Microbiology - Block 3 - Part 4

davidwurbel7's version from 2015-07-28 15:51

Anaerobic Gram Negative Bacteria

Question Answer
Gram negative rods. Anaerobic. Modified LPS with reduced activity. Proliferates in presence of bile, hydrolyzes esculine – producing black precipitate on bile-esculine agar. Resistant to β-lactam antibiotics and gentamicinBacteroides fragilis
Bacterium is part of the normal flora of the human colon and is generally commensalBacteroides fragilis
Metronidazole, carbapenems, tigecycline. Cephamycin class, including cefoxitin. Unasyn or Zosyn - beta-lactam/beta-lactamase inhibitor combinations. Clindamycin is no longer recommended due to increasing resistanceBacteroides fragilis
Obligate pathogen, extracellular. Distinct helical shape. Gram negative spirochetes. Anaerobic. EndoflagellatedTreponema pallidum pallidum
Symptomatic. Patient is highly contagious. Painless chancres. Bacteria detected in dark-field or fluorescent microscopy of lesion (50% of patients will be negative by nonspecific serologyPrimarily Syphilis
Symptomatic. Patient is highly contagious. All serology tests are positiveSecondary Syphilis
Asymptomatic. Contagious. Positive serologyEarly Latent Syphilis
Asymptomatic. Not as contagious. Positive serologyLate Latent Syphilis
Patients are not infectious. Positive serologyTertiary Syphilis
Diagnosis by clinical symptoms. Direct observation of the spirochete by dark field microscopy. Venereal Disease Research Laboratory (VDRL). Rapid Plasma Reagin (RPR) testTreponema pallidum pallidum
Treatment for all stages of syphilis.Penicillin G
Obligate pathogen, extracellular. Distinct helical shape (02.-0.3μM wide 15-20μM long). Considered as a diderm (double-membrane bacterium (non- Gram negative nor positive). Anaerobic. EndoflagellatedBorrelia burgdorferi
The tick must be attached for 36 to 48 hours before the bacteria can spreadLyme Disease
Early localized Lyme disease treatmentDoxycycline
Early localized Lyme disease treatment for young children or pregnant womenAmoxicillin, Cefuroxime or Azithromycin
Early disseminated or late Lyme disease treatmentCeftriaxone IV
Gram negative. Slow growing. Obligate pathogen, extracellular. Distinct helical shape (longer than 20μM). Microaerophilic. Periplasmic flagella. Auxotroph for most amino acids. Linear genome and linear and circular plasmidsBorrelia recurrentis
Relapsing 9-day cycle presents - sudden fever, chills, headaches, muscle or joint aches, and nausea. Rash may occurLouse Born Relapsing Fever (LBRF)
Relapsing 9-day cycle presents - sudden fever, chills, headaches, muscle or joint aches, and nauseaTick Born Relapsing Fever (TBRF)
Both Louse Born Relapsing Fever (LBRF) and Tick Born Relapsing Fever (TBRF) treated withTetracycline-Class Antibiotics
Gram negative, distinct helical shape. Larger spirochetes with tight terminal hooks that are visible in dark-field microscopy. Requires high humidity and neutral (6.9-7.4) pH for survival in the environment. Chemoheterotroph. Aerobic. Extracellular pathogen. Periplasmic flagella. Genomic DNA is allocated into two circular chromosomesLeptospira
Virulence factors include lamilin binding proteins, evasion of phagocytosis and immune responses, resistance to complement, outer membrane proteins (OMPs), LPS and hemolysinsLeptospira interrogans
A severe form of Leptospirosis characterized by jaundice, kidney failure and bleedingWeil's Disease
A severe form of leptospirosis causing bleeding from the lungsSevere Pulmonary Hemorrhage Syndrome (SPHS)
Lasts 3-7d. Sudden fever, chills, intense headache, severe myalgia, abdominal pain, conjunctival suffusion. A transient petechial or punctate red palatal enanthem occurs in the first day or two. Skin rash originates from epithelial vascular damage. The skin is suffused, described as a warm pink in colorLeptospirosis Phase I
Antibodies are present in serologyLeptospirosis Phase II
Multiple organ damage and failure (liver -jaundice, kidneys, heart and lung) are the most serious and life-threatening symptoms. Also extreme fatigue, hearing lossWeil’s disease Phase II
Respiratory distress, and azotemiaSevere Pulmonary Hemorrhage Syndrome (SPHS) Phase II
Effective antibiotics include - Penicillin G, Amplicillin, Amoxicillin and Doxycycline. In more severe cases - Cefotaxime or CeftraxoneLeptospirosis
Gram negative. Nonmotile. Obligate intracellular parasite. Can be grown only in tissue or embryo (chicken) cultures. Highly pleomorphic – cocci, rods, thread-likeRickettsia
Facilitates adherence of Rickettsia rickettsii to the host cellOuter Membrane Proteins  (rOmp A and rOmp B)
Rickettsia rickettsii attaches to endothelial cells and induces thisPhagocytosis
Transmission by ticksRickettsia rickettsii
