Acute haematogenous osteomyelitis in children: is there any evidence for how long we should treat?

Study protocol: short against long antibiotic therapy for infected orthopedic sites - the randomized-controlled SALATIO trials

BACKGROUND

Few studies address the appropriate duration of post-surgical antibiotic therapy for orthopedic infections; with or without infected residual implants. We perform two similar randomized-clinical trials (RCT) to reduce the antibiotic use and associated adverse events.

METHODS

Two unblinded RCTs in adult patients (non-inferiority with a margin of 10%, a power of 80%) with the primary outcomes "remission" and "microbiologically-identical recurrences" after a combined surgical and antibiotic therapy. The main secondary outcome is antibiotic-related adverse events. The RCTs allocate the participants between 3 vs. 6 weeks of post-surgical systemic antibiotic therapy for implant-free infections and between 6 vs. 12 weeks for residual implant-related infections. We need a total of 280 episodes (randomization schemes 1:1) with a minimal follow-up of 12 months. We perform two interim analyses starting approximately after 1 and 2 years. The study approximatively lasts 3 years.

DISCUSSION

Both parallel RCTs will enable to prescribe less antibiotics for future orthopedic infections in adult patients.

TRIAL REGISTRATION

ClinicalTrial.gov NCT05499481. Registered on 12 August 2022.

PROTOCOL VERSION

2 (19 May 2022).

Intraperitoneal vancomycin treatment of multifocal methicillin-resistant Staphylococcus aureus osteomyelitis in a patient on peritoneal dialysis

PURPOSE

We report the case of a 2-year-old girl with end-stage renal disease managed by peritoneal dialysis (PD) who developed methicillin-resistant staphylococcal osteomyelitis of the left shoulder and was successfully treated with intraperitoneal (IP) administration of vancomycin for 2 weeks followed by oral clindamycin therapy.

SUMMARY

The patient was hospitalized with tactile fever and a 3-day history of worsening fussiness. Radiography of the left shoulder showed findings indicative of osteomyelitis. Vancomycin was administered via central venous line for 3 days, during which time the patient underwent PD 24 hours a day. After magnetic resonance imaging revealed proximal humeral osteomyelitis, septic arthritis of the shoulder joint, and osteomyelitis of the scapula, the patient underwent incision and drainage of the left shoulder joint. Both blood and joint drainage cultures grew methicillin-resistant Staphylococcus aureus that was sensitive to vancomycin. The patient's central venous catheter was removed on hospital day 4; due to difficulties with peripheral i.v. access and a desire to avoid placing a peripherally inserted central venous catheter, vancomycin administration was changed to the IP route, with vancomycin added to the PD fluid. During IP treatment, serum vancomycin levels were maintained at 13.5 to 18.5 mg/L, and the calculated ratio of vancomycin area under the curve to minimum inhibitory concentration was maintained above 400. After completing a 14-day course of IP vancomycin therapy, the patient was switched to oral clindamycin, with subsequent complete resolution of osteomyelitis.

CONCLUSION

IP vancomycin was effective for treatment of invasive S. aureus infection in this case. This approach should be considered in patients undergoing PD for whom peripheral i.v. access options are limited and/or not preferred.

Osteomyelitis in Children from Rural Population of Uttar Pradesh

Occurrence of Staphylococcus aureus in children with osteomyelitis. This study was conducted at K. M. M. C. & Hospital, Mathura (UP). A total of 60 patients with osteomyelitis contributed to this study from October 2017 to October 2019. Patients with known immunodeficiency syndromes were excluded. Specimen collections were meticulously performed to avoid contamination which was accomplished by needle aspiration or surgical sampling. Staphylococcus aureus was recovered in more than half of the cases of osteomyelitis in both infants and children. Amikacin, Clindamycin and Cefazolin were effective in such cases. The distal end of the femur and upper-end tibia were the most common sites of infection where boys were more infected than girls. The haematogenous route was the main cause of the transmission of osteomyelitis in children. Principally Staphylococcus aureus causes the majority of cases of osteomyelitis in children followed by H. influenza, Group B Streptococcus, P. aeruginosa, E. coli and Serratia marcescens.

The role of the msaABCR operon in implant-associated chronic osteomyelitis in Staphylococcus aureus USA300 LAC

BACKGROUND

The msaABCR operon regulates several staphylococcal phenotypes such as biofilm formation, capsule production, protease production, pigmentation, antibiotic resistance, and persister cells formation. The msaABCR operon is required for maintaining the cell wall integrity via affecting peptidoglycan cross-linking. The msaABCR operon also plays a role in oxidative stress defense mechanism, which is required to facilitate persistent and recurrent staphylococcal infections. Staphylococcus aureus is the most frequent cause of chronic implant-associated osteomyelitis (OM). The CA-MRSA USA300 strains are predominant in the United States and cause severe infections, including bone and joint infections.

