Haemophilus, HACEK, Pasteurella, Brucella, Francisella Supplemental Notes (2024) - PDF

BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON Haemophilus Genus influenza. Later determined to be a secondary Morphology: Gram-negative, pleomorphic invader rather than the primary causati...

BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON Haemophilus Genus influenza. Later determined to be a secondary Morphology: Gram-negative, pleomorphic invader rather than the primary causative agent coccobacilli or rods; can appear as small of influenza. coccobacilli or long filaments. Virulence Factors Growth Conditions: Nonmotile, facultatively Capsule: anaerobic, ferment carbohydrates. o Major virulence factor; responsible for Biochemical Properties: serologic grouping (a, b, c, d, e, f). Generally oxidase and catalase positive. o Type b (Hib): Previously a leading cause of Reduce nitrates to nitrites. invasive infections in children; now less Nutritional Requirements: common due to vaccination. Characterized Obligate parasites on mucous membranes; by polyribitol phosphate, providing require preformed growth factors from antiphagocytic properties. blood (X factor: hemin/hematin, V factor: o Non-typeable Strains: Lack capsule; NAD). associated with less severe, localized Growth Media: infections. o Chocolate (CHOC) Agar: Contains lysed red Immunoglobulin A (IgA) Proteases: blood cells, providing both X and V factors; Cleaves secretory IgA, aiding in evading inactivates NADases. immune responses. o Sheep Blood Agar (SBA): Only supports Adherence Mechanisms: growth of organisms requiring X factor; V Strain Differences: Most non-typeable factor dependent Haemophilus spp. may strains adhere to epithelial cells; display satellitism around V factor- Type b strains generally do not, which producing organisms. may contribute to their propensity for Species Associated with Humans: systemic infections. Pathogenic: H. influenzae, H. aegyptius, Outer Membrane Components: H. ducreyi Proteins and LPS: Contribute to Non-pathogenic or Opportunistic: H. invasiveness, attachment, and parainfluenzae, H. haemolyticus, H. antiphagocytic functions. LPS can parahaemolyticus, H. paralyze ciliated respiratory paraphrohaemolyticus, H. pittmaniae, epithelium. H. aegyptius, H. ducreyi Historical Note: H. segnis renamed Clinical Manifestations of Haemophilus Aggregatibacter segnis, H. aphrophilus influenzae Infections and H. paraphrophilus combined into A. Disease Patterns aphrophilus. Invasive Disease (Encapsulated Strains) o Septicemia Haemophilus influenzae o Meningitis Historic Perspective o Arthritis Initial Misidentification: Originally named o Epiglottitis during the 1889-1890 influenza pandemic due o Tracheitis to frequent isolation from patients with o Pneumonia BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON Localized Disease (Non-Typeable Strains - Current Statistics NTHi) United States: o Conjunctivitis o 70% of invasive H. influenzae infections o Sinusitis are caused by NTHi strains. o Otitis Media (middle ear o Serotype f accounts for 18% of invasive infections) infections. Note: H. influenzae, along with Streptococcus o Annual estimates: 6100 invasive cases pneumoniae, is a common cause of middle ear and 1015 deaths. infections in children. Adenoids can act as Developing Countries: reservoirs, leading to chronic infections and o Serotype b: Remains a significant cause biofilm formation. of bacterial pneumonia and meningitis deaths in children due to lack of Infections in Specific Populations vaccination. Children: o o Middle Ear Infections: Common; NTHi Infections Associated with Other Haemophilus strains can lead to chronic infections. Species o Meningitis: Predominantly caused by H. Haemophilus aegyptius influenzae serotype b (Hib) before Conjunctivitis: Acute, contagious widespread vaccination. Symptoms include "pinkeye." headache, stiff neck, and respiratory disease. Haemophilus influenzae Biogroup aegyptius o Epiglottitis: Rapid onset with acute Brazilian Purpuric Fever (BPF): Severe inflammation