Onset of fever, nausea, vomiting, and loss of appetite. Rash (macropapular) – 2-5 days after the onset of fever. Small, flat pink macules develop peripherally (wrists, forearms, ankles, and feet). After 7 days rash (petechial) appears darkened red to purple and has more generalized distribution. Late symptoms include diarrhea, abdominal and joint pain, and pinpoint reddish lesions. Severe cases involve the respiratory system, central nervous system, gastrointestinal system or the renal system.Rocky Mountain Spotted Fever
Drug of choice for Rocky Mountain Spotted FeverDoxycycline
Severe headache, sustained high fever (39°C- 102°F) and chills, cough, Rash – (5 days after the onset of fever) –starts on a chest and spreads to trunk and extremities. severe muscle pain, falling blood pressure, stupor, sensitivity to light, delirium and deathEndemic Typhus
Endemic typhus is caused byRickettsia prowazekii
Transmission mostly in lice but can also be flying squirrel and tickRickettsia prowazekii
Rickettsia prowazekii may cross–react with this bacteriaRickettsia typhi
Drug of choice for Endemic typhusDoxycycline
Headache. Fever. Muscle & joint pain. Nausea and vomiting. Rash after 6 days from the onset of signs– discrete in 40–50% of patients neurological signs in 45% of patients (confusion, stupor, seizures or imbalance)Murine (Endemic) Typhus
Transmission by fleas on ratsRickettsia typhi
Small (0.2–1.0 μm) Gram negative. Obligate intracellular parasite of polymorphonuclear leucocytes and neutrophils (unusual cell tropism). Resides within a vacuole to form a morula microcolony. Lacks LPS. Lacks peptidoglycan on the outer membrane – causing fragility. The cell integrity is mediated by cholesterol – retrieved from the host cellAnaplasma
Small cocci-shaped (0.2–1.0 μm) Gram negative. Obligate intracellular parasite of Monocytes and Macrophages. Enabled a mechanism ensuring survival in cells of the immune system. Resides within a vacuole to form a morula microcolony. Lacks LPS. Lacks peptidoglycan on the outer membrane – causing cell fragility. The cell integrity is mediated by cholesterol – retrieved from the host cellEhrlichia
Transmitted by ticks from a mouseAnaplasma phagocytophilium
Transmitted by ticks from a deerEhrlichia chaffeensis
Causes an increase in IL-8 production, which attracts neutrophils to the point of infectionAnaplasma phagocytophilium
Acquires host cellular cholesterol from the low-density lipoprotein (LDL)- mediated uptake pathway, depleting cell stores of LDLAnaplasma phagocytophilium
Acquires host cellular cholesterol, however the cellular sources are yet to be determinedEhrlichia chaffeensis
Risk associated with blood transfusions and organ transplants from infected donorAnaplasma phagocytophilium
Fever, chills and shaking. Skin rash (less than 10% of cases). Myalgia, joint pain. Nausea, vomiting, loss of appetite, weight loss. abdominal pain and diarrhea. Cough (pulmonary infiltrates). sensitivity to light. Severe headache, extreme confusion, memory loss, temporary loss of basic motor skills. Lab finding include thrombocytopenia, leukopenia, elevated levels of serum transaminaseHuman Ganulocytic Anaplasmosis (HGA)
Clinically, HGA is indistinguishable fromHuman Monocytic Ehrlichiosis
DOC for Human Ganulocytic Anaplasmosis (HGA) and Human Monocytic Ehrlichiosis (HME)Doxycycline
Administered for pregnant women, post-delivery pediatric and some doxycycline-allergic patients for Human Ganulocytic Anaplasmosis (HGA) and Human Monocytic Ehrlichiosis (HME)Rifampin
Small (0.2–1.0 μm) Gram negative coccobacilli - there are two cell types (1) large cell variants (LCVs) and (2) small cell variants (SCVs). SCVs are rod-shaped and compact. The LCV form a spore-like particle (SLP). Resistant to environmental conditions (temperature, UV, osmotic pressure), aerobic. Acidophilic bacteria, requiring a pH of 4.5-5 to grow. Obligate intracellular parasite. Reproduce by binary fission. SLPs are released from degenerating LCVs, and that the SLPs are precursors to SCV cells. Extremely low transmission rate only needing 1-10 bacteria to cause the infectionCoxiella burnetii
Extremely low transmission rate makes this bacteria the most infectious microorganism known to dateCoxiella burnetii
Incubation period lasts 2-3 weeks. Causes flu-like symptoms. Sudden onset of fever and profuse perspiration, chills. Headache, muscle pain, joint pain. Loss of appetite. Upper respiratory problems, dry cough, pleuritic pain, atypical pneumonia; may progress to ARDS. Confusion, nausea, vomiting, and diarrheaQ Fever
The first choice of antibiotics are for treatment of Q feverTetracyclines or Quinolones or Doxycycline with Hydroxychloroquine
Prevention of Q Fever available for people working with animals and high endemic regionsWhole-cell, Inactivated Vaccine

