Endospore

Tularemia

An infection common in wild rodents that is passed to humans through contact with infected animal tissues or by ticks, biting flies, and mosquitoes.

Also known as rabbit fever and deer fly fever, amongst others.

Eukaryotes of microbiology

Slime mould

Diphtheria is known for creating a slimy/sticky/smelly exudate in the throat and mouth, but there are quite a few variations on its etiology and presentation.

A. Common type of diphtheria. Child three years old, seen on fourth day of illness. Exudate covering pharynx, tonsils, and uvula. Received 16,000 units of antitoxin. Throat clear on sixth day. Discharged cured.

B. Follicular type of diphtheria. Child seven years old, seen on second day of illness. The membrane involved the lacunae of the tonsils. Resembles follicular tonsillitis. Received 6,000 units of antitoxin total.

C. Hemorrhagic type of diphtheria. Child seven-and-a-half years old, seen on sixth day of illness. Tonsillar and post-pharyngeal exudate. Severe nasal and post-pharyngeal hemorrhages during exfoliation of membrane. Received in all 15,000 units of antitoxin. Throat clear on ninth day of illness. Myocarditis developed. Case discharged cured four weeks after admission. 

D. Septic type of diphtheria. Child eight years old, seen on fifth day of illness. The pseudo-membrane in this case covered the hard palate and extended in one large mass down the pharynx, completely hiding the tonsils.

Diseases of Infancy and Childhood. Louis Fischer, M.D., 1917.

Antimicrobial Agents  - Cell wall inhibitors

Based on mode of action • divided into families based on chemical structure

 Modes of action Interference with: 

cell wall synthesis 

protein synthesis 

nucleic acid synthesis 

plasma membrane integrity 

metabolic pathway 

Inhibitors of Bacterial Cell Wall (peptidoglycan) Synthesis 

The Beta-lactam Family 

The Glycopeptides 

Peptidoglycan is composed of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) repeat units, and amino acids.  Each NAM is linked to peptide chain and the peptide chains are cross-linked.

β-lactams 

Includes penicillin derivatives (penams), cephalosporins (cephems), monobactams, and carbapenems.

class of broad-spectrum antibiotics containing a β-lactam ring

Bacterial transpeptidase enzymes are responsible for catalysing cross-linking of the peptide chains

β-lactam ring bind to these transpeptidases – this inhibits cross-linking between peptide chains and prevents synthesis of stable PG

Cell wall synthesis ceases and the bacterial cells eventually die due to osmotic instability or autolysis. 

Glycopeptides 

Polypeptide agents - basic structural elements amino acids 

Vancomycin: 

complexes with peptide portion of peptidoglycan’s precursor units 

vancomycin is a large hydrophilic molecule able to form hydrogen bonds with the terminal D-alanyl-D-alanine moieties of the NAM/NAG-peptides

preventing PG transglycosylation reaction – PG precursor subunits (NAG-NAM+peptide) cannot be inserted into peptidoglycan matrix;

Vancomycin also alters bacterial-cell-membrane permeability and RNA synthesis

Uses:  serious Gram positive infections e.g. MRSA wound infection

Adverse effects:

damage to auditory nerve 

hearing loss (ototoxicity) 

“Red man/neck” syndrome - rash on face, neck, upper torso 

Antimicrobial Agents  - Cell wall inhibitors

Based on mode of action • divided into families based on chemical structure

 Modes of action Interference with: 

cell wall synthesis 

protein synthesis 

nucleic acid synthesis 

plasma membrane integrity 

metabolic pathway 

Inhibitors of Bacterial Cell Wall (peptidoglycan) Synthesis 

The Beta-lactam Family 

The Glycopeptides 

Peptidoglycan is composed of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) repeat units, and amino acids.  Each NAM is linked to peptide chain and the peptide chains are cross-linked.

β-lactams 

Includes penicillin derivatives (penams), cephalosporins (cephems), monobactams, and carbapenems.

class of broad-spectrum antibiotics containing a β-lactam ring

Bacterial transpeptidase enzymes are responsible for catalysing cross-linking of the peptide chains

β-lactam ring bind to these transpeptidases – this inhibits cross-linking between peptide chains and prevents synthesis of stable PG

Cell wall synthesis ceases and the bacterial cells eventually die due to osmotic instability or autolysis. 

Glycopeptides 

Polypeptide agents - basic structural elements amino acids 

Vancomycin: 

complexes with peptide portion of peptidoglycan’s precursor units 

vancomycin is a large hydrophilic molecule able to form hydrogen bonds with the terminal D-alanyl-D-alanine moieties of the NAM/NAG-peptides

preventing PG transglycosylation reaction – PG precursor subunits (NAG-NAM+peptide) cannot be inserted into peptidoglycan matrix;

Vancomycin also alters bacterial-cell-membrane permeability and RNA synthesis

Uses:  serious Gram positive infections e.g. MRSA wound infection

Adverse effects:

damage to auditory nerve 

hearing loss (ototoxicity) 

“Red man/neck” syndrome - rash on face, neck, upper torso 

Me this week

Chlamydia trachomatis conjunctivitis in a newborn (ophthalmia neonatorum) Conjunctivitis is usually bilateral and occurs during the second week after delivery. Infection occurs from contamination of the eyes on passage through an infected endocervical canal. Chlamydia trachomatis pneumonia also commonly occurs at the same time.

Cysteine Growth Requirements

MICROBIOLOGY MNEMONIC

BoyFriend Lost Penis

B rucella

F rancisella

L egionella

P asteurella

or….

The four sisters “Ella” worship in the “cystein” chapel

Brucella

Francisella

Legionella

Pasteurella

Tick-Borne Diseases