Clinical Microbiology Fifth Year

1. Bacterial infections of mouth
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Staphylococcal mucositis
Streptococci - Pharyngitis
Gonorrhea - Pharyngitis
Syphilis – Chancre
Tuberculosis – Chronic non healing
granulomatous lesions

2. Staphylococcal mucositis
• Causes severe mucositis of mouth in IC patients
• In conjunction with Candida albicans it can cause
Angular cheilitis.
• Systemic diseases – Crohn’s disease, Comatose,
Dehydrated, Elderly, patients on Intra Venous Fluids.
• Oral discomfort, mucosal erythema, crusting and
bleeding, sometimes aspiration pneumonia
• Responds to regular oral lavage, Flucloxacillin.

3. Streptococci
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Gram positive spherical bacteria
Arranged in chains or pairs
Part of normal flora of mouth
Catalase negative.
Important species - S. pyogenes, S. viridans
(viridans group), S. agalactiae, S. equisimilis
S.mutans (dental caries)

4. Virulence factors
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Pyrogenic Exotoxin
Hemolysins
Streptokinase (Fibrinolysin)
Hyaluronidase
Deoxyribonucleases (Streptodornase)

5. Pathogenicity - S. pyogenes
• Primary site of invasion is throat
• Sore throat is the most common disease.
• It may be localized as tonsillitis or diffused as
Pharyngitis
• Tonsillitis is more common in older children
and adults, Pharyngitis is common in children
• Lesions – painful, erythmatous, inflammed.

6. Viridans group (S.viridans)
• Normal residents of mouth and upper RT
• May species S. mitis, mutans, salivarius,
sanguis.
• Usually non pathogenic but can on occasions.
• Endocarditis - Following dental extraction or
other dental procedures transient bacteremia
and implanted in damaged or prosthetic heart
valves, form vegetations.
• Prophylactic antibiotic coverage is mandatory

7. Scarlet Fever by S. pyogenes
• Can affect the tongue or cheeks.
• A typically strawberry or raspberry colored
tongue is seen at an early stage.
• S. pyogenes produces scarlatinal toxin or
Pyrogenic exotoxin(super antigen)
• The rest of the mouth and throat are also
affected.

8. Dental caries by S. mutans
• Mutans – assumes bacillary forms in acidic Ph
• Breaks down dietary sucrose, producing acid
and a tough adhesive dextran.
• Acid damages dentine, dextrans bind together
food debris, epithelial cells, mucus and
bacteria to form plaques then leading to caries

9. Diagnosis and Management
• DIAGNOSIS - Throat swab - Gram stain(cocci in
chains but not confirmative)
• Culture – blood agar(hemolysis α or β no
hemolysis)
• Blood culture in endocarditis, many samples
• Antibody titer estimation.
• TREATMENT – Antibiotic sensitivity testing,
Penicillin G, Cephalosporins.

10. Gonococci - Microbiology
• Family - Neisseriaceae, Genus – Neisseria
• Gram negative oval or spherical cocci
• Diplococcus with adjacent sides concave,
typically Kidney shaped.
• Oxidase positive.
• Aerobic, non motile, non spore forming.
• Found predominantly within PMN’s in smears
• Selective medium – Thayer-Martin medium

11. Oral gonorrhea- Gonococcal pharyngitis
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Gonorrohea = flow of seeds
Primary site of infection - genitalia
Commonest site in oral cavity – Pharynx
C/F – Oral lesions are variable,
Ulceration, Pain, Edema,
Vesiculation, Inflammation,
Submandibular lymphadenopathy,

13. Contd,,,,
• Can resemble Acute Necrotizing Gingivitis
exhibiting a necrotic Pseudomembrane
covering ulcerations OR
A severe Erythematous inflammatory
response of oral mucosa.
• When seen as ulcers can be mistaken for
Streptococcal infections or Multiple aphthous
stomatitis

14. • DIAGNOSIS
-- GRAM TAIN (G-ve intracellular diplococci)
-- Culture (selective medium) Thayer-Martin
medium
--Positive oxidase test
• TREATMENT
-- Penicillin or Tetracycline
-- Ceftazidime or Ceftriaxone 2grams single
dose

15. Syphilis
• Sexually-transmitted disease (STD) produced
by Treponema pallidum, a microaerophilic
spirochete which mainly infects humans and is
able to invade practically any organ in the
body.
• 3 stages in syphils – Primary,
- Secondary
- Tertiary and
- Congenital

16. Primary syphilis
• Usually the consequence of orogenital or oroanal
contact with an infectious lesion.
• Incubation period is between one and four weeks
and range is 9- 90 days.
• Oral syphilis manifests as a SOLITARY ULCER.
• Following contact, T. pallidum penetrates the genital
or oral mucosa, multiplies at the site of entry, and
systemically spreads via the lymphatics and blood.

17. • Chancre (ulcer )– The earliest lesion is painless
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deep, erosive, indurated, red or purple or brown
base and an irregular raised border.
Always accompanied by regional lymph node
enlargement, multiple, rubbery and discrete.
Chancres contain many viable Treponemes, and are
highly infectious.
Because it is transient and painless in nature, the
initial lesion is asymptomatic.
Genital in 85% of cases, anal in 10%, and
oropharyngeal in 4%.

