Comparison of clinical features and outcomes of staphylococcus aureus vertebral osteomyelitis caused by methicillin-resistant and methicillin-sensitive strains

Natural products acting against S. aureus through membrane and cell wall disruption

Covering: 2015 to 2022Staphylococcus aureus (S. aureus) is responsible for several community and hospital-acquired infections with life-threatening complications such as bacteraemia, endocarditis, meningitis, liver abscess, and spinal cord epidural abscess. In recent decades, the abuse and misuse of antibiotics in humans, animals, plants, and fungi and the treatment of nonmicrobial diseases have led to the rapid emergence of multidrug-resistant pathogens. The bacterial wall is a complex structure consisting of the cell membrane, peptidoglycan cell wall, and various associated polymers. The enzymes involved in bacterial cell wall synthesis are established antibiotic targets and continue to be a central focus for antibiotic development. Natural products play a vital role in drug discovery and development. Importantly, natural products provide a starting point for active/lead compounds that sometimes need modification based on structural and biological properties to meet the drug criteria. Notably, microorganisms and plant metabolites have contributed as antibiotics for noninfectious diseases. In this study, we have summarized the recent advances in understanding the activity of the drugs or agents of natural origin that directly inhibit the bacterial membrane, membrane components, and membrane biosynthetic enzymes by targeting membrane-embedded proteins. We also discussed the unique aspects of the active mechanisms of established antibiotics or new agents.

Untargeted proteomic differences between clinical strains of methicillin-sensitive and methicillin-resistant Staphylococcusaureus

Staphylococcus aureus is a common disease-causing bacterium that has developed resistances to a wide variety of antibiotics. This increasing antibiotic resistance has made management of these infections difficult. A better understanding of the general differences among clinical S. aureus strains beyond the well characterized resistance mechanisms may help in identifying new anti-microbial targets. This study aimed to identify and compare the general differences in protein profiles among clinical strains of S. aureus sensitive and resistant to methicillin. The proteomic profiles of five methicillin sensitive (MSSA) and five methicillin resistant (MRSA) S. aureus strains were analyzed by ultra-performance liquid chromatography-mass spectrometry. Protein identification was done using Progenesis QI for Proteomics and the UniProt S. aureus database. Proteins that play roles in virulence, metabolism, and protein synthesis were found to be present at different abundances between MSSA and MRSA (Data available via ProteomeXchange with identifier PXD021629). This study shows differences in protein profiles between antibiotic sensitive and antibiotic resistant clinical strains of S. aureus that may affect the resistance mechanism. Further research on these differences may identify new drug targets against methicillin resistant S. aureus strains.

Tackling multidrug-resistant Staphylococcus aureus by natural products and their analogues acting as NorA efflux pump inhibitors

Staphylococcus aureus (S. aureus) is a pathogen responsible for various community and hospital-acquired infections with life-threatening complications like bacteraemia, endocarditis, meningitis, liver abscess, and spinal cord epidural abscess. Antibiotics have been used to treat microbial infections since the introduction of penicillin in 1940. In recent decades, the abuse and misuse of antibiotics in humans, animals, plants, and fungi, including the treatment of non-microbial diseases, have led to the rapid emergence of multidrug-resistant pathogens with increased virulence. Bacteria have developed several complementary mechanisms to avoid the effects of antibiotics. These mechanisms include chemical transformations and enzymatic inactivation of antibiotics, modification of antibiotics' target site, and reduction of intracellular antibiotics concentration by changes in membrane permeability or by the overexpression of efflux pumps (EPs). The strategy to check antibiotic resistance includes synthesis of the antibiotic analogues, or antibiotics are given in combination with the adjuvant. The inhibitors of multidrug EPs are considered promising alternative therapeutic options with the potential to revive the effects of antibiotics and reduce bacterial virulence. Natural products played a vital role in drug discovery and significantly contributed to the area of infectious diseases. Also, natural products provide lead compounds that sometimes need modification based on structural and biological properties to meet the drug criteria. This review discusses natural products and their derived compounds as NorA efflux pump inhibitors (EPIs).

Exposure and Health Effects of Bacteria in Healthcare Units: An Overview

Healthcare units consist of numerous people circulating daily, such as workers, patients, and companions, and these people are vehicles for the transmission of microorganisms, such as bacteria. Bacteria species may have different allergenic, pathogenic, infectious, or toxic properties that can affect humans. Hospital settings foment the proliferation of bacteria due to characteristics present in the indoor hospital environment. This review article aims to identify the potential health effects caused by bacterial contamination in the context of healthcare units, both in patients and in workers. A search was carried out for articles published in PubMed, Web of Science and Scopus, between 1 January 2000 and 31 October 2021, using the descriptor hospital exposure assessment bacteria. This bibliographic research found a total of 13 articles. Bacteria transmission occurs mainly due to the contact between healthcare workers and patients or through the handling of/contact with contaminated instruments or surfaces. The most common bacterial contaminants are Escherichia coli, Pseudomonas aeruginosa, Staphylococcus spp., Staphylococcus aureus and Micrococcus luteus, and the principal health effects of these contaminants are hospital-acquired infections and infections in immunocompromised people. A tight control of the disinfection methods is thus required, and its frequency must be increased to remove the microbial contamination of wards, surfaces and equipment. A better understanding of seasonal variations is important to prevent peaks of contamination.