RESULTS

The USA300 LAC strain caused significant bone damage, as evidenced by the presence of severe bone necrosis with multiple foci of sequestra and large numbers of multinucleated osteoclasts. Intraosseous survival and biofilm formation on the K-wires by USA300 LAC strains was pronounced. However, the msaABCR deletion mutant was attenuated. We observed minimal bone necrosis, with no evidence of intramedullary abscess and/or fibrosis, along reduced intraosseous bacterial population and significantly less biofilm formation on the K-wires by the msaABCR mutant. microCT analysis of infected bone showed significant bone loss and damage in the USA300 LAC and complemented strain, whereas the msaABCR mutant's effect was reduced. In addition, we observed increased osteoblasts response and new bone formation around the K-wires in the bone infected by the msaABCR mutant. Whole-cell proteomics analysis of msaABCR mutant cells showed significant downregulation of proteins, cell adhesion factors, and virulence factors that interact with osteoblasts and are associated with chronic OM caused by S. aureus.

CONCLUSION

This study showed that deletion of msaABCR operon in USA300 LAC strain lead to defective biofilm in K-wire implants, decreased intraosseous survival, and reduced cortical bone destruction. Thus, msaABCR plays a role in implant-associated chronic osteomyelitis by regulating extracellular proteases, cell adhesions factors and virulence factors. However additional studies are required to further define the contribution of msaABCR-regulated molecules in osteomyelitis pathogenesis.

Four versus six weeks of antibiotic therapy for osteoarticular infections after implant removal: a randomized trial

BACKGROUND

The optimal duration of antibiotic therapy for treating orthopaedic implant infections after surgical drainage and complete implant removal is unknown.

METHODS

This was a single-centre, unblinded, prospective trial randomizing (1:1) eligible patients to either 4 or 6 weeks of systemic, pathogen-targeted antibiotic therapy. Clinical trial registration number: ClinicalTrials.gov (NCT0362209).

RESULTS

We analysed 123 eligible patients (62 in the 4 week antibiotic arm and 61 in the 6 week arm) in the ITT analysis. The patients' median age was 64 years, 75 (61%) were men and 38 (31%) were immunocompromised. The most common types of infection treated included: two-stage exchange procedure for prosthetic joint infection (n = 38); orthopaedic plate infection (44) and infected nail implants (11). The median duration of post-explant intravenous antibiotic therapy was 4 days. Overall, 120 episodes (98%) were cured microbiologically and 116 (94%) clinically after a median follow-up period of 2.2 years. During follow-up, four patients had a clinical recurrence with a pathogen other than the initial causative agent. We noted recurrence of clinical infection in four patients in the 4 week arm and three patients in the 6 week arm (4/62 versus 3/61; χ2 test; P = 0.74); in all cases, this occurred at around 2 months following the end of antibiotic treatment.

CONCLUSIONS

We found no statistically significant difference in the rates of clinical or microbiological remission between patients randomized to only 4 compared with 6 weeks of systemic antibiotic therapy after removal of an infected osteoarticular implant.

Review on calcium- and magnesium-based silicates for bone tissue engineering applications

Bone is a self-engineered structural component of the human body with multifaceted mechanical strength, which provides indomitable support to the effective functioning of the human body. It is indispensable to find a suitable biomaterial for substituting the bone as the bone substitute material requirement is very high due to the rate of bone fracture and infection lead to osteoporosis in human beings increases rapidly. It is not an easy task to design a material with good apatite deposition ability, a faster rate of dissolution, superior resorbability, high mechanical strength, and significant bactericidal activity. Since the synthetic hydroxyapatite was not able to achieve the dahlite phase of hydroxyapatite (natural bone mineral phase), silicates emerged as an alternate biomaterial to meet the need for bone graft substitutes. All silicates do not exhibit the properties required for bone graft substitutes, as their composition and methodology adopted for the synthesis are different. Calcium, magnesium, and silicon play a major role in the formation of bone mineral and their metabolism during bone formation. In this review, the relationship between composition and activity of calcium, magnesium-based silicates have been discussed along with the future scope of these materials for hard tissue engineering applications.

Short postsurgical antibiotic therapy for spinal infections: protocol of prospective, randomized, unblinded, noninferiority trials (SASI trials)

BACKGROUND

There are several open scientific questions regarding the optimal antibiotic treatment of spinal infections (SIs) with or without an implant. The duration of postsurgical antibiotic therapy is debated.

