Oro-facial gangrene (noma/cancrum oris): pathogenetic mechanisms

Ultrastructural and glycoproteomic characterization of Prevotella intermedia: Insights into O-glycosylation and outer membrane vesicles

Prevotella intermedia, a Gram-negative bacterium from the Bacteroidota phylum, is associated with periodontitis. Other species within this phylum are known to possess the general O-glycosylation system. The O-glycoproteome has been characterized in several species, including Tannerella forsythia, Porphyromonas gingivalis, and Flavobacterium johnsoniae. In our study, we used electron cryotomography (cryoET) and glycoproteomics to reveal the ultrastructure of P. intermedia and characterize its O-glycoproteome. Our cryoET analysis unveiled the ultrastructural details of the cell envelope and outer membrane vesicles (OMVs) of P. intermedia. We observed an electron-dense surface layer surrounding both cells and OMVs. The OMVs were often large (>200 nm) and presented two types, with lumens being either electron-dense or translucent. LC-MS/MS analyses of P. intermedia fractions led to the identification of 1655 proteins, which included 62 predicted T9SS cargo proteins. Within the glycoproteome, we identified 443 unique O-glycosylation sites within 224 glycoproteins. Interestingly, the O-glycosylation motif exhibited a broader range than reported in other species, with O-glycosylation found at D(S/T)(A/I/L/M/T/V/S/C/G/F/N/E/Q/D/P). We identified a single O-glycan with a delta mass of 1531.48 Da. Its sequence was determined by MS2 and MS3 analyses using both collision-induced dissociation and high-energy collisional dissociation fragmentation modes. After partial deglycosylation with trifluoromethanesulfonic acid, the O-glycan sequence was confirmed to be dHex-dHex-HexNAc (HPO3 -C6 H12 O5 )-dHex-Hex-HexA-Hex(dHex). Bioinformatic analyses predicted the localization of O-glycoproteins, with 73 periplasmic proteins, 53 inner membrane proteins, 52 lipoproteins, 26 outer membrane proteins, and 14 proteins secreted by the T9SS.

Retrospective Characterization of Noma Cases Found Incidentally across Nigeria during Outreach Programs for Cleft Lip from 2011-2020

Reports of cases of noma in Nigeria remain scarce despite its known and devastating effects on victims. This report presents a retrospective cross-sectional study based on data regarding on patients with noma encountered incidentally during Oral Health Advocacy Initiative outreach on orofacial diseases across 34 states and the Federal Capital Territory in Nigeria over 10 years (2011-2020), which was aimed at contributing to an understanding of the epidemiology of noma in Nigeria. The data were collated and analyzed, and are presented in frequency distribution tables and charts. A total of 7,195 patients with noma were encountered. The northeastern region had the greatest number of patients (n = 1,785, 24.8%) whereas the southwestern region had the least (n = 196, 2.7%). When aggregated by state, Ondo State had the least number of patients (n = 31, 0.4%) whereas Kano State had the greatest (n = 623, 8.7%). Patient age ranged from 3 to 70 years, with a slight male preponderance (56.9%). This report highlights the fact that noma is prevalent in Nigeria but remains neglected, with extensive but preventable physical, emotional, and social debilitation and devastation of the victims across all age groups. There is a need for a more robust survey to determine the true burden of the disease. There is also an urgent need for collaboration between governments and nongovernmental organizations to institute appropriate interventions by way of public education and enlightenment, as well as case detection and early treatment to mitigate the devastating consequences of delayed or poorly managed cases.

A Web of Science-Based Bibliometric Analysis of Global Noma Publications

The World Health Organization recognizes noma as a global health problem and has suggested prioritizing research into this disease. A bibliographic search of original articles published in the Web of Science database up to 2022 was performed. A bibliometric analysis was carried out with the bibliometrix package in R and VOSviewer. We identified 251 articles published in 130 journals. The first publication was in 1975, the highest number of publications was in 2003, and the average number of citations per document was 12.59. The author with the highest number of publications was Enwonwu CO, and the Noma Children's Hospital had the highest number of articles on this topic. Plastic and Reconstructive Surgery was the journal with the most publications, and the study by Petersen PE was the most cited. The country of corresponding authors that had the most publications and the most significant number of total citations was the United States. "Children" and "Reconstruction" were the most used keywords. In conclusion, there are few publications on noma worldwide, confirming the neglected status of this disease. Urgent actions are needed to increase evidence in regard to the epidemiology of noma and public health interventions to mitigate the ravages of this disease.

Insertional Inactivation and Gene Complementation of Prevotella intermedia Type IX Secretion System Reveals Its Indispensable Roles in Black Pigmentation, Hemagglutination, Protease Activity of Interpain A, and Biofilm Formation

Prevotella intermedia, a Gram-negative oral anaerobic bacterium, is frequently isolated from the periodontal pockets of patients with chronic periodontitis. In recent years, the involvement of the bacterium in respiratory tract infections as well as in oral infections has been revealed. P. intermedia possesses several potent virulence factors, such as cysteine proteinase interpain A encoded by the inpA gene. The genome of P. intermedia carries genes of the type IX secretion system (T9SS), which enables the translocation of virulence factors across the outer membrane in several pathogens belonging to the phylum Bacteroidetes; however, it is still unclear whether the T9SS is functional in this microorganism. Recently, we performed targeted mutagenesis in the strain OMA14 of P. intermedia. Here, we successfully obtained mutants deficient in inpA and the T9SS component genes porK and porT. None of the mutants exhibited protease activity of interpain A. The porK and porT mutants, but not the inpA mutant, showed defects in colony pigmentation, hemagglutination, and biofilm formation. We also obtained a complemented strain for the porK gene that recovered all the above abilities. These results indicate that T9SS functions in P. intermedia and that interpain A is one of the T9SS cargo proteins. IMPORTANCE The virulence factors of periodontal pathogens such as Prevotella intermedia have not been elucidated. Using our established procedure, we succeeded in generating type IX secretion system mutants and gene complementation strains that might transfer virulence factors to the bacterial surface. The generated strains clearly indicate that T9SS in P. intermedia is essential for colonial pigmentation, hemagglutination, and biofilm formation. These results indicated that interpain A is a T9SS cargo protein.

