spread of infections

Chapter 12: Spread of Infection

Objective

Summarize knowledge of the infectious routes within the head/neck region, including how to prevent the spread of dental infections.

Infection Process Overview

The healthy body usually lives in balance with a number of normal flora in residence.
However, certain nonresident microorganisms called pathogens can invade and initiate an infection.
Pathogens contain specific factors that help advance the infection process, such as:
- Capsules
- Spores
- Toxins

Odontogenic Infection

Dental infections, also referred to as odontogenic infections (or dentoalveolar infections in medical terminology), involve the teeth or associated tissue.
These infections are caused by oral pathogens, usually consisting of more than one species (polymicrobial).
These organisms are prevalent on the surfaces of the teeth, in the oral mucous membranes, and also found in gingival sulci and saliva.

Sources of Odontogenic Infection

Odontogenic infections may arise from either dental origin or from secondary nonodontogenic sources.
Infections of dental origin typically result from:
- Progressive dental caries
- Extensive periodontal disease
- Implant placement (periimplantitis)
Majority of intraoral infections result from the dominance of the resident aerobic Streptococcus viridans (specific group includes S. mutans).
Approximately 60% of these infections also contain other species such as:
- Peptostreptococcus
- Fusobacterium
- Prevotella

Infection Mechanisms

Most odontogenic infections initially stem from the increased formation of dental biofilm (plaque).
Pathogens can penetrate deeper oral tissues due to trauma caused by dental procedures, including:
- Contamination during dental surgery (e.g., tooth extraction)
- Needle tracks from local anesthetics
Some odontogenic infections may result as secondary infections stemming from surrounding oral cavity tissues, such as the skin, tonsils, ears, or sinuses.
It is crucial to diagnose and treat these nonodontogenic sources early during dental care to avoid further spread and complications.

Types of Pathologic Lesions

Odontogenic infections can cause several types of pathologic lesions, depending on the infection location and involved tissue, including:
- Abscess
- Cellulitis
- Osteomyelitis

Abscess

An abscess forms in the oral cavity when there is localized entrapment of pathogens from a chronic odontogenic infection in a closed tissue space, typically bordered by the oral mucosa.
- Example Figure 12-1: Intraoral Abscess

Abscess Classification

Abscesses can be categorized as either acute or chronic.
Early acute stages of abscess formation may not be detectable via radiographs.
- Example Figure 12-2: Chronic Extraoral Abscess

Abscess Characteristics

An abscess fills with suppuration, producing a fluctuant feel upon palpation.
Components of suppuration include pathogenic bacteria, white blood cells, tissue fluid, and debris.

Periapical Abscess

Periapical abscess formation may occur with progressive caries when pathogens invade the sterile pulp, allowing the infection to spread apically.
- Reference: Periapical Radiograph

Periodontal Abscess

Pathogens may also become trapped in deepened gingival sulci (periodontal pockets) in cases of severe periodontal disease, leading to a periodontal abscess.
- Reference: Periapical Radiograph: Periodontal Abscess

Pericoronitis

An erupting mandibular third molar may cause a pericoronal abscess or pericoronitis, especially under certain circumstances.
- Example Figure 12-5

Fistula Formation

In advanced infection stages, chronic abscess formation can create tracts known as fistulae in skin, oral mucosa, or bone.
The opening of the fistula from the tract is referred to as a stoma.
- Example Figure 12-3

Fistula Case Example

An example of a fistula includes one formed from an abscess linked to a mandibular first molar; an opening of the fistulous tract may be observed on the skin beneath the chin.
Additionally, a periapical radiolucency may be present indicating the abscess area.
- Source: Fehrenbach MJ (2014).

Pustule Formation

The soft tissue over a fistula may also have an associated extraoral or intraoral pustule.
A pustule is defined as a small, elevated, circumscribed lesion of either skin or oral mucosa containing suppuration.
- Example Figure 12-4

Pustule Characteristics

The position of the pustule largely depends on the relationship between the fistula and the overlying muscle attachments.
Infections tend to follow the path of least resistance; differently, muscle attachments to the bone serve as barriers to infection spread.