and intense edema of the systemic disease with high mortality. epiglottis, which can cause airway Characterized by conjunctivitis, high obstruction. fever, petechial rash, septicemia, and o Bacterial Tracheitis: Life-threatening shock. condition that can follow a viral respiratory infection. Requires prompt treatment with Haemophilus ducreyi broad-spectrum antibiotics. Chancroid: A highly communicable genital ulcer disease. Causes Adults: nonindurated, painful lesions and o Localized Infections: NTHi strains can inguinal lymphadenopathy. Common in cause bronchitis and pneumonia, Latin America, Africa, and Asia; especially in those with risk factors such as underreported in the U.S. smoking, chronic obstructive pulmonary Miscellaneous Species disease, or concurrent infections. H. parainfluenzae: Low pathogenicity; o Invasive Infections: NTHi strains can may cause otitis media, acute sinusitis, occasionally cause meningitis and neonatal and rare endocarditis (often post-dental sepsis, particularly in procedures). immunocompromised or debilitated H. parahaemolyticus: Rarely causes individuals. pharyngitis. BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON Laboratory Diagnosis of Haemophilus spp. Colony Morphology Specimen Processing and Isolation H. influenzae: Smooth, convex colonies Common Specimens: Blood, CSF, with a distinct odor. middle ear exudate, joint fluids, H. ducreyi: Small, flat, tan or yellow respiratory tract specimens, colonies with a "clumpy" appearance. conjunctivae swabs, vaginal swabs, H. aegyptius: Similar to H. influenzae abscess drainage. but requires enriched media. Special Notes: Microscopic Morphology o Respiratory Specimens: Bronchial Small, gram-negative coccobacilli or washing is preferred. Nasal and filaments. nasopharyngeal swabs are less valuable. Capsules may appear as clear halos o Genital Specimens for H. ducreyi: Clean around organisms. with saline, use moistened swab or Microscopic examination may show aspirate pus, and plate directly. “school of fish” or “railroad tracks” o Prompt Processing: Haemophilus spp. patterns for H. ducreyi. die rapidly; prompt processing and immediate culture are crucial. Laboratory Identification X Factor and V Factor Requirements: Culture Media and Growth Conditions o H. influenzae: Requires both X H. influenzae: (heme) and V (NAD) factors. o Chocolate (CHOC) agar with bacitracin o Testing Method: Use of (300 mg/L). impregnated strips or disks. o Incubate at 33°-37°C in 5-10% CO2. Porphyrin Test o Growth: Translucent, tannish colonies o Differentiates heme-producing with a "mousy" odor after 18-24 hours. species. o Principle of the test is based on H. ducreyi and H. aegyptius: the ability of the organism to o Enriched CHOC agar or Nairobi biplate; convert the substrate δ- H. ducreyi grows best at 33°C. aminolevulinic acid (ALA) into o Incubate in high humidity with 5-10% porphyrins or porphobilinogen, CO2. which are intermediates in the o Growth: Small, flat colonies for H. synthesis of X factor ducreyi; for H. aegyptius, enriched CHOC o H. influenzae: Negative (no agar with IsoVitaleX or Vitox. fluorescence or color change). Other Haemophilus spp.: Biochemical Tests: H. parainfluenzae: Tannish, drier o Tests: Carbohydrate fermentation, colonies. indole, urease, and ornithine H. parahaemolyticus: β-hemolytic on decarboxylase. horse/rabbit blood agar. o Systems: RapID-NH, Crystal Neisseria/Haemophilus, NH ID Card. BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON Antimicrobial Susceptibility Testing Key HACEK Members Recommended Treatments: Aggregatibacter aphrophilus o Invasive H. influenzae: Cefotaxime, Found in dental plaque and gingival ceftriaxone, alternative options include scrapings; involved in endocarditis and trimethoprim-sulfamethoxazole, bone/joint infections. imipenem, ciprofloxacin. Convex, granular, yellow colonies with o Non-Life-threatening H. influenzae: an opaque zone on CHOC agar. Amoxicillin-clavulanate, Growth: Better in CO2; V factor– second/third-generation dependent and V