Differences Between Methicillin-susceptible Versus Methicillin-resistant Staphylococcus aureus Infections in Pediatrics: Multicenter Cohort Study Conducted in Bogotá, Colombia, 2014-2018

BACKGROUND

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) has changed in recent years. The present article is intended to establish differences between clinical, laboratory and imaging findings and outcomes of MSSA and MRSA infections, as well as among subgroups of infection such as skin and soft tissue infection, osteoarticular, bacteremia or pneumonia in a pediatric population from Bogota, Colombia.

METHODS

Retrospective cohort study using clinical records of patients under 18 years of age treated at the participating centers in Bogota, Colombia, between 2014 and 2018. The first positive S. aureus culture was studied. MSSA and MRSA were compared. The χ2 test, Fisher exact test, and Kruskal-Wallis test were calculated, and the statistical significance was presented using the difference and its 95% CI.

RESULTS

Five hundred fifty-one patients were included; 211 (38%) corresponded to MRSA and 340 (62%) to MSSA for a total of 703 cultures. A significantly higher probability of having an MSSA infection than MRSA was found in patients with previous heart disease (3.3% vs. 0.5%), neurologic disease (5.9% vs. 2.5%), recent major surgeries (11% vs. 5%) or who has an implanted device (11% vs. 4%). In contrast, in severe MRSA infections (bacteremia, osteoarticular infections and pneumonia), a higher rate of complications was seen (admission to the pediatric intensive care unit, mechanical ventilation and vasoactive support), and in osteoarticular MRSA, more than 1 surgery per case was seen (89% vs. 61%). Laboratory results and mortality were similar.

CONCLUSIONS

MRSA was associated with a more severe course in bacteremia, osteoarticular infections and pneumonia. Some classical risk factors associated with MRSA infections were found to be related to MSSA. In general, with the exception of skin and soft tissue infection, there was an increased risk of pediatric intensive care unit admission and mechanical and inotropic support with MRSA in a pediatric population.

Varying clinical presentations of nontuberculous mycobacterial disease : Similar to but different from tuberculosis

The incidence rate of pulmonary nontuberculous mycobacterial disease (PNTMD) in Japan is the highest among major industrialized nations. Although the typical clinical course and radiological manifestations of PNTMD are different from those of pulmonary tuberculosis (TB), confusion about these mycobacterial diseases leads to a diagnostic pitfall. Diagnostic challenges include the coexistence of Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM), false positives for NTM in MTB nucleic acid amplification tests, microbial substitution, and abnormal radiological manifestations caused by NTM. Features of extrapulmonary NTM diseases, such as pleurisy, vertebral osteomyelitis, and disseminated disease, are different from the corresponding tuberculous diseases. Moreover, the immunological background of the patient (status of human immunodeficiency virus infection with or without antiviral therapy, continuation or discontinuation of immunosuppressive therapy, use of immune checkpoint inhibitor, pregnancy and delivery, etc.) influences the pathophysiology of mycobacterial diseases. This review describes the varying clinical presentations of NTM disease with emphasis on the differences from TB. J. Med. Invest. 68 : 220-227, August, 2021.

Responsiveness of routine diagnostic tests for vertebral osteomyelitis may be influenced by the infecting organism

BACKGROUND CONTEXT

Vertebral osteomyelitis (VO) becomes increasingly more prevalent as people age, and it is a condition seen frequently by referral center spine surgeons. It can take as long as 6 months for a proper diagnosis to be made. Staphylococcus aureus (S. aureus) is the most common isolated organism in up to 80% of the affected population. The clinical presentation of vertebral osteomyelitis is typically non specific (back pain), which can make timely diagnosis challenging. Fever is often absent. Serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell count (WBC) and serum polymorphonuclear leukocyte percentage (PMN%) are traditionally used as first-line tests because of their perceived sensitivity to help diagnose vertebral osteomyelitis. It is not known whether these test values are affected by the infecting organism.

PURPOSE

To determine whether individual first-line diagnostics differed based on infecting organism and whether certain organisms are associated with lower lab values. Additionally, this study sought to determine if VO caused by lower virulent (eg, culture-negative and nonpyogenic organisms) could contribute to delays in treatment due to lack of elevated biomarkers.

STUDY DESIGN/SETTING

Single-center retrospective cohort study.