Noma: A Neglected Area for Research

Noma, a debilitating and destructive orofacial gangrene, remains endemic in the poor countries of sub-Saharan Africa and other noma hotbeds across the globe, mainly in countries characterized as underdeveloped economies with significant impoverished populations. Noma mostly affects children and infants. This is in spite of the universally held notion that noma is a preventable disease. Indeed, the current noma status quo has been cast as a human rights shortfall, since this devasting disease overwhelmingly affects children from poor countries. At the recently held Noma Research Day, a renewed call for the World Health Organization (WHO) to recognize and include noma as one of the neglected tropical diseases was accompanied by a recognition that research into all aspects of noma has waned or remained completely lacking-particularly that which addresses the basic science questions of the etiology, pathophysiology/pathobiology, and underlying mechanisms of the disease. Yet, a lack of incremental knowledge on the various aspects of noma continues to hamper our composite understanding of its biology. Without a fundamental understanding of the biology of noma, current preventive measures and treatment modalities will continue to fall short of the goals of prevention and eradication. This opinion piece draws renewed attention to the urgency of listing noma as a neglected tropical disease by the WHO. It also calls for major international research funding agencies, including the WHO and the National Institutes of Health, to renew their resolve to robustly fund structured, collaborative, and coordinated proposals that address questions on the epidemiology, etiology, pathophysiology/pathobiology, and molecular mechanisms of the disease. This is with a view to achieving more effective public health approaches toward prevention and to designing potential therapeutic regimens for early lesions. These steps are key to the ultimate eradication of noma.

Noma – a neglected disease of malnutrition and poor oral hygiene: A mini-review

Objectives:

The aim of this review was to describe malnutrition and poor oral hygiene, the most common risk factors for noma.

Methods:

A vigorous literature searches were conducted on databases such as Scopus, Elsevier, Web of Science, PubMed, Virtual Health Library, and Google Scholar by inserting keywords such as ‘noma’ OR ‘cancrum oris’ OR ‘cancrum oris cases’. A total of 65 articles gathered. Of these, 38 articles found to be eligible for this study.

Results:

A total of 38 full-length articles were included in the review. According to the evidence gathered and summarized in this review, malnutrition, especially protein-energy malnutrition and vitamin deficiencies, makes the oral mucosa susceptible to opportunistic pathogens of noma, and then, in so doing, pathogens invade the oral cavities. Malnutrition has a bidirectional relationship with noma. Since noma is a disease of the oral cavity, poor oral hygiene has the potential of predispose and worsen the disease’s progress.

Conclusion:

Malnutrition and poor oral hygiene found to be ingrained in the pathogenesis of noma. For effective management and prevention of noma, it is necessary to underpin adequate nutritional supplementation (including vitamins). As a primary prevention strategy, healthcare workers’ training should be strengthened to improve the diagnosis and treatment of oral infections, including noma.

Proteomic analysis of the periodontal pathogen Prevotella intermedia secretomes in biofilm and planktonic lifestyles

Prevotella intermedia is an important species associated with periodontitis. Despite the remarkable clinical significance, little is known about the molecular basis for its virulence. The aim of this study was to characterize the secretome of P. intermedia in biofilm and planktonic life mode. The biofilm secretome showed 109 proteins while the planktonic secretome showed 136 proteins. The biofilm and the planktonic secretomes contained 17 and 33 signal-peptide bearing proteins, 13 and 18 lipoproteins, respectively. Superoxide reductase, sensor histidine kinase, C40 family peptidase, elongation factor Tu, threonine synthase etc. were unique to biofilm. Of the ~ 30 proteins with predicted virulence potential from biofilm and planktonic secretomes, only 6 were common between the two groups, implying large differences between biofilm and planktonic modes of P. intermedia. From Gene Ontology biofilm secretome displayed a markedly higher percent proteins compared to planktonic secretome in terms of cellular amino acid metabolic process, nitrogen compound metabolic process etc. Inflammatory cytokine profile analysis revealed that only the biofilm secretome, not the planktonic one, induced important cytokines such as MIP-1α/MIP-1β, IL-1β, and IL-8. In conclusion, the revealed differences in the protein profiles of P. intermedia biofilm and planktonic secretomes may trigger further questions about molecular mechanisms how this species exerts its virulence potential in the oral cavity.

Is Blood Transfusion Justified During Soft Tissue Surgery in Noma Patients? A One-Year Appraisal at Noma Children Hospital, Sokoto, Nigeria

BACKGROUND

Non-utilization of blood and inappropriate blood transfusion are common in surgical operations. Some surgical procedures are associated with minimal bleeding that does not warrant blood transfusion. No previous study has looked at the pattern of blood loss in noma defect repair to determine the possible need for blood transfusion.

AIM/OBJECTIVES

This study aimed to determine the total amount of blood loss, the number of units of blood transfused, and the correlation between estimated blood loss and total operating time in patients who had surgical correction of noma defects.

MATERIALS AND METHODS

This is a hospital-based cross-sectional study of 35 patients who underwent surgical correction of noma defects. Age, sex, pre- and post-operative haemoglobin (Hb), number of requested blood units, total operating time, and total estimated blood loss were recorded. The methods used for the blood loss estimation were gauze swabs, Abdo-packs, drapes, and suction bottles.

RESULTS

Comparison of the mean pre- and post-operative Hb did not yield any statistically significant difference. The total estimated blood loss in these surgeries was in the range of 65-209 mL, with a mean of 117.20 ± 35.88 mL. No correlation between estimated blood loss and total operating time was noted (P = 0.940). No blood was transfused in any of the subjects.

CONCLUSION

This study observed minimal blood loss in surgical corrections of the soft tissue noma defect. Apart from blood grouping, there may be no need for routine cross-matching of blood pre-operatively for surgical repair of noma defect. However, more studies are needed to buttress this finding.

Noma (cancrum oris): A scoping literature review of a neglected disease (1843 to 2021)

Background

Noma (cancrum oris) is an ancient but neglected and poorly understood preventable disease, afflicting the most disenfranchised populations in the world. It is a devastating and often fatal condition that requires urgent and intensive clinical and surgical care, often difficult to access as most cases of noma occur in resource-limited settings. We conducted a scoping review of the literature published on noma to understand the size and scope of available research on the disease and identify research gaps that need to be addressed to evolve our understanding of how to address this disease.

Methods

We searched 11 databases and collected primary peer reviewed articles on noma in all languages, the final search was conducted on 24^th August 2021. The oldest manuscript identified was from 28^th March 1843 and the most recently published manuscript was from 3^rd June 2021. Search terms included cancrum oris and noma. Data was extracted using a standardised data extraction tool and key areas of interest were identified. The Preferred Reporting Items for Systemic review and Meta-Analyses requirements were followed.

