A BACTERIAL INFECTION IS THE INVASION OF BODY T ISSUES BY DISEASE-CAUSING

BACTERIA , THEIR MULTIPL ICATION AND THE REACTION OF BODY T ISSUES TO THESE

MICROORGANISMS AND THE TOXINS THAT THEY PRODUCE.

Bacterial Infection

Topics

Leprosy Tularemia Botryomycosis Actinomycosis Syphilis Gonorrhoea Tuberculosis Cat-Scratch Disease Scarlet fever Diphtheria Meliodosis Tetanus Rhinoscleroma Noma

Leprosy

Also called as Hansen’s Disease.

Caused by Mycobacterium leprea.

Affects skin, peripheral nerves, upper respiratory tract, eyes, testes, bones and joints.

It is unique in exhibiting dopa oxidase activity.

Staining smears taken from skin and nasal mucosa with ZN method demonstrate the presence of the bacilli.

Tuberculoid Type Lepramatous Type

Lesions are characterised by single or multiple macular, erythematous eruptions.

Peripheral nerves are involved with loss of sensation accompanied by loss of sweating of affected skin.

These develop early erythematous macules or papules that lead to progressive thickening of skin and characteristic nodules.

Facial nerve paralysis occurs due to facial nerve involvement.

Types

Histopathology

Well formed granulomatous inflammation demonstrating clusters of histiocytes and macrophages

Pathogenesis

Host’s defenses are crucial in determining patient’s response to disease.

Tuberculoid type of leprosy is characterized by strong CMI, positive lepromin test, granuloma formation, paucity of bacilli.

Lepromatous type of leprosy is characterized by suppressed CMI, negative lepromin test, no granuloma formation and multiple bacilli.

Diagnosis and Treatment

Tests for humoral responses are monoclonal antibodies, ELISA, PCR, etc.

In children sweat function test is used.

MDT is used which includes rifampicin, dapsone and clofazimine is used for treatment.

Tuberculoid type rifampicin + dapsone for 6 months.

Lepramatous type rifampicin + dapsone + clofazimine

Tularemia

Also called Rabbit Fever.

It is highly communicable and transmitted from infected mammals to humans.

It occurs more frequently in adults.

Clinical Features

Based on site of infection, tularemia has 6 clinical symptoms:

a). Ulceroglandular(most common)b). Glandularc). Oropharyngald). Pneumonice). Oculoglandularf). typhoidal

Treatment

Disease responds to antibiotic therapy.

Streptomycin is the drug of choice.

Also responds well to adequate doses of gentamicin and tetracycline.

Botryomycosis

It is a chronic granulomatous infection.

A number of common bacteria such as staphylococcus, streptococcus, Escherichia, pseudomonas and probably many others may serve as etiologic agents of the disease.

Histopathology

Treatment

This condition may be caused by a variety of different micro organisms of low virulence.

Therefore, pathogenesis may be related more to a modified host resistance or tissue hypersensitivity than to a specific micro organisms.

Treatment is non specific, however surgical invention aids in cure.

Actinomycosis

It is a chronic, granulomatous, suppurative and fibrosing disease caused by anaerobic or microphilic gram positive, non acid fast, branched filamentous bacteria.

They are a normal flora of oral cavity, colon and vagina.

It is characterized by formation of abscesses that tend to drain by formation of sinus tracts.

They are classified according to the location of lesions as- -cervicofacial -abdominal -pulmonary forms

It appears to be an endogenous infection and not communicable.

Histopathology

Tongue lesions

Tonsil lesions

Treatment and Prognosis

Long standing fibrosis cases are treated by draining the abcsess, excising the sinus tract with high doses of antibiotics.

Surgical drainage of abcsesses and excision of sinus tract is necessary to accelerate healing.

Syphilis

It is a veneral i.e. sexually transmitted disease caused by spirocheates, treponema pallidum.

It is transmitted by following routes:CoitusTransfusion of infected bloodMother to foetal transmission

Acquired syphilis Congenital syphilis

Mainly contracted as a veneral disease.

It may also be acquired by dentists while working on infected patients in a contagious state.

Its divided into 3 types based on their appearance and type of lesions:

a).Primaryb).Secondaryc). Tertiary

It is only transmitted from infected mother to foetus only.

It is a very rare disease.Morphological features

are :a). Saddle noseb). Bony lesions,

mucocutaneous lesionsc). High palatal archd). Mulberry molar

Types

Demonstration of treponemas

Serological test

Dark ground microscopyDirect flourescent

antibody staining for T.pallidum.