factor–independent cephalosporins. strains. H. ducreyi: Azithromycin, ceftriaxone, Aggregatibacter actinomycetemcomitans ciprofloxacin, erythromycin. Previously classified as Actinobacillus. Resistance Detection: Linked to periodontitis and o β-lactamase Production: Use endocarditis. chromogenic cephalosporin test Major virulence factors include (Cefinase) or acidometric tests. collagenase and a leukotoxin that is o Tests: Nitrocefin for β-lactamase activity; toxic to polymorphonuclear cells and pH indicator strips for acidometric monocytes testing. Colony Morphology: “Star shape with four to six points” on SBA after 48 HACEK is an acronym for a group of gram- hours; granular in broth. negative bacilli known for their fastidious Growth: Requires CO2; slow growth. growth requirements and association with Biochemical Reactions: Catalase endocarditis. The group includes: positive, oxidase variable, does not Haemophilus spp. (e.g., H. grow on MAC agar. Urease negative, paraphrophilus) glucose fermentation positive. Aggregatibacter Treatment: Sensitive to penicillin, actinomycetemcomitans (formerly aminoglycosides, third-generation Actinobacillus actinomycetemcomitans cephalosporins, quinolones, and A. aphrophilus) chloramphenicol, and tetracycline. Cardiobacterium hominis Resistance to vancomycin and Eikenella corrodens erythromycin is common. Kingella spp. Cardiobacterium hominis Common Features: Normal microbiota of the nose, mouth, Fastidious Growth: Requires special throat, and GI tract; often associated growth conditions, including increased with endocarditis, sometimes CO2 levels. meningitis. Endocarditis: Often associated with Slow growth on SBA and CHOC agar; heart valve infections, particularly produces "pitting." Forms rosettes or prosthetic or damaged valves. sticklike structures. BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON Biochemical Reactions: Oxidase o Oxidase positive positive, catalase negative, indole o Asaccharolytic positive. Ferments weakly; serum may o Catalase negative be needed. o Yellow pigment production Treatment: Sensitive to β-lactams, Colony Appearance: chloramphenicol, and tetracycline. o Pit or Corrode “Corroding” : About 45% Variable response to aminoglycosides, of isolates pit the agar surface. erythromycin, clindamycin, and o Odor: May have a chlorine bleach-like vancomycin. smell. Media Growth: Key Reactions and Characteristics of HACEK o Nonhemolytic on SBA but may show Organisms slight greening. Enhanced by CO2; generally slow- o Does not grow on MAC or EMB agar. growing. o In broth, may adhere to sides and Fastidious, often requiring specific produce granules. growth conditions and media. Antibiotic Sensitivity: Opportunistic pathogens, particularly in Sensitive: Penicillin, ampicillin, individuals with compromised health. cefoxitin, chloramphenicol, carbenicillin, imipenem. Resistant: Clindamycin, narrow- Eikenella corrodens spectrum cephalosporins. Normal biota found in the oral and bowel cavities. Kingella spp. Infections: Associated with trauma, K. kingae (important in pediatric especially human bites or fights (e.g., osteoarthritis) clenched fist wounds). Also linked to K. denitrificans poor dental hygiene, oral surgery, and K. oralis infections in immunocompromised K. potus individuals. Clinical Significance: Clinical Manifestations: K. kingae: Common cause of osteoarthritis in Cause of Adult Periodontitis, children; also associated with HACEK meningitis, empyema, pneumonia, endocarditis, especially in osteomyelitis, arthritis, postoperative immunocompromised individuals. tissue infections. K. denitrificans: Associated with endocarditis. In drug addicts, can cause cellulitis due to oral contamination of needles. Growth and Characteristics: Growth and Characteristics: Morphology: Coccobacillary to short Morphology: Gram-negative coccobacilli. bacilli with squared ends, forming pairs Growth Conditions: Best under increased CO2 or short chains. with hemin. Staining: Tends to resist decolorization Biochemical Reactions: in Gram stains. o Nonmotile BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON Growth Conditions: Antibiotic Sensitivity: o Nutritionally fastidious Sensitive: Imipenem, erythromycin, o Oxidase positive clindamycin, tetracycline, o Catalase negative chloramphenicol, quinolones, β- o Ferment glucose and other sugars with lactams. no gas. Resistant: Aminoglycosides. Media Growth: Treatment for C. canimorsus and C. o Can grow on Neisseria selective agar cynodegmi infections: Penicillin. (e.g., MTM medium) and may resemble Pasteurella N. gonorrhoeae. Zoonosis: Acquired from animal bites or Colony Morphology: exposure to infected animals/products. o K. kingae: Two types—spreading, Common Presentation: Cutaneous corroding colonies or smooth, convex, β- infections from animal bites, especially hemolytic colonies. feline. o K. denitrificans: Two types—smooth, Species: convex or spreading, corroding. P. multocida: Most frequently isolated; Antibiotic Sensitivity: includes P. multocida, P. septica, P. Generally susceptible to penicillin. gallicida. Others: P. canis, P. stomatis, P. Capnocytophaga dagmatis. Infections: Associated with septicemias, Growth and Characteristics: soft tissue infections, peritonitis, and Morphology: Gram-negative, nonmotile, endocarditis. C. canimorsus and C. facultative anaerobic coccobacilli; may appear cynodegmi are linked to severe ovoid or filamentous. infections from animal bites. Staining: Bipolar staining (safety pin Growth and Characteristics: appearance). Morphology: Thin, fusiform, spindle-shaped Biochemical Reactions: bacilli; may exhibit gliding motility. o Catalase and oxidase positive (most Growth Conditions: Requires increased CO2. isolates). Pigmentation: Colonies often have a yellow- o Ferment glucose with weak to moderate orange pigment. acid production without gas. Biochemical Reactions: Media Growth: o Ferment sucrose, glucose, maltose, o Grows on SBA and CHOC agar, producing lactose. grayish colonies. o Nonhemolytic except C. haemolytica (β- o Does not grow on MAC agar. hemolytic). o P. multocida may produce mucoid o Oxidase and catalase negative for most colonies with a green-to-brown halo after species; positive for C. canimorsus and C. 48 hours. cynodegmi. Antibiotic Sensitivity: Media Growth: Often adherent colonies on Sensitive: Penicillin, with some agar. May resemble E. corrodens. variation in susceptibility based on species. BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON Brucella spp. o Onset: Usually within a year of Disease: Brucellosis, a zoonotic infection with exposure. global distribution. Chronic Stage: Species: Six terrestrial species; four commonly o Symptoms: Depression, arthritis, chronic associated with human illness: fatigue syndrome. o B. melitensis o Onset: Commonly manifests 1 year or o B. abortus more after exposure. o B. suis o o B. canis Morphology: Small, gram-negative, aerobic, Two additional species: nonmotile, unencapsulated coccobacilli or o B. ovis bacilli. o B. neotomae Colony Appearance: Smooth, raised, Marine Mammals: Recent years have seen translucent colonies on agar. additional species isolated from marine Intracellular Pathogen: Facultative intracellular, mammals. residing within mononuclear phagocytic cells. Bioterrorism: Considered a category B select biological agent due to its ease of dissemination Diagnosis: and moderate morbidity. Direct Examination: Often challenging; typically involves blood or bone marrow samples. Epidemiology and Transmission: o Acute cases: 50-80% yield positive blood Risk Groups: Veterinarians, hunters, laboratory cultures. workers, and individuals exposed to animals or o Chronic cases: Only about 5% yield positive animal products. cultures. Transmission Routes: Aerosol, percutaneous, Serology: Frequently used in conjunction with and oral (e.g., ingestion of unpasteurized milk). patient history and disease status for diagnosis. Rarely transmitted person-to-person through Culture Growth: sexual contact or breastfeeding. o Requires CO2; grows on SBA and CHOC Reportable Disease: Brucellosis is