PATIENT SAMPLE

We reviewed clinical data of 133 patients (60% male) diagnosed with VO from 2015-2019 in a US Midwest academic hospital.

OUTCOMES MEASURES

Primary outcome measures included the maximum temperature upon presentation, serum C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell count (WBC), and percentage neutrophils during the hospital admission.

METHODS

Inclusion criteria were adult patients diagnosed with vertebral osteomyelitis who underwent blood culture and/or biopsy prior to treatment. All patients enrolled in the study were diagnosed with VO and confirmed via magnetic resonance imaging (MRI). MRI findings associated with VO included destruction of endplates, increased signal in vertebral bodies, and the surrounding disc on T2-weighted imaging were confirmed. The patients had laboratory work up and clinical follow up regardless of positive culture or negative culture. The mean peak inflammatory marker levels were compared among organisms with student's t test. Demographics, comorbidities, and CCI were collected and multivariable logistic regression models were used. Receiver operating characteristic curve analysis was performed to delineate separate, optimal cut offs for CRP, ESR, WBC, and PMN% for patients with culture positive osteomyelitis RESULTS: Patients' average age was 57.0±13.7 years with a mean BMI of 30.5±9.70 kg/m², and a mean Charleston Comorbidity Index (CCI) of 3.17±2.35. Staphylococcus aureus and antibiotic resistant organisms (MRSA and VRE) demonstrated a higher mean CRP and ESR than culture negative, fungal and TB cases. Staphylococcus aureus, antibiotic resistant organisms, and coagulase negative Staphylococcus demonstrated a higher mean WBC than culture negative as well as fungal and TB cases. Staphylococcus aureus, antibiotic resistant organisms, coagulase negative Staphylococcus, and Streptococcus species had a higher mean peak PMN%, than culture negative as well as fungal and TB case. Temperature did not correlate with a diagnosis of osteomyelitis.

CONCLUSIONS

Serum laboratory markers in the diagnosis of VO appear to be influenced by the infecting organism type. Laboratory values in patients diagnosed with VO with culture negative or non-pyogenic organisms are lower compared to antibiotic resistant and S. aureus organisms. Fever did not correlate with a diagnosis of VO.

Vertebral osteomyelitis in patients with Staphylococcus aureus bloodstream infection: Evaluation of risk factors for treatment failure

OBJECTIVES

Staphylococcus aureus is the most common cause of pyogenic vertebral osteomyelitis (VO). Studies indicate that S. aureus VO results in poor outcome. We aimed to investigate risk factors for treatment failure in patients with Staphylococcus aureus bloodstream infection (SAB) and VO.

METHODS

We conducted a post hoc-analysis of data from a German bi-center prospective SAB cohort (2006-2014). Patients were followed-up for one year. Primary outcome was treatment failure defined as relapse and/or death within one year.

RESULTS

A total of 1069 patients with SAB were analyzed, with 92 VO patients. In addition to antibiotic treatment, surgery was performed in 60/92 patients. Treatment failed in 44/92 patients (death, n = 42; relapse, n = 2). Multivariable analysis revealed higher age (HR 1.04 [per year], 95%CI 1.01-1.07), Charlson comorbidity index (HR 1.20, 95%CI 1.06-1.36), presence of neurologic deficits (HR 2.53, 95%CI 1.15-5.53) and local abscess formation (HR 3.35, 95%CI 1.39-8.04) as independent risk factors for treatment failure. In contrast, surgery seemed to be associated with a favourable outcome (HR 0.45 (95%CI 0.20-0.997)).

CONCLUSION

SAB patients with VO exhibit a high treatment failure rate. Red flags are older age, comorbidities, neurologic deficits and local abscess formation. Whether these patients benefit from intensified treatment (e.g. radical surgery, prolongation of antibiotics) should be investigated further.

De novo methicillin-resistant Staphylococcus aureus vs. methicillin-sensitive Staphylococcus aureus infections of the spine, similar clinical outcome, despite more severe presentation in surgical patients

Vertebral osteomyelitis (VO) is a severe infection of the vertebral body and the adjacent disc space, where Staphylococcus aureus is most commonly isolated. The objective of this retrospective study was to determine risk factors for and compare outcome differences between de novo methicillin-resistant Staphylococcus aureus (MRSA) VO and methicillin-sensitive Staphylococcus aureus (MSSA) VO. A retrospective cohort study was performed by review of the electronic medical records of 4541 consecutive spine surgery patients. Among these 37 underwent surgical treatment of de novo MRSA and MSSA spinal infections. Patient demographics, pre- and postoperative neurological status (ASIA impairment score), surgical treatment, inflammatory laboratory values, nutritional status, comorbidities, antibiotics, hospital stay, ICU stay, reoperation, readmission, and complications were collected. A minimum follow-up (FU) of 12 months was required. Among the 37 patients with de novo VO, 19 were MRSA and 18 were MSSA. Mean age was 52.4 and 52.9 years in the MRSA and MSSA groups, respectively. Neurological deficits were found in 53% of patients with MRSA infection and in 17% of the patients with MSSA infection, which was statistically significant (p < 0.05). Chronic renal insufficiency and malnutrition were found to be significant risk factors for MRSA VO. Preoperative albumin was significantly lower in the MRSA group (p < 0.05). Patients suffering from spinal infection with chronic renal insufficiency and malnutrition should be watched more carefully for MRSA. The MRSA group did not show a significant difference with regard to final clinical outcome despite more severe presentation.

