Coccobacilli facultative anaerobes

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IMMUNOLOGY

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Nov 24, 2024

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Chapter 2 Acyanotic Defects MICROBRE OVERVIEW = Intermediate shape between cocci = Gram-negative, facultative anaerobes, (spherical bacteria), bacilli (rod-shaped nonmotile, nonspore-forming bacteria) BRUCELLA osms.it/brucella (" PATHOLOGY & CAUSES ) Trensmission = Contact with infected animals (e.g. sheep, cattle, goats, pigs, etc) = Entry of bacteria through skin lesions, conjunctival inoculation, inhalation of contaminated aerosol = |[ngestion of contaminated animal = Characteristics = Zoonotic infection = Urease, catalase positive = Facultatively intracellular = Sensitive to heat, ionizing radiation, products (e.g. unpasteurized milk, cheese; disinfectants, pasteurization undercooked meat) = Virulence factors = Remains viable up to two days in milk at » Lipopolysaccharide (LPS): promotes cell 8°C/46.4°F, three weeks in frozen meat, entry, evasion, intracellular killing three months in goat cheese = Type IV secretion system (key virulence L Pathogenesis factor): injection of effector molecules 9 into host cell — modifies endoplasmic = [noculation of bacteria — ingestion by reticulum, enables replication polymorphonuclears, macrophages = Culture — passage to local lymph nodes — bacteria replicates intracellularly — some bacteria avoid intracellular killing by different strategies (e.g. inducing = |solation specimen: blood, bone marrow, body fluids, tissues = Media: biphasic (solid, liquid) Ruiz- phagocyte apoptosis, inhibiting Castaneda blood culture/modern phagocyte-lysosome fusion) — chronic automated blood culture systems infection (faster, more effective) = Raised, convex colonies with smooth, TYPES shiny surface = Causative agent of brucellosis Acute infection = Most common zoonotic infection to cause = Localized infection (30% of cases), can disease in humans affect any organ OSMOSIS.ORG 349

350 OSMOSIS.ORG = Skeletal (most common): arthritis, spondylitis, sacroiliitis, osteomyelitis = Pulmonary: bronchitis, interstitial pnheumonitis, lobar pneumonia, pulmonary nodules, pleural effusion, empyema, abscesses = Cardiac: endocarditis, myocarditis, pericarditis, endarteritis = Alimentary: cholecystitis, ileitis, colitis, pancreatitis = Reticuloendothelial: reactive hepatitis, granulomas, acute hepatitis with focal necrosis (B. melitensis), formation of noncaseating sarcoidosis-like granulomas (B. abortus), suppurative abscess formation (B. suis) in liver = Genitourinary: orchitis, epididymitis = Hematological: anemia, leukopenia, thrombocytopenia, pancytopenia, disseminated intravascular coagulation = Neurologic: meningitis, encephalitis, myelitis, radiculitis, neuritis, mycotic aneurysms, brain abscess = Ocular: uveitis, keratoconjunctivitis, corneal ulcers, iridocyclitis, nummular keratitis, choroiditis, optic neuritis, papilledema, endophthalmitis = Dermatologic: nonspecific skin eruptions, ulcerations, petechiae, purpura, granumanifestationslomatous vasculitis, abscesses Chronic infection = Symptoms persist one year after diagnosis; localized infection, relapse RISK FACTORS = Occupational exposure o _ab health care workers, farmers, slaughterhouse workers, veterinarians COMPLICATIONS = Infection during pregnancy — intrauterine infection, premature delivery, spontaneous abortion, miscarriage = Endocarditis damage, destroy heart valves = | eading cause of death by brucellosis = Skeletal = May cause long-term damage, bone/ joint malformations = Neurologic = May lead to permanent brain damage = Ocular = Visual impairment LV AARN. W)Y o AV ] Liver, spleen commonly affected; causes sarcoidosis-like granulomas in liver Rare, causes mild disease Small ruminants (goats, sheep) Causes severe disease, fevers of unknown origin, hepatosplenomegaly, pancytopenia Swine, rodents Causes suppurative abscess formation in liver

