Gram Negative Bacilli II PDF

GRAM NEGATIVE BACILLI - 2 Dr. Richard Goering INTRODUCTION Aerobic & facultatively anaerobic gramnegative bacilli Enterobactericaeae & relatives Pseudomonas & relatives Haemophilus & relatives Vibronaceae Campylobacter & relatives Haemophilus, Vibrio, Campylobacter, and Relatives Dr. Richard Goering...

GRAM NEGATIVE BACILLI - 2 Dr. Richard Goering INTRODUCTION Aerobic & facultatively anaerobic gramnegative bacilli Enterobactericaeae & relatives Pseudomonas & relatives Haemophilus & relatives Vibronaceae Campylobacter & relatives Haemophilus, Vibrio, Campylobacter, and Relatives Dr. Richard Goering INTRODUCTION Aerobic & facultatively anaerobic gramnegative bacilli Enterobactericaeae & relatives Pseudomonas & relatives Haemophilus & relatives Vibronaceae Campylobacter & relatives Haemophilus & Relatives Piratory PEKES URT of humans & animals use a lotofnutrients ingrowthmedia Nutritionally fastidious Usually primary pathogens multipleforms Gram negative pleomorphic coccobacilli shorttruncatedrods Haemophilus & Relatives Haemophilus species HACEK group Pasteurella Francisella tularensis Brucella Legionella Bordetella Haemophilus influenzae Pleomorphic coccobacilli Facultatively anaerobic Nutritionally fastidious Oxidase positive phagocytize moredifficultto Many strains encapsulated – primary virulence factor strain Type b – HIB vaccine Haemophilus influenzae Diseases Type b - meningitis, sepsis, cellulitis, septic arthritis, epiglottitis Nontypeable & other types - sinusitis, important otitis media, others eye infection Biogroup aegyptius - conjunctivitis & Brazilian purpuric fever Invasive Haemophilus influenzae MMWR Vol 64; No. 53; 8/11/17 Haemophilus influenzae Normal acute otitis media (AOM) w/ effusion Haemophilus influenzae Epidemiology Indigenous to humans Colonizes URT; person-to-person tubecanal short Primarily causes disease in children eustacian Higher rates of invasive Hib disease among American Indian/Alaskan Native children Lab diagnosis - gram stain/culture Haemophilus influenzae Treatment Life-threatening infections - 3rd gen cephalosporins, ampicillin (if ß-lactamase -) Other infections - oral agents; amoxicillin/clavulanate, 2nd gen. cephalosporins, quinolones, new macrolides, trim/sulfa Prevention – HIB vaccine; rifampin chemoprophylaxis Haemophilus parainfluenzae Growth factors help differentiate Normal flora - URT Endocarditis, otitis media, epiglottitis, conjunctivitis, pneumonia, others Lab diagnosis - gram stain & culture Treatment - similar to H. influenzae Haemophilus ducreyi Growth factors help differentiate Normal habitat is urogenital tract 44.9.4 as Causes chancroid (soft chancre) - STD Lab diagnosis - culture Treatment - erythromycin, azithromycin Yatreansmitt Haemophilus ducreyi Chancroid HACEK Group (fastidious gram-negative coccobacillary organisms) Cause 5-10% of bacterial native valve thinkendocarditisURT associated diseases endocarditis don'tmemorizeindividual Haemophilus aphrophilus Actinobacillus actinomycetemcomitans** Cardiobacterium hominis Eikenella corrodens Kingella kingae microorganisms * Now Aggregatibacter aphrophilus ** Now Aggregatibacter actinomycetemcomitans HACEK Group H. aphrophilus - normal URT flora; can also cause otitis media, conjunctivitis, epiglottis, pneumonia; Lab Dx - culture; A. actinomycetemcomitans - normal flora of genitourinary URT & GUT of humans & animals; can also cause periodontitis & brain abscess; Lab Dx culture; HACEK Group C. hominis - Bulbous ends; normal flora of URT; Lab Dx - culture; E. corrodens - long, slender; normal flora of oral cavity; also can cause oral infections & human bite wound