Common Bacterial Pathogens Flashcards
Staphylcoccus
Gram (+)
Catalase (+)
S. Aureus
Gram (+)
Coagulase (+)
Staphylococcus
Causes:
Skin and soft tissue infection, Osteomyelitis, Pneumonia, Endocarditis, Septic arthritis, Bacteremia
Check if susceptible or resistant to Methicillin (MRSA)
S. Epidermidis
Gram (+)
Coagulase (-)
Staphylococcus
Normal to skin flora
Can cause clinical disease in immunocompromised hosts or those with prosthetic devices.
S. Saprophyticus
Gram (+)
Coagulase (-)
Staphylococcus
Found in urine cultures from urinary tract infections from sexually active women.
Streptococcus
Catalase (-)
α-hemolytic
Partial lysing fo RBCs
S. pneumoniae
S. viridans group
β-hemolytic
Complete lysing of RBCs
S. pyrogenes (Group A)
S. agalactiae (Group B)
Group C, F, G
γ-hemolytic
Non-hemolytic, inability to lyse RBCs
S. bovis (Group D)
Enterococcus (E. faecalis, E. faecium)
S. Pneumoniae
Gram (+)
α-hemolytic
Streptococcus
Virulence is encapsulated with polysaccharides (protected from phagocytosis)- basis for PPSV23 and PCV13
Causes: Pneumonia, Meningitis
S. viridans
Gram (+)
α-hemolytic
Streptococcus
Found in intestinal tract, oral cavity and upper respiratory tract.
Causes: Dental caries, tooth infections
Endocarditis and bacteremia (if it enters the bloodstream during dental procedures)
S. pyogenes
Gram (+)
β-hemolytic
Streptococcus
Lancefield Group A
Causes: Strep throat (streptococcal pharyngitis) Skin infections (cellulitis, impetigo, necrotizing fasciitis
S. agalactiae
Gram (+)
β-hemolytic
Streptococcus
Lancefield Group B
Causes: Neonatal menignitis, pneumonia, sepsis (if transmitted during birth)
S. bovis
Gram (+)
γ-hemolytic
Streptococcus
found in an intestinal organism
Can cause: Sepsis (when found in blood), Endocarditis
Associated with colon cancer
E. faecalis
Gram (+)
γ-hemolytic
Enterococcus
Most common Enterococcus
E. faecium
Gram (+)
γ-hemolytic
Enterococcus
Associated with more antibiotic resistance, particularly to vancomycin
can be VRE (vancomycin resistant enterococcus)
Peptostreptococci
Gram (+)
Anaerobic
Normal flora of the mouth, upper respiratory tract, GI tract and female genital tract.
Involved in polymicrobial infections. Often causes foul smelling pus contained in an abscess.
C. diphtheriae
Gram (+) bacilli
Causes: diphtheria by releasing toxins.
Tdap vaccine has made diphtheria almost non existent.
Mycobacteria
Gram (+) bacilli
Causes: tuberculosis and leprosy
M. avium is associated with HIV (prophylaxis is utilized)
Cutibacterium acnes
Gram (+) bacilli
common cause of acne, can also cause osteomyelitis in people with prosthetics (mostly in hip or shoulder.
Lactobacillus spp.
Gram (+) bacilli
Normal flora in the GI tract and vaginal tract.
Streptomyces
Gram (+) bacilli
Actinobacterium
Largest produces of antibiotics (Neomycin, Streptomycin, Chloramphenicol, Bleomycin)
Rarely causes disease in humans
Clostridiodes difficile (C.diff)
Gram (+)
Spore forming
Anaerobic
Causes: pseudomembranous colitis (diarrhea)
C. diff infection is a consequence of the overuse of broad spectrum antibiotics.
Clostridium
Gram (+)
Spore forming
Anaerobic
C. botulinum - causes botulism
C. tetani - causes tetanus (component of Tdap)
C. perfringens - causes gas gangrene.
Enterobacteriaceae
Gram (-) rods/bacilli (GNR)
Normal to the flora of the GI tract
PEK:
Proteus (P. mirabilis)
Escherichia (E. coli)
Klebsiella
Not normal:
Salmonella
Shigella
ESKAPE organisms
Enterococcus faceium S. aureus Klebsiella pneumoniae Acinetobacter baumannii Pseudomonas aeruginosa Enterobacter spp.