METHODS

We will perform two unblinded randomized controlled trials (RCTs). We hypothesize that shorter durations of systemic antibiotic therapy after surgery for SI are noninferior (10% margin, 80% power, α = 5%) to existing (long) treatment durations. The RCTs allocate the participants to two arms of 2 × 59 episodes each: 3 vs. 6 weeks of targeted postsurgical systemic antibiotic therapy for implant-free SIs or 6 vs. 12 weeks for implant-related SIs. This equals a total of 236 adult SI episodes (randomization scheme 1:1) with a minimal follow-up of 12 months. All participants receive concomitant multidisciplinary surgical, re-educational, internist, and infectious disease care. We will perform three interim analyses that are evaluated, in a blinded analysis, by an independent study data monitoring committee. Besides the primary outcome of remission, we will also assess adverse events of antibiotic therapy, changes of the patient's nutritional status, the influence of immune suppression, total costs, functional scores, and the timely evolution of the (surgical) wounds. We define infection as the presence of local signs of inflammation (pus, wound discharge, calor, and rubor) together with microbiological evidence of the same pathogen(s) in at least two intraoperative samples, and we define remission as the absence of clinical, laboratory, and/or radiological evidence of (former or new) infection.

DISCUSSION

Provided that there is adequate surgical debridement, both RCTs will potentially enable prescription of less antibiotics during the therapy of SI, with potentially less adverse events and reduced overall costs.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04048304. Registered on 5 August 2019.

PROTOCOL VERSION

2, 5 July 2019.

Evaluation of the current use of imaging modalities and pathogen detection in children with acute osteomyelitis and septic arthritis

Diagnostic tools for the management of acute osteomyelitis (OM) and septic arthritis (SA) have improved over the last decade. To investigate the influence and availability of magnetic resonance imaging (MRI) and nucleic acid testing (NAT), a retrospective cohort study was done. Patients admitted with acute OM or SA between 2005 and 2014 were identified using ICD-10 discharge codes. Ninety-six children were identified: OM, n = 45; SA, n = 42; and OM + SA, n = 9. Diagnostic imaging was performed in 100% of OM or OM + SA and 95% of SA patients. MRI was performed in 85% of OM patients, 26% of SA patients and 100% OM + SA patients. In patients with OM or SA, concomitant joint/bone involvement was detected in 24 and 36% of patients, respectively. In 58% of patients, a pathogen was detected (Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae being most common). Blood and tissue culture were positive in 41 and 86% for OM patients and in 14 and 41%, respectively, for SA patients. In 42% of patients, no pathogen was identified, of which 40% had no material for blood or tissue culture/NAT taken.

CONCLUSION

Optimal use of imaging modalities including MRI and systematic pathogen detection including NAT should be advocated to limit use of broad spectrum antibiotics and treatment duration. What is Known: • Magnetic resonance imaging and sonography have the best sensitivity for detection of acute osteomyelitis and septic arthritis in children. • Systematic use of blood cultures, tissue cultures and nucleic acid testing improves pathogen detection in children with acute osteomyelitis and septic arthritis. What is New: • The added value of imaging modalities other than magnetic resonance and sonography for detection of osteomyelitis and septic arthritis is limited, and their routine use should be questioned. • Despite availability of optimal pathogen detection methods, missed opportunities to improve pathogen detection are frequent.

Duration of intravenous antibiotic therapy for children with acute osteomyelitis or septic arthritis: a feasibility study

BACKGROUND

There is little current consensus regarding the route or duration of antibiotic treatment for acute osteomyelitis (OM) and septic arthritis (SA) in children.

OBJECTIVE

To assess the overall feasibility and inform the design of a future randomised controlled trial (RCT) to reduce the duration of intravenous (i.v.) antibiotic use in paediatric OM and SA.

DESIGN

(1) A prospective service evaluation (cohort study) to determine the current disease spectrum and UK clinical practice in paediatric OM/SA; (2) a prospective cohort substudy to assess the use of targeted polymerase chain reaction (PCR) in diagnosing paediatric OM/SA; (3) a qualitative study to explore families' views and experiences of OM/SA; and (4) the development of a core outcome set via a systematic review of literature, Delphi clinician survey and stakeholder consensus meeting.

SETTING

Forty-four UK secondary and tertiary UK centres (service evaluation).

PARTICIPANTS

Children with OM/SA.

INTERVENTIONS

PCR diagnostics were compared with culture as standard of care. Semistructured interviews were used in the qualitative study.