Results

The review included 147 articles, the majority of the studies (n = 94, 64%) were case reports. Most manuscripts (n = 81, 55%) were published in the 2000s, 49 (33%) were from the 1900s and 17 (12%) from the 1800s. The main areas of interest identified were the history and epidemiology of the disease, noma’s clinical progression and aetiology, treatment regimens, mortality rates and the risk factors for the development of noma.

Conclusions

Noma has been reported in the literature for hundreds of years; however important gaps in our understanding of the disease remain. Future research should focus on determining the burden and distribution of disease; the true mortality rate, pathogenic cause(s) and the factors that influence prognosis and outcomes after treatment.

Noma is a devastating and often fatal condition that mainly affects children in severely disenfranchised communities. Noma is preventable and requires urgent basic medical care in the early stages of disease. Once the disease reaches the last stage, sequelae, survivors require expert surgical care, usually difficult to access as most cases of noma occur in resource-limited settings. We conducted a scoping review of the literature published on noma to understand the size and scope of available research on the disease and to identify research priorities that will evolve our understanding of how to eradicate this disease. Our review showed that noma has been reported in the literature for hundreds of years; however several major gaps in knowledge still exist. There is appreciation among the small community of clinicians and researchers involved in noma care and research that these gaps in knowledge impact on the ability to develop and implement sound evidence-based policies and activities aimed at eradicating noma from communities that continue to be afflicted by this ancient disease. The main focus of future research should be to study the burden and distribution of disease; the true mortality rate, and the pathogenic cause(s) and the factors that influence prognosis and outcomes after treatment.

Outcomes at 18 mo of 37 noma (cancrum oris) cases surgically treated at the Noma Children's Hospital, Sokoto, Nigeria

Background

Noma is a rapidly progressing infection of the oral cavity frequently resulting in severe facial disfigurement. We present a case series of noma patients surgically treated in northwest Nigeria.

Methods

A retrospective analysis of routinely collected data (demographics, diagnosis and surgical procedures undergone) and in-person follow-up assessments (anthropometry, mouth opening and quality of life measurements) were conducted with patients who had surgery >6 mo prior to data collection.

Results

Of the 37 patients included, 21 (56.8%) were male and 22 (62.9%) were aged >6 y. The median number of months between last surgery and follow-up was 18 (IQR 13, 25) mo. At admission, the most severely affected anatomical area was the outer cheek (n = 9; 36.0% of patients had lost between 26% and 50%). The most frequent surgical procedures were the deltopectoral flap (n = 16; 43.2%) and trismus release (n = 12; 32.4%). For the eight trismus-release patients where mouth opening was documented at admission, all had a mouth opening of 0–20 mm at follow-up. All patients reported that the surgery had improved their quality of life.

Conclusions

Following their last surgical intervention, noma patients do experience some improvements in their quality of life, but debilitating long-term sequelae persist.

Insertional Inactivation of Prevotella intermedia OxyR Results in Reduced Survival with Oxidative Stress and in the Presence of Host Cells

One of the most abundant bacteria in the subgingival pockets of patients with bleeding following mechanical periodontal therapy is Prevotella intermedia. However, despite its abundance, the molecular mechanisms of its contribution to periodontal disease are not well known. This is mainly due to the lack of genetic tools that would allow examination of the role of predicted virulence factors in the pathogenesis of this bacterium. Here, we report on the first mutant in the P. intermedia OMA14 strain. The mutation is an allelic exchange replacement of the sequences coding for a putative OxyR regulator with ermF sequences coding for the macrolide-lincosamide resistance in anaerobic bacteria. The mutant is severely impaired in its ability to grow with eukaryotic cells, indicating that it is an important target for interventional strategies. Further analyses reveal that its ability to grow with oxidative stress species, in the form of hydrogen peroxide and oxygen, is severely affected. Transcriptome analysis reveals that the major deregulated genes code for the alkylhydroperoxide reductase system, AhpCF, mediating protection from peroxide stress. Moreover, genes coding for Dps, CydA and Ftn are downregulated in the mutant strain, as further verified using qRT-PCR analysis. In conclusion, we succeeded in generating the first P. intermedia mutant and show that the OxyR-deficient strain is unable to survive with a variety of host cells as well as with oxidative stress.

Mycobacterial and Plasmodium ovale-associated destruction of the jaw bones

OBJECTIVES

The project aims were to identify infectious mechanisms responsible for an extreme form of mandibular osteonecrosis and osteomyelitis in West African populations and test the hypothesis that Mycobacterium tuberculosis plays a pivotal role.

MATERIALS AND METHODS

DNA was extracted from mandibular fragments of 9 of 19 patients previously included in a prospective study leading to the mycobacterial hypothesis. Amplified DNAs were used for preparing libraries suitable for next-generation sequencing. For comparison of the whole-genome sequencing data of the 9 patients with DNAs of both microbiota and human tissues, DIAMOND v0.9.26 was used to align sequencing reads to NCBI-nr database and MEGAN 6 for taxonomy binning and identification of Mycobacterium tuberculosis strains.

RESULTS

The data show that mandibular bone fragments of all 9 patients not only contain Homo sapiens and Mycobacterium tuberculosis DNAs; they also contain DNAs of Plasmodium ovale wallikeri, Staphylococcus aureus, Staphylococcus hominis, and Prevotella P3-120/intermedia; as well as large numbers of DNAs from other infectious components.

CONCLUSIONS

The data obtained provide direct evidence to support the conclusion that combinations of Mycobacterium tuberculosis, Plasmodium ovale wallikeri, and other oral bacteria are involved in this particular type of mandibular destruction in West African individuals of many ages.

Facing Africa: Describing Noma in Ethiopia

Noma affects the most marginalized communities in the world, beginning as oral ulceration and rapidly progressing to orofacial gangrene. With a mortality rate estimated to be as high as 90% and with very few able to access treatment in its active phase, very little is understood about the disease. This retrospective review of patients treated by Facing Africa for deformity and functional impairment secondary to noma between May 2015 and 2019 highlights some of the difficulties encountered by those afflicted. Eighty new patients with historical noma defects were identified and were seen over the course of nine surgical missions, with notes providing valuable geographical, socioeconomic, and psychosocial information. The mean self-reported age of onset was 5 years and 8 months, with a median time of 18 years from onset to accessing treatment. Before intervention, 65% covered their face in public, 59% reported difficulty eating, 81% were unhappy with their appearance, and 71% experienced bullying. We aimed at emphasizing the significant burden, both psychologically and physically of noma, demonstrating the disparity between recent decades of progress in the well-being of Ethiopians in general and the access to health care and mental health support for some of those most in need.