Treatment of Abscess

The most common treatment for suppurating odontogenic infections includes surgical drainage and addressing the definitive source of infection (restoration or extraction of the infected teeth).
Treatment illustrated as Incision and Drainage

Cellulitis

Cellulitis of the face and neck can manifest in odontogenic infections, representing an acute, diffuse inflammation of soft tissue spaces unlike a localized abscess.
- Example Figure 12-6

Clinical Symptoms of Cellulitis

Common clinical signs and symptoms include:
- Pain
- Tenderness
- Redness
- Diffuse edema, creating a substantial and firm swelling that may feel doughy or indurated upon palpation.
- Example Figure 12-6

Treatment of Cellulitis

Treatment consists of administering systemic antibiotics and removing the infection's cause.
- Treatment method illustrated as Cellulitis with Incision & Drainage

Osteomyelitis

Osteomyelitis is an inflammation of the bone marrow that can be related to odontogenic infection.
It can affect any bone in the body or be generalized and develops typically due to pathogens invading tissues of a long bone from a skin or pharyngeal infection.

Imaging for Osteomyelitis

In cases affecting the jawbones, pathogens often originate from a periapical abscess, an extension of cellulitis, or surgical site contamination.
- Reference: Figure 12-7: Panoramic Radiograph

Location of Osteomyelitis

Osteomyelitis frequently presents in the mandible but rarely occurs in the maxilla due to the mandible's thicker cortical plates and lower vascularization levels.
Continued osteomyelitis leads to bone resorption and sequestra buildup (dead bone pieces separated from sound bone).
These changes are detectable through radiographic evaluation.

Histology of Osteomyelitis

Low-power microscopy of acute osteomyelitis shows nonviable bone, with observable bacterial colonies and inflammatory cells between trabecular bone.
- Reference: Figure 12-XX

Imaging Techniques for Osteomyelitis

Additional imaging techniques may include CT scans and bone scans for better insight into osteomyelitis.

Neurological Symptoms of Osteomyelitis

Development of paresthesia (burning or prickling sensations) in the mandible may occur if the infection spreads to the mandibular canal affecting the inferior alveolar nerve, potentially causing localized paresthesia of the lower lip if the infection is distal to the mental foramen where the mental nerve exits.

Treatment of Osteomyelitis

Treatment involves:
- Drainage of the infected area
- Surgical removal of any sequestra
- Administration of antibiotics
Hyperbaric oxygen therapy may also be required for some patients.
The incidence of osteomyelitis in the jaw is now uncommon due to accessible dental care and antibiotics.

Infection Resistance Factors

Over 50% of gram-negative anaerobic bacteria can produce the beta-lactamase enzyme, which leads to initial tissue damage in head and neck infections and contributes to many treatment failures in odontogenic infections.
Beta-lactamase enables these pathogens to evade penicillin therapy and protect penicillin-susceptible co-pathogens by releasing the enzyme into their environment.
Questions remain regarding which common antibiotic can counteract beta-lactamase.

Medically Compromised Patients

The normal flora in the oral cavity typically does not cause infection; however, if the body’s natural defenses are diminished, opportunistic infections can emerge.
- Example Figure 12-8: Osteoradionecrosis

Categories of Medically Compromised Patients

This includes individuals with conditions such as:
- Human Immunodeficiency Virus (HIV)
- Uncontrolled diabetes
- Anemia
- Those undergoing transplant or cancer therapy
Such patients are at a heightened risk of complications from odontogenic infections due to their extensive medical histories.

Spread of Odontogenic Infection

Odontogenic infections, originating in teeth and associated oral tissue, can have substantial consequences if they spread to vital structures, tissues, or organs.
Localized abscesses often establish fistula in skin, oral mucosa, or associated bone, allowing natural drainage and lowering further spread risk; however, such drainage does not always occur, thus maintaining a risk of infection spread.

Spread Patterns

Occasionally, odontogenic infections may spread to paranasal sinuses or disseminate via the vascular or lymphatic systems, or through fascial spaces in the head and neck.