RESULTS

Data were obtained on 313 cases of OM/SA, of which 218 (61.2%) were defined as simple disease and 95 (26.7%) were defined as complex disease. The epidemiology of paediatric OM/SA in this study was consistent with existing European data. Children who met oral switch criteria less than 7 days from starting i.v. antibiotics were less likely to experience treatment failure (9.6%) than children who met oral switch criteria after 7 days of i.v. therapy (16.1% when switch was between 1 and 2 weeks; 18.2% when switch was > 2 weeks). In 24 out of 32 simple cases (75%) and 8 out of 12 complex cases (67%) in which the targeted PCR was used, a pathogen was detected. The qualitative study demonstrated the importance to parents and children of consideration of short- and long-term outcomes meaningful to families themselves. The consensus meeting agreed on the following outcomes: rehospitalisation or recurrence of symptoms while on oral antibiotics, recurrence of infection, disability at follow-up, symptom free at 1 year, limb shortening or deformity, chronic OM or arthritis, amputation or fasciotomy, death, need for paediatric intensive care, and line infection. Oral switch criteria were identified, including resolution of fever for ≥ 48 hours, tolerating oral food and medicines, and pain improvement.

LIMITATIONS

Data were collected in a 6-month period, which might not have been representative, and follow-up data for long-term complications are limited.

CONCLUSIONS

A future RCT would need to recruit from all tertiary and most secondary UK hospitals. Clinicians have implemented early oral switch for selected patients with simple disease without formal clinical trial evidence of safety. However, the current criteria by which decisions to make the oral switch are made are not clearly established or evidence based.

FUTURE WORK

A RCT in simple OM and SA comparing shorter- or longer-course i.v. therapy is feasible in children randomised after oral switch criteria are met after 7 days of i.v. therapy, excluding children meeting oral switch criteria in the first week of i.v. therapy. This study design meets clinician preferences and addresses parental concerns not to randomise prior to oral switch criteria being met.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Clinical Care Guideline for Improving Pediatric Acute Musculoskeletal Infection Outcomes

BACKGROUND

Acute pediatric musculoskeletal infections are common, leading to significant use of resources and antimicrobial exposure. In order to decrease variability and improve the quality of care, Children's Hospital Colorado implemented a clinical care guideline (CCG) for these infections. The purpose of this study is to evaluate clinical and resource outcomes PRE and POST this CCG.

METHODS

Retrospective chart review evaluated patients admitted to a large pediatric quaternary referral center (CHCO) diagnosed with acute osteomyelitis, septic arthritis, pyomyositis, and/or musculoskeletal abscess prior to and after guideline implementation. Primary outcomes included length of stay and overall antibiotic use, with additional secondary clinical, process, and therapeutic outcomes examined.

RESULTS

82 patients were identified in both the pre-CCG and post-CCG cohorts. There was a reduction in the median of all primary outcomes, including length of stay (0.6 median days decrease, P = .04), length of IV antibiotic therapy (4.9 median days decrease, P < .0001), and days of IV antibiotic therapy (6.4 median days decrease, P = .0004). Our median length of stay post-CCG was 4.9 days, the shortest reported length of stay for pediatric acute musculoskeletal infections to date. Additionally, there was a 24.5 hour reduction in median length of fever (P = .02), faster CRP normalization (P < .0001), 50% decrease in the number of related readmissions (P = .02), 34% decrease in central venous catheters placed (P < .0001), decreased time to first culture (P = .02), and 79% pathogen identification post-CCG (P = .056).

CONCLUSIONS

Implementation of a CCG for acute musculoskeletal infections improves patient, process and resource outcomes.

Acute Hematogenous Osteomyelitis in Children: Pathogenesis, Diagnosis, and Treatment

Acute hematogenous osteomyelitis (AHO) in children is an ideal condition to study due to its representation of a wide spectrum of disorders that comprise pediatric musculoskeletal infection. Proper care for children with AHO is multidisciplinary and collaborative. AHO continues to present a significant clinical challenge due to evolving epidemiology and complex pathogenesis. A guideline-driven, multidisciplinary approach has been introduced and shown to effectively reduce hospital stay, improve the timing and selection of empirical antibiotic administration, reduce delay to initial MRI, reduce the rate of readmission, and shorten antibiotic duration.

Group A Streptococcal Suppurative Arthritis and Osteomyelitis of the Shoulder With Brachial Plexus Palsy in a Newborn

Osteoarticular infections in the newborn period are rare. A serious complication is paralysis of the affected extremity resulting from either pain or direct involvement of the nerve. We report a newborn with combined osteomyelitis and suppurative arthritis caused by Streptococcus pyogenes presenting with right brachial plexus palsy.

