gram + rods Flashcards
lactobacillus
1) α- or non-hemolytic
2) Homofermenters (e.g., L. casei):
lactic acid production from glucose fermentation
3) Heterofermenters (e.g., L. fermentum):
lactic acid, acetate, ethanol and carbon dioxide
production from glucose fermentation
4) Acidogenic (acid production) and aciduric (acid tolerant)
5) Genitourinary tract, GI tract and oral cavity
vagina
1) The predominant normal vaginal flora in adult women consists of
Lactobacillus spp.
- Maintenance of low pH in vagina (prevention of the growth of
pathogens) because they metabolize glycogen
2) Other bacteria: coagulase-negative Staphylococci, and Bacteroids
- about 20% carry the group
B β-hemolytic Streptococci
normal gut biome
Generally, intestinal microbiota, such as
Lactobacillus (and Bifidobacterium), serve to
protect the body by outcompeting pathogens
(microbial antagonism). Therefore, Lactobacilli
are believed to play a beneficial role in
maintaining the homeostasis of intestinal flora.
probiotics
1) inhibit growth of pathogen
2) modulate host immune system
3) enhance host barrier function
lactobacilli in oral cavity
1) isolated from the oral cavity (dental plaque and
tongue)
- first year of child’s life
lactobacilli diseases
in the
presence of risk factors and underlying conditions, they
can cause infections such as endocarditis, bacteremia,
meningitis, dental caries, and intra-abdominal
abscesses including liver abscess, pancreatic necrosis
infection, pulmonary infections, and
pyelonephritis
corynebacteria
1) Gram-positive anaerobes
– Pleomorphic, non-spore-forming bacteria
– Ubiquitous on plants and in animals and humans
– Colonize the skin and respiratory, gastrointestinal,
urinary, and genital tracts
– Divide via snapping division
(a form of binary fission)
2) Causes diphtheria
-Inhibits protein synthesis in eukaryotes
3) Transmitted from person to person via
respiratory droplets or skin contact
corynebacterium diphtheriae disease
1) Diphtheria is a localized infection (upper respiratory
tract and skin), usually of the throat.
2) Production of a distinctive thick, grayish, adherent
exudate (pseudomembrane)
Corynebacterium diphtheriae
3) Pseudomembrane formation
as a result of the combined
effects of:
– Bacterial growth
– DT production
– Tissue/cellular necrosis
4) Systemic effects of DT:
Myocarditis and neuropathy (if DT is extremely potent)
corynebacterium treatmnet
Diagnosis
* Initial diagnosis based on presence of a
pseudomembrane
* Elek’s test used to confirm diagnosis
– The test involves immunodiffusion, which
ultimately results in immunoprecipitation
2) antitoxin neutralizes effects
of the toxin
* Penicillin or erythromycin kills the bacterium
* Surgery may be needed to open a blocked
airway
actinomycetes
1) Gram-positive anaerobes
– G(+) rod-shaped anaerobes, can be filamentous (A.
israelli)
– Some, such as A. naeslundii, are heavily fimbriated
(cell surface structures involved in attachment)
– Non-motile, non-acid-fast
– VFs: Little is known…
2) Acidogenic: succinic, acetic and lactic acids from
glucose fermentation
3) A part of the normal flora of the oral cavity (a major
component of dental plaque) and gastrointestinal tract
(and vagina).
actinomyces sp
1) Oral Actinomyces spp.: A. israelli, A. gerencseriae, A.
odontolyticus, A. naeslundii, A. viscosus, A. myeri
and A. georgiae (associated with dental caries)
2) actinomycosis
- a local abscess with multiple draining sinuses
and low-grade systemic symptoms)- Cervicofacial (by local invasion)
- Abdominal (by local invasion)
- Thoracic
bacillus
1) endospore forming bacilli
2) b. anthracis
- anthrax
- principally affects domestic herbivores
3) B.anthracis may be used as a biological weapon or for
bioterrorism
– In such a case, mail handlers, military personnel,
and response workers who may be exposed during a
bioterror event involving anthrax spores
bacillus characteristics
1) capsule (anti-phagocytic)
2) Anthrax toxins (exotoxins): composed of 3 subunits
- Edema factor (EF, adenylate cyclase): shock
- Lethal factor (LF, metalloprotease): shock,
immunosuppression
- Protective antigen (PA, receptor binding
protein):Pore formation in the endosomal
membrane, enabling EF and LF to cross into the
cytoplasma
5) Transmission occurs via one of three routes:
* Inhalation of spores
* Inoculation of spores through break in the skin
* Ingestion of spores
Bacillus
three clinical manifestation
Three clinical manifestations (based on the
transmission pattern):
1) Inhalation anthrax
– Requires inhalation of airborne endospores
– After the endospores germinate in the lungs,
they secrete toxins that are absorbed into the
bloodstream, producing toxemia.
– High mortality rate
2) Cutaneous anthrax (95% of human cases)
– Produces ulcer called an eschar
– Fatal in 20% of untreated patients
3) (Gastrointestinal anthrax: Rare in humans)
Bacillus anthracis
bacillus anthracis treatment
All types of anthrax infection can be treated with antibiotics.
– Inhalation anthrax is treated with a combination of antibiotics
(i.v.) such as ciprofloxacin plus another antimicrobials.
– Cutaneous anthrax is treated with antibiotics taken by mouth,
usually for 7 to 10 days. Doxycycline and ciprofloxacin are
most often used.
– Antitoxin (since antibiotics do not inactivate accumulated
anthrax toxin!!
