BACTERIOLOGY
Aerobic Gram-Positive Bacilli
Non-Spore-Forming, Nonbranching Catalase-Positive Bacilli
Corynebacterium
General Characteristics:
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Large diverse groups of bacteria that includes animal and human pathogens as
well as saprophytes and plant pathogens.
Most of the species are found as normal biota on skin and mucous membranes of
humans and animals.
Based on 16S rRNA sequencing, corynebacterial are closely related to
_______________ and ____________.
Slightly curved, gram-positive rods with unparallel sides and slightly wider ends,
producing a described “____________” or coryneform.
_________________ - variable shapes and sizes; described as “Chinese letters”
or “Picket fences”; results from irregular shaping during cell division.
Aerobes or Facultative aerobes.
“Klebs-Loeffler” bacillus
Diphtheroid appearance is evident.
Corynebacterium diphtheriae
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Most virulent Corynebacterium species.
Causative agent of diphtheria.
Virulence Factor/s:
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Diphtheria Toxin – Major virulence factor; produced by the strains of C. diphtheriae
infected with a lysogenic bacteriophage, which carries the ____ gene for diphtheria
toxin; Exceedingly potent and is lethal for humans in amounts of _____ ng/kg of
body weight; The toxicity of the toxin is due to its ability to block _________
_____________ in eukaryotic cells.
Clinical Infections:
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Respiratory Diphtheria – found worldwide but is uncommon in North America and
Western Europe; Characterized by formation of a tough gray-to-white
__________________ which attaches to the tissues that may appear on the tonsils
and then spread downwards into the larynx and trachea; Suffocation may occur if
the membrane blocks the air passage or if it is dislodged.
Cutaneous Diphtheria – prevalent in the tropics; consists of nonhealing ulcers with a
dirty gray membrane.
Demyelinating Peripheral Neuritis – can result in paralysis following the acute illness.
Corynebacterium amycolatum
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Most frequently recovered Corynebacterium species from human clinical material.
Part of the normal skin microbiota.
Often associated with prosthetic joint infection.
Corynebacterium jeikeium
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Named after Johnson and Kaye, who first linked this organism with human infections.
Part of the normal skin microbiota.
Infections are typically limited to patients who are immunocompromised, have
undergone invasive procedures, or have a central line catheters or prosthetic devices.
The most common cause of _______________-_____________ ____________ ______
____________ in adults.
Corynebacterium pseudotuberculosis
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Primarily a veterinary pathogen.
Human infections typically have been associated with contact with sheep and are rare.
Causes ____________ ____________ in humans.
Listeria
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Found in soil, water, sewage, and decaying vegetation.
Found in feces of humans, swine, poultry.
Listeria monocytogenes
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Most significant human isolate of listeria.
Major source of infection: Contaminated food (Cabbage, raw fruit, pasteurized and
unpasteurized dairy products)
Highest risks: Pregnant females, fetuses, newborns.
Classical intracellular parasite – taken up by cells of host’s reticuloendothelial system.
Etiologic agent of listeriosis (Most common manifestation of listeriosis is ___________.)
Virulence Factors:
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Listeriolysin O – damages the phagosome membrane, effectively preventing killig the
organism by the macrophage.
Catalase
Superoxide dismutase
Pjospholipase C
Protein p60 – induces phagocytosis through increased adhesion and penetration into
mammalian cells.
Listeriosis
In Pregnant Women
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Most commonly seen during the ______ __________.
Pregnant woman with listeriosis may experience a flulike illness with fever,
headache, and myalgia. At this point, the organism is in the bloodstream and has
seeded the uterus and fetus. It may progress and result in premature labor or
________ __________ within __ - __ days.
In the Newborns
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Pneumonia – common manifestation for early-onset listeriosis (Fetus is infected
either in utero or during the first following birth)
Meningitis, conjunctivitis, septicemia – typical manifestations for late-onset
listeriosis (Occurs several days to weeks after birth)
The disease is most likely to manifest as meningitis.
In the Immunosuppressed Host
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CNS infection, Endocarditis – Most common manifestations.
Infection of apparently healthy individuals may occur through intestinal tract
when they eat food contaminated with the organism.
Outbreaks have occurred as a result of eating contaminated _______,
__________, and __________.
Contaminated ___________, ____________, and ________________ have
served as vehicles for this food-borne disease.
Note: Anton’s Ocular Test