Treponemas in tissue by:a). Silver impregnation

methodb). Immunoflourescent

staining

Non treponemal test

Treponemal test

Diagnosis

VDRL

RPR

TPI TPHA

Histopathology

Prophylaxis

Early syphilis: Benzathine benzyl penicillin 24 lac units i.m. in a single dose after sensitivity test.

Late syphilis: Benzathine benzyl penicillin 24 lacs units i.m. once weekly for 3 weeks.

Hutchinson's Triad

Hypoplasia of incisor and molar teeth.

8th nerve deafness and interstitial keratitis.

75% of congenital syphilis patients suffer from one or more components of Hutchinson's triads.

Gonorrhoea

It is a veneral disease affecting the male and female genitourinary tract.

It is caused by gram negative diplococci Neisseria gonorrhoea.

The bacterium is a strict parasite and dies rapidly outside the host in 1 to 2 hr in exudates and in 3 to 4 days in culture.

Oral Manifestations

Extra genital infection of the oral cavity occurs as a result of oral-genital contact or inoculation through infected hands.

Lips may develop acute painful ulceration, gingiva may become erythematous with or without necrosis.

Tongue may present red, dry ulcerations or become glazed or swollen with painful erosions.

Gonococcal pharyngitis and tonsilitis are also well recognized.

Diagnosis and Treatment

Diagnosis is established by bacteriological examination of smear or culture.

Organism is sensitive to large doses of penicillin or doxycycline.

Tuberculosis

It is an infectious, granulomatous disease caused by mycobacterium tuberculosis.

Primarily affects lungs but also affected are intestines, bones, joints, meninges, lymph glands, skin and other tissues.

The bacterium is a facultative intracellular parasite.

It causes pulmonary or generalized infection in immunocompromised patients.

Pathogenesis

Bacilli-host interaction: droplet nuclei inhaled by patient

Most bacilli are exhaled by ciliary reaction and 10% enters the alveoli

Initial stage is asymptomatic but 2 – 4 weeks after infection, specific immunity develops and accumulation of a large number of activated macrophages at the site of primary lesion.(granulomatus or tubercles are formed).

Lesion consists of epithelioid cells, langerhans cells, plasma cells and fibroblasts

Central part of the lesion contains caseous necrosis (dry cheesy, granular and yellow in appearance).

Ranne complex necrotic material may undergo calcification(in lung parenchyma or hilar lymph nodes.

Sometimes necrotic material may liquefy, discharging in the lungs leading to cavity formation.

Histopathology

Tuberculosis granulomas demonstrated by ZN stain

Oral Manifestations

Most commonly affected site is tongue. Others are palate, lips, buccal mucosa, gingiva and frenula.

Usual presentation is irregular superficial or deep painful ulcers which tend to increase in size slowly.

It may also involve the bone of the maxilla and mandible.

Microorganisms may enter the pulp chamber and root canal of the tooth with an open cavity.

Treatment

Isoniazid (NPH) combined with rifampicin for 9 months

INH and rifampicin and pyrazinamide for 2 months followed by INH and rifampicin for 4 months.

Other drugs used are streptomycin and ethambutol.

Cat-Scratch Disease

It is a condition caused by Bartonella lenselae a gram negative bacillus demonstrable with silver stain.

It occurs at any age most commonly in children and young adults by a traumatic break in the skin by scratch or by household bite of cat, dog or monkeys.

Histopathology

Lymph node necrosis

Swelling due to inflammation

Treatment and Prognosis

Prognosis is good since the disease is self limiting and regresses within a period of weeks or months.

Incision and drainage of involved node may be necessary.

Antibiotic therapy is ineffective

Scarlet Fever

It is a highly contagious, systemic infection.It occurs predominantly in children.It is caused by β-heamolytic streptococci,

streptococcus pyogens which produces a pyrogenic exotoxin

These organisms produce clear heamolysis around colonies on blood agar plates.

Scarlet fever may reflect a hypersensitivity reaction requiring prior exposure to the toxin.

Histopathology

Necrotic conective tissue

Oral Manifestation

Chief manifestations are termed as ‘Stomatitis scarlatina’.

Small, red macules may appear in the hard and soft palate and uvula which are called Forchheimer spots.

Palate and throat is often fiery red.

Tonsils and faucial pillars are usually swollen and sometimes covered with a grayish exudate.

In early course of the disease, tongue exhibits a white coating and the fungiform pappila are edematous and hyperemic. This phenomenon has been described clinically as ‘strawberry tongue’.