Infections often encountered in the hospital and community settings
Proteus (P. mirabilis)
Gram (-) GNR
Enterobacteriaceae
Normal flora to GI tract
Causes: UTIs, bacteremia, pneumonia
Escherichia (E. coli)
Gram (-) GNR
Enterobacteriaceae
Normal GI flora
Causes: urinary, biliary, GI or GU infections
Can cause infections at certain locations: blood, prostate, lung, bone and meninges
Klebsiella
Gram (-) GNR
Enterobacteriaceae
Normal respiratory and GI tract flora (small %)
KPC (Klebsiella pneumoniae carbapenemase) causes resistant to most beta lactams
Causes: Pneumonia, sepsis, UTIs, intra-abdominal infections
Salmonella
Gram (-) GNR
Enterobacteriaceae
Transmitted from animals to humans through fecal-oral route
NOT considered normal flora
Causes: diarrhea, Enteritis, enteric fever (typhoid fever), bacteremia.
Shigella
Gram (-) GNR
Enterobacteriaceae
infections are almost always limited to the GI tract.
NOT considered normal flora
Causes: diarrhea, affects the CNS
Non-Fermenting Gram Negative Bacilli
Gram (-) GNR
Pseudomonas aeruginosa (PSA)
Acinetobacter (A. baumanii)
Pseudomonas aeruginosa
Gram (-) GNR
Non-Fermenting
Distinctive sweet smell
Causes : BE PSEUDo: Burns, Endocarditis, Pneumonia, Sepsis, External otitis media, UTI, Diabetic osteomyelitis
Acinetobacter (A. baumanii)
Gram (-) GNR
Non-Fermenting
Multidrug resistant organism (MDRO)
Resistant to carbapenems
Causes: UTI, bacteremia, pneumonia, wound infection, infections of implantable devices (IV catheters)
Anaerobic Gram Negative Bacilli
Bacteroides
Gram (-) GNR
Normal to GI flora
Abscess formation
Below the diaphragm anaerobe
Bacteroides (B. fragilis)
Gram (-) GNR
Anaerobic
Causes: Intra-abdominal infections, wound infections, pelvic inflammatory disease, ovarian abscess, bacteremia
Gram negative Cocco-bacilli
Gram (-)
Cocco-bacilli
Haemophilus influenzae (H. influenzae)
Moraxella catarrhalis
H. Influenzae
Gram (-)
Cocco-bacilli
Found on mucous membranes of the upper respiratory tract (common respiratory flora)
Does NOT cause influenzae (virus)
Causes: respiratory tract infections, otitis media, acute sinusitis
Hib vaccine is given to prevent H. influenzae type b meningitis in children.
Moraxella
Gram (-)
Cocco-bacilli
Normal flora to the respiratory tract
Causes: sinusitis, bronchitis, otitis media and pneumonia
Gram Negative Diplococci
Gram (-)
Diplococci
N. gonorrhoeae
N. meningitidis
N. gonorrhoeae
Gram (-)
Diplococci
Sexually transmitted, infections occur in genitourinary tract, eye, rectum and throat
N. meningitidis
Gram (-)
Diplococci
Causes meningitis (after bloodstream infection) Spread through respiratory droplets
2 vaccines: meningococcal polysaccharide vaccine and meningococcal conjugate vaccine
Atypical bacteria
They do not grow on normal media or do not stain by normal gram stain methods
Legionella pneumophilia
Mycoplasma (M. pneumoniae)
Chlamydia
Legionella pneumophilia
Gram (-)
Aerobic
Causes Legionnaires pneumonia (from inhaling contaminated water droplets)
Also causes pneumonia and Pontiac Fever
Legionella becomes intracellular (antibiotics must have adequate intracellular concentration)
Mycoplasma
Lacks a cell wall.
Causes mild forms of respiratory infections (walking pneumonia). Occurs with significant lag time (2-3 weeks)
Symptoms: fever, sore throat, malaise and dry hacking cough
Chlamydia
C. trachomatis causes the STD
C. psittaci is carried by birds can cause pneumonia in humans
C. pneumoniae causes community acquired pneumonia in young adults.