Specific Spread Mechanisms to Paranasal Sinuses

Paranasal sinuses can become infected directly due to the spread of disease from teeth and related dental tissue, resulting in secondary sinusitis.
A perforation or abnormal hole in the sinus wall caused by infection can further increase the likelihood of infection dissemination.

Imaging of Maxillary Sinusitis

Secondary sinusitis of dental origin predominantly occurs in maxillary sinuses since the maxillary posterior teeth are closely adjacent to these sinuses.

Spread to Maxillary Sinusitis

Maxillary sinusitis may stem from odontogenic infections such as a periapical abscess formed from a maxillary posterior tooth, which can perforate the sinus floor, thereby involving the sinus mucosa.
Contaminated teeth or root fragments may be inadvertently displaced into the sinus during extractions, potentially inciting an infection.

Clinical Notes on Maxillary Sinusitis

Symptoms of sinusitis typically include headache (often localized to the affected sinus), foul-smelling nasal or pharyngeal discharge, fever, and weakened state.
Tenderness and warmth in the skin over the inflamed sinus may be observed when palpating and examining the area.

Imaging Evaluation for Maxillary Sinusitis

Radiographic evaluation may reveal increased radiopacity (cloudiness) or even perforation; bilateral comparisons of paired sinuses are essential, while magnetic resonance imaging (MRI) may also be warranted.
- Reference: Figure 3-56B; Waters View Radiograph

Spread through the Vascular System

The vascular system provides a means for infection spread originating from teeth and associated oral tissues, allowing pathogens to travel within veins which drain the infected site to surrounding tissues, structures, or organs.
Odontogenic infections may disseminate via bacteremia or via an infected thrombus.

Bacteremia

During dental treatment, bacteria in the vascular system may lead to bacteremia.
In patients at high risk for infective endocarditis, these bacteria can lodge in compromised tissues, potentially culminating in severe heart infections that could lead to catastrophic damage.

Infected Thrombus

An infected thrombus may dislodge from blood vessel walls and travel as an embolus.

Infected Embolus

Infected emboli can flow through veins, draining from the oral cavity to areas such as the cranial cavity's dural venous sinuses.
Blood from cerebral veins travels through these sinuses to veins of the head and neck (particularly the internal jugular vein), and due to the lack of functional valves in these veins, infection could spread into the cranial cavity.

Cavernous Sinus Thrombosis

The cavernous sinus is notably at risk for serious, potentially fatal, spread of odontogenic infections.

Pathophysiology of Cavernous Sinus Thrombosis

Odontogenic infections draining into the cavernous sinus can trigger inflammatory responses, leading to increased blood stasis and thrombus formation.
The presence of an infected thrombus transported as an embolus into this venous sinus can cause cavernous sinus thrombosis.

Routes to Cavernous Sinus Thrombosis

Incorrect administration of posterior superior alveolar block injections can result in needle track contamination, leading to infection in the pterygoid plexus of veins.

Symptoms of Cavernous Sinus Thrombosis

Symptoms of cavernous sinus thrombosis include:
- Fever
- Drowsiness
- Rapid pulse
- Loss of function in the sixth cranial nerve (abducens), causing paralysis of this nerve.
- Reference: Figure 12-7

Complications of Cavernous Sinus Thrombosis

This condition can culminate in meningitis, an inflammation of the meninges surrounding the brain or spinal cord, requiring immediate hospitalization with intravenous antibiotics and anticoagulants.

Spread through the Lymphatic System

Pathogens can migrate from a primary lymph node near the infection site to secondary nodes in more distant sites via the lymphatic system of the head and neck.

Pathways of Spread through Lymphatics

Lymphatic vessels connect series of nodes from the oral cavity to other tissues or organs, allowing for the infection spread.

Lymph Node Involvement

Submandibular nodes serve as primary nodes for all teeth and associated tissues, except for:
- Maxillary third molars (drain into superior deep cervical nodes)
- Mandibular incisors (drain into submental nodes)
The submandibular nodes empty into superior deep cervical nodes.
Superior deep cervical nodes further drain into inferior deep cervical nodes or directly into the jugular trunk, integrating into the vascular system.

