Chapter 5: Bacterial infections Flashcards
Koch’s postulates
four criteria designed to establish a causal relation between microbe and disease
Impetigo
-‐ Arises over pre-‐existing dermatitis (impetiginized dermatitis), cuts, abrasions or insect bites
-‐ Increased in HIV, diabetes and dialysis
-‐ Non-‐bullous impetigo (impetigus contagiosa): most common. Caused by S. pyogenes. “Cornflakes glued to the skin”. DDx: exfoliative cheilitis and recurrent herpes
-‐ Bullous impetigo (staphylococcal impetigo): caused by S.aureus. Thin, brown crust (“lacquer”).
More in newborns.
Erysipela
-‐ Aka Saint Anthony’s fire. Most caused by group A, B-‐hemolytic streptococci (S.pyogene), in areas of previous trauma. Spreads through lymphatics, which become filled with leukocytes and bacteria.
-‐ Debilitated pts (diabetic, immunosupressed, obese, alcoholic) at increased risk
-‐ Most cases in leg in areas of tinea pedia (athlete’s foot)
-‐ Facial erysipelas: Butterfly rash aspect (ddx with lupus and melasma) and eyelid swelling (ddx angioedema). Orange peel texture of skin (peau d’orange)
Streptococcal tonsillitis and pharyngitis
-‐ Viral (70%) or bacterial (group A, B-‐hemolytic streptococci).
-‐ Rheumatic fever can complicate
Scarlet fever
-‐ Caused by group A, B-‐hemolytic streptococci.
-‐ Bacterial toxins attack blood vessels producing skin rash
-‐ Exanthem of tonsils, phanryx, soft palate and tongue (~ to diphteria)
-‐ Oral: white strawberry tongue (first 2 days), then red strawberry tongue (days 4-‐5)
-‐ Skin: sunburn with goose pimples; sandpaper aspect
-‐ Pastia’s line: transverse red streaks in skin folds secondary to vessel fragility in scarlet fever
Tonsillar concretions and tonsilolithiasis
-‐ Tonsillar concretions: compact mass of keratin, bacteria, and foreign material
-‐ Tonsilolith: dystrophic calcification of concretions
Diphtheria
-‐ Caused y Corynebacterium diphteria (Klebs-‐Loffer). Produces toxin that causes necrosis, causing yellow exudates in mucosal surfaces (nose, tonsils,etc)
-‐ Bull neck (edematous neck enlargement), chronic ulcers of skin (assoc w/ insect bites), paralysis, exudate of oropharynx (yellow-‐white than gray/black
Syphilis
-‐ Chancre: lesion in primary syphilis (98% genital; if oral=ulcer or PG-‐like in the upper lip of males and lower lip of females)
-‐ Secondary syphilis: widespread maculopapular skin rash, mucous patches (white mucosa from exocystosis and spongiosis), and condyloma lata (~papilloma)
-‐ Mucous patches may fuse to create serpetine or snail-‐track pattern (tongue, lip, BM, palate)
-‐ Split papules: mucous patch centered over oral commissure
-‐ Lues maligna: widespread secondary syphilis, especially in HIV+
-‐ Tertiary syphilis: vascular and CNS complications
-‐ Argyll Robertson pupil: does not react to light, but reacts to accomodation (3ary syphilis)
-‐ Gumma: granulomatous inflammation (nodule or ulcer) on palate or tongue. Can perforate palate
-‐ Interstitial glossitis: lobulated tongue with gummata in 3ary syphilis (contracture of lingual musculature after healing of gummas)
-‐ Luetic glossitis: diffuse atrophy and loss of tongue papillae
-‐ Congenital syphilis: Hutchinson’s teeth, ocular keratitis (opacified cornea), and eight nerve deafness
-‐ Hutchinson’s teeth: Hutchison incisors and mulberry molars (Fournier’s molars and Moon’s molars)
-‐ Congential syphilis: frontal bossing, short MX, high arched palate, saddle nose.