Protocatechuic Acid as a Topical Antimicrobial for Surgical Skin Antisepsis: Preclinical Investigations

Background

There is a need for novel skin antiseptic agents to combat the health-care burdens associated with surgical site infection (SSI) and bacterial resistance. The purpose of this proof-of-principle pilot study was to investigate the potential of the phenolic compound protocatechuic acid (PCA) as a topical antimicrobial for surgical skin antisepsis.

Methods

The Kirby-Bauer method of disc diffusion was used to investigate the in vitro antimicrobial activity and comparative effectiveness of PCA and 7 related compounds against SSI pathogens. To explore the in vivo efficacy of topical PCA for providing deep, penetrating skin antisepsis, living Cutibacterium acnes was intradermally injected into the skin of female BALB/c mice. Mice were assigned to treatment with daily applications of topical PCA at 3 doses (78, 39, and 19.5 mM) or no treatment (n = 2 mice per group). After 96 hours, infected skin samples were harvested to compare mean C. acnes counts by treatment.

Results

Compared with other polyphenols, PCA demonstrated the broadest spectrum of antimicrobial activity against tested SSI pathogens, including drug-resistant organisms. At 96 hours following infection, the mean C. acnes burden in untreated mice was 6.65 log colony-forming units (CFUs) per gram of skin. Compared with the untreated group, daily topical application of 78 mM of PCA was associated with a significantly lower C. acnes CFU burden in mice skin (mean, 5.51 log CFUs per gram of skin; p = 0.0295). Both lower dosages of topical PCA failed to show an effect.

Conclusions

PCA demonstrated laboratory efficacy against pathogens implicated in SSI, including drug-resistant organisms. In vivo, topical PCA demonstrated dose-dependent skin penetration and antimicrobial activity against mouse skin C. acnes loads. Human clinical studies exploring the antimicrobial efficacy of topical PCA for preoperative shoulder skin antisepsis are warranted.

Clinical Relevance

Topical PCA may have the potential to improve current shoulder SSI treatment and prevention protocols.

Biofunctionalization of selective laser melted porous titanium using silver and zinc nanoparticles to prevent infections by antibiotic-resistant bacteria

Antibiotic-resistant bacteria are frequently involved in implant-associated infections (IAIs), making the treatment of these infections even more challenging. Therefore, multifunctional implant surfaces that simultaneously possess antibacterial activity and induce osseointegration are highly desired in order to prevent IAIs. The incorporation of multiple inorganic antibacterial agents onto the implant surface may aid in generating synergistic antibacterial behavior against a wide microbial spectrum while reducing the occurrence of bacterial resistance. In this study, porous titanium implants synthesized by selective laser melting (SLM) were biofunctionalized with plasma electrolytic oxidation (PEO) using electrolytes based on Ca/P species as well as silver and zinc nanoparticles in ratios from 0 to 100% that were tightly embedded into the growing titanium oxide layer. After the surface bio-functionalization process, silver and zinc ions were released from the implant surfaces for at least 28 days resulting in antibacterial leaching activity against methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, the biofunctionalized implants generated reactive oxygen species, thereby contributing to antibacterial contact-killing. While implant surfaces containing up to 75% silver and 25% zinc nanoparticles fully eradicated both adherent and planktonic bacteria in vitro as well as in an ex vivo experiment performed using murine femora, solely zinc-bearing surfaces did not. The minimum inhibitory and bactericidal concentrations determined for different combinations of both types of ions confirmed the presence of a strong synergistic antibacterial behavior, which could be exploited to reduce the amount of required silver ions by two orders of magnitude (i.e., 120 folds). At the same time, the zinc bearing surfaces enhanced the metabolic activity of pre-osteoblasts after 3, 7, and 11 days. Altogether, implant biofunctionalization by PEO with silver and zinc nanoparticles is a fruitful strategy for the synthesis of multifunctional surfaces on orthopedic implants and the prevention of IAIs caused by antibiotic-resistant bacteria. STATEMENT OF SIGNIFICANCE: Implant-associated infections are becoming increasingly challenging to treat due to growing antibiotic resistance against antibiotics. Here, we propose an alternative approach where silver and zinc nanoparticles are simultaneously used for the biofunctionalization of rationally designed additively manufactured porous titanium. This combination of porous design and tailored surface treatment allows us to reduce the amount of required silver nanoparticles by two orders of magnitude, fully eradicate antibiotic-resistant bacteria, and enhance the osteogenic behavior of pre-osteoblasts. We demonstrate that the resulting implants display antibacterial activity in vitro and ex vivo against methicillin-resistant Staphylococcus aureus.

