Bacterial Infections Flashcards
Staphylococcus aureus - morphology and gram stain
Gram positive (purple) bunches of cocci
Streptoccus pneumoniae - morphology, gram stain
Gram positive (purple) diplococci
Staphylococcus epidermidis - morphology and gram stain
Gram positive (purple) bunches of cocci
Neisseria meningitidis - morphology and gram stain
Gram negative (pink) diplococci
Neisseria gonorrhoea - morphology and gram stain
Gram negative (pink) diplococci
Clostridium difficile - morphology and gram stain
Gram postive (purple) rods
Clostridium perfringens - morphology and gram stain
Gram positive (purple) rods
Streptococcus pyogenes - morphology, gram stain and group
Gram positive (purple) chains of cocci, referred to as Group A Streptococci or GAS
Escherichia coli - morphology and gram stain
Gram negative (pink) rods
Salmonella - morphology and gram stain
Gram negative (pink) rods
Bordetella - morphology and gram stain
Gram negative (pink) cocci
Non typhoidal salmonella (NTS) - morphology and gram stain
Gram negative (pink) rods
Typhoidal salmonella (enteric fever) - morphology and gram staining
Gram negative (pink) rods
Haemophilus influenzae - morphology and gram stain
Gram negative (pink) cocci
What is the test for gram staining?
1 - Stain slide with crystal violet for 1-2 minutes
2 - Flood slide with Gram’s iodine for 1-2 minutes
3 - Decolourize slide by briefly washing with acetone for 2-3 seconds
4 - Stain with safranin counterstain for 2 minutes
5 - View under microscope
What are the main differences between Gram positive and negative bacteria?
Gram negative bacteria have an outer membrane.
Gram positive have 90% peptidoglycan and negative have 10%.
What are the implications of differences between gram positive and gram negative bacteria?
Susceptible to different antibiotics, different ability to survive infection control procedures and cause different diseases.
Cocci can be arranged…
Singularly, in pairs, in bunches, in chains.
Rods can be arranged…
Singularly or in chains.
Rods can be shaped…
Fat or thin, long or short.
Streptococcus pyogenes is (?)-haemolytic and which colour does this show on blood agar?
Beta-haemolytic and this shows as yellow with zone of clearing around colonies. (Beta-better at degrading)
Streptococcus pneumonia is (?)-haemolytic and which colour does this show on blood agar?
Alpha-haemolytic and this shows as green and is partially degrading.
Clostridium difficile and perfringens form what?
Anaerobic (air hating) spores.
Neisseria meningitidis is capsulated/non-capsulated?
Capsulated.
Neisseria gonorrhoea capsulated/non-capsulated?
Non-capsulated.
Haemophilus influenzae capsulated/non-capsulated?
Capsulated.
Neisseria meningitidis is motile/non-motile?
Non-motile.
Neisseria gonorrhoea is motile/non-motile?
Motile.
Neisseria meningitidis is referred to as what?
The meningococci.
Non-haemolytic bacteria is called what?
The enterococci.
Which of these is more important medically? Alpha and beta haemolytic or non-haemolytic.
Alpha and beta haemolytic.
Which bacteria are classified by putting on blood agar (haemolytic)?
Streptococcus (e.g. this method is used to determine streptococcus pneumoniae from streptococcus pyogenes).
What percentage of infections caused by Haemophilus influenzae are invasive?
80%.
Haemophilus influenzae causes what mainly?
Meningitis - however not most common cause of meningitis due to vaccine.
Bordetella pertussis causes what?
Whooping cough.
The only reservoir for bordetella pertussis is what?
Humans.
Whooping cough most commonly affects who, and what are the important death rates for this group?
Under 1’s, with 90% of deaths from this in babies under 3 months old.
Recent cases of whooping cough has been observed in which age range?
15-40 year olds.
Whooping cough is more severe in whom: adults or babies?
Babies, cases in adults are more mild.
Neisseria gonorrhoea is commonly called what?
The gonococci.
Neisseria gonorrhoea is ranked where in STD’s in the UK?
2nd.
What type of infections does Neisseria gonorrhoea cause?