( SIGNS & SYMPTOMS ) = Range from asymptomatic to severe illness = Onset of symptoms can be acute/insidious = [ncubation = 1-4 weeks to several months = Acute generalized infection = Acute undulating fever (key sign), arthralgia, myalgia, fatigue, headache, night sweats, malaise, weight loss = Hepatomegaly, splenomegaly, lymphadenopathy = Foul-smelling perspiration (characteristic sign) = Localized infection = Symptoms depend on organ/organ system affected ( DIAGNOSIS ) LAB RESULTS = Rising titers of specific antibodies = |nitial rise in IgM class titers, followed in several weeks by predominance of IgG antibodies; both decrease over time with treatment = Anemia, thrombocytopenia Microbe identification = Positive bodily fluids/tissue culture = Serum agglutination, enzyme-linked immunosorbent assay (ELISA) = Polymerase chain reaction (PCR) Chapter 64 Coccobacilli: Facultative Anaerobes = Lysis-centrifugation technique OTHER DIAGNOSTICS = History of travel, food consumption, occupation ( TREATMENT ) MEDICATIONS = Six-week course of doxycycline plus streptomycin/gentamicin/doxycycline plus rifampin = |[n children < eight years old = Trimethoprim-sulfamethoxazole (TMP- SMX) plus rifampin SURGERY = Surgical interventions sometimes necessary for osteoarticular manifestations (e.g. pyogenic joint effusions), hepatosplenic granulomas/abscesses, cardiac complications (e.g. valve replacement surgery) OTHER INTERVENTIONS = Prophylaxis = Biosafety level 3 in laboratories recommended while handling Brucella cultures o No vaccines for humans; live attenuated vaccines containing strains of B. abortus, B. melitensis used for animals OSMOSIS.ORG 351

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HAEMOPHILUS DUCREY] osms.it/haemophilus-ducreyi ( PATHOLOGY & CAUSES ) = Virulence factors = Lipooligosaccharide = Pjli: provides attachment of bacteria = Soluble cytolethal distending toxin, cytotoxic hemolysin, hemoglobin- binding protein, copper-zinc superoxide dismutase, filamentous hemagglutinin- like protein, zinc-binding periplasmic protein = Culture = |solation specimen: genital ulcer swab, lymph node aspirate = Media: enriched growth medium contains factor X (hemin), serum incubated at 33-35°C/91.4-95°F with CO.; small, heterogenous, gray/ translucent colonies = Causative agent of sexually transmitted genital ulcer called chancroid (AKA ulcus molle), associated inguinal lymphadenopathy = Some strains causes cutaneous ulcers in children in South Pacific, parts of equatorial Africa Transmission = Sexual intercourse (genital ulcers) = Nonsexual transmission (cutaneous ulcers) Pathogenesis = Incubation = 4-10 days = |[noculation through epidermal microabrasions — attachment of bacteria to extracellular matrix in skin via pil, 352 OSMOSIS.ORG lipooligosaccharide — attachment to cells via specific heat shock protein (GroEL) — cytotoxin release, epithelial injury — formation of erythematous papule — evolves into pustule — pustule ruptures, forms ulcer RISK FACTORS = Uncircumcised individuals, poverty, multiple sexual partners COMPLICATIONS » |ncreases risk for HIV contraction ( SIGNS & SYMPTOMS ) = Single/multiple painful genital ulcers on erythematous base, 1-2cm/0.39-0.79in diameter with sharply demarcated borders; base of ulcer covered with purulent exudate, bleeds easily when scraped = Predilection sites = Prepuce, coronal sulcus, glans penis in individuals who are biologically male = [ abia, vaginal introitus, perianal area in individuals who are biologically female = Individuals who are biologically female = Dysuria, dyspareunia, vaginal discharge, rectal bleeding, painful defecation = Inguinal lymphadenopathy in approx. 50% of cases {(more common in individuals who are biologically male) = Painful fluctuant buboes (swollen lymph nodes); if untreated, may spontaneously rupture, form draining sinus, releases pus

( DIAGNOSIS ) LAB RESULTS Microbe identification = Diagnosis of confirmed chancroid = Culture (not widely available) = Nucleic acid amplification tests o Not available outside of clinical research purposes = Polymerase chain reaction (PCR) multiplex = Detection of bacterial DNA = Histologic characteristics of chancroid OTHER DIAGNOSTICS = Diagnostic criteria for probable chancroid = > one painful genital ulcers = No evidence of Treponema pallidum infection (by darkfield microscopy/ serologic testing) = No evidence of Herpes simplex virus (HSV) infection = Appearance of genital ulcers, regional lymphadenopathy = Purulent exudate in superficial epidermis with perivascular, interstitial mononuclear infiltrate in dermis Chapter 64 Coccobacilli: Facultative Anaerobes Figure 641 An ulcer on the glans penis of a male with chancroid. The ulcer is typically painful, unlike the ulcer of primary syphilis. ( TREATMENT ) MEDICATIONS = Single-dose therapy with azithromycin/ ceftriaxone = Alternative = Multiple-dose therapy with ciprofloxacin/erythromycin OTHER INTERVENTIONS = Fluctuant lymphadenopathy = Needle aspiration, drainage to prevent spontaneous rupture OSMOSIS.ORG 353