reportable agar. due to public health implications, with o Can also be isolated on MTM or Martin- approximately 100 cases reported annually. Lewis media. Clinical Presentation: o Growth usually appears within 18 hours; Acute Stage: plates should be held for 4 days before o Symptoms: Fever, malaise, headache, being reported as negative. anorexia, arthralgia, myalgia, and back Biochemical Reactions: pain. Oxidase: Positive o Onset: Typically 1 to 4 weeks post- Catalase: Positive exposure. Urease: Positive within 2 hours Subchronic/Undulant Stage: Differentiation: o Symptoms: Undulating fevers (rise in Biochemical Tests: Urease positivity the afternoon/evening, fall in the helps differentiate Brucella from similar morning), arthritis, epididymoorchitis. organisms (e.g., Bordetella BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON bronchiseptica, Acinetobacter spp., H. o Ulceroglandular: Ulcer at inoculation influenzae). site with regional lymph node Colony Morphology: Combined with growth on enlargement. SBA and biochemical tests. o Pneumonic: Contracted via inhalation. o Glandular, Oropharyngeal, Safety and Handling: Oculoglandular, Typhoidal Forms. Biosafety Level: Brucella spp. should be handled under biosafety level 3 conditions due Case Fatality Rate: 2% to 9% in the U.S. to aerosol transmission. Symptoms: Vary by form but may include fever, Laboratory Risk: About 2% of cases are ulcer formation, swollen lymph nodes, laboratory-acquired; risk of infection from pneumonia, and systemic symptoms. laboratory exposure ranges from 30% to 100% depending on several factors. Morphology: Small, nonmotile, gram-negative bacilli or coccoid bacteria. Francisella spp. Growth Requirements: Strictly aerobic and F. tularensis (primary species causing human fastidious. infections) Media: Requires supplementation with Subspecies: cysteine, cystine, or thiosulfate. Can be grown ▪ F. tularensis subsp. tularensis (Type A): on CHOC, MTM, and buffered charcoal yeast Causes the most severe disease. extract (BCYE) agars, and thioglycollate broth. ▪ F. tularensis subsp. holarctica (Type B): Avoidance: Broth cultures are not Produces a similar disease but is less fatal. recommended due to aerosol risk. ▪ F. tularensis subsp. mediasiatica: Less Growth Characteristics: commonly associated with human disease. o Media Support: MAC and EMB agars do ▪ Other Species: At least seven more species, not support growth. less commonly associated with human o Incubation: Growth may not be visible infections. before 48 hours at 37°C. Plates should be Disease: Tularemia checked daily for 14 days. Alternate Names: Rabbit fever, deerfly fever, o Colony Appearance: Gray-white, raised lemming fever, water rat trappers' disease. colonies with a smooth appearance. Transmission: Biochemical Reactions: o Routes: Ingestion, inhalation, arthropod Oxidase: Negative bites (ticks, biting flies), or contact with Urease: Negative infected tissues. Catalase: Weakly positive o Incidence: About 100 cases reported β-lactamase Activity: Positive annually in the U.S. Satellite or X and V Test: Negative CDC Classification: Category A select biological agent due to ease of dissemination Diagnosis: and potential for high mortality. Presumptive Identification: Clinical Presentation: Tests: Direct fluorescent antibody (DFA), Common Forms (45% to 80% of cases): immunohistologic staining with monoclonal BACTERIOLOGY LEC 3YZ 2024 HAEMOPHILUS, HACEK, PASTEURELLA, BRUCELLA, FRANCISELLA SUPPLEMENTAL NOTES - CPSACOPON antibody, PCR, slide agglutination, or single serology test. Confirmation: Culture identification or a fourfold increase in antibody titer. Alternative Methods: MALDI-TOF MS for accurate identification of Francisella strains and subspecies. Safety and Handling: Infectious Dose: As few as 50 organisms can cause infection. Laboratory Acquired Infections: Notable cases of infections in laboratory settings, including incidents at Boston University. Biosafety Level: Should be handled under biosafety level 3 conditions due to high infectious risk.