infections; Lab Dx - culture, pits agar; K. kingae – coccobacillus; normal flora of URT; also can cause osteomyelitis & septicemia; Lab Dx - culture; Pasteurella P. multocida most common pathogen Most common cause of soft tissue infection in humans following bites or scratches from dogs and cats. Small coccobacilli Normal habitat - URT of birds & mammals, especially cats Lab diagnosis - gram stain & culture Treatment - penicillin or tetracycline Francisella tularensis Causes tularemia; biowarfare agent Fastidious; BSL 2/3 agent Found in rabbits, rodents & hares Transmission bite of infected tick handling infected animals ingesting contaminated food & water inhalation Francisella tularensis Clinical manifestations Sudden onset fever/chills Headache, myalgias, arthralgias, others Ulceroglandular form (45-80%) - skin/oral lesions; painful lymphadenopathyenlargedlymphnodes Pneumonic form - chest pain, pneumonia, hemoptysis eyeinfection Ocular, pharyngeal forms; sepsis, meningitis Pathogenesis - poorly understood Francisella tularensis Tularemia ulcer lymphadenopath y Francisella tularensis Lab Diagnosis Culture - blood, aspirate, swab of ulcer; caution - lab associated infections Serology highlyinfectiousto work with Treatment Gentamicin (streptomycin), doxycycline Alternatives - ciprofloxacin, chloramphenicol most common incentral 4.5 MMWR Vol 64; No. 53; 8/11/17 Brucella Small coccobacillus; aerobic; fastidious to be itharder relognit Biochemically inert; urease positive; makes immunologically insertthemselves in hostcell Ex gutepithelia respondedto Facultative intracellular parasites - intracellular survival in phagocytic cells Several subspecies different animals; zoonoses Middle East, Mediterranean, Latin America, SE Europe, Asia, Africa, Carribbean USA - foodborne disease - unpasteurized dairy products or undercooked meat; inhalation, or direct contact MMWR Vol 64; No. 53; 8/11/17 Brucella Fever (undulating), malaise, night sweats, myalgias, anorexia Osteomyelitis, endocarditis, other organ system infections; mortality 2% mainly due to endocarditis Diagnosis - culture (blood, bone marrow, organ tissue/fluid), serology Treatment - doxycycline + rifampin (or gentamicin) Legionella Family - Legionellaceae Obligate aerobes Nutritionally fastidious Reservoir - aqueous environment L. pneumophila - most common watercoolingsystemvents hotel “Legionnaires” disease - July 1976 Pontiac Fever - 1968 Transmission - aerosolization, aspiration, ingestion? MMWR Vol 64; No. 53; 8/11/17 Legionella Risk factors - water colonization, smoking, chronic lung disease, old age, immunosuppression Pathology - multifocal, acute, fibrinopurulent pneumonitis; intracellular survival in phagocytes Diagnosis - cxr, culture, DFA, serology, urine antigen, PCR Treatment - azithromycin, ciprofloxacin Bordetella B. pertussis & parapertussis Causes pertussis (whooping cough) Disease of childhood/adults Contagious; attack rate >90% Humans sole reservoir Transmission - aerosol route Pathogenesis – pertussis toxin, others PERTUSSIS vaccinehelp rate CDC PERTUSSIS - CLINICAL 3stages Catarrhal stage - weeks; symptoms non-specific (cold); high diagnostic recovery rate Paroxysmal stage - 1-4 weeks; violent coughing, “whoop”; poor diagnostic recovery rate Convalescent stage - symptoms slowly decrease; ≤ 6 months PERTUSSIS - DIAGNOSIS NOTpreferred Culture - NP; low sensitivity Serology - difficult to interpret PCR Test of choice NP (nasopharyngeal) aspirate or swabs Good sensitivity (60-90%); good specificity TREATMENT/PREVENTION Antibiotics not effective after catarrhal stage earlydiagnosis is keyin pertussis Antibiotics limit spread of infection