Selection of an appropriate empiric antibiotic regimen in hematogenous vertebral osteomyelitis

Background

Empiric antibiotic therapy for suspected hematogenous vertebral osteomyelitis (HVO) should be initiated immediately in seriously ill patients and may be required in those with negative microbiological results. The aim of this study was to inform the appropriate selection of empiric antibiotic regimens for the treatment of suspected HVO by analyzing antimicrobial susceptibility of isolated bacteria from microbiologically proven HVO.

Method

We conducted a retrospective chart review of adult patients with microbiologically proven HVO in five tertiary-care hospitals over a 7-year period. The appropriateness of empiric antibiotic regimens was assessed based on the antibiotic susceptibility profiles of isolated bacteria.

Results

In total, 358 cases of microbiologically proven HVO were identified. The main causative pathogens identified were methicillin-susceptible Staphylococcus aureus (33.5%), followed by methicillin-resistant S. aureus (MRSA) (24.9%), Enterobacteriaceae (19.3%), and Streptococcus species (11.7%). Extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and anaerobes accounted for only 1.7% and 1.4%, respectively, of the causative pathogens. Overall, 73.5% of isolated pathogens were susceptible to levofloxacin plus rifampicin, 71.2% to levofloxacin plus clindamycin, and 64.5% to amoxicillin-clavulanate plus ciprofloxacin. The susceptibility to these oral combinations was lower in cases of healthcare-associated HVO (52.6%, 49.6%, and 37.6%, respectively) than in cases of community-acquired HVO (85.8%, 84.0%, and 80.4%, respectively). Vancomycin combined with ciprofloxacin, ceftriaxone, ceftazidime, or cefepime was similarly appropriate (susceptibility rates of 93.0%, 94.1%, 95.8%, and 95.8%, respectively).

Conclusions

Based on our susceptibility data, vancomycin combined with a broad-spectrum cephalosporin or fluoroquinolone may be appropriate for empiric treatment of HVO. Fluoroquinolone-based oral combinations may be not appropriate due to frequent resistance to these agents, especially in cases of healthcare-associated HVO.

Short- versus long-course antibiotics in osteomyelitis: A systematic review and meta-analysis

Current practice of long-term antibiotic use in patients with osteomyelitis is controversial. Recent studies showed short-term antibiotic use to be non-inferior to long-term use, but the results of these studies have been inconsistent. In this review, the PubMed and Embase databases were searched from inception through to June 2018 for randomised controlled trials (RCTs), cohort studies or case-control studies comparing two different durations of antibiotic use. Short antibiotic courses were defined as antibiotics administered for a shorter period than the recommended 4-6 weeks. A random-effects model was used to calculate summary odds ratios (ORs) of treatment failure in patients treated with short-course antibiotics compared with long-course antibiotics. A total of 15 articles (5 RCTs and 10 observational studies) and 3598 patients were included. The overall OR of treatment failure in patients receiving short-course antibiotics was 1.50 [95% confidence interval (CI) 0.97-2.34]. Subgroup analysis revealed that a short course of antibiotic treatment was associated with an increased treatment failure rate in vertebral osteomyelitis (OR = 2.06, 95% CI 1.18-3.57) while having a similar rate to a long antibiotic course in acute osteomyelitis of childhood (OR = 1.86, 95% CI 0.75-4.64). Meta-regression found a higher proportion of Staphylococcus aureus infection was related to a higher risk of treatment failure in patients with vertebral osteomyelitis (Coef. = 4.996; P = 0.032). Short-course antibiotics are safe and effective in children with acute osteomyelitis. Long-course antibiotics may still be preferred in vertebral osteomyelitis, especially in patients with S. aureus infection.

Factors predictive of relapse in adult bacterial osteomyelitis of long bones

Background

Osteomyelitis is a difficult-to-cure infection with a high relapse rate despite combined medical and surgical therapies. Some severity factors, duration of antimicrobial therapy and type of surgical procedure might influence osteomyelitis relapse.

Methods

116 patients with osteomyelitis were followed for ≥1 year after hospital discharge. Demographic, microbiological and clinical data, eight severity factors and treatment (surgical and antibiotic) were analyzed.

