8/29, 28%). The majority of NABs and blood cultures performed were negative, but of the positive tests Staphylococcus aureus was the most prevalent bacteria. 86% (25/29) had an MRI before a diagnosis was made and 72% (13/18) had an NAB performed post-diagnosis.

CONCLUSIONS

MRI is a popular and helpful tool in diagnosing spinal osteomyelitis de novo. NAB cultures are often negative but can be useful in determining antibiotic treatment.

LEVEL OF EVIDENCE

Level IV.

No increased risk of acute osteomyelitis associated with closed or open long bone shaft fracture

OBJECTIVES

Osteomyelitis of the long bones can result from hematogenous spread, direct inoculation or from a contiguous focus of infection. The association of osteomyelitis after long bone fractures has widely been believed to be true by practicing surgeons since the 1950s, even though the evidence has been poor. We hypothesized that long bone shaft fracture and major bone surgery are independent risk factors for osteomyelitis in adult trauma patients.

METHODS

The National Trauma Data Bank (NTDB) was queried between 2007 and 2015 for patients ≥18 years of age presenting after trauma. Patients with long bone shaft fractures (femur, tibia/fibula, humerus) were identified and rate of acute osteomyelitis was calculated. Univariable logistic regression was performed. A multivariable logistic regression was performed to identify risk factors for development of acute osteomyelitis.

RESULTS

From 5,494,609 patients, 358,406 were identified to have long bone shaft fractures (6.5%) with the majority being tibia/fibula (44.3%). The osteomyelitis rate in long bone shaft fractures was 0.05%. Independent risk factors for osteomyelitis included major humerus surgery and major tibia/fibula surgery. The strongest risk factor was non-pseudomonas bacteremia. Long bone shaft fractures were not found to be an independent risk factor for osteomyelitis (p > 0.05).

CONCLUSIONS

Long bone shaft fractures are not independently associated with increased risk for osteomyelitis. Major extremity surgery on the humerus and tibia/fibula, but not femur, are independent risk factors for osteomyelitis. However, the strongest risk factor is non-pseudomonas bacteremia.

Spontaneous Bilateral Sternoclavicular Joint Septic Arthritis and Lumbar Discitis: An Unusual Case in a Healthy Adult

Introduction

Septic arthritis of the sternoclavicular (SC) joint is a rare condition. Typically, it presents in patients with risk of infection and is usually unilateral. In this report, we describe a case of spontaneous bilateral sternoclavicular joint infection of an otherwise healthy adult.

Case Presentation

A 67-year-old man presented in our hospital complaining of 2-week history of neck and chest pain which was radiating to his shoulders bilaterally. Clinical examination revealed erythema and swelling of the sternoclavicular area. Inflammatory markers were raised. Image investigation with CT and MRI was undertaken and verified the presence of bilateral sternoclavicular joint infection. The patient received prolonged course of intravenous antibiotics since his admission. The patient was discharged in a good condition and followed up in clinic.

Conclusion

High index of clinical suspicion of SC joint infection is important for early diagnosis to avoid further complications.

Multifocal septic arthritis, gluteal abscess and spondylodiscitis by Streptococcus dysgalactiae subspecies equisimilis after an intramuscular injection

We present the case of a 63-year-old man, admitted for hand cellulitis and acute kidney injury. A Streptococcus dysgalactiae subsp equisimilis (SDSE) was isolated in blood cultures and despite directed intravenous antibiotherapy, the patient evolved unfavourably, with dorsolumbar spondylodiscitis, multifocal septic arthritis and abscesses. CT also showed densification of the gluteal muscles, multiple air bubbles in the psoas, paraspinal muscles and spinal canal that were associated with an intramuscular injection administered 1 week earlier for a backache. After escalation of the antibiotherapy and intensive supportive measures, the patient showed improvement and was discharged after 8 weeks of antibiotherapy.The incidence of invasive SDSE infections has been growing, especially in immunosupressed patients. In this case, despite no predisposing factor identified, it evolved to severe sepsis. The intramuscular injection, a trivialised but not harmless procedure, was the assumed port of entry, as previously described in another case report.

Molecular characterization of invasive Streptococcus dysgalactiae subsp. equisimilis. Multicenter study: Argentina 2011-2012