18. • Lip is common site in oral syphilis.
• Oral chancres are common on upper lip in
men, lower lip in women.
• The tongue, palate and nostrils are occasional
sites of chancre development.
• Diagnosis of primary syphilis
- Monoclonal antibody immuno peroxidase staining
techniques from biopsy material.
- Molecular methods in situ and tissue PCR.
- Detecting IgM antibodies to T. pallidum may detect early
infection.

20. Secondary syphilis
• Oral lesions arise in at least 30% of patients with
secondary syphilis.
• Hard palate, Buccal mucosa or Commissures.
• Occurs about 2 to 10 weeks after infection.
• Hematogenous dissemination of Treponema
pallidum from primary lesions.
• ‘Rubbery’ cervical or generalized lymphadenopathy
• 2 principal oral features are mucous patches and
maculo-papular rashes.

21. Secondary syphilis
• Muco-cutaneous lesions (papular, macular, annular
or follicular) eruption usually confined to the palate.
• Mucous patches coalesce to form ‘snail-track ulcers’
• ULCERONODULAR DISEASE (LUES MALIGNA)
explosive generalized form, fever, headache, myalgia,
papulo pustular eruption ,sharply demarcated ulcers
with hemorrhagic brown crusts, commonly on the
face and scalp (‘Moth-eaten alopecia’ Syphilitic
leukoderma-patches of hypo pigmentation)
• Condylomata lata

22. Secondary oral syphilis
with lesions on the soft
palate.
Secondary oral syphilis:
mucous patches covered
by grayish, white pseudome
mbranes of the lower
vestibular mucosa

23. Tertiary Syphilis
• After a variable period of latency, tertiary or
late stage disease develops in about one third
of untreated secondary syphilis patients.
• Manifestations may take up to 10 years to
appear and then present themselves as
benign tertiary (gummatous lesions),
Cardiovascular syphilis, or Neurosyphilis

24. Tertiary syphilis
• Gumma (manifests initially as 1 or more painless swelling,
ulceration, breakdown and healing, eventual bone destruction,
palatal perforation and oro-nasal fistula formation)
• Most commonly found on the hard palate or tongue, may be
on soft palate, lower alveolus, and parotid gland
• Osteomyelitis
• Atrophic and interstitial glossitis
• Syphilitic leukoplakia
• Syphilitic sialadenitis
• Trigeminal neuropathy (Hitzig’s syndrome)
• Argyll-Robertson pupil

25. Congenital syphilis
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Moon’s/Mulberry molars.
Hutchinson’s incisors.
Facial deformity High arched or ‘gothic’ palate
Maxillary hypoplasia ‘Bulldog’ jaw
Saddle shaped deformity of nose
Frontal bossing.
Mucous patches.
Rhagades (scars radiating from lips)
Cranial neuropathies(facial nerve paralysis)

26. Perioral fissuring
(rhagades) in a 3 yearold patient with
congenital syphilis

27. Diagnosis
• Dark field microscopy - Direct observation.
• Serology –
1. Non treponemal tests,–VDRL or RPR
2. Treponemal specific tests
FTA-ABS,
TPHA (Hem Agglutination),
MHA-TP (Microhemagglutination)
• Molecular methods – tissue PCR for all types
of syphilis.

28. Treatment
Condition
Treatment
Alternative if allergy
Primary, secondary and
early
latent syphilis
2.4 million U IM benzathine
penicillin G
Doxycycline 100 mg po bds
for 14 days or
tetracycline 500 mg po qds
for 14 days
Late latent and tetiary
syphilis
7.2 million U IM benzathine
penicillin G as three doses
of 2.4 million units at 1
week intervals
Doxycycline 100 mg po bds
for 28 days or
tetracycline 500 mg po qds
for 28 days
Retreatment (unless CSF
indicates neurosyphilis)
7.2 million U IM benzathine
penicillin G as three doses
of 2.4 million units at 1
week intervals

30. Oral Tuberculosis
• Primary infection in lungs
• Oral cavity - Primary lesions manifest as single,
painful, non healing chronic ulcers.
• Ulcer has an indurated, irregular, undermined
margin, and a necrotic base.
• Oral lesions variable –ulcerations, nodules, fissures,
plaques, granulomas.
• Most commonly the tongue, followed by the palate,
the lips, the buccal mucosa, and the gingiva
• Cervical and submandiular lymphadenopathy
• Other features of Tuberculosis mat be present.

31. Ulcer on the ventrum
of the tip of the
tongue, with slightly
elevated margins and
a wide zone of
surrounding
erythema.
Dorsum of anterior
one-third of the tongue
with erythematous,
lobulated appearance.

32. Ziehl-Neelsen stain
showing two acid-fast
bacilli (arrows)
The chronic
granulomatous lesion in
the submucosa of the lip

33. Diagnosis
• Biopsy-histological examination (caseating
granuloma), Z-N stain – AFB seen,
Fluorescent stains
• Culture : Lowenstein-Jensen medium
• Skin testing (Mantoux test)
• Molecular methods - PCR.

34. Treatment –
• Combination chemotherapy with Anti T drugs
• Anti Tubercular Treatment –
Rifampicin, Isoniazid, Streptomycin,
Ethambutol, Pyrazinamide.
• Course of Six months treatment
• 4 drug combination for first 2 months (isoniazid rifampicin,
pyrazinamide, ethambutol) – Initiation phase -followed by 4
months of two drug combination (rifampicin, isoniazid) –
continuation phase