Language and beliefs in relation to noma: a qualitative study, northwest Nigeria

Background

Noma is an orofacial gangrene that rapidly disintegrates the tissues of the face. Little is known about noma, as most patients live in underserved and inaccessible regions. We aimed to assess the descriptive language used and beliefs around noma, at the Noma Children’s Hospital in Sokoto, Nigeria. Findings will be used to inform prevention programs.

Methods

Five focus group discussions (FGD) were held with caretakers of patients with noma who were admitted to the hospital at the time of interview, and 12 in-depth interviews (IDI) were held with staff at the hospital. Topic guides used for interviews were adapted to encourage the natural flow of conversation. Emergent codes, patterns and themes were deciphered from the data derived from IDI’s and FGDs.

Results

Our study uncovered two main themes: names, descriptions and explanations for the disease, and risks and consequences of noma. Naming of the disease differed between caretakers and heath care workers. The general names used for noma illustrate the beliefs and social system used to explain the disease. Beliefs were varied; participant responses demonstrate a wide range of understanding of the disease and its causes. Difficulty in accessing care for patients with noma was evident and the findings suggest a variety of actions taking place before reaching a health center or health worker. Patient caretakers mentioned that barriers to care included a lack of knowledge regarding this medical condition, as well as a lack of trust in seeking medical care. Participants in our study spoke of the mental health strain the disease placed on them, particularly due to the stigma that is associated with noma.

Conclusions

Caretaker and practitioner perspectives enhance our understanding of the disease in this context and can be used to improve treatment and prevention programs, and to better understand barriers to accessing health care. Differences in disease naming illustrate the difference in beliefs about the disease. This has an impact on health seeking behaviours, which for noma cases has important ramifications on outcomes, due to the rapid progression of the disease.

Noma (cancrum oris) is an orofacial gangrene that rapidly disintegrates the hard and soft tissues of the face. Little is known about noma as most cases live in underserved and inaccessible regions. We aimed to assess the language used and beliefs around noma, in northwest Nigeria. Findings will be used to inform prevention programs. Five focus group discussions were held with caretakers of patients with noma admitted to the hospital at the time of interview, and 12 in-depth interviews were held with staff at the hospital. Our study uncovered two main themes: names; descriptions and explanations for the disease, and risks and consequences of noma. Naming of the disease differed between caretakers and heath care workers. Difficulty in accessing care for patients with noma was evident. Barriers to care and lack of knowledge and trust were evident. The impact of noma was not limited to physical presentation; stigmatisation was mentioned as a key difficulty. Differences in disease naming illustrate the difference in beliefs and has an impact on health seeking behaviour, which for noma cases, has severe ramifications due to the rapid progression of the disease.

Noma (cancrum oris): An unresolved global challenge

Noma (canrum oris) is a mutilating necrotizing disease of uncertain etiology, but it is accepted that it is caused primarily by a polybacterial infection with secondary ischemia. The consequent necrotizing fasciitis, myonecrosis, and osteonecrosis results in destruction of facial structures with severe functional impairment and disfigurement. It most frequently affects children, particularly in sub‐Saharan Africa, who are malnourished or debilitated by systemic conditions including but not limited to malaria, measles, and tuberculosis; and less frequently debilitated HIV‐seropositive subjects. In the vast majority of cases, in susceptible subjects, noma is preceded by necrotizing stomatitis. However, it has been reported, albeit rarely, that noma can arise without any preceding oral lesions being observed. Noma is not recurrent and is not transmissible.

Pattern of noma (cancrum oris) and its risk factors in Northwestern Nigeria: A hospital-based retrospective study

Background:

Noma (cancrum oris) remains the scourge of children and the “face of poverty” in Sub-Saharan Africa. Recent data on the burden of noma and its risk factors are needed for evaluating and redesigning interventions for its prevention and control.

Objectives:

This study aimed to determine the pattern of noma and its risk factors in Northwestern Nigeria.

Materials and Methods:

It was a retrospective study that looked into cases of noma (cancrum oris) admitted into the Noma Children Hospital, Sokoto, Nigeria, between January 1999 and December 2011. Information on patients’ bio-data, the site and severity of lesions, and presence of trismus and its severity were extracted from the patients’ case files and analyzed using descriptive statistics.

Results:

One hundred and fifty-nine (8.3%) of the 1923 patients admitted to the hospital from January 1999 to December 2011 were diagnosed with fresh noma. The mean age of the patients was 3.0 ± 1.4 years, and majority of them, 139 (87.4%) were aged 1–5 years. The soft-tissue lesions essentially involved multiple sites but most commonly the outer and inner cheeks (84.3%). The most common risk factors identified were measles (47.2%) and protein-energy malnutrition (42.1%). There were rises and falls in the prevalence of noma in the period studied.

Conclusion:

This study showed a high burden of noma in Northwestern Nigeria, mostly among children aged 1–5 years, and with soft-tissue lesions involving multiple sites. Measles and malnutrition were the major risk factors identified, and the disease trend showed a wave-like pattern. There is an urgent need to eliminate the disease in Nigeria through prevention and control of infectious diseases and malnutrition.

Jaw Osteonecrosis Preceded by Dengue Fever - Possible Pathogenetic Mechanism

Introduction:

Osteonecrosis of jaw (ONJ) is a debilitating condition which can lead to compromised dentition. Various causes for ONJ are suggested in the literature such as drugs, trauma, radiation, chemicals, bacterial, and fungal infections. Knowing etiology for particular case of ONJ is important to prevent further progression of this debilitating condition. It is the first case of ONJ reported with dengue virus as a possible etiology.

Case Report:

This article presents a case of 46-year-old male patient with extensive osteonecrosis of maxilla preceded by dengue fever. In the present case, all known causes for osteonecrosis were ruled out. The present article discusses dengue infection as a possible etiologic agent for ONJ.

Conclusion:

In the present case, probable cause for ONJ can be established as a dengue virus necessitating the need for proper preventive methods to avoid further complication of osteonecrosis.

Risk factors for diagnosed noma in northwest Nigeria: A case-control study, 2017

Background

Noma (cancrum oris), a neglected tropical disease, rapidly disintegrates the hard and soft tissue of the face and leads to severe disfiguration and high mortality. The disease is poorly understood. We aimed to estimate risk factors for diagnosed noma to better guide existing prevention and treatment strategies using a case-control study design.