Drugs of choice - erythromycin, azithromycin, trimethoprim/ sulfamethoxazole Prevention – TDaP vaccine VIBRIONACEAE & RELATIVES Vibrio cholerae Other Vibrio species Plesiomonas comma like Vibrio cholerae shortgyrated Curved gnb, oxidase +; motile Causes cholera - “a flow of bile” Clinical manifestations Acute onset of profuse watery diarrhea (rice-water) Dehydration electrolyteimbalances Altered mentation Circulatory collapse - hypotension 25-50% mortality rate if untreated Vibrio cholerae Epidemiology Habitat - algae or zooplankton; free-living Contaminated water & food; shellfish 7 pandemics in modern era 7th pandemic ongoing (since 1961) El Tor biotype of V. cholerae O1 To antigen Africa, southern Asia Recently South America, central Asia, & western Europe Vibrio cholerae Epidemiology Recent epidemics in Kenya, Congo, Somalia, Yemen Sporadic USA cases - shellfish Risk factors - malnutrition, ingestion of contaminated water or inadequately cooked helpother organismsto survive shellfish, reduced gastric acidity (H. pylori infection), poor sanitation; warmer months Vibrio cholerae Pathogenesis Large inoculum ingested Intestinal mucosa colonized; motility outerintestinal layer Penetrates mucin (mucinase) Attachment via pili Cholera toxin - major virulence factor; fluid & electrolyte secretion in intestines Other enterotoxins may be involved Vibrio cholerae Diagnosis Clinical Severe dehydration High WBC, hyperglycemia Stool culture Special selective/differential media Not routinely sought - inform lab Multiplex PCR Vibrio cholerae Treatment Rehydration & maintenance Antibiotics - tetracycline, doxycycline, quinolones or trimeth/sulfa Prevention - water treatment; Vaxchora only vaccine FDA cleared; 2 others (Dukoral & ShanChol) available elsewhere OTHER Vibrio species V. vulnificus - wound infections, septicemia V. alginolyticus - wound infections causessimilar diarrheatocholerae V. parahemolyticus - gastroenteritis, wound infections - Fecal / oral (seafood) Lab diagnosis - culture, halophilic Treatment - chloramphenicol, tetracycline, gentamicin Campylobacter & Relatives Campylobacter jejuni Other Campylobacter species Helicobacter pylori Campylobacter jejuni Curved or spiral shaped; oxidase + Common cause of infectious diarrhea (e.g., foodborne); June-August; usually sporadic Lower abdominal pain, fever, diarrhea with blood & pus usuallynotlife threatening Self-limited; 5-10% relapse if untreated Assoc with Guillein-Barre syndrome (1/1000) Exposure to animals, contaminated water; person-to-person transmission Campylobacter jejuni Pathogenesis - large inoculum; attachment; motility flagella; enterotoxin; cytotoxin; invasive Lab diagnosis - stool culture; stool antigen; multiplex PCR Treatment Rehydration Antibiotics - if given early, children, severe infections, unresolved infections Erythromycin, other macrolides, quinolones C. coli - similar to C. jejuni; C. fetus - septicemia Helicobacter pylori candegradeureaseIspliturea producegas Curved or spiral shaped, urease + Causes gastritis & peptic ulcers Associations: Gastric adenocarcinoma gastriccancers Gastric lymphomas Protection from GERD, PresenceofHPylorihelps GERD reflux SXs Nausea, vomiting, anorexia, epigastric pain, belching Worldwide; colonization increases with age Pathogenesis not well understood Helicobacter pylori Diagnosis endoscopy w/biopsy - histology, culture, urease serology - infection not disease stool antigen canspliturea3producegas breath test (urease) Treatment Protein pump inhibitor (PPI) + amoxicillin + clarithromycin PPI + bismuth salt + tetracycline + metronidazole Helicobacter pylori Gull-wing shaped Organisms in gastric biopsy