Infected osteoradionecrosis of the mandible: follow-up study suggests deterioration in outcome for patients with Actinomyces-positive bone biopsies

Mandibular Osteoradionecrosis: Defining the Microbial Milieu and Antimicrobial Resistance at the Time of Rescue Flap Surgery

OBJECTIVE

To report the microorganisms and their antibiotic sensitivity profile from tissue cultures and stains at the time of anterolateral thigh fascia lata (ALTFL) rescue flap for management of mandibular osteoradionecrosis (ORN).

METHODS

Retrospective chart review of patients who underwent ALTFL rescue flap for native mandibular ORN between 2011 and 2022.

RESULTS

Twenty-six cases comprising 24 patients (mean age 65.4 years, 65.4% male) with mandibular ORN from whom tissue cultures and gram stain were obtained at the time of ALTFL rescue flap. 57.7% grew bacterial species, while 34.6% grew fungal species. Multibacterial speciation was noted in 26.9% of cultures. A combination of bacterial and fungal growth was also seen in 15.4% of cases. All gram-positive cocci (GPC) were pansensitive to antibiotics except for one case of Staphylococcus aureus, which was resistant to levofloxacin. Gram-negative bacilli (GNB) species were isolated in 50.0% of cases. All fungal growth was due to Candida species. No growth was noted in 23.1% of cases. Multidrug resistance was noted in 53.8% of cases when GNB was isolated.

CONCLUSION

We report 76.9% of our cases of mandibular ORN had microbial growth from tissue cultures obtained at the time of the ALTFL rescue flap. Fungal growth was noted in a substantial number of cases and should be obtained as a specimen when pursuing culture-driven antibiotic therapy. Most GPCs were pansensitive to antibiotics, while GNBs were often the harbinger of multidrug resistant mandibular ORN.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:166-169, 2024.

Bacterial spectrum analysis and antimicrobial susceptibility study of osteoradionecrosis of the jaw in Southern China

OBJECTIVE

Osteoradionecrosis of the jaw (ORNJ) is one of the most common and serious complications after radiotherapy of head and neck malignancies due to the high incidence of nasopharyngeal cancer in Southern China. Clinicians lack understanding and consensus on anti-infective treatment in ORNJ lesions. This research aims to provide evidence for rational use of antibiotics by reviewing the bacterial spectrums and antimicrobial susceptibility test of ORNJ patients.

METHODS

We collected patient who was diagnosed with ORNJ from November 2012 to June 2019 in our hospital. Exudate or bone unexposed wound surface sampling, agar plates culturing, and susceptibility testing were analyzed. Descriptive statistics were used for data presentation.

RESULTS

A total of 219 samples were collected in our retrospective study. The most common cultured bacteria were Klebsiella pneumoniae (15.10%), Pseudomonas aeruginosa (13.54%), and Staphylococcus aureus (10.94%). Methicillin-resistant Staphylococcus aureus (MRSA) accounted for 5.21% in the whole positive samples. Ticarcillin, Ofloxacin, Vancomycin, Tigecycline, and Meropenem were more susceptible than other antibiotics to treat uncontrollable infection.

CONCLUSIONS

Our research provided objective evidence for understanding the types of local bacterial flora and drug susceptibility in ORNJ lesions and gave a guiding reference for empirical antibiotics medication.

Actinomyces and related organisms in human infections

Actinomyces israelii has long been recognized as a causative agent of actinomycosis. During the past 3 decades, a large number of novel Actinomyces species have been described. Their detection and identification in clinical microbiology laboratories and recognition as pathogens in clinical settings can be challenging. With the introduction of advanced molecular methods, knowledge about their clinical relevance is gradually increasing, and the spectrum of diseases associated with Actinomyces and Actinomyces-like organisms is widening accordingly; for example, Actinomyces meyeri, Actinomyces neuii, and Actinomyces turicensis as well as Actinotignum (formerly Actinobaculum) schaalii are emerging as important causes of specific infections at various body sites. In the present review, we have gathered this information to provide a comprehensive and microbiologically consistent overview of the significance of Actinomyces and some closely related taxa in human infections.

Oxidative stress in bisphosphonate-related osteonecrosis of the jaws

OBJECTIVES

To analyze whether oxidative stress (OS) changes are present in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ) versus controls.

MATERIALS AND METHODS

Oxidative stress was analyzed in serum and unstimulated saliva of three groups: Group 1 consisted of 24 patients who had been treated with intravenous bisphosphonates (ivBPs) and developed BRONJ, group 2 consisted of 20 patients who had received ivBPs and did not develop BRONJ, and group 3 comprised 17 control subjects. Reduced glutathione (GSH), malondialdehyde (MDA), oxidized glutathione (GSSG), and 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxo-dG) levels, as well as the GSSG/GSH ratio, were measured.