Methods

Cases were patients admitted between May 2015 and June 2016, who were under 15 years of age at reported onset of the disease. Controls were individuals matched to cases by village, age and sex. Caretakers answered the questionnaires. Risk factors for diagnosed noma were estimated by calculating unadjusted and adjusted odds ratios (ORs) and respective 95% confidence intervals (CI) using conditional logistic regression.

Findings

We included 74 cases and 222 controls (both median age 5 (IQR 3, 15)). Five cases (6.5%) and 36 (16.2%) controls had a vaccination card (p = 0.03). Vaccination coverage for polio and measles was below 7% in both groups. The two main reported water sources were a bore hole in the village (cases n = 27, 35.1%; controls n = 63, 28.4%; p = 0.08), and a well in the compound (cases n = 24, 31.2%; controls n = 102, 45.9%; p = 0.08). The adjusted analysis identified potential risk and protective factors for diagnosed noma which need further exploration. These include the potential risk factor of the child being fed pap every day (OR 9.8; CI 1.5, 62.7); and potential protective factors including the mother being the primary caretaker (OR 0.08; CI 0.01, 0.5); the caretaker being married (OR 0.006; CI 0.0006, 0.5) and colostrum being given to the baby (OR 0.4; CI 0.09, 2.09).

Interpretation

This study suggests that social conditions and infant feeding practices are potentially associated with being a diagnosed noma case in northwest Nigeria; these findings warrant further investigation into these factors.

Noma or cancrum oris is an orofacial gangrene that rapidly disintegrates the hard and soft tissue of the face. Little is known about noma as most cases live in underserved, difficult to reach locations. There is a dearth of literature on the risk factors for the development of noma. Médecins Sans Frontières (MSF) in collaboration with the Nigerian Ministry of Health runs projects at the Noma Children’s Hospital in Sokoto. A case control study was conducted in northwest Nigeria to explore exposures associated with diagnosed noma using unadjusted and adjusted conditional logistic regression models. Potential risk and protective factors for diagnosed noma were identified and these findings need further exploration. The study identified that feeding pap to the child every day was a potential risk factor for diagnosed noma (possibly a proxy for poor variety in the diet). The following potential protective factors for diagnosed noma were identified: the mother being the primary caretaker, the caretaker being married, and colostrum being given to the baby. Noma is a neglected disease, and current risk factors suggest that intervention efforts could be more effective by focussing on access to health care, the benefits of breastfeeding and a varied diet. However, more research is needed in order to better understand the pathogenesis of this disease in order to improve prevention, early detection and treatment.

Noma in an HIV infected patient in Guinea-Bissau: a case report

BACKGROUND

Noma is a multifactorial and multibacterial opportunistic infection that initially causes necrotic gingivitis but rapidly spreads to the nearby orofacial tissue resulting in sloughing and severe deformation of the facial structures. The majority of cases are seen in young children under the age of 6 years. Noma is strongly associated with poverty, malnutrition and immunosuppression, and is often preceded by severe systemic infections such as measles and malaria. Only few cases of noma infection in adults have been described.

CASE REPORT

We present here a case report with a 32-year-old Guinean woman who was diagnosed with noma infection and on that occasion discovered that she was HIV-1 seropositive. After treatment with amoxicillin/clavulanic acid and metronidazole for her noma infection the woman was transferred to the national hospital where antiretroviral treatment was initiated.

CONCLUSION

Noma is an opportunistic infection and immunodeficiencies such as HIV should always be suspected when presenting in an adult patient.

Noma as a complication of false teeth (Ebiino) extraction: a case report

Background

Ebiino, also known as false tooth extraction, is a traditional practice done mainly in the remote areas of African countries, including Uganda. It involves the extraction of tooth buds in babies with common childhood illnesses such as fever, cough, and diarrhea. It is thought that the tooth buds are responsible for the ailments seen in these infants. The practice is performed by traditional healers using unsterile instruments. The complications associated with this dangerous practice have been mentioned in the literature and include anemia and septicemia, among others. This case report describes a baby with noma, an orofacial gangrenous infection.

Case presentation

A 16-month-old girl from western Uganda belonging to the Banyankole ethnic group was admitted to Mbarara University Teaching Hospital with a 5-day history of a dark lesion on the left cheek. The lesion had started from the left upper gum at the site where a tooth bud had been extracted 1 week prior to admission. The child had experienced occasional cough and fever and also had erupting tooth buds. These tooth buds had been seen as the cause of the cough and fever by the traditional herbalist; hence, they were extracted. An unsterile instrument had been used for the procedure. At the hospital, a local examination showed necrotic tissue involving the left cheek and extending into the left upper gingival area of the girl’s mouth. A clinical diagnosis of orofacial gangrene (noma) was then made.

Conclusions

Ebiino, or false tooth extraction, is still practiced in some remote areas of Uganda. Noma has been mentioned as a possible complication of this traditional practice; however, case reports in the literature are scant. Public awareness of the dangers of this practice is therefore still required to prevent this dangerous complication.

Necrotizing Periodontal Diseases in Children: A Literature Review and Adjustment of Treatment

Necrotizing ulcerative gingivitis, sometimes observed in young children, may lead to necrotizing stomatitis and noma. Therefore, its interception is a necessity and a challenge for the paediatric practitioners. First, this article aims to propose a systematic review of recent literature on the use of local antiseptic and antibiotic prescription in this particular periodontal condition. Then, a protocol is proposed to have a simple, costless and reproducible treatment on children.

Noma Neonatorum From Multidrug-Resistant Pseudomonas aeruginosa: An Underestimated Threat?

We present the case of an extremely low birth weight infant with diffuse gingival noma, initially misdiagnosed as thrush. Multidrug-resistant Pseudomonas aeruginosa strain was cultured and treated with systemic and local colistin with complete healing. Noma neonatorum from multidrug-resistant pathogens may appear in neonatal intensive care units. Old antibiotics may help.Noma (cancrum oris) is a devastating gangrenous disease that leads to destruction of facial tissue with significant morbidity and mortality in children and young adults. Noma has virtually disappeared from Europe and North America, but it is still common among children and young adults in India, Africa, and South America. Noma is a polymicrobial opportunistic infection related to malnutrition and immune dysfunction. In the neonate, a similar but distinct condition, known as "noma neonatorum" was described in 1977, in which gangrenous lesions involve the mucocutaneous junctions of oral, nasal, and anal area, and, occasionally, the eyelids and the scrotum. The neonatal disease has been linked to Pseudomonas aeruginosa, prematurity, and low birth weight. There is no established treatment, and mortality is almost inevitable in the few reported cases. In this study, we present the first European case of noma neonatorum from a multidrug-resistant strain of P aeruginosa.