Results

Mean age was 53 years and 74.1% were men. Tibia (62.1%) and S. aureus (58.5%) were the most commonly involved bone and bacteria, respectively. Mean follow-up was 67.1 months. Forty-six patients underwent bone debridement, 61 debridement plus flap coverage and 9 antimicrobial therapy only. Twenty-six patients (22.4%) relapsed, at a mean of 11.2 months since hospital discharge. Duration > 3 months (p = 0.025), number of severity factors (P = 0.02) and absence of surgery (P = 0.004) were associated with osteomyelitis relapse in the univariate analysis. In the Cox regression analysis, osteomyelitis duration > 3 months (P = 0.012), bone exposure (P = 0.0003) and type of surgery (P < 0.0001) were associated with relapse. Regarding the surgical modalities, bone debridement with muscle flap was associated with better osteomyelitis outcomes, as compared with no surgery (P < 0.0001) and debridement only (P = 0.004).

Conclusions

Osteomyelitis extending for > 3 months, bone exposure and treatment other than surgical debridement with muscular flap are risk factors for osteomyelitis relapse.

Individual variation is the key to the development of a vaccine against Staphylococcus aureus: a comparative study between mice lineages

Bacterial infections occur worldwide and are a major public health problem. Among pathogens, Staphylococcus aureus is the main causative agent of bacterial diseases in the world. This study aimed to evaluate which components of the immune system could act protectively against a S. aureus infection in intradermally immunized mice. C57BL/6 and A/j mice were immunized intradermally with S. aureus inactivated by heat and then challenged with viable strains in an air pouch model. At 6, 12, and 24 h after the challenge, euthanasia was performed, and the cellular profile of the inflammatory infiltrate, cytokines, and the bacterial load were evaluated in the air pouch lavages. Immunized mice demonstrated that the intradermal immunization with S. aureus promoted protection in C57BL/6 mice by reducing the bacterial, which was correlated with increased serum concentration of IgG antibodies (IgG1 and IgG2a) against S. aureus. The increase in IgG2a antibody levels was correlated with a decrease of bacterial load in intradermally immunized C57BL/6 mice, along with production of IL-17A at the inflammation site, as well as IgG1consumption. Similar results were not found in the A/j lineage. In conclusion, a vaccine against S. aureus should focus more on the individual characteristics of the host because it is a determinant factor for the success of the immunization.

Bacteria antibiotic resistance: New challenges and opportunities for implant-associated orthopedic infections

There has been a dramatic increase in the emergence of antibiotic-resistant bacterial strains, which has made antibiotic choices for infection control increasingly limited and more expensive. In the U.S. alone, antibiotic-resistant bacteria cause at least 2 million infections and 23,000 deaths a year resulting in a $55-70 billion per year economic impact. Antibiotics are critical to the success of surgical procedures including orthopedic prosthetic surgeries, and antibiotic resistance is occurring in nearly all bacteria that infect people, including the most common bacteria that cause orthopedic infections, such as Staphylococcus aureus (S. aureus). Most clinical cases of orthopedic surgeries have shown that patients infected with antibiotic-resistant bacteria, such as methicillin-resistant S. aureus (MRSA), are associated with increased morbidity and mortality. This paper reviews the severity of antibiotic resistance at the global scale, the consequences of antibiotic resistance, and the pathways bacteria used to develop antibiotic resistance. It highlights the opportunities and challenges in limiting antibiotic resistance through approaches like the development of novel, non-drug approaches to reduce bacteria functions related to orthopedic implant-associated infections. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:22-32, 2018.

Pyogenic Vertebral Osteomyelitis: Clinical Features, Diagnosis, and Treatment

Pyogenic vertebral osteomyelitis (PVO) may result in neurological deficits and sequelae, so early diagnosis and appropriate treatment are critical. Many previous studies on PVO exist, but our paper has aimed to comprehensively summarize the clinical aspects of PVO. Through review of the vast literature on the clinical research of PVO an overview of the clinical characteristics, diagnostic methods, treatment and prognosis is provided.

The role of biofilms in persistent infections and factors involved in ica-independent biofilm development and gene regulation in Staphylococcus aureus

Staphylococcus aureus biofilms represent a unique micro-environment that directly contribute to the bacterial fitness within hospital settings. The accumulation of this structure on implanted medical devices has frequently caused the development of persistent and chronic S. aureus-associated infections, which represent an important social and economic burden worldwide. ica-independent biofilms are composed of an assortment of bacterial products and modulated by a multifaceted and overlapping regulatory network; therefore, biofilm composition can vary among S. aureus strains. In the microniches formed by biofilms-produced by a number of bacterial species and composed by different structural components-drug refractory cell subpopulations with distinct physiological characteristics can emerge and result in therapeutic failures in patients with recalcitrant bacterial infections. In this review, we highlight the importance of biofilms in the development of persistence and chronicity in some S. aureus diseases, the main molecules associated with ica-independent biofilm development and the regulatory mechanisms that modulate ica-independent biofilm production, accumulation, and dispersion.

