Microbiology - Block 2 - Part 4

davidwurbel7's version from 2015-07-06 03:39

Streptococcus pneumonia

Question Answer
GPC diplococcus, capsule. Catalase negative (-), Alpha-hemolytic on BA, Bile soluble, Optochin sensitive. Positive quellung reaction(Detects capsule)Streptococcus pneumonia
Predisposing factors include antecedent viral resp. infection with influenza or measles infection, Chronic obstructive pulmonary disease (COPD) and Asplenia predisposes to septicemiaStreptococcus pneumonia
Secretory IgA protease protects this organism by cleaving IgAStreptococcus pneumonia
Streptococcus pneumonia is protected from secreted immunoglobulin by thisSecretory IgA Protease
This structure of Streptococcus pneumonia is antiphagocyticPolysaccharide capsule
A cytotoxin that binds to host cell membranes creating pores and destroys host cells mostly ciliated epithelial cells and phagocytic cellsPneumolysin
Organism the can cause Pneumonia, Meningitis, Otitis media and SinusitisStreptococcus pneumonia
MCC of community-acquired lobar pneumoniaStreptococcus pneumonia
Abrupt onset – shaking chills, high fever. Productive cough with blood-tinged sputum. Usually localized to lower lobesLobar Pneumonia
MCC of adult meningitisStreptococcus pneumonia
Acute onset with high fever, nuchal rigidity, photophobia (increased sensitivity to light), altered mental status (confusion), nausea and/or vomitingBacteria Meningitis
CSF presents with High neutrophils, Low glucose, Gram stain - Numerous neutrophils + GPC pairs with capsular antigen detected in CSFBacteria Meningitis
One of the most common causes of sinusitis and otitis mediaStreptococcus pneumonia
Empiric therapy for serious pneumococcal infectionsVancomycin + Ceftriaxone
Once antibiotic sensitivity test (AST) results available use onlyMono-Antibiotic Therapy
Drug of choice for otitis media and sinusitis in childrenErythromycin
High risk patients which include asplenic and elderly in nursing homes should receiveVaccination

Streptococcus Viridians

Question Answer
GPC chains. Alpha-hemolytic on BA, Catalase negative (-), Bile insoluble, Optochin insensitive. Positive quellung reaction(Detects capsule). Normal flora in the oropharynxStreptococcus Viridians
Plaque & dental cariesStreptococcus mutans
MCC of subacute bacterial endocarditisStreptococcus Viridians
Infection of previously damaged heart valves. Infection is slow progressionStreptococcus Viridians
Treatment for endocarditisPenicillin G + aminoglycoside

Streptococcus bovis

Question Answer
Gram positive coccus chains, catalase – Alpha or non-hemolytic. Does not grow in 6.5%NaClStreptococcus bovis
Strongly associated with underlying malignancy or premalignant lesions of the colon Streptococcus bovis
MCC of endocarditis in those with gastro-intestinal malignancies (cancer colon)Streptococcus bovis
If Strep bovis is isolated in blood cultures of a patient (S.bovis bacteremia) → evaluate the patient forGastrointestinal Malignancy
Mostly sensitive to penicillins and other antibioticsStreptococcus bovis


Question Answer
Gram positive cocci (pairs and short chains). Catalase negative. Grow in presence of 6.5%NaCl. Hydrolyze esculin in 40% bileEnterococcus
Urinary tract infections, Peritonitis, biliary tract infections and Subacute endocarditisEnterococcus
Urinary tract infection in hospitalized pts with indwelling catheter on broad-spectrum antibioticsEnterococcus
Pts acutely ill with abdominal pain, swelling, fever, and positive blood culturesPeritonitis
Those with previously damaged heart valves. Associated with persistent bacteremiaSubacute Endocarditis
Resistance to aminoglycosides and penicillin/ampicillin emerging Vancomycin-resistant strains (VRE)Enterococcus
Linezolid, Quinupristin/daflopristin, Selected fluoroquinolones used to treatMulti-Drug Resistant Enternococcus
Prophylactic use of this in pts with damaged heart valves before urinary tract/intestinal manipulationsPenicillin and Gentamycin
Gram positive rod/bacillus (GPR). Cuneiform “chinese letter” arrangement. Highly contagiousCorynebacterium diphtheriae
Patient in severe respiratory distress, respiratory stridor. Exudative pharyngitis with a yellowish, leathery thick adherent membrane extending to uvula and soft palate. Marked bilateral cervical lymphadenopathyDiphtheria
Exotoxin produced by Corynebacterium diphtheriaeDiphtheria toxin
Inhibits protein synthesis – ribosylation of EF-2 is the mechanism of action ofDiphtheria Toxin
Heart and nerve tissues are targets of this toxinDiphtheria Toxin
Diphtheria toxin is this type of toxinA-B Component Toxin
Complications include myocarditis with cardiac arrhythmias, inflammation and damage of nerves, paralysis of soft palate and recurrent laryngeal nerve palsyDiphtheria Toxin
Corynebacterium diphtheriae on Tellurite medium / Tinsdale produce this color coloniesBlack Colonies
Elek test showsToxin Demonstration
Treatment for diphtheria includesErythromycin/Penicillin + Antitoxin
Treatment for diphtheria with complications involving heartIntravenous penicillin + aminoglycoside for 4-6 weeks

