Essential concepts in medical Bacteriology - Mathilde Lescat

The essential concepts to know in MEDICAL BACTERIOLOGY

Mathilde Lescat Assistant Professor, Université Paris Sorbonne Nord, France

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Major families of bacteria

Diagnosis by standard culture

Gram + cocci

Gram + bacillus

Staphylococci Streptococci Enterococci Anaerobes (Peptostreptococcus sp)

Corynebacteria Listeria monocytogenes Anaerobies (Clostridium sp)

Gram - bacillus

Gram - cocci

Enterobacteriaceae Parvobacteria (Haemophilus sp, HACCEK, Pasteurella sp, Brucellla melitensis, Bartonella sp) Strict aerobic (Pseudomonas aeruginosa) Anaérobies (Bacteroides sp, Prevotella sp...)

Neisseria meningitidis Neisseria gonnorhoeae Anaerobes (Veillonella sp)

Intracellular bacteria

Spirochetes

Mycobacteria

Chlamydiae sp, Mycoplasma sp Legionella pneumophila Ricketsiae, Coxiella sp

Intra cellulaires

Treponema pallidum Borrelia burgdorferi Leptospira sp

Diagnosis by serology, specific culture or molecular biology

The great commensal sites

Oropharyngeal / nose microbiota: Streptococci, Neisseria sp, Hemophilia, Staphylococcus aureus, Chlamydiae, Mycoplamses, Anaerobes (Veillonella sp ...)

Digestive microbiota: Anaerobes ++++ (Bacteroides sp, Clostridium sp ...) Enterobacteriaceae (E. coli), enterococci (Enterococcus faecalis)

Vaginal microbiota: Lactobacilli +++, Mycoplasmas, Enterobacteriaceae and Enterococci transiently

Skin microbiota: Staphylococci, corynebacteria

Main commensal sites in animals and vectors associated with anthropozoonoses

Rickettsia sp Yersinia pestis

Leptospires,

Pasteurella multocida, Bartonella henselae

Rickettsia sp, Borrelia sp

Chhlamydiae psitacci

Coxiella burnetti Brucella melitensis Escherichia coli O157:H7

Saprophytic bacteria from the environment

Strict aérobic Gram negative bacteria (Pseudomonas aeruginosa)

Vibrio cholerae, Aeromonas hydrophila

Legionnella pneumophila

Listeria monocytogenes

The main infections

Lung infections: Community: Streptococcus pneumoniae, Haemophilus influenzae, atypical (Chlamydiae, Mycoplasmas, Legionella) Nosocomial: Enterobacteriaceae Staphylococcus aureus, Pseudomonas aeruginosa

Meningitis (adult, child) Streptococcus pneumoniae, Neisseria meningitidis, Listeria monocytogenes

Endocarditis: Streptococci, Staphylococci

Digestive infections Ulcers: Helicobacter pylori Extraintestinal: Anaerobes, Enterobacteriaceae, Enterococci Diarrhea: Salmonella, Shigella, Yersina enterocolytica, Campylobacter sp

Genital infections low: Gonococci, Chlamydiae, Syphilis, High: Enterobacteriaceae, Anaerobes Maternal-fetal infections: E. coli, Streptococcus agalactiae, Listeria

Urinary tract infections Enterobacteriaceae (E. coli), enterococci (E. faecalis), Streptococcus agalactiae, Staphylococus saprophyticus

Skin infections: Staphylococcus aureus, Streptococcus pyogenes Material associated: Pseudomonas aeruginosa, Staphylococci, Enterobacteriaceae

Main resistances to antibiotics

Decreased ATB concentration

ATB destruction

Target Modification

New targets, or modification of existing targets

Enzymes

Efflux, Impermeability

MDRO and (multi drug resistant organisms)

Vancomycin resistant enterococci*

MRSA

Multiresistant Pseudomonas aeruginosa and Acinetobacter baumanii

ESBL Gram negative producers

Carbapenem Enterobacteriaceae producers*

*emerging highly resistant bacteria

The main first-line treatments

Meningeal infections (adult, child) 3rd generation cephalosporin vancomycin, amoxicillin

Lung infections: Communautary: Amoxicillin-clavulanate, Amoxicillin, C3G, Macrolide Nosocomial: Tazocillin

Endocarditis 3rd generation cephalosporin , Amoxicillin + aminoglycoside

Genital infections Low: tetracycline, macrolide, Fluoroquinolone (CT) 3rd generation cephalosporin (NG) High: 3rd generation cephalosporin+ metronidazole + tetracycline Maternal fetal infections: 3rd generation cephalosporin, amoxicillin

Digestive infection Ulcers: Chlarythromycin Extra intestinal: Amoxicillin-clavulanate, 3rd generation cephalosporin + metronidazolel, tazocillin Diarrhea: Doxycycline, Fluoroquinolone

Urinary tract infections Cystitis: Fosfomycin, sulfamethoxazole, Fluoroquinolone High: 3rd generation cephalosporin, fluoroquinolone

Skin infections Amoxiciilin, Amoxicillin-clavulanate