Management of acute osteomyelitis: a ten-year experience

Osteomyelitis is an infection of the bone; proper management requires prolonged antibiotic treatment. Controversy exists as to when a patient should transition from intravenous to oral antibiotics. However, due to the high bioavailability of some oral antibiotics, optimal time to transition from high to low bioavailability antibiotics is a more valid consideration. Additionally, there are questions surrounding the efficacy of certain antibiotics, specifically trimethoprim-sulfamethoxazole (TMP-SMX), in treating osteomyelitis. After obtaining Institutional Review Board approval from both universities, a retrospective chart review was conducted, utilizing an author-created severity scale, on all patients seen by Pediatric Infectious Diseases at the Universities of Michigan and Toledo with an acute osteomyelitis diagnosis from 2002-2012. There were 133 patients, 106 treated successfully. Success was defined in this study specifically as treatment of <14 weeks without recurrence within 30 days of stopping antibiotics or permanent site disability. Seventeen patients were treated with TMP-SMX at comparable cure rates. Patients with pre-existing bone defects (noted in radiological reports), initial erythrocyte sedimentation rate (ESR)≥70, hematogenous osteomyelitis with soft tissue extension, and skull osteomyelitis were associated with increased failure rate. Switch to low bioavailability antibiotics occurred, on average, at 3.5 weeks; however, switching before then was not associated with decreased cure rate. As prevalence of methicillin-resistant Staphylococcus aureus (MRSA), especially clindamycin-resistant MRSA, increases, TMP-SMX appears to be an acceptable antibiotic. There does not appear to be a minimum length of high bioavailability treatment required for cure. Prior bone defect, extensive infection, ESR≥70, or skull osteomyelitis may be indications for more aggressive management.

Bone and Joint Infections in Children: Acute Hematogenous Osteomyelitis

Acute hematogenous osteomyelitis (AHO) is one of the commonest bone infection in childhood. Staphylococcus aureus is the commonest organism causing AHO. With use of advanced diagnostic methods, fastidious Kingella kingae is increasingly becoming an important organism in etiology of osteoarticular infections in children under the age of 3 y. The diagnosis of AHO is primarily clinical. The main clinical symptom and sign in AHO is pain and tenderness over the affected bone especially in the metaphyseal region. However, in a neonate the clinical presentation may be subtle and misleading. Laboratory and radiological investigations supplement the clinical findings. The acute phase reactants such as C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are frequently elevated. Ultrasonography and MRI are key imaging modalities for early detection of AHO. Determination of infecting organism in AHO is the key to the correct antibiotic choice, treatment duration and overall management and therefore, organism isolation using blood cultures and site aspiration should be attempted. Several effective antibiotics regimes are available for managing AHO in children. The choice of antibiotic and its duration and mode of delivery requires individualization depending upon severity of infection, causative organism, regional sensitivity patterns, time elapsed between onset of symptoms and child's presentation and the clinical and laboratory response to the treatment. If pus has been evidenced in the soft tissues or bone region, surgical decompression of abscess is mandatory.

Acute bacterial osteomyelitis in children

PURPOSE

To review the records of 24 paediatric patients treated for acute bacterial osteomyelitis.

METHODS

Records of 14 male and 10 female paediatric patients (mean age, 9.4 years) who underwent medical treatment alone (n=3) or combined with surgery (n=21) for acute bacterial osteomyelitis were reviewed. Medical treatment included use of antibiotics and supportive care. Surgery was indicated when the largest dimension of fluid collection was >1 cm.

RESULTS

Of the 24 patients, Staphylococcus aureus was isolated in 18, group-D salmonella in 3, and no organism in 3. The mean time from admission to diagnosis was 1.87 days. For those treated surgically, the mean time from diagnosis to surgery was 1.19 days and the mean time from admission to surgery was 2.86 days. Four patients underwent multiple surgeries, 2 of whom developed chronic osteomyelitis and also had negative culture and delayed surgery by >10 days previously. No other patient had any complications.

CONCLUSION

Early surgical intervention for acute bacterial osteomyelitis in children increased diagnostic yield with cultures. For patients with fluid collection <1 cm in the largest dimension, medical treatment alone was effective. Patients with complications were characterised by negative culture, multiple surgeries, and delayed surgery.