[Noma]

Noma is a necrotizing ulcerative stomatitis known since Antiquity. It occurs mostly in poor countries, the Sahel countries being the most affected. Each year, several hundred thousand cases are reported. Noma affects especially malnourished children who are less than 6 years old and rarely adults with acquired immunodeficiency (HIV, cancer). Ulcerative lesion is occurring rapidly due to the production of endotoxins by bacteria from oral commensal, telluric and animal origin. Necrotic debridement leads to huge defects: loss of soft tissue (skin, nerves, vessels, eye), bone (maxilla, mandible) and teeth. Death occurs rapidly in a few weeks in 80 % of the cases. In case of survival, the consequences are functional, aesthetic, psychological and social. The goal of the treatment in the acute phase is the patient's survival and the fight against limited mouth opening. The management of the phase of sequela is an anaesthetic, surgical and physiotherapy challenge. Its purpose is the social reintegration of the patient.

Fusobacterial head and neck infections in children

Fusobacterium species are increasingly recognized as a cause of head and neck infections in children. These infections include acute and chronic otitis, sinusitis, mastoiditis, and tonsillitis; peritonsillar and retropharyngeal abscesses; Lemierre syndrome; post-anginal cervical lymphadenitis; and periodontitis. They can also be involved in brain abscess and bacteremia associated with head and neck infections. This review describes the clinical spectrum of head and neck fusobacterial infection in children and their management.

Noma affected children from Niger have distinct oral microbial communities based on high-throughput sequencing of 16S rRNA gene fragments

We aim to understand the microbial ecology of noma (cancrum oris), a devastating ancient illness which causes severe facial disfigurement in>140,000 malnourished children every year. The cause of noma is still elusive. A chaotic mix of microbial infection, oral hygiene and weakened immune system likely contribute to the development of oral lesions. These lesions are a plausible entry point for unidentified microorganisms that trigger gangrenous facial infections. To catalog bacteria present in noma lesions and identify candidate noma-triggering organisms, we performed a cross-sectional sequencing study of 16S rRNA gene amplicons from sixty samples of gingival fluid from twelve healthy children, twelve children suffering from noma (lesion and healthy sites), and twelve children suffering from Acute Necrotizing Gingivitis (ANG) (lesion and healthy sites). Relative to healthy individuals, samples taken from lesions in diseased mouths were enriched with Spirochaetes and depleted for Proteobacteria. Samples taken from healthy sites of diseased mouths had proportions of Spirochaetes and Proteobacteria that were similar to healthy control individuals. Samples from noma mouths did not have a higher abundance of Fusobacterium, casting doubt on its role as a causative agent of noma. Microbial communities sampled from noma and ANG lesions were dominated by the same Prevotella intermedia OTU, which was much less abundant in healthy sites sampled from the same mouths. Multivariate analysis confirmed that bacterial communities in healthy and lesion sites were significantly different. Several OTUs in the Orders Erysipelotrichales, Clostridiales, Bacteroidales, and Spirochaetales were identified as indicators of noma, suggesting that one or more microbes within these Orders is associated with the development of noma lesions. Future studies should include longitudinal sampling of viral and microbial components of this community, before and early in noma lesion development.

Noma is a traumatic disease characterized by oral-facial lesions that often lead to severe disfigurement and ultimately shame and isolation from the community. Because the causes of noma are likely to be numerous, and reaching those who suffer from this illness is challenging, the etiology of noma remains ill-defined. Although it is known that oral hygiene and nutrition influence the development of noma, evidence suggests that one or more microbes play a crucial role in development of noma lesions. Previous studies have examined the DNA of microbes in lesions to determine which species are present and how their abundances differ between healthy mouth sites and noma lesions. These studies used techniques that were state-of-the-art at the time, though we know they likely only scratched the surface of the resident microbial diversity. Here we extend these studies by digging deeper to characterize a larger diversity of microbial species in noma and control samples, with the goal of better identifying which microbes are uniquely present or have altered abundances in noma lesions.

FusoBase: an online Fusobacterium comparative genomic analysis platform

Fusobacterium are anaerobic gram-negative bacteria that have been associated with a wide spectrum of human infections and diseases. As the biology of Fusobacterium is still not well understood, comparative genomic analysis on members of this species will provide further insights on their taxonomy, phylogeny, pathogenicity and other information that may contribute to better management of infections and diseases. To facilitate the ongoing genomic research on Fusobacterium, a specialized database with easy-to-use analysis tools is necessary. Here we present FusoBase, an online database providing access to genome-wide annotated sequences of Fusobacterium strains as well as bioinformatics tools, to support the expanding scientific community. Using our custom-developed Pairwise Genome Comparison tool, we demonstrate how differences between two user-defined genomes and how insertion of putative prophages can be identified. In addition, Pathogenomics Profiling Tool is capable of clustering predicted genes across Fusobacterium strains and visualizing the results in the form of a heat map with dendrogram.

Database URL:http://fusobacterium.um.edu.my.

Report of an Infant with Noma (Cancrum Oris)

Noma (cancrum oris) is an infectious disease that destroys the oro-facial tissues and other neighboring structures in its fulminating course. The starting point of the disease is acute ulcero-necrotic gingivitis, which results in an extensive gangrenous plaque destroying all of the soft tissues of the face. It predominantly affects children aged 2-16 years and is primarily seen in areas where the socioeconomic standards are low and there is poor hygiene, as in developing countries. We discuss possible predisposing factors in cancrum oris such as malnutrition, infectious diseases, HIV infection, and immune compromise conditions. Poverty is the most important risk factor. We report the case of a 6-month-old child with noma and review the characteristic features of this disease.