RESULTS

Mean serum and saliva levels of MDA, GSSG, and 8-oxo-dG and the GSSG/GSH ratio were significantly higher in patients with BRONJ than in controls. We found no significant difference in OS according to BRONJ stage, sex, or location in the jaws. Logistic regression analysis revealed that the GSSG/GSH ratio was a significant factor predicting the development of BRONJ (P = 0.01).

CONCLUSIONS

Oxidative stress was detected in patients with BRONJ, and the GSSG/GSH ratio was the most significant OS variable found; it was a significant factor predicting the development of BRONJ.

Histological findings on jaw osteonecrosis associated with bisphosphonates (BONJ) or with radiotherapy (ORN) in humans

OBJECTIVE

To describe the histological features of bone tissue harvested from patients affected by jaw osteonecrosis associated with bisphoshponates (BONJ) or with radiotherapy (ORN), in undecalcified ground sections.

MATERIALS AND METHODS

Sixteen bone tissue samples from 14 patients with BONJ and two patients with ORN were processed in order to obtain both ground, undecalcified sections and decalcified sections. The sections underwent histometric and morphometric analysis.

RESULTS

Bone tissue samples obtained from patients with BONJ or ORN of the jaws shared some histological characteristics. Common histological features included the loss of bone architecture, the absence of a proper Haversian system and proper marrow spaces, the presence of necrotic spots of non-mineralized tissue, areas of empty osteocytic lacunae next to areas of hypercellularity, the presence of resorption pits with rare osteoclast-like cells and the presence of bacteria and of an inflammatory infiltrate. A violet rib of tissue characterized by large resorption pits facing was frequently observed between the mineralized bone and the inflammatory infiltrate.

CONCLUSIONS

The histological features of BONJ and ORN are similar and resemble those of osteomyelitis. Even though it is not clear whether infection is the cause or consequence of bone exposure, inflammatory cells, bacteria or their products may have a massive, direct lytic effect on bone tissue challenged by bisphosphonates.

In vitro bactericidal effect of Nd:YAG laser on Actinomyces israelii

A bactericidal effect has been reported by the use of near-infrared laser light on both Gram-positive and Gram-negative bacteria. The aim of this study was to evaluate the effect of Nd:YAG laser on Actinomyces israelii, filamentous bacteria causing cervicofacial actinomycosis. Experiments were realized on bacterial cells in saline suspension or streaked on Mueller-Hinton (MH) agar plates with or without India ink. Laser application was performed in Eppendorf tubes with different powers and frequencies for 40 s; bacterial suspensions were then streaked on agar plates and incubated at 35 °C in proper conditions for 5 days before colony enumeration. A reduction of colony number variable from 60.13 to 100 % for powers of 2, 4, and 6 W at 25-50 Hz of frequency was observed in comparison with growth control. For agar plates, laser application was performed with different powers at 50 Hz for 60 s. A growth inhibition was observed after 5 days of incubation on MH plates with powers of 6 W and on MH-ink plates with all applied powers. This preliminary study showed a bactericidal effect caused by Nd:YAG laser application worthy to be evaluated in further experiments in vivo.

Osteoradionecrosis contains a wide variety of cultivable and non-cultivable bacteria

Background

Direct microscopy, anaerobic culture and DNA–DNA hybridization have previously demonstrated an association between microorganisms and osteoradionecrosis (ORN). The purpose of our study was to use culture independent molecular techniques to detect bacteria in necrotic bone lesions of the mandible after radiation therapy.

Design

Bacterial DNA was extracted from eight deep medullar specimens from resected mandibles (six cases), including one patient with relapse. 16S rRNA genes were PCR amplified, cloned, transformed into Escherichia coli and sequenced to determine species identity and closest relatives.

Results

From the analysis of 438 clones, 59 predominant species were detected, 27% of which have not been cultivated. The predominant species detected from radionecrotic mandibles were Campylobacter gracilis, Streptococcus intermedius, Peptostreptococcus sp. oral clone FG014, uncultured bacterium clone RL178, Fusobacterium nucleatum, and Prevotella spp. The study demonstrated intersubject variability of the bacteria present in ORN. In contrast to the diverse bacterial profile detected in primary infection, only a few members of the oral indigenous flora were identified from the relapse case.

Conclusions

Diverse bacterial profiles in specimens of ORN in marrow spaces of the mandible were detected by culture independent molecular techniques. To better understand the pathogenesis and to improve the therapy of the infection, detection of all members of the complex bacterial flora associated with ORN is necessary.