-‐ Saber shin (anterior bowing of tibia due to periostitis
-‐ Higoumenakis sign: unilateral enlargement of clavicle
-‐ Rhagades: premature perioral fissuring
-‐ Scaphoid scapula: concavity of scapulae
-‐ Clutton’s joint: painless synovitis and enlargement of joints (knees)
-‐ Stains: Whartin-‐Starry or Steiner; serology: VDRL, RPR, FTA-‐ABS (best)
-‐ Jarisch-‐Herxheiner reaction: initial response to tx seen in pts with syphilis (fever, malaise, headache, exarcebation of skin lesions) due to secondary release of endotoxin when antibiotics kill large amounts of microorganisms
Gonorrhea
-‐ Neisseria gonorrheae. Most common reportable bacterial infection in the US
-‐ More women (80% asymptomatic in W, 10% in M); 19x more in AA
-‐ Men: urethra; women: cervix
-‐ Pelvic inflammatory disease: gonorrhea in uterus and ovarian tubes (most signifc complication)
-‐ Disseminated gonorrhea: papules and pustules with hemorrhage in skin of extremities
-‐ Oral: NUG-‐like (w/o odor), aphtae-‐like in soft palate and oropharynx
-‐ Gonococcal ophtalmia neonatorum: infection with gonorrhea of infant’s eye during birth
Tuberculosis
-‐ Miliary TB: multiple small foci of infection (millet seed)
-‐ TB: lung apex, low-‐grade fever (vs pneumonia, high grade fever), cough
-‐ Lupus vulgaris: involvement of skin in TB
-‐ Consumption: wasting syndrome of the body in TB
-‐ Oral TB: chronic painless ulcer (rarely nodular, granular or leukoplakic). Primary (gingiva, mucobuccal fold, extraction site) or secondary (tongue, palate, lips)
-‐ Scrofula: infection with M.bovis causing enlargement of oropharyngeal and cervical LN (which may become calcified). Lung involvement unusual.
-‐ Tubercle: granuloma in patient with TB (histology term)
-‐ Stains: acid-‐fast and Ziehl-‐Neelsen
-‐ PPD indicates exposure only. False negative in HIV+, sarcoidosis, Hodgkin’s, and measles
-‐ TB tx: isoniazid+rifampin+pyrazinamide
-‐ BCG (Bacille Calmet-‐Guerin): vaccine against TB
Leprosy
-‐ Tuberculoid (localized) and lepromatous (diffuse)
-‐ Paucibacillary: (related to tuberculoid) few lesions
-‐ Multibacillary (related to lepromatous:): leonine fascies, collapse of nose bridge, yellow/red oral papules that ulcerate)
-‐ Facies leprosa: due to bone destruction. Triad of atrophy of anterior nasal spine, atrophy of max alveolar ridge, and endonasal inflammation
-‐ Pulp involvement: leads to red discoloration of crown (due to vascular damage)
-‐ Granulomas seen only in tuberculoid form. Few bacilli.
-‐ Lepra cells: vacuolated histiocytes, seen mainly in multibacillary lepra. Rich in bacilli.
-‐ Stains: acid fast (Fite method). Tx: rifampin
NOMA
-‐ Fusobacterium necrophorum and Prevotella intermedia
-‐ Frequently preceeded by measles, but also herpes, varicella, scarlet fever, malaria, TB, gastroenteritis, and bronchopneumonia. Also poor AIDS, cancer, poor OH, poverty, malnutrition, etc.
Actinomycosis
-‐ A.israelli or A.viscosus (gram+, silver+)
-‐ Colonies in tonsillar crypts may form concretions
-‐ Cervico-‐facial (55%), abdomino-‐pelvic (25%), pulmonary (15%) and others (skin, iliocecal, GU)
-‐ Sulfur granules (large yellow flecks representing colonies of bateria): seen in actinomycosis, but also botryomycosis (S. aureus infection). In botryomycosis, there’s abundant necrosis with admixed basophilic concretions surrounded by an eosinophilic band (Splendori-‐Hoeppli phenomenon-‐ in vivo formation of eosinophilic material around microorg)
-‐ Wooden induration of angle of MD with abscess and sinus tract; tongue; sub-‐MD gland and parotid; osteomyelitis; tonsillar hyperplasia; periapical; in cysts
-‐ Stain: Grocott methenamine silver, Brown & Brenn (B&B)
Cat-‐scratch disease
-‐ Bartonella henselae and quintana
-‐ Most common cause of chronic regional lymphadenopathy in children
-‐ Papule/pustule along scratch line; 50% single LN involved; intra-‐oral: mass in buccal mucosa
-‐ Oculoglandular syndrome of Parinaud: conjunctival granuloma and preauricular lymphadenopathy in cat-‐scratch disease
-‐ Histo: granulomatous inflammation with central stellate abscess
-‐ Stain: Wharthin-‐Starry or Brown-‐Hopps staining
-‐ Bacillary angiomatosis: subcutaneous vascular prolif caused by B.henselae. Clinically similar to KS, histologically similar to histiocytoid hemangioma
Sinusitis
-‐ Most cases due to blockage of ostiomeatal complex
-‐ Most common predisposing factors: recent upper respiratory viral infection and allergic rhinitis
-‐ Acute sinusitis: S.pneumoniae, H.influenza and M.catarrhalis
-‐ Antrolith: mucous, pus or clot undergoes dystrophic calcification. Also fungus ball and exogenous material can calcify