Acute Primary Hematogenous Osteomyelitis in the Epiphysis of the Distal Tibia: A Case Report With Review of the Literature

Osteomyelitis originating in the epiphysis of the long bones is quite rare and is usually found at either the distal femur or the proximal tibia. We report the case of a 12-year-old male with epiphyseal osteomyelitis that had developed in the distal tibia. To the best of our knowledge, this is the first published case report. The patient's history of a trauma that resembled an ankle sprain had delayed the diagnosis and subsequently led him to develop septic arthritis. The ankle is a common site of simple trauma; however, epiphyseal osteomyelitis is rare at this site. Therefore, if the symptoms continue or worsen after trauma, the clinician should check the affected site and take a more aggressive approach to make an early diagnosis.

Fungal osteomyelitis of maxillofacial bones: Rare presentation

Osteomyelitis is defined as inflammation of the medullary cavities, haversian system and adjacent cortex of bone. Osteomyelitis involving maxilla is quite rare when compared to that of mandible. Fungal osteomyelitis is very rarely seen and documented in the maxillofacial area. It is devastating to patients if it is invasive in nature. A prospective study was undertaken from December 2011 to December 2013. Biopsied hard tissue bits were decalcified and sections were stained with H&E, periodic acid Schiff and Grocott methenamine silver. Culture sensitivity was carried out in all cases. Surgical intervention followed by antifungal therapy was advocated to treat the patients. The current series showed five cases of fungal osteomyelitis which included candidal osteomyelitis, aspergillosis and mucormycosis with slight predominance of maxilla over mandible. Osteomyelitis of facial bones needs to be investigated thoroughly as there is no difference in clinical presentation between bacterial and fungal osteomyelitis. The diagnostic workup with biopsy and culture sensitivity helps to identify the pathogen at the earliest. Appropriate antifungal treatment needs to be advocated for successful treatment.

Mouse models for infectious diseases caused by Staphylococcus aureus

Staphylococcus aureus - a commensal of the human skin, nares and gastrointestinal tract - is also a leading cause of bacterial skin and soft tissue infection (SSTIs), bacteremia, sepsis, peritonitis, pneumonia and endocarditis. Antibiotic-resistant strains, designated MRSA (methicillin-resistant S. aureus), are common and represent a therapeutic challenge. Current research and development efforts seek to address the challenge of MRSA infections through vaccines and immune therapeutics. Mice have been used as experimental models for S. aureus SSTI, bacteremia, sepsis, peritonitis and endocarditis. This work led to the identification of key virulence factors, candidate vaccine antigens or immune-therapeutics that still require human clinical testing to establish efficacy. Past failures of human clinical trials raised skepticism whether the mouse is an appropriate model for S. aureus disease in humans. S. aureus causes chronic-persistent infections that, even with antibiotic or surgical intervention, reoccur in humans and in mice. Determinants of S. aureus evasion from human innate and adaptive immune responses have been identified, however only some of these are relevant in mice. Future research must integrate these insights and refine the experimental mouse models for specific S. aureus diseases to accurately predict the failure or success for candidate vaccines and immune-therapeutics.

A secreted bacterial protease tailors the Staphylococcus aureus virulence repertoire to modulate bone remodeling during osteomyelitis

Osteomyelitis is a common manifestation of invasive Staphylococcus aureus infection. Pathogen-induced bone destruction limits antimicrobial penetration to the infectious focus and compromises treatment of osteomyelitis. To investigate mechanisms of S. aureus-induced bone destruction, we developed a murine model of osteomyelitis. Microcomputed tomography of infected femurs revealed that S. aureus triggers profound alterations in bone turnover. The bacterial regulatory locus sae was found to be critical for osteomyelitis pathogenesis, as Sae-regulated factors promote pathologic bone remodeling and intraosseous bacterial survival. Exoproteome analyses revealed the Sae-regulated protease aureolysin as a major determinant of the S. aureus secretome and identified the phenol-soluble modulins as aureolysin-degraded, osteolytic peptides that trigger osteoblast cell death and bone destruction. These studies establish a murine model for pathogen-induced bone remodeling, define Sae as critical for osteomyelitis pathogenesis, and identify protease-dependent exoproteome remodeling as a major determinant of the staphylococcal virulence repertoire.

[Acute osteomyelitis: epidemiology, clinical manifestations, diagnosis and treatment]

BACKGROUND AND AIMS

The present study focuses on the epidemiology, clinical and laboratory data, and management of osteomyelitis in a pediatric third level hospital.

METHODOLOGY

All cases of children under 15 years-old admitted with osteomyelitis between 2000 and 2011 were retrospectively reviewed until July 2006, then prospectively from then until 2011.