354 OSMOSIS.ORG HAEMOPHILUS INFLUENZAE ~ osms.it/haemophilus-influenzae ( PATHOLOGY & CAUSES ) = Haemophilus: blood loving = Characteristics = Catalase, oxidase positive = Virulence factors = Polysaccharide capsule: prevents phagocytosis; causes ciliostasis, evades mucociliary clearance of bacteria; classified into six serotypes based on capsular antigens (A, B, C, D, E, F); some strains unencapsulated (AKA nontypable); most clinical isolates Haemophilus influenzae type B (Hib)/ nontypable = [gA1l protease, adherence factors, antigenic variation, biofilm formation = Gram stain of exudate shows bacteria arranged in chains (“school of fish”) = Culture = |solation specimen: cerebrospinal fluid (CSF), urine, serum, synovial fluid = Media: chocolate agar/Fildes medium (hemolyzed erythrocytes) with factor X (hemin), V (nicotinamide adenine dinucleotide) supplementation in aerobic, only factor X supplementation in anaerobic environment = Convex, smooth, grey/transparent colonies = Gram-negative coccobacillus — meningitis, respiratory tract infections = Nontypeable strains colonize nasopharynx of 40-80% children, adults = Hib colonizes 3—5% children TYPES Hib = Epiglottitis in older children, adults = Cellulitis (most common in young children) = Pneumonia = Sometimes with meningitis, epiglottitis = Meningitis, septic arthritis, osteomyelitis Nontypable = | ess invasive due to lack of capsule; causes mild localized respiratory tract disease in children, adults = More severe in immunocompromised/ predisposed individuals = Otitis media, sinusitis, purulent conjunctivitis, bacterial pneumonia in children (in low-income countries), neonatal bacteremia = Community-acquired pneumonia in adults with underlying lung disease = Exacerbation of chronic obstructive pulmonary disease (COPD) = Meningitis in individuals with predisposition/conditions causing leakage of CSF fluid (e.g. sinusitis, otitis media, head trauma) Transmission = Direct contact with respiratory tract secretions/airborne respiratory droplets Pathogenesis = |[noculation — passage through upper respiratory tract — adherence to respiratory epithelium, LPS inhibits mucociliary clearance — colonization spreads throughout respiratory tract — sinuses, otitis, pneumonia = |gA1 protease, antigenic variation, paracytosis, biofilm formation — perseverance of bacteria RISK FACTORS = Viral infection, sickle-cell disease, asplenia, HIV infection, malignancies, congenital deficiencies of complement components COMPLICATIONS = Nontypable in neonates, iImmunocompromised individuals — septicemia, meningitis, septic arthritis = Hib meningitis — subdural effusion/ empyema; ischemic/hemorrhagic cortical

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infarction; cerebritis (nonviral parenchymal infection of brain); ventriculitis; intracerebral abscess; hydrocephalus; neurologic seqguelae (e.g. permanent sensorineural hearing loss, seizures, intellectual disability) = Hib pneumonia can spread to pericardium — purulent pericarditis ( SIGNS & SYMPTOMS ) Hib = Meningitis = Fever, lethargy, irritability, vomiting, altered mental status = Fulminant course — rapid neurologic deterioration, respiratory arrest = Positive Kernig'’s sign: inability to straighten leg when hip flexed to 90° = Positive Brudzinski’s sign: flexing of neck by examiner — flexing of hips, knees = Epiglottitis s Fever, sore throat, difficulty speaking, dyspnea — severe stridor, dysphagia, pooling of secretions, drooling = “Tripod” posture: individual takes sitting position with trunk leaning forward, neck hyperextended, chin thrust forward to get more air through obstructed airway = Cellulitis = Fever; warm, tender area of erythema/ violaceous discoloration on cheek/ periorbital area = Septic arthritis = Fever, pain, swelling, tenderness, decreased mobility of affected joint Nontypeable = Otitis media = Fever, ear pain, irritability, sleep disturbance, otorrhea = Red bulging tympanic membrane with decreased mobility upon pneumatic otoscopy examination = Often conjoined with conjunctivitis = Sinusitis = Fever, persistent purulent nasal discharge or cough > 10 days = Tenderness over involved paranasal sinuses Chapter 64 Coccobacilli: Facultative Anaerobes ( DIAGNOSIS ) DIAGNOSTIC IMAGING Laryngoscopy = Red, swollen epiglottis; aryepiglottic folds = Examine with caution; possible laryngeal spasm X-ray = Thumb sign on epiglottis (radiographic corollary of omega sign) LAB RESULTS Microbe identification = Positive Gram stain, bacterial culture of CSF, synovial fluid, epiglottis, pleural, pericardial, other sterile fluids = [ atex agglutination, enzyme immunoassay, coagglutination = Type B capsular antigen detection in CSF, serum, urine = Definitive diagnosis = Culture of fluid obtained by sinus aspiration, tympanocentesis, tracheal/ lung aspiration, bronchoscopy, bronchoalveolar lavage Figure 64.2 An X-ray image of the chest demonstrating diffuse airway shadows in an individual with bronchopneumonia. H. influenzae is a causative organism of bronchopneumonia. OSMOSIS.ORG 355