Urethral, rectal, throat - men and women. Endocervical - women. Eye infections in newborns - contracted during passage through birth canal - conjunctivitis - yellow, crusty eyes.
Neisseria gonorrhoea is symptomatic/asymptomatic?
Asymptomatic - causes increase in cases in new sexual partners as not showing signs of infection.
Neisseria gonorrhoea can lead to what?
Pelvic inflammatory disease and ectopic pregnancy.
What is the leading cause of meningitis?
Neisseria meningitidis.
What type of meningitis is caused by Neisseria meningitidis?
Typically Group B due to lack of vaccine.
Meningitis caused by Neisseria meningitidis can be associated with what and what does this mean must happen?
Septicaemia - prompt antibiotics are needed.
Non-typhoidal salmonella is abbreviated to what?
NTS.
Typhoidal salmonella is sometimes called what?
Enteric fever.
Non-typhoidal salmonella causes what?
Gastrointestinal disease previously associated with eggs. Associated with gastroenteritis and diarrhoea.
How is non-typhoidal salmonella transmitted?
Faecal-oral route or contaminated foods.
Typhoidal salmonella causes what?
Typhoid fever.
What are the symptoms of typhoid fever?
Systemic symptoms - fever. Symptoms to look out for are diarrhoea in the returning traveller.
Typhoidal salmonella is maintained by carriers how?
Passing it on through poor hygiene- e.g. Typhoid Mary.
The enterobacteriaceae includes what?
Escherichia coli and salmonella.
Escherichia coli typically colonises/infects the GI tract.
Typically colonises but virulent (disease-causing) strains can cause infections.
What type of infections does Escherichia coli commonly cause?
UTI’s - simple - resolve without treatment, complicated - can lead to kidney infections such as pyelonephritis. Bacteraemia, GI infections (travellers diarrhoea).
Predisposing factors for developing UTI’s include what?
Being female (shorter urethra), sexual intercourse, pregnancy and catheterisation.
Escherichia coli also causes what?
Severe infection is caused by EHEC (enterohaemorrhagic e.coli) e.g. E.coli 0157 - can lead to haemorrhagic colitis and haemolytic uremic syndrome. Rarely causes neonatal meningitis.
Clostridium perfringens flourishes in what?
Necrotic (dead) tissue.
Clostridium perfringens can cause what?
Gas gangrene.
Treatment for clostridium perfringens is what?
Surgical debridement or amputation.
Streptococcus pyogenes can cause what?
Tonsillitis, skin and soft tissue infections such as impetigo and cellulitis and necrotising infections such as necrotising fasciitis.
Necrotising fasciitis is also referred to as what?
Flesh eating disease.
Streptococcus pneumoniae is capsulated/non-capsulated?
Capsulated.
The presence of a capsule around streptoccus pneumoniae is linked to what?
Invasive infections.
Invasive infections are linked to what?
Capsules around the bacterium.
Streptococcus pneumoniae can cause what?
Pneumonia, meningitis, septicaemia, otitis media, ear infections, septic arthritis and sinusitis.
Urgent antibiotics are needed for meningitis - true/false?
True.
Symptoms of pneumococccal meningitis in adults include?
Blotchy, non-blanching, red rash; headache; fever; nausea and vomiting.
Streptococcus pneumonia colonises the nasopharynx in..
5-10% healthy adults, 40% healthy children.
Symptoms of pneumococcal meningitis in under 2 year olds include?
Floppy; unresponsive; pale, blotchy skin; staring expression; loss of appetite and vomiting.
How is streptococcus pneumonia treated?
Depends on sensitivity - if sensitive - penicillin. Vancomycin can be used. Sensitivity takes time to determine due to needing to grow culture.
How streptococcus pneumonia be prevented?
Vaccination: Pneumococcal conjugate vaccine in under two’s, pneumococcal polysaccharide vaccines in over 65’s.
Invasive pneumococcal diseases mainly affect?
Under two’s: 20% cases, over 65’s.
Symptoms of pneumonia (Streptococcus pneumoniae)?
Productive cough, rusty sputum, fever.
Streptococcus pneumoniae accounts for what percentage of pneumonias?
25-60%.