RESULTS

A total of 50 patients were identified (52% males) with median age at diagnosis of 2 years. Principal onset manifestations were pain (94%), functional impairment (90%) and fever (72%). The femur (32%), fibula (28%) and calcaneus (22%) were most affected bones. Leucocytosis > 12.000/μl was found in 56%, elevated ESR > 20 mm/h in 26%, and elevated CRP > 20 mg/L in 64%. Blood culture was positive in 20%, with group A streptococcus being the most frequently isolated bacteria (11%). All diagnoses were confirmed by a (99)Tc scintigraphy bone scan. Antibiotic therapy was initially intravenously (mean time of administration: 10 days ± 3 SD), followed by oral medication (mean time of administration: 18 days ± 6 SD). Surgery was necessary in 3 patients. Evolution of all cases was excellent, despite 3 exceptions that resolved over time.

CONCLUSIONS

The current short-term intravenous therapy led to shorter hospitalizations. There were no statistically significant differences between time from clinical onset or in CRP levels at discharge compared to long-term therapies prior to 2006.

Infection of orthopedic implants with emphasis on bacterial adhesion process and techniques used in studying bacterial-material interactions

Staphylococcus comprises up to two-thirds of all pathogens in orthopedic implant infections and they are the principal causative agents of two major types of infection affecting bone: septic arthritis and osteomyelitis, which involve the inflammatory destruction of joint and bone. Bacterial adhesion is the first and most important step in implant infection. It is a complex process influenced by environmental factors, bacterial properties, material surface properties and by the presence of serum or tissue proteins. Properties of the substrate, such as chemical composition of the material, surface charge, hydrophobicity, surface roughness and the presence of specific proteins at the surface, are all thought to be important in the initial cell attachment process. The biofilm mode of growth of infecting bacteria on an implant surface protects the organisms from the host immune system and antibiotic therapy. The research for novel therapeutic strategies is incited by the emergence of antibiotic-resistant bacteria. This work will provide an overview of the mechanisms and factors involved in bacterial adhesion, the techniques that are currently being used studying bacterial-material interactions as well as provide insight into future directions in the field.

Osteomielite hematogênica aguda em Pediatria: análise de casos atendidos em hospital universitário

OBJETIVO: Descrever a ocorrência, a evolução e o desfecho de pacientes com osteomielite hematogênica aguda na faixa etária pediátrica. MÉTODOS: Estudo descritivo de 21 casos de pacientes de zero a 14 anos com diagnóstico de osteomielite hematogênica aguda, em acompanhamento no Ambulatório de Infectologia Pediátrica da Escola Paulista de Medicina entre 2005 e 2009. A coleta de dados ocorreu pelo levantamento de prontuários. Realizaram-se a análise descritiva e o teste de correlação de Spearman, com intervalo de confiança de 95%. RESULTADOS: Foi identificada maior incidência no sexo masculino e em crianças maiores de cinco anos. Febre e dor foram os sintomas mais frequentes. Os ossos longos foram os mais acometidos. O principal agente etiológico identificado foi o Staphylococcus aureus. Em média, o tempo de sintomatologia até o diagnóstico foi de 9,7 dias, o de internação, 24,7 dias, e o total de antibioticoterapia foi de 71,7 dias. A resolução completa do quadro ocorreu em 71,4% dos casos, com permanência de sequelas em 28,6% deles, sendo a evolução para osteomielite crônica a principal delas. CONCLUSÕES: As características dos pacientes e da doença referentes a sexo, idade, etiologia e evolução mostram-se concordantes com o descrito na literatura. O tempo de tratamento foi de aproximadamente dez semanas, valor acima do habitualmente encontrado nos diferentes estudos. Não foram encontradas correlações significantes entre o tempo de sintomatologia até o diagnóstico, o tempo de internação e o tempo total de antibioticoterapia, havendo a limitação do tamanho da amostra.

Influence of Culture Results on Management and Outcome of Pediatric Osteomyelitis and/or Septic Arthritis

Children with uncomplicated osteomyelitis and/or septic arthritis were more likely (P < .01) to have positive focus than blood cultures. Those who grew a pathogen and/or started on a single antibiotic were more likely to be discharged on a single antibiotic, and those sent home on oral therapy had fewer adverse events.