Later, the tongue coating is lost and appears red and glistening and smooth except the pappliae this is called as ‘raspberry tongue’.

Diptheria

It is an acute, life threatening infection and communicable disease of skin and mucous membrane.

Caused by toxemic strains of corneybacterium diptheria.

Characterized by local inflammation and formation of a graying adherent psuedomembrane which bleeds on removal.

Also referred as ‘The strangling angel of children’.

Clinical Features

Signs and symptoms arise 1 to 5 days after exposure.

Swelling of neck (Bull neck).

Onset is gradual.

Manifestations are fever, sore throat, weakness, headache, change of voice.

Of patients Of tonsils

Diptheria cases:Pseudomembrane present

Diptheria carriers:Pseudomembrane absent

On the basis of location of pseudomembrane:

a). Pharyngealb). Laryngealc). Tracheald). Tonsillare). Nasalf). Conjunctivalg). Cutaneoush). Genital

Classification

Oral Manifestations

Formation of ‘Diptheric Membrane’. In oral cavity, appears as non specific ulcers. Soft palate is temporarily paralysed. Patients have peculiar nasal twang.

If infection spreads unchanged in repiratory tract:

a). Larynx becomes edematous, covered by pseudomembrane.b). Husky voicec). Suffocation if airways is not cleared.

Meliodosis

Specific infection in man and animals.

Caused by burkholderia pseudomallei.

It is endemic in certain areas of far east including Burma, India, Indo-china, malaysia and thialand.

Diagnosis and Treatment

Diagnosed by culturing the organism from clinical and throat sample.

Treatment involves:

Incision and drainage accompanied by massive antibiotic therapy.

Tetracycline alone or in combination with chloremphenicol is drug of choice.

Acute Chronic

FeverDiarrhoeaAcute pulmonary

infectionDeath as a result of

septicemia

In those patients who have survived acute type.

It is of granulomatous type, characterized by multiple, small, non specific abscesses.

Clinical Features

Tetanus

Tetanus is an acute infection of the nervous system characterized by intense activity of motor neurons and resulting in severe muscle spasms.

It is caused by exotoxin of the anaerobic gram positive bacillus clostridium tetani.

Most commonly occurs in non immunized, partially immunized or even fully immunized people.

In infants were umbilical cord is cut with unsterile instrument or in children with otorrhea.

After acute trauma.

Pathogenesis

Suitable anaerobic conditions favour the spores of clostridium to enter the wounds and germinate.

These produce tetanospasmin(potent neurotoxin)

It binds to the peripheral motor nerve terminals and enters the axons cell body in the brain stem and spinal cord in a retrograde direction.

Toxins migrate to the synapse where they block the receptors of glycine and GABA which increases the resting state of locomotor neurons thereby producin rigidity.

Generalized Tetanus Local Tetanus

Lock jaw due to the spasm of masseter is the first symptom.

Dysphagia, stiffness or pain in the neck, shoulder or back muscles occurs concurrently.

Laryngeal spasm leading to asphyxia.

Spasm of muscle near the wound is uncommon.

Cephalic tetanus characterized by spasm of muscle and facial palsy is rare.

Acute oral infection, trauma, TMJ dysfunction and even hysteria may be manifested.

Types

Prophylaxis

Wound debriment and booster doses of tetanus toxoid.

For unimmunized indivisuals, anti-tetanus serum(ATS) 1500 units or TIG 250 units should be given.

Rhinoscleroma

It is a chronic, slowly progressive, localized infectious, granulomatous disease caused by bacillus klebsiella rhinoscleromatus which is a gram negative, non motile bacillus.

Mode of infection is through nasal exudates.Granulomatous lesions are chiefly found in upper

respiratory tract involving nose, lacrymal glands, orbit, skin and paranasal sinuses.

Oral lesions impair taste, anesthesia of the soft palate and enlargement of the uvula and upper lip are described.

Treatment

Administration of tetracycline or ciprofloxacin.

If left untreated, outcome is fatal.

Noma

It means a rapidly spreading mutilating, gangrenous stomatitis that occurs usually in debilitated or nutritionally deficient persons.

Occurs chiefly in undernourished persons.

The condition is usually seen around the gingiva and progressed to destruction of the mouth and the lower lip.

Clinical Features

Treatment

The prognosis is considerably better if antibiotics are administered before the patient reaches the final stage.

Immediate treatment of any existing malnourishment further improves the probability of saving the patient.