Listeria Monocytogenes

Question Answer
Small Gram positive rod. Facultative Intracellular parasite. Tumbling motility. Cold growth - Grows at refrigeration temps. Transmission - Foodborne. Across the placenta (mother to fetus)Listeria monocytogenes
Soft cheeses. Deli meats. Cabbages (coleslaw). Unpasteurized milk products are associated with this bacteriaListeria monocytogenes
Allows Listeria to escape from phagosomeListeriolysin-O
Once inside a host cell, Listeria assembies actin filaments for motilityActin-Jet Filament
Antibodies to Listeria are ineffective because Listeria isFacultative Intercellular Parasite
Cellular immunity important for clearance of this bacteria and individuals with impaired cell-mediated immunity are at risk for severe infectionsListeria monocytogenes
May present with fever, fatigue, aches may result in fetal loss (miscarriage)Pregnant Woman
May present with early-onset disease – granulomatosis infantiseptica. Late-onset disease - Septicemia and meningitis inNewborns
May present with septicemia and meningitisImmunocompromised and Geriatrics
Early - onset disease acquired transplacentally. Disseminated abscesses and granulomas. Baby will die unless treated quickly. Also causes spontaneous abortionGranulomatosis Infantiseptica
Late - onset disease → occurs at 2-3 weeks. Transmission during delivery. Usually accompanied by septicemia. Cannot be differentiated clinically from other neonatal meningitidesMeningitis
Gram stain of CSF . Tumbling motility. Cultured in cold enrichmentLab Diagnosis - Listeria
Treatment of Listeria meningitisPenicillin/Ampicillin + Gentamycin
Listeria are resistant to this group of antibioticsCephalosporins

Minor Gram Positive Rod Bacteria

Question Answer
Gram positive rod. Pathogen and colonizer of animals, mammals, birds, fish, especially turkeys and swineErysipelothrix rhusiopathiae
Infection is usually zoonotic and primarily occupational such as with abattoir workers, butchers, veterinariansErysipelothrix rhusiopathiae
Local swelling and redness of skin. Does not suppurate (No pus). Self limited, but can treat with antibiotics. Rarely bacteremia, sepsis, and endocarditisErysipeloid
Gram-positive rods. Normal flora of the GI tract and vagina which it is Important in maintaining pH of 4.5. Non-pathogenic and used as a probioticLactobacillus
Gram-positive rods. Normal flora of skin. Implicated in acne vulgaris. Common contaminants of blood cultures and body fluid culturesPropionibacterium