Streptococcus dysgalactiae subsp. equisimilis (SDSE) has virulence factors similar to those of Streptococcus pyogenes. Therefore, it causes pharyngitis and severe infections indistinguishable from those caused by the classic pathogen. The objectives of this study were: to know the prevalence of SDSE invasive infections in Argentina, to study the genetic diversity, to determine the presence of virulence genes, to study antibiotic susceptibility and to detect antibiotic resistance genes. Conventional methods of identification were used. Antibiotic susceptibility was determined by the disk diffusion and the agar dilution methods and the E-test. Twenty eight centers from 16 Argentinean cities participated in the study. Twenty three isolates (16 group G and 7 group C) were obtained between July 1 2011 and June 30 2012. Two adult patients died (8.7%). Most of the isolates were recovered from blood (60.9%). All isolates carried speJ and ssa genes. stG62647, stG653 and stG840 were the most frequent emm types. Nineteen different PFGE patterns were detected. All isolates were susceptible to penicillin and levofloxacin, 6 (26.1%) showed resistance or reduced susceptibility to erythromycin [1 mef(A), 3 erm(TR), 1 mef(A)+erm(TR) and 1 erm(TR)+erm(B)] and 7 (30.4%) were resistant or exhibited reduced susceptibility to tetracycline [2 tet(M), 5 tet(M)+tet(O)]. The prevalence in Argentina was of at least 23 invasive infections by SDSE. A wide genetic diversity was observed. All isolates carried speJ and ssa genes. Similarly to other studies, macrolide resistance (26.1%) was mainly associated to the MLS_B phenotype.

Evolution of the capsular operon of Streptococcus iniae in response to vaccination

Streptococcus iniae causes severe septicemia and meningitis in farmed fish and is also occasionally zoonotic. Vaccination against S. iniae is problematic, with frequent breakdown of protection in vaccinated fish. The major protective antigens in S. iniae are the polysaccharides of the capsule, which are essential for virulence. Capsular biosynthesis is driven and regulated by a 21-kb operon comprising up to 20 genes. In a long-term study, we have sequenced the capsular operon of strains that have been used in autogenous vaccines across Australia and compared it with the capsular operon sequences of strains subsequently isolated from infected vaccinated fish. Intriguingly, strains isolated from vaccinated fish that subsequently become infected have coding mutations that are confined to a limited number of genes in the cps operon, with the remainder of the genes in the operon remaining stable. Mutations in strains in diseased vaccinated fish occur in key genes in the capsular operon that are associated with polysaccharide configuration (cpsG) and with regulation of biosynthesis (cpsD and cpsE). This, along with high ratios of nonsynonymous to synonymous mutations within the cps genes, suggests that immune response directed predominantly against capsular polysaccharide may be driving evolution in a very specific set of genes in the operon. From these data, it may be possible to design a simple polyvalent vaccine with a greater operational life span than the current monovalent killed bacterins.

[A case of acute septic osteomyelitis onset due to Streptococcus dysgalactiae subsp. equisimilis in an elderly diabetic patient]

Group C streptococci are increasingly causing invasive infections such as that we report here. A 70-year-old man being treated for diabetes and seen at the emergency room for neck pain and fever was hospitalized for possible sepsis. His temperature was 39.8 degrees C, regular pulse 101 bpm, and pain reinforced in flexing and cervical rotation. Streptococcus dysgalactiae subsp. equisimilis (SDSE) was cultured from blood. Neck pain gradually decreased with of 2 million units PCG 6 times/day. Magnetic resonance imaging (MRI) of the cervical spine showed high-intensity areas in fat-suppression imaging at C7, Thl and intervertebral disks plus enhancement around the vertebral body, yielding a diagnosis of cervicothoracic vertebral osteomyelitis. Antimicrobial intravenous therapy continuede 6 weeks. The man was discharged after 45 days without relapse.

Complete genome sequencing and analysis of a Lancefield group G Streptococcus dysgalactiae subsp. equisimilis strain causing streptococcal toxic shock syndrome (STSS)

Background

Streptococcus dysgalactiae subsp. equisimilis (SDSE) causes invasive streptococcal infections, including streptococcal toxic shock syndrome (STSS), as does Lancefield group A Streptococcus pyogenes (GAS). We sequenced the entire genome of SDSE strain GGS_124 isolated from a patient with STSS.

Results

We found that GGS_124 consisted of a circular genome of 2,106,340 bp. Comparative analyses among bacterial genomes indicated that GGS_124 was most closely related to GAS. GGS_124 and GAS, but not other streptococci, shared a number of virulence factor genes, including genes encoding streptolysin O, NADase, and streptokinase A, distantly related to SIC (DRS), suggesting the importance of these factors in the development of invasive disease. GGS_124 contained 3 prophages, with one containing a virulence factor gene for streptodornase. All 3 prophages were significantly similar to GAS prophages that carry virulence factor genes, indicating that these prophages had transferred these genes between pathogens. SDSE was found to contain a gene encoding a superantigen, streptococcal exotoxin type G, but lacked several genes present in GAS that encode virulence factors, such as other superantigens, cysteine protease speB, and hyaluronan synthase operon hasABC. Similar to GGS_124, the SDSE strains contained larger numbers of clustered, regularly interspaced, short palindromic repeats (CRISPR) spacers than did GAS, suggesting that horizontal gene transfer via streptococcal phages between SDSE and GAS is somewhat restricted, although they share phage species.