The clinical spectrum of Actinomyces-associated lesions of the oral mucosa and jawbones: correlations with histomorphometric analysis

OBJECTIVES

To characterize the clinical manifestations of Actinomyces-associated lesions of the oral mucosa and jawbones, and to correlate the clinical course and treatment requirements with the findings of histomorphometric analysis.

STUDY DESIGN

The study was a 10-year retrospective analysis of archived cases with microscopic identification of Actinomyces infection. Actinomyces colonies were identified, using hematoxylin-eosin, Gram, and periodic acid-Schiff stains, exhibiting filamentous morphology with color variation between center and periphery. Only colonies with adjacent tissue reaction (inflammation, fibrosis) were analyzed. Actinomyces density (AD) was calculated by dividing total number of colonies by tissue surface, Actinomyces relative surface (ARS) was calculated by dividing total bacterial surface by tissue surface.

RESULTS

The study included 106 cases (48 male, 58 female; aged 13-84 years, mean 50.5 years). Cases presented a wide clinical spectrum, involving jawbone and/or oral soft tissues. Cases included osteomyelitis associated with bisphosphonates, osteoradionecrosis, osteomyelitis unrelated to radiation or bisphosphonates, periapical lesions, odontogenic cysts, periimplantitis, and lesion mimicking periodontal disease. The AD correlated with median length of antibiotic treatment (R = 0.284; P = .028).

CONCLUSIONS

Because we were able to identify 106 such cases, the results indicate that Actinomyces-associated lesions may not be as rare as would be expected from the relatively low number of cases in the literature. Actinomyces-associated lesions presented in a wide spectrum of clinical settings and a variety of contributing factors. Quantitative analysis of the number of bacterial colonies (representing bacterial load) could help in evaluating the aggressive potential of the lesion and help in treatment planning.

Importance of microcracks in etiology of bisphosphonate-related osteonecrosis of the jaw: a possible pathogenetic model of symptomatic and non-symptomatic osteonecrosis of the jaw based on scanning electron microscopy findings

The aim of this study was to evaluate a possible role of microcracks in the pathogenesis of bisphosphonate-related osteonecrosis of the jaw (ONJ) and to discuss an etiological model. Bone samples from 35 patients with ONJ were analyzed. Control samples were taken from five patients with osteomyelitis (OM), ten patients with osteoradionecrosis, seven patients with osteoporosis and bisphosphonate medication without signs of ONJ, and six osteoporotic elderly patients. Samples were examined using scanning electron microscopy. In 54% of the bone samples of patients with ONJ, microcracks were seen. Inflammatory and connective tissue reactions within the microcracks were evident in 82% of the cases, indicating that these cracks were not artificial. In contrast, only 29% of samples from patients with oral bisphosphonate medication without ONJ, no sample from patients with OM, none of the osteoradionecrosis group, and only 17% from patients with osteoporosis showed microcracks. Statistically significant differences could be found between the ONJ group and the group after irradiation and the group with OM, respectively. The evidence of microcracks could be a first step in the pathogenesis of bisphosphonate-related ONJ. The accumulation of these microcracks leads to a situation that could be named "non-symptomatic ONJ". Disruptions of the mucosal integrity may then allow bacterial invasion, leading to jawbone infection with exposed bone, fistulas, and pain. This state could be called "symptomatic ONJ". Furthermore, an assumed local immunosuppression as indicated by various studies could explain the severe courses of therapy-resistant ONJ as regularly observed.

Actinomyces--gathering evidence of human colonization and infection

The roles of the 'classical'Actinomyces spp. as colonizers of oral cavities of man and animals, in development of intra-oral infections and as agents of actinomycosis have been well documented. This mini-review focuses on perceptions of human colonization and infection that have emerged in the past decade, largely as a result of advances in classification, identification and direct detection from clinical material. Arguably, of the greatest importance is the recognition of actinomycosis as a major factor and indicator of poor prognosis in both infected osteoradionecrosis and bisphosphonate-associated osteonecrosis of the jaws. Among recently described species, Actinomyces graevenitzii has been isolated almost exclusively from oral and respiratory sites and may be a causative agent of actinomycosis. Conversely, several other Actinomyces spp. are isolated commonly from superficial soft tissue infections. Members of the genus Actinobaculum, which is closely related to Actinomyces, are strongly associated with urosepsis. Isolation and identification of Actinomyces and related genera by conventional methods remain difficult. Diagnosis is commonly belated and based solely upon histological findings. Development of direct detection methods may aid patient management and further elucidate clinical associations.