Interaction of Prevotella intermedia strain 17 leucine-rich repeat domain protein AdpF with eukaryotic cells promotes bacterial internalization

Prevotella intermedia is an oral bacterium implicated in a variety of oral diseases. Although internalization of this bacterium by nonphagocytic host cells is well established, the molecular players mediating the process are not well known. Here, the properties of a leucine-rich repeat (LRR) domain protein, designated AdpF, are described. This protein contains a leucine-rich region composed of 663 amino acid residues, and molecular modeling shows that it folds into a classical curved solenoid structure. The cell surface localization of recombinant AdpF (rAdpF) was confirmed by electron and confocal microscopy analyses. The recombinant form of this protein bound fibronectin in a dose-dependent manner. Furthermore, the protein was internalized by host cells, with the majority of the process accomplished within 30 min. The internalization of rAdpF was inhibited by nystatin, cytochalasin, latrunculin, nocodazole, and wortmannin, indicating that microtubules, microfilaments, and signal transduction are required for the invasion. It is noteworthy that preincubation of eukaryotic cells with AdpF increased P. intermedia 17 internalization by 5- and 10-fold for HeLa and NIH 3T3 fibroblast cell lines, respectively. The addition of the rAdpF protein was also very effective in inducing bacterial internalization into the oral epithelial cell line HN4, as well as into primary cells, including human oral keratinocytes (HOKs) and human umbilical vein endothelial cells (HUVECs). Finally, cells exposed to P. intermedia 17 internalized the bacteria more readily upon reinfection. Taken together, our data demonstrate that rAdpF plays a role in the internalization of P. intermedia 17 by a variety of host cells.

Host response, malnutrition and oral diseases. Part 2

Acute phase proteins enhance antioxidant defenses; they are involved in the activation of complement components, opsonization and increase in platelet aggregation as well as inhibition of the respiratory burst in the course of inflammation. Malnutrition plays an important role in the course of response of acute phase proteins. The role of nutrients as antioxidants or as key components of antioxidant enzymes is commonly known. In the course of various inflammatory states, including oral diseases, disorders are observed in caloric requirements of the organism and the requirements for specific amino acids. Numerous experimental studies in animals have also confirmed the relationship between protein- calorie malnutrition and hypofunction of the salivary glands. Studies in children with malnutrition syndrome showed a significantly lower volume of saliva compared to properly nourished children. Depleted nutritional reserves due to long-term chronic malnutrition cause a significant reduction in resistance, progressive damage to the oral mucosa, and reduce resistance to colonization and invasion of pathogenic microorganisms.

Microarray analysis of microbiota of gingival lesions in noma patients

Noma (cancrum oris) is a gangrenous disease of unknown etiology affecting the maxillo-facial region of young children in extremely limited resource countries. In an attempt to better understand the microbiological events occurring during this disease, we used phylogenetic and low-density microarrays targeting the 16S rRNA gene to characterize the gingival flora of acute noma and acute necrotizing gingivitis (ANG) lesions, and compared them to healthy control subjects of the same geographical and social background. Our observations raise doubts about Fusobacterium necrophorum, a previously suspected causative agent of noma, as this species was not associated with noma lesions. Various oral pathogens were more abundant in noma lesions, notably Atopobium spp., Prevotella intermedia, Peptostreptococcus spp., Streptococcus pyogenes and Streptococcus anginosus. On the other hand, pathogens associated with periodontal diseases such as Aggregatibacter actinomycetemcomitans, Capnocytophaga spp., Porphyromonas spp. and Fusobacteriales were more abundant in healthy controls. Importantly, the overall loss of bacterial diversity observed in noma samples as well as its homology to that of ANG microbiota supports the hypothesis that ANG might be the immediate step preceding noma.

Risk factors for noma disease: a 6-year, prospective, matched case-control study in Niger

BACKGROUND

Noma is a poorly studied disease that leads to severe facial tissue destruction in children in developing countries, but the cause remains unknown. We aimed to identify the epidemiological and microbiological risk factors associated with noma disease.

METHODS

We did a prospective, matched, case-control study in Niger between Aug 1, 2001, and Oct 31, 2006, in children younger than 12 years to assess risk factors for acute noma. All acute noma cases were included and four controls for each case were matched by age and home village. Epidemiological and clinical data were obtained at study inclusion. We undertook matched-paired analyses with conditional logistic regression models.

FINDINGS

We included 82 cases and 327 controls. Independent risk factors associated with noma were: severe stunting (odds ratio [OR] 4·87, 95% CI 2·35-10·09) or wasting (2·45, 1·25-4·83); a high number of previous pregnancies in the mother (1·16, 1·04-1·31); the presence of respiratory disease, diarrhoea, or fever in the past 3 months (2·70, 1·35-5·40); and the absence of chickens at home (1·90, 0·93-3·88). After inclusion of microbiological data, a reduced proportion of Fusobacterium (4·63, 1·61-13·35), Capnocytophaga (3·69, 1·48-9·17), Neisseria (3·24, 1·10-9·55), and Spirochaeta in the mouth (7·77, 2·12-28·42), and an increased proportion of Prevotella (2·53, 1·07-5·98), were associated with noma. We identified no specific single bacterial or viral pathogen in cases.

INTERPRETATION

Noma is associated with indicators of severe poverty and altered oral microbiota. The predominance of specific bacterial commensals is indicative of a modification of the oral microbiota associated with reduced bacterial diversity.

FUNDING

Gertrude Hirzel Foundation.

Fusobacterial infections in children

Fusobacteria are members of the oral and gastrointestinal flora and are important potential pathogens in children. They are increasingly recognized as a cause of infections in children. These include infections of the head and neck (Lemierre syndrome, acute and chronic mastoiditis, chronic otitis and sinusitis, tonsillitis, peritonsillar and retropharyngeal abscesses, postanginal cervical lymphadenitis, periodontitis), brain, lungs, abdomen, pelvis, bones, joints, and blood. This review describes the clinical spectrum of fusobacterial infection in children and their management.

Noma (cancrum oris) in the South African context

Noma (cancrum oris) is a destructive necrotising disease affecting orofacial tissues predominantly of malnourished young children. It is characterised by a rapid acute onset which usually starts in the mouth, spreads intra-orally destroying soft tissue and bone and progresses to perforate the facial skin, causing disfigurement. Polybacterial anaerobic infection is critical too, but is not alone sufficient for the initiation of noma. Cofactors, first and foremost malnutrition, but also systemic viral and bacterial infections are crucial to the development of noma. A patient with necrotising stomatitis or noma must be admitted to hospital for antibiotic treatment, fluid and electrolytes as well as nutritional supplementation and general supportive treatment. The epidemiology of noma in the South African population is unknown, and the clinicopathological features are poorly characterised. Although worldwide there is no evidence that HIV infection is a strong risk factor for noma, HIV infection may play a substantial role in the pathogenesis of noma in South Africa.