Conclusion

Genome wide comparisons of SDSE with GAS indicate that SDSE is closely and quantitatively related to GAS. SDSE, however, lacks several virulence factors of GAS, including superantigens, SPE-B and the hasABC operon. CRISPR spacers may limit the horizontal transfer of phage encoded GAS virulence genes into SDSE. These findings may provide clues for dissecting the pathological roles of the virulence factors in SDSE and GAS that cause STSS.

Detection of Streptococcus dysgalactiae subsp. equisimilis in equine nasopharyngeal swabs by PCR

Streptococcus (S.) dysgalactiae subsp. equisimilis is responsible for severe diseases in humans, including primary bacteraemia, pneumonia, endocarditis, and toxic shock syndrome. Infection in some animal species can also occur, although a few studies have looked into cross-species infectivity. In horses, S. equisimilis is generally considered infrequent or opportunistic, but has recently been isolated from cases of strangles-like disease. Rapid and sensitive diagnostic techniques could enable epidemiological studies and effective investigation of outbreaks involving these bacteria. In this study, PCR protocols previously described in cattle and in humans to detect the species S. dysgalactiae and the subspecies equisimilis were evaluated to detect specific sequences in equine samples. For this purpose, 99 monolateral nasal swabs were collected from horses from stud farms with a history of S. equisimilis infection and were tested blindly by bacteriological isolation and by single and duplex PCR. DNA for PCR was extracted both from the colonies grown on agar media and from enrichment broth aliquots after incubation with nasal swab samples. S. equisimilis was identified by bacteriological isolation in 23 out of 99 swab samples, and PCR assays on these colonies were fully concordant with bacteriological identification (kappa statistic = 1.00). In addition, PCR of the enrichment broth aliquots confirmed the bacteriological results and detected S. equisimilis in 6 samples more than the bacteriological examination (kappa statistic = 0.84). The PCR protocols appeared to be reliable for the rapid identification of S. equisimilis in equine nasal swab samples, and could be useful for microbiological diagnosis.

Invasive infection caused by Streptococcus dysgalactiae subsp. equisimilis: characteristics of strains and clinical features

Among clinically isolated β-hemolytic streptococci, Streptococcus pyogenes and S. agalactiae were considered the main pathogens in humans until recently. In 1996, S. dysgalactiae subsp. equisimilis (SDSE) was proposed as a novel taxon among human-derived streptococcal isolates. SDSE has Lancefield group C or G antigens, exhibits strong β-hemolysis, and exerts streptokinase activity upon human plasminogen and proteolytic activity upon human fibrin. Similarly to group A streptococci, SDSE possesses virulence factors including M protein, streptolysin O, streptolysin S, streptokinase, hyaluronidase, C5a peptidase, and others. SDSE may exist among the normal flora of the skin, oropharynx, and gastrointestinal and genitourinary tracts. In the twenty-first century, invasive SDSE infection (i.e., cellulitis, urosepsis, and pneumonia) leading to various disseminated diseases is being diagnosed increasingly in Japan, elsewhere in Asia, in Europe, and in America. Particularly, among elderly patients, these invasive diseases are encountered increasingly in Japanese hospital emergency departments. Analysis of the part of the emm gene encoding the amino acid sequence at the N-terminal end of the M protein is used to determine the molecular epidemiology of SDSE. The distribution of emm types from patients with invasive or noninvasive infections differs between surveillance results from different countries. In this review, we summarize the characteristics of phenotypes and virulence factors in SDSE strains; the review also focuses on emerging SDSE infectious disease and future vaccination research.

Spondylodiscitis and paraspinal abscess caused by β-haemolytic group G streptococci spreading from infected leg ulcers

We report a case of spondylodiscitis due to Streptococcus dysgalactiae subsp. equisimilis spreading from infected leg ulcers. The route of infection could be unequivocally demonstrated by culturing identical isolates from leg wounds, blood culture and intra-surgery specimens from the spine. The present case illustrates the pathogenic potential of group G streptococci also for non-diabetic adults.

Surgical treatment of pyogenic vertebral osteomyelitis with spinal instrumentation

Pyogenic vertebral osteomyelitis responds well to conservative treatment at early stage, but more complicated and advanced conditions, including mechanical spinal instability, epidural abscess formation, neurologic deficits, and refractoriness to antibiotic therapy, usually require surgical intervention. The subject of using metallic implants in the setting of infection remains controversial, although more and more surgeons acknowledge that instrumentation can help the body to combat the infection rather than to interfere with it. The combination of radical debridement and instrumentation has lots of merits such as, restoration and maintenance of the sagittal alignment of the spine, stabilization of the spinal column and reduction of bed rest period. This issue must be viewed in the context of the overall and detailed health conditions of the subjecting patient. We think the culprit for the recurrence of infection is not the implants itself, but is the compromised general health condition of the patients. In this review, we focus on surgical treatment of pyogenic vertebral osteomyelitis with special attention to the role of spinal instrumentation in the presence of pyogenic infection.