Question Answer
Large gram positive rods (long chains). Produce endospores. Found in environmentBacillus
Causes food poisoning. Emetic form and Diarrheal form, Ocular infectionsBacillus cereus
Causes anthrax - cutaneous, pulmonary or gastrointestinalBacillus anthracis
GPR, forms endospores. Causes food poisoning and ocular infections (following trauma). Enterotoxins - heat-stable, proteolysis-resistant enterotoxin – emesis. Heat-labile enterotoxin - diarrheaBacillus cereus
Contaminated rice. Also potato, pasta and cheese dishes. heat-stable enterotoxin. Vomiting, nausea, cramps within 1 – 6 hours. Lasts less than a day with no fever, no diarrheaEmetic Form Bacillus cereus
Associated with meat, fish, vegetables, or sauces. Diarrhea, abdominal cramps, nausea. Incubation is longer → 6-14 hoursDiarrheal Form Bacillus cereus
Follow penetrating injury to the eye (fish hook, metal sliver)Ocular Infections Bacillus cereus
Primarily disease of herbivores. Human infections - Contact with infected animals/products (wool/hides). Wool-sorter’s & hide-porter’s disease. Occupational hazard - Handlers of processed hides, goat hair, wool, bone products, infected wildlifeBacillus anthracis
Spores can be used as agent of bio-warfare or bio-terrorismBacillus anthracis
Gram positive rod, spore-former. Capsule – poly-D-glutamate (polypeptide). Edema factor (EF), Lethal factor (LF), Protective antigen (PA)Bacillus anthracis
Capsule (glutamate capsule) that is anti-phagocyticBacullus anthracis
Edema toxin - Calmodulin-dependent adenylate cyclase. Increases cyclic AMP → severe edema. Lethal toxin - Zinc-metalloprotease leading to tissue necrosisBacillus anthracis
Toxin produced by Bacillus anthracis that is Calmodulin-dependent adenylate cyclase. Increases cyclic AMP → severe edemaEdema Toxin
Toxin produced by Bacillus anthracis that is Zinc-metalloprotease leading to tissue necrosisLethal Toxin
Cutaneous anthrax is also known asHide-Porter's Disease
95% cases of anthrax . Central black eschar * with surrounding pustules “malignant pustule”. Marked extensive edemaCutaneous Anthrax
Pulmonary anthrax is also known asWoolsorter’s Disease
Inhalation of spores. Incubation period 1-5 days. Phase 1: insidious onset with a low grade fever, malaise, nonproductive cough and occasional complaint of substernal discomfort. Resembles viral respiratory tract infection. There is a temporary resolution of symptoms. Phase 2 sudden onset of high fever, tachycardia, tachypnea and severe chest pain. Examination: widened mediastinum, enlarged hilar lymph nodes, pleural effusionsPulmonary Anthrax
Ciprofloxacin or Doxycycline is the treatment forAnthrax


Question Answer
Gram positive Rods, Obligate anaerobes. Sporeforming. Found in soil. Produces toxins - Enterotoxin a and Cytotoxin bClostridium
Clostridium tetani causes this disease or conditionTetanus
Clostridium difficile causes this disease or conditionPseudomembranous Colitis
Clostridium botulinum causes this disease or conditionBotulism
Clostridium perfringens causes this disease or conditionGas Gangrene
Gram positive spore-forming rod, Reservoir - Soil. Colonizes GI tract of healthy individuals. Hospitals: spores contaminate surfaces. Transmission - ingestion of spores. Antibiotic-associated GI tract disease. Hospitalized pts on antibiotics. Disease ranges from mild, self-limited diarrhea to Pseodomembranous colitisClostridium dificile
Antibiotic therapy key factor that alters colonic flora. Primarily in hospitalized patients that have received or are currently receiving antibiotic therapy can induce thisPseudomembranous Colitis
Disrupts tight junctions, PMN attractantEnterotoxin a
Cytotoxic by disrupting actin cytoskeletonCytotoxin b
Yellowish patches on the mucosa of the colon seen on colonoscopy/sigmoidoscopyPseudomembranous Colitis
Diagnosis is by detection of toxins in fecesPseudomembranous Colitis
First inducer of antibiotic-associated colitisClindamycin
Second inducer of antibiotic-associated colitisCephalosporins
Treatment for mild to moderate colitisMetronidazole or Oral Vancomycin
Treatment for severe colitisMetronidazole + Vancomycin
Newest treatment for reintroducing normal colon floraFecal Transplants
Gram positive rod with bulging spores (tennis-racquet/drum-stick appearance). Anaerobe. Spores found in soil, splinters, rusty nails. Potent neurotoxin - tetanospasminClostridium tetani
Treatment includes surgical debridement of the wound. Tetanus immunoglobulin G intramuscularly or intrathecally. Tetanus toxoid. IV Metronidazole and Diazepam or phenobarbitalTetanus
Those with inadequate vaccine-induced immunity and neonates born to unvaccinated mothers (no passive immunity conferred to baby from mother)Individuals at High Risk
Blocks release of inhibitory neurotransmitters glycine and GABA (gamma-aminobutyric acid)Tetanospasmin
Unopposed muscle contractions and spasmsSpastic Paralysis
Contraction of the erector spinae muscles producing arching of the backOpisthotonus
Contraction of the facial musclesRisus Sardonicus
Spasms of masseter muscles - trimus/lockjaw. Sustained contraction of facial muscles – risus sardonicus. Persistent back spasms - opisthotonus. Drooling, sweating, irritabilityGeneralized Tetanus
Unhygenic conditions during birth and improper umbilical care practices. Initial local infection of umbilical stump becomes generalized. Mortality rate 90%Neonatal Tetanus
Clinical diagnosis is based on history of trauma and no previous immunization along with the clinical presentationTetanus