Noma (cancrum oris): a report of a case in a young AIDS patient with a review of the pathogenesis

Noma (cancrum oris) is a mutilating necrotising disease of the orofacial tissues. It affects predominantly debilitated malnourished children, in whom the necrotic process may cause severe damage to mid-facial structures. Its aetiopathogenesis is uncertain, but its course is fulminating, and without timely intervention the disease may be fatal. Antibiotic treatment during any stage of necrotising stomatitis and of its sequel noma can stop progression of the disease; therefore detection and treatment of early intraoral necrotising lesions whether necrotising gingivitis, necrotising periodontitis or necrotising stomatitis are critical in preventing noma. We present an extreme case of noma in a malnourished HIV-seropositive child. There was an acute necrotic process affecting both the maxilla and the mandible with denudation of bone, spontaneous exfoliation of teeth, necrotising fasciitis and myonecrosis which destroyed the lips and cheeks and extended to the infra-orbital margins. There was severe disfigurement and severe impairment of function. Noma is primarily an anaerobic bacterial infection with secondary ischaemia leading to osteonecrosis and mid-facial destruction.

Noma in an Afghani child: a case report

We present a case of Cancrum Oris, also known as Noma, in a child treated by an Otorhinolaryngologist at a United States-led Joint Forces hospital in Afghanistan. Noma is a deadly, necrotizing infection of the face that is rarely seen in wealthy nations but can cause significant morbidity in third world countries. Through a literature review, we report the incidence, risk factors, clinical features, and proposed treatment for this disease.

Risk factors for osteonecrosis of the jaws: a case-control study from the CONDOR dental PBRN

Case reports and cohort studies have linked bisphosphonate therapy and osteonecrosis of the jaws (ONJ), but neither causality nor specific risks for lesion development have been clearly established. We conducted a 1:3 case-control study with three dental Practice-based Research Networks, using dentist questionnaires and patient interviews for collection of data on bisphosphonate therapy, demographics, co-morbidities, and dental and medical treatments. Multivariable logistic regression analyses tested associations between bisphosphonate use and other risk factors with ONJ. We enrolled 191 ONJ cases and 573 controls in 119 dental practices. Bisphosphonate use was strongly associated with ONJ (odds ratios [OR] 299.5 {95%CI 70.0-1282.7} for intravenous [IV] use and OR = 12.2 {4.3-35.0} for oral use). Risk markers included local suppuration (OR = 7.8 {1.8-34.1}), dental extraction (OR = 7.6 {2.4-24.7}), and radiation therapy (OR = 24.1 {4.9-118.4}). When cancer patients (n = 143) were excluded, bisphosphonate use (OR = 7.2 {2.1-24.7}), suppuration (OR = 11.9 {2.0-69.5}), and extractions (OR = 6.6 {1.6-26.6}) remained associated with ONJ. Higher risk of ONJ began within 2 years of bisphosphonate initiation and increased four-fold after 2 years. Both IV and oral bisphosphonate use were strongly associated with ONJ. Duration of treatment > 2 years; suppuration and dental extractions were independent risk factors for ONJ.

NOMA: A Preventable "Scourge" of African Children

Noma is a serious orofacial gangrene originating intraorally in the gingival-oral mucosa complex before spreading extraorally to produce a visibly destructive ulcer. Although cases of noma are now rarely reported in the developed countries, it is still prevalent among children in third world countries, notably in sub-Sahara Africa, where poverty, ignorance, malnutrition, and preventable childhood infections are still common. This review summarizes historical, epidemiological, management, and research updates on noma with suggestions for its prevention and ultimate global eradication. The global annual incidence remains high at about 140,000 cases, with a mortality rate exceeding 90% for untreated diseases. Where the patients survive, noma defects result in unsightly facial disfigurement, intense scarring, trismus, oral incompetence, and social alienation. Although the etiology has long been held to be infectious, a definitive causal role between microorganisms cited, and noma has been difficult to establish. The management of noma with active disease requires antibiotics followed by reconstructive surgery. Current research efforts are focused towards a comprehensive understanding of the epidemiology, and further elucidation of the microbiology and pathogenesis of noma.Although a formidable public health challenge, noma can be prevented with a potential for subsequent global eradication. To achieve both desirable goals, detection of early disease is crucial because these early lesions respond to conventional antibiotic treatments when instituted side by side with nutritional rehabilitation, and obviates the necessity for extensive surgical reconstruction often indicated in late stage disease. The eradication of noma in the developed world in the mid 20(th) century bears out the notion of a similar outcome following effective preventive strategies in Africa. A fundamental and necessary step towards attaining this goal is for the international community to adopt a perception of noma as an urgent global public health challenge. Research effort toward deciphering the microbiology, molecular events, and pathogenesis of noma also should intensify.

Nutrition and oral mucosal diseases

Oral manifestations of nutritional deficiencies can affect the mucous membranes, teeth, periodontal tissue, salivary glands, and perioral skin. This contribution reviews how the water-soluble vitamins (B(2), B(3), B(6), B(12), C, and folic acid), fat-soluble vitamins (A, D, and E), and minerals (calcium, fluoride, iron, and zinc) can affect the oral mucosa.

AdpC is a Prevotella intermedia 17 leucine-rich repeat internalin-like protein

The oral bacterium Prevotella intermedia attaches to and invades gingival epithelial cells, fibroblasts, and endothelial cells. Several genes encoding proteins that mediate both the adhesion and invasion processes are carried on the genome of this bacterium. Here, we characterized one such protein, AdpC, belonging to the leucine-rich repeat (LRR) protein family. Bioinformatics analysis revealed that this protein shares similarity with the Treponema pallidum LRR (LRR(TP)) family of proteins and contains six LRRs. Despite the absence of a signal peptide, this protein is localized on the bacterial outer membrane, indicating that it is transported through an atypical secretion mechanism. The recombinant form of this protein (rAdpC) was shown to bind fibrinogen. In addition, the heterologous host strain Escherichia coli BL21 expressing rAdpC (V2846) invaded fibroblast NIH 3T3 cells at a 40-fold-higher frequency than control E. coli BL21 cells expressing a sham P. intermedia 17 protein. Although similar results were obtained by using human umbilical vein endothelial cells (HUVECs), only a 3-fold-increased invasion of V2846 into oral epithelial HN4 cells was observed. Thus, AdpC-mediated invasion is cell specific. This work demonstrated that AdpC is an important invasin protein of P. intermedia 17.