Clinical features, outcomes, and survival factor in patients with vertebral osteomyelitis infected by methicillin-resistant staphylococci

PURPOSE

To elucidate clinico-radiological features, therapeutic outcomes, and survival factors of vertebral osteomyelitis patients infected by methicillin-resistant staphylococci (MRS).

METHODS

Vertebral osteomyelitis patients admitted to the orthopaedic department between 2007 and 2011 (n = 248) were selected for this multicenter study. We compared patients' backgrounds, therapeutic course, and in-hospital mortality between MRS and methicillin-susceptible staphylococci (MSS). We also examined survival factors of vertebral osteomyelitis due to MRS.

RESULTS

Sixteen patients of MRS vertebral osteomyelitis and 55 patients of MSS were included in this study. In MRS vertebral osteomyelitis, the rates of comorbid diabetes mellitus, involvement of >2 vertebral bodies, in-hospital mortality, and operation of surgical debridement were higher compared to those in MSS vertebral osteomyelitis. Univariate analysis showed that operation of surgical debridement was a factor related to survival in MRS patients.

CONCLUSIONS

Higher rate of comorbid diabetes mellitus, involvement of >2 vertebral bodies, in-hospital mortality, and performing surgical debridement are peculiar features of MRS vertebral osteomyelitis compared to MSS vertebral osteomyelitis. If patients with MRS vertebral osteomyelitis respond poorly to antibiotic therapy, it might be better to consider surgical debridement not to lose an opportunity of operation due to exacerbation of systemic conditions.

Vertebral osteomyelitis in adults: an update

INTRODUCTION

The incidence of vertebral osteomyelitis is increasing, attributed to an ageing population with inherent co-morbidities and improved case ascertainment.

SOURCES OF DATA

References were retrieved from the PubMed database using the terms 'vertebral osteomyelitis' and 'spondylodiscitis' between January 1, 2009 and April 30, 2014 published in English as checked in May 2014 (>1000 abstracts checked).

AREAS OF AGREEMENT

Blood cultures and whole spine imaging with magnetic resonance imaging are essential investigations. Thorough debridement is the mainstay of surgical management, although placing metalwork in active infection is becoming increasingly common.

AREAS OF CONTROVERSY

The extent of pursuing spinal biopsies to determine aetiology, antimicrobial choices and duration, monitoring the response to treatment, and surgical techniques and timing all vary widely in clinical practice with heterogeneous studies limiting comparisons. Surgery, rather than conservative approaches, is being proposed as the default management choice, because it can, in carefully selected patients, offer faster reduction in pain scores and improved quality of life.

AREAS TIMELY FOR DEVELOPING RESEARCH

Further studies are needed to define the most effective technique for spinal biopsies to maximize determining aetiology. High-quality trials are required to provide an evidence base for both the medical and surgical management of vertebral osteomyelitis, including challenging medical management as the default option.

Susceptibility Pattern of Microorganisms Isolated by Percutaneous Needle Biopsy in Nonbacteremic Pyogenic Vertebral Osteomyelitis

Pyogenic vertebral osteomyelitis (VO) is diagnosed according to several lines of evidence: clinical, biological, radiological, and histological. Definitive diagnosis requires the isolation of a causative pathogen or histological confirmation. The aim of our study was to describe the microorganisms isolated by percutaneous needle biopsy (PNB) and to analyze their susceptibility patterns, in order to assess the possibility of empirical combination therapy for the treatment of nonbacteremic patients without resorting to PNB. Based on a French prospective multicenter study of 351 patients with VO, we compiled clinical, biological, and radiological findings for 101 patients with microbiologically confirmed VO. Based on antibiotic susceptibility testing of PNB isolated pathogens, the suitabilities of four antibiotic combinations were analyzed: ofloxacin plus rifampin, levofloxacin plus rifampin, ciprofloxacin plus clindamycin, and ciprofloxacin plus amoxicillin-clavulanate. The main causative pathogens identified were coagulase-negative Staphylococcus spp. (26% of isolates), followed by Staphylococcus aureus (21%), Streptoccocus spp. (13%), and enterobacteria (21%). Empirical antibiotic combination therapy was effective in nearly 75% of cases, and the different combinations gave similar results, except for ofloxacin-rifampin, which was effective in only 58% of cases. A "perfect" empirical antibiotic therapy does not exist. If PNB is not possible, a combination of a fluoroquinolone with clindamycin or rifampin can be used, but the high risk of microbiological failure does not allow the exclusion of PNB. (This study has been registered with EudraCT, number 2006-000951-18, and ClinicalTrials.gov, number NCT00764114.).

Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management

Staphylococcus aureus is a major human pathogen that causes a wide range of clinical infections. It is a leading cause of bacteremia and infective endocarditis as well as osteoarticular, skin and soft tissue, pleuropulmonary, and device-related infections. This review comprehensively covers the epidemiology, pathophysiology, clinical manifestations, and management of each of these clinical entities. The past 2 decades have witnessed two clear shifts in the epidemiology of S. aureus infections: first, a growing number of health care-associated infections, particularly seen in infective endocarditis and prosthetic device infections, and second, an epidemic of community-associated skin and soft tissue infections driven by strains with certain virulence factors and resistance to β-lactam antibiotics. In reviewing the literature to support management strategies for these clinical manifestations, we also highlight the paucity of high-quality evidence for many key clinical questions.

Antibiotic treatment for 6 weeks versus 12 weeks in patients with pyogenic vertebral osteomyelitis: an open-label, non-inferiority, randomised, controlled trial

BACKGROUND

Duration of treatment for patients with vertebral osteomyelitis is mainly based on expert recommendation rather than evidence. We aimed to establish whether 6 weeks of antibiotic treatment is non-inferior to 12 weeks in patients with pyogenic vertebral osteomyelitis.

METHODS

In this open-label, non-inferiority, randomised controlled trial, we enrolled patients aged 18 years or older with microbiologically confirmed pyogenic vertebral osteomyelitis and typical radiological features from 71 medical care centres across France. Patients were randomly assigned to either 6 weeks or 12 weeks of antibiotic treatment (physician's choice in accordance with French guidelines) by a computer-generated randomisation list of permuted blocks, stratified by centre. The primary endpoint was the proportion of patients who were classified as cured at 1 year by a masked independent validation committee, analysed by intention to treat. Non-inferiority would be declared if the proportion of cured patients assigned to 6 weeks of treatment was not less than the proportion of cured patients assigned to 12 weeks of treatment, within statistical variability, by an absolute margin of 10%. This trial is registered with EudraCT, number 2006-000951-18, and Clinical Trials.gov, number NCT00764114.

FINDINGS

Between Nov 15, 2006, and March 15, 2011, 359 patients were randomly assigned, of whom six in the 6-week group and two in the 12-week group were excluded after randomisation. 176 patients assigned to the 6-week treatment regimen and 175 to the 12-week treatment regimen were analysed by intention to treat. 160 (90·9%) of 176 patients in the 6-week group and 159 (90·9%) of 175 of those in the 12-week group met the criteria for clinical cure. The difference between the groups (0·05%, 95% CI -6·2 to 6·3) showed the non-inferiority of the 6-week regimen when compared with the 12-week regimen. 50 patients in the 6-week group and 51 in the 12-week group had adverse events, the most common being death (14 [8%] in the 6-week group vs 12 [7%] in the 12-week group), antibiotic intolerance (12 [7%] vs 9 [5%]), cardiorespiratory failure (7 [4%] vs 12 [7%]), and neurological complications (7 [4%] vs 3 [2%]).

INTERPRETATION

6 weeks of antibiotic treatment is not inferior to 12 weeks of antibiotic treatment with respect to the proportion of patients with pyogenic vertebral osteomyelitis cured at 1 year, which suggests that the standard antibiotic treatment duration for patients with this disease could be reduced to 6 weeks.

FUNDING

French Ministry of Health.

Therapeutic outcomes of hematogenous vertebral osteomyelitis with instrumented surgery

BACKGROUND

Patients with hematogenous vertebral osteomyelitis (HVO) occasionally require instrumentation for spinal stabilization. However, placing instrumentation in the setting of spinal infection raises concerns about recurrent infection due to bacteria adhering to the foreign material. In this study, we evaluated the therapeutic outcomes of patients with HVO who underwent instrumented surgery.

METHODS

We conducted a retrospective chart review of adult patients with microbiologically diagnosed HVO who underwent surgical intervention in 5 tertiary care hospitals over an 8-year period.

RESULTS

A total of 153 patients with HVO underwent surgical management for their infections. Of these 153 patients, 94 (61.4%) underwent surgical debridement alone (noninstrumented surgery) and 59 (38.6%) underwent surgical debridement and instrumentation (instrumented surgery). The median durations of antibiotic therapy were 66 and 80 days for the noninstrumentation and instrumentation groups, respectively (P = .22). Clinical outcomes were similar between the groups, including rates of infection-related death (2.1% vs 0%; P = .52), primary failure (1.1% vs 5.1%; P = .30), and recurrence (4.8% vs 6.8%; P = .72). Among the instrumentation group, there was a significant decreasing trend for recurrence according to total duration of antibiotic therapy: 22.2% (4-6 weeks), 9.1% (6-8 weeks), and 2.6% (≥ 8 weeks; P = .04). Duration of pre-instrumentation antibiotic therapy and single-stage operation (vs 2-stage operation) were not risk factors for recurrence.

CONCLUSIONS

Spinal instrumentation in patients with HVO may be safe with pathogen-directed prolonged antibiotic therapy and should not be abandoned or delayed solely because of the risk of recurrence.