*Microbiology 2 (lecture 3) Flashcards
What species are genus is gram negative cocci?
Niesseria spp.
What does Neisseria gonorrhoea cause?
Gonorrhoea
What does Neisseria meningitides cause?
Meningitis
What does Bordetella pertussis cause?
Whooping cough
What does Haemophilus influenzae cause?
Exacerbation of COPD
What does E. coli, Klebsiella sp. and proteus sp. cause?
UTI and wound infection
What does Helicobacter sp. cause?
Gastritis
What does bactericides sp. cause?
Gut commensals
Wound infection
Are Neisseria sp. aerobic or anaerobic?
Aerobic
How does Neisseri appear on gram film?
in pairs (diplococci)
What is the commonest cause of bacterial meningitis?
Neisseria meningitidis
What are coliforms?
A term used to describe species of gram negative bacilli that look like E. coli on gram film and when cultured on blood agar (many are part of normal bowel flora)
What are 6 examples of cloakrooms?
E. coli Klebsiella sp. Proteus sp. Salmonella sp. Shigella sp. E. coli O157
Are coliforms aerobic or anaerobic?
Grow best aerobically but can also grow anaerobically
How are the coliforms differentiated from each other`/
Biochemcial reactions
Antigenic structure of cell wall (serotyping) - O antigens (cell wall) and H antigen (flagella)
Name 4 examples of gut commensal coliforms?
Most strains of E coli
Klebsiella spp.
Enterobacter spp.
Proteus spp.
3 examples of gut pathogen coliforms?
Salmonella spp
Shigella spp
Verotoxin (VTEC) producing E. coli
What are 2 examples of verotoxin producing E coli?
E coli O157
E coli O104
What is the first line antibiotic used for the treatment of infections caused by coliforms?
Gentamicin
why do patients with coliform sepsis become very unwell very quickly?
Due to the endotoxin released from he gram negative cell wall when the bacteria die
What is the molecule which is the endotoxin in gram negative bacteria?
Lipopolysaccharide (LPS)
Released from cell wall when bacteria dies which is taken up by cells such as macrophages, which in turn release cytokines, setting off the inflammatory response to infection (and the sepsis pathway)
Which gram negative bacilli are strict aerobes?
Pseudomonas aeruginosa Legionella pneumophila (legionnaires disease)
Which gram negative bacilli is a small curved bacilli?
Camylobacter
What is an example of a spiral gram negative bacilli?
Helicobater sp.
What is an example of a small gram negative (cocco) bacillus
Haemophillus influenzae
What is the gram positive anaerobic bacilli?
Clostridium spp.
Where is clostridium spp. normally found?
What allows it to survive outside the body for many months?
Normal bowel flora of man and animals
It produces spores
What is the gram negative anaerobic bacilli?
Bacteroides spp.
where is the bactericides spp. normally found?
Many different species make up normal bowel flora
Usually non-pathogenic and will only cause infection if they get into a normally sterile site
What is the first line treatment for infections by anaerobes?
Metronidazole
What is the first line treatment for infections caused by clostridium spp.?
Metronidazole
What is the first line treatment for infections caused by Bacteroides spp.?
Metronidazole
How are mycobacteria stained?
e.g. mycobacterium tuberculosis, have a thick waxy coat and therefore are stained either as acid fast bacilli or acid-alcohol fast bacilli
What are spiral shaped bacteria that do not stain with gram stain?
2 examples
Spirochaetes e.g. Treponema pallidum (causes syphilis), Borrelia burgdoferi (causes Lyme disease)
What 2 types of DNA does bacteria have?
Chromosome
Extrachromosomal e.g. plasmid
What creates genetic variation in bacteria? (2)
Mutation
Gene transfer
(this is important because resistance to antibiotics may develop and spread rapidly as a result of bacterial genetic variation)
What are the 3 types of gene transfer?
Transformation
Conjugation
Transduction
What is transformation? (genetic variation)
DNA released from dead bacteria can be taken up by the living bacteria and incorporated into plaids or the bacterial chromosome
What is conjugation? (genetic variation)
Bacterial “sex” - a sex pilus (fimbria) is produced by one bacteria through which plasmid DNA can be transferred
What is transduction? (genetic variation)
Viruses that infect bacteria can transfer bits of DNA from one bacterium to another
In terms of enzymes, what is one way by which bacteria can become resistant to antibiotics?
Production of enzymes that destroy antibiotics before they have time to work
What are 3 examples of enzymes that are produced by some bacteria = antibiotic resistance along with what antibiotics they are resistant to?
Beta-lactamase (early penicillins e.g. amoxicillin)
Extended spectrum beta-lactamase (ESBL- resistance to all the penicillins and cephalosporins)
Carbapenemase (resistance to all penicillin, all cephalosporins and the carbapenems - antibiotic of last resort)
In terms of binding sites, what is another cause of antibiotic resistance?
Altered antibiotic binding sites - antibiotics can’t bind
What causes MRSA?
Alteration of the penicillin binding protein = staph aureus becomes resistant to flucloxacillin
What is the common mechanism of resistance in fungi such as Candida spp.?
Up-regulation of efflux pumps