OSMOSIS.ORG ( TREATMENT ) MEDICATIONS Prevention = Conjugate Hib vaccines o Routine vaccination of infants of two months = Rifampin chemoprophylaxis o Individuals in close contact with infected; incompletely vaccinated individuals in households with infants/ children < four years old Hib with meningitis = Third generation cephalosporins = Adults: ceftriaxone = Children: ceftriaxone plus dexamethasone (decreases immune response to released LPS upon bacterial death, lowers chance for destruction of neurons, neurologic sequelae) = Epiglottitis (life-threatening condition; prompt treatment paramount) = Ceftriaxone Nontypable = Amoxicillin/clavulanate, broad-spectrum cephalosporins, macrolides (azithromycin/ clarithromycin), fluoroguinolones SURGERY = Epiglottitis = Placement of artificial airway PASTEURELLA MULTOCIDA osms.it/pasteurella-multocida ( PATHOLOGY & CAUSES ) = Characteristics = Zoonotic infection (e.g. birds, cats, dogs, rabbits, cattle, pigs); oxidase, catalase, nitrate reduction positive = Virulence factors = Polysaccharide capsule: prevents phagocytosis; divided into serogroups based on capsular antigens (A, B, C, D, E) = Lipopolysaccharide: endotoxin = Sialidases, hyaluronidase, surface adhesins, iron acquisition proteins, pasteurella multocida toxin (PMT) = Culture = |solation specimen: respiratory tract samples, CSF = Media: sheep blood, chocolate, HS, Mueller—-Hinton agar at 37°C/98.6F; opague/gray colonies 1-2mm in diameter = Medically important subspecies = P, multocida subsp multocida, P. multocida subsp septica, P. multocida subsp gallicida Transmission = Most commonly cat/dog bites, scratches, licks TYPES = Soft tissue infections = Cellulitis at site of inoculation (most common) — abscess, necrotizing soft tissue infections, septic arthritis, osteomyelitis = Respiratory infections = Due to underlying chronic pulmonary disease; glossitis, pharyngitis, sinusitis, otitis media, epiglottitis, tracheobronchitis, pneumonia, empyema, lung abscess = Invasive infection (immunocompromised, infants) = Bacteremia, meningitis, intra-abdominal infections (peritonitis, appendicitis), endocarditis, septic arthritis, ocular infection

Chapter 64 Coccobacilli: Facultative Anaerobes Pathogenesis = [noculation — attachment of bacteria to ( D'AGNOS|S ) e e~ LABRESULTS Microbe identification COMPLICATIONS = Culture, PCR, serological testing = Sepsis, septic shock OTHER DIAGNOSTICS C SIGNS & SYMPTOMS ) = History of animal contact = Cat bites pose higher risk for developing . Soft tissue infections osteomyelitis, septic arthritis o Wound inflammation, cellulitis with purulent drainage; regional C TREATMENT ) lymphadenopathy Respiratory tract infections MEDICATIONS = Fever, malaise, dyspnea, pleuritic chest = Penicillins pain = Tetracyclines = Cephalosporins = Quinolones = Sepsis = Purpura fulminans (rash rapidly progresses from petechiae, purpura to gangrene/limb amputation) = Respiratory infection = Wheezing, rhonchi, dullness OSMOSIS.ORG 357

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Coccobacilli facultative anaerobes

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