Antibiotic treatment for acute haematogenous osteomyelitis of childhood: moving towards shorter courses and oral administration

Acute haematogenous osteomyelitis (AHOM) of childhood usually affects the long bones of the lower limbs. Although almost any agent may cause AHOM, Staphylococcus aureus is the most common bacterium, followed by Streptococcus pneumoniae and, in some countries, Salmonella spp. and Kingella kingae. Magnetic resonance imaging (MRI) has improved the diagnostic accuracy of traditional radiography and scintigraphy. Except for the pre-treatment diagnostic sample from bone before the institution of antibiotic therapy, no other surgery is usually required. Traditionally, non-neonatal AHOM has been treated with a 1-3-month course of antibiotics, including an intravenous (i.v.) phase for the first weeks, but recent prospective randomised studies challenge this approach. For most uncomplicated cases, a course of 20 days including an i.v. period of 2-4 days suffices, provided large enough doses of a well-absorbed agent (clindamycin or a first-generation cephalosporin, local resistance permitting) are used, administration is four times daily and most symptoms and signs subside within a few days. Serum C-reactive protein (CRP) is a good guide in monitoring the course of illness, and the antimicrobial can usually be discontinued if CRP has decreased to <20 mg/L. Newer and costly agents, such as linezolid, should be reserved for cases due to resistant S. aureus strains. AHOM in neonates and immunocompromised patients probably requires a different approach. Because sequelae may develop slowly, follow-up for at least 1 year post hospitalisation is recommended.

Mandibular osteomyelitis in children mimicking juvenile recurrent parotitis

OBJECTIVE

To describe pediatric cases with mandibular osteomyelitis initially diagnosed and treated as juvenile recurrent parotitis.

METHODS

We reviewed the patient data of all our pediatric patients treated at Helsinki University Central Hospital, a tertiary care hospital, between 1998 and 2010 who had the initial diagnosis of recurrent parotitis which in fact was osteomyelitis.

RESULTS

Over a period of 12 years, six children (aged 5-17 years, five girls) presented with mandibular osteomyelitis primarily diagnosed as recurrent parotitis. Diagnostic delay ranged from 1.5 months to 6.0 years before the final diagnosis of mandibular osteomyelitis confirmed in MRI. Of the six cases undergoing biopsies, bacterial culture showed Actinomyces or Streptococcus viridans in four cases. All patients received antimicrobial treatment. Two received hyperbaric oxygen therapy with no resolution of symptoms. Debridement was performed in these two cases as well, and in the second case persistent symptoms led to bisphosphonate treatment.

CONCLUSIONS

Juvenile parotitis is in most cases a clinical diagnosis, and treatment is symptomatic. In contrast, mandibular osteomyelitis is a severe disease requiring lengthy treatment. Because symptoms of these two entities may mimic each other, unclear cases require MRI.

Staphylococcus aureus osteomyelitis in Hawaii

BACKGROUND

The clinical and laboratory findings and outcomes of methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) Staphylococcus aureus osteomyelitis have not been studied in Hawaii.

METHODS

Retrospective inpatient chart reviews of 62 culture-proven osteomyelitis patients between 1996 and 2007 were performed.

RESULTS

Fifteen patients (24%) had MRSA infection, and 47 patients (76%) had MSSA infection. Length of stay, chronic health problems, total duration of fever, and length of treatment were not significantly different between MRSA- and MSSA-infected patients. The peak erythrocyte sedimentation rate and C-reactive protein values were higher among MRSA infected patients (P values: .009 and .003, respectively).The systemic complication rate was higher in MRSA-infected patients (P value: .018).

CONCLUSIONS

Differing from other pediatric staphylococcal infections in Hawaii, the majority of the patients had MSSA infection. Pacific Islander and Native Hawaiian ethnicities were affected disproportionately and had MRSA infection more frequently. MRSA-infected patients had frequent surgical procedures and systemic complications.

Interaction of staphylococci with bone

Staphylococci, in particular Staphylococcus aureus, are the predominant cause of bone infections worldwide. These infections are painful, debilitating and with the rise in antibiotic-resistant forms, increasingly difficult to treat. The growth in the number of prosthetic joint replacement procedures also provides new opportunities for these infections to take hold. Comprehending the mechanisms by which staphylococci interact with and damage bone is critical to the development of new approaches to meet this challenge. This review summarises current understanding of the mechanisms by which staphylococci infect and damage bone. We address the role of the inflammatory response to staphylococcal infection in disrupting the homeostatic balance of bone matrix deposition and resorption and thereby mediating bone destruction. A number of virulence factors that have been shown to contribute to bone infection and pathology are discussed, however no single factor has been defined as being specific to bone infections. Although traditionally considered an extracellular pathogen, there is increasing evidence that staphylococci are able to invade host cells, and that an intracellular lifestyle may facilitate long-term persistence in bone tissue, enabling evasion of antimicrobials and host immune responses. ‘Small colony variant’ strains, with mutations disabling the electron transport pathway appear particularly adept at invading and persisting within host cells, and exhibit enhanced antimicrobial resistance, and may represent a further complication in the treatment and management of staphylococcal bone disease.