Obligate Intercellular Bacteria

Question Answer
Small, Obligate intracellular pathogen (OIP). Do NOT gram stain. Do not make their own ATP. Infect mucous membranes. Infected cells – Cytoplasmic “inclusion” bodiesChlamydia
EB = Elementary body is present in this stageInfectious Stage
RB = Reticulate body is present in this stageReplication Stage
Reticulate bodies - Found inside host cells, metabolically active, replicating. Elementary bodies - Infective forms, inactive, extracellular. Not seen on gram stain. Reservoir - Human genital tract and eyes. Transmission - Sexual contact and during birthChlamydia trachomatis
Infects non-ciliated columnar or cuboidal epithelial cells of mucosal surfacesChlamydia trachomatis
The most common cause of potentially preventable blindness in the world. Transmission - eye-to-eye via droplet nuclei, contaminated hands, fliesChlamydia trachomatis Serotypes A, B and C
In-turned eyelashes. Corneal abrasion, ulceration, and pannus formation (blood vessels invade cornea). Can lead to blindness.Chlamydia trachomatis Serotypes A, B and C
Most common bacterial cause of STD in USA. Often asymptomatic.Chlamydia trachomatis (Serotype D-K)
In males - Nonspecific urethritis (non-gonococcal). Patients present with Dysuria, Thin watery discharge, Numerous neutrophils but NO bacteria = sterile pyuriaChlamydia trachomatis (Serotype D-K)
In females - Urethritis and cervicitis. This is the source of conjunctivitis / atypical pneumonia in newborns. Pelvic inflammatory disease (PID). Sexually transmitted infection of female genital tract. Acute process with mucopurulent discharge. Potential for fallopian tube scarring and for ectopic pregnancy as a resultChlamydia trachomatis (Serotype D-K)
Conjunctivitis with Urethritis and Reactive ArthritisReiter’s Syndrome
Neonatal conjunctivitis characterized by mucopurulent dischargeChlamydia trachomatis (Neonatal Inclusion Conjunctivitis)
Sexually transmitted chronic ulcerative disease. A painless papule or an ulcer develops on the genital mucosa or nearby skin > heals. This is followed by inflammation of lymphnodes draining the area causing swollen, tender lymphadenopathy “buboes” rupture. Inguinal lymphadenopathy. Groove sign due to enlargement of both the femoral and inguinal nodesChlamydia trachomatis Serotypes L1-3
Cytoplasmic inclusions seen on - Giemsa stained smear/ Pap smear. Fluorescent antibody stained smear. Culture - cannot grow on cell-free media. Grows in tissue/cell culturesDiagnosis – Chlamydia trachomatis
Doxycycline or Azithromycin and ceftriaxone for co-infectionChlamydia Treatment (Ocular/Genital)
Doxycycline or erythromycinLymphogranuloma venereum (LGV) Treatment
ErythromycinNewborn Conjunctivitis Treatment
Obligate Intracellular bacterium. Reservoir - Human respiratory tract. Transmission- Respiratory dropletsChlamydophila pneumoniae
Atypical “walking “ pneumonia. Scant sputum, dry cough and hoarseness, flu-like symptoms. Many times asymptomatic or mild infections. Rarely but potential association with atherosclerosisChlamydophila pneumonia
Treatment - Erythromycin and tetracyclineChlamydophila pneumonia
Causes - Ornithosis or psittacosis. A zoonosis due to inhalation. Reservoir - Aerosols of dried bird secretions and feces. Occupational hazard: Vets, zoo-keepers, petshop workers. Treatment with DoxycyclineChlamydophila psittaci
Common complaint – 1 in 3 woman. Symptoms. Abnormal vaginal discharge with itching, pain. Triggering Factors - Imbalance in microbial flora of vagina, OR Infection of vaginaBacterial Vaginosis
Numbers of Lactobacilli diminished. Replaced by Gardnerella (GNB) and Mobiluncus. Presentation - Thin, grey, vaginal discharge. No vulvar/vaginal irritation. Fishy odor after coitusBacterial Vaginosis
Epithelial cells covered bacteria. pH > 4.5. Positive whiff test - Add KOH → fishy odorBacterial Vaginosis Diagnosis
Treatment of bacteria vaginosisMetronidazole or Clindamycin
Smallest free living organism. No cell wall so poor Gram stain. No peptidoglycan or cell wall. Cell membrane has cholesterol “Fried egg” colonies on Eaton’s agar. Habitat/Transmission - Respiratory droplets. Pathogenic only for humans. AdhesinsMycoplasma
Most common cause of Community-acquired atypical pneumonia ("Walking pneumonia")Mycoplasma
Diagnosis by elevated titer of cold agglutininsMycoplasma
Treat with Doxycycline or Erythromycin. No Beta-lactams can be usedMycoplasma
Outbreaks associated with young patients (5-15 years)Mycoplasma
Cell membrane resembles host because of cholesterol so triggers auto-reactive antibodiesMycoplasma
Non productive (no exudate) cough, Long lasting cough (2-3 weeks). X-ray shows small areas of infection. “Patchy infiltrates”. Absence of leukocytosis"Walking Pneumonia"