Lymphadenopathy

Involved lymph nodes undergo hypertrophy due to infection, resulting in lymphadenopathy, manifested by size increase and change in consistency making them palpable.
- Reference: Figure 10-22

Spread via Fascial Spaces

Spaces in the head and neck allow the transmission of odontogenic infections, enabling pathogens to migrate through fascial spaces from the initial infected site to more distant locations driven by inflammatory exudate spread.

Cellulitis from Spread via Spaces

Infections affecting spaces can encounter cellulitis, which alters normal facial proportions.
- Example illustrated in Figure 12-6

Specific Shared Spaces

If maxillary teeth and related tissues are infected, the infection may spread into:
- Vestibular space of the maxilla
- Buccal space
- Canine space
If mandibular teeth and associated tissues are implicated, the infection may extend into:
- Vestibular space of the mandible
- Buccal space
- Submental space
- Sublingual space
- Submandibular space
- Masticator spaces
- Body of the mandibular space, as dictated by tooth location and infection severity.

Impact of Mylohyoid Muscle

The aspect of mylohyoid muscle insertion along the mandible directs which specific subspace of the mandible is impacted by odonto-genic infections.

Spread Pattern with Lower Molars

The apex of the mandibular first molar is positioned superiorly to the mylohyoid muscle; thus, infections involving this tooth or teeth anterior to it will primarily affect the sublingual space.

Spread Pattern with Mandibular Molars

Conversely, the apices of the mandibular second and third molars are located beneath the mylohyoid muscle. Thus, infections here will lead to invasion of the submandibular space.

Imaging for Submandibular Space

Abscess formation accompanied by cellulitis may be evaluated through imaging techniques such as CT and bone scans.

Ludwig Angina

Ludwig angina represents one of the most severe lesions in the jaw region, characterized by cellulitis in the submandibular space.

Progression of Ludwig Angina

Infection progresses to bilaterally infiltrate the submandibular space, potentially spreading into the parapharyngeal space and extending to the retropharyngeal space of the neck.

Risks of Retropharyngeal Space Involvement

When the retropharyngeal space (referred to as the “danger space” in dental practice) is involved, laryngeal edema can result, leading to respiratory obstruction, asphyxiation, and possible death.
Ludwig angina is a medical emergency involving immediate hospitalization; emergency interventions (e.g., cricothyrotomy) may be necessary to secure a patent airway.

Impact of Oral Piercings

The surge in popularity of oral piercings has correlated with an increase in serious infections within oral sites, including occurrences of Ludwig angina.

Prevention of Spread of Infection

Early diagnosis and treatment of infections must be prioritized across all patients.
Precautions must be undertaken to prevent contamination at surgical sites (e.g., extractions or implant placements) and stringent infection control measures should be implemented during dental procedures.

Importance of Medical History

A comprehensive medical history and routine updates will empower dental professionals to conduct safe treatments for medically compromised patients and avert significant complications arising from active dental diseases.
Medical consultations may be warranted when there is uncertainty regarding the risks associated with opportunistic infections.

Links to Systemic Diseases

Scientific evidence denotes connections between severe oral infections and increased susceptibility to critical systemic diseases including:
- Cardiovascular disease
- Diabetes mellitus
- Adverse pregnancy outcomes
- Pulmonary infections
- Possibly rheumatoid arthritis.

Case Study 12.0

Patient Profile:
- Age: 54 years
- Sex: Female
- Chief Complaint: "What is this bump on my gums?"
- Medical History: Type 2 diabetes
- Current Medications: Oral medication for diabetes
- Lifestyle: Smokes one pack of cigarettes daily
- Occupation: Nurse with three children
- Physical Measurements: Height 5’ 8’’, Weight 225 lbs
Context: Patient expresses concern over gingival tissue associated with an 8 mm periodontal pocket, necessitating prompt maintenance appointments and full mouth periodontal evaluations along with updates on home care instructions.