Classification of Pathogenic Bacteria

Question 1

Eschericha coli (enterohaemorrhgic E. coli)

Answer 1

gram neg bacilli 
lactose fermenting coliform 
commensal of GI tract
most common cause of UTIs 
also causes neonatal meningitis and some strains cause diarrhoea

Question 2

E. coli 0157

Answer 2

causes bloody darrohea and haemolytic-ureamic syndrome

Question 3

Pseudomonas species

Answer 3

gram neg oxidase positive rods
water and soil organism
can contaminate medical equipment
hospital acquired cause of sepsis - pneumonia, UTI
respiratory infection in cystic fibrosis
sensitive to a limited range of antibiotics

Question 4

Prevotella

Answer 4

gram neg bacillus oral flora anaerobe
previously called bactericides
involved in dental infections and aspiration pneumonia
usually penicillin and metronidazole sensitive

Question 5

Porphyromas

Answer 5

gram neg bacillus miscellaneous anaerobe

found in mouth and else where

Question 6

Haemophilus influenzae

Answer 6

gram neg fastidious cocco-bacilli
capsulated strains type b (Hib) cause childhood meningitis and epiglottitis (vaccine available)
non-capsulate strains cause exacerbations of CAOD, sinusitis and otitis media
does not cause influenza!

Question 7

Helicobacter pylori

Answer 7

gram neg curved bacilli
microaerophilic
strongly urease positive
causes gastritis and peptic ulceration

Question 8

Klebsiella spp.

Answer 8

gram neg coliform bacilli
lactose fermenting
causes UTI, HAIs and occasionally pneumonia
may become resistant to antibiotics

Question 9

Salmonella enterica

Answer 9

gram neg lactose non-fermenting
self-lifting enterocolitis (w/ or w/o bloody diarrhoea)
2nd most common cause of bacterial diarrhoea in UK

Question 10

Salmonella typhi

Answer 10

gram neg lactose non-fermenting 
cause of typhoid fever 
fever and constipation in early stages 
risk during foreign travel 
vaccine available

Question 11

Shigella species

Answer 11

gram neg coliform
lactose non-fermenting rods
4 species, only 1 endemic in UK (shigella sonnei)
causes dysentery (blood & pus in stool)
low infective dose - easily spread, outbreaks common in nurseries

Question 12

Proteus species

Answer 12

gram neg coliform
lactose non-fermenting
causes UTIs - often associated w/ renal calculi (as urease it produces makes urine alkaline)

Question 13

Bacteriodes fragillis group

Answer 13

gram neg bacilli anaerobes
part of normal colonic flora
often present in mixed intra-abdominal infection s
resistant to penicillin, sensitive to metronidazole

Question 14

Coxiella burnetti

Answer 14

gram neg obligate intracellular 
causes Q fever - usually no symptoms but can have febrile symptoms for up to 2 weeks 
can cause pregnant woman to miscarry 
spread to humans by infected animals 
highly resistant to environmental stress

Question 15

Eschericha coli (enterotoxogenic E. coli)

Answer 15

gram neg bacilli
lactose fermenting coliform
commonest cause of traveller’s diarrhoea

Question 16

Neisseria gonorrhoeae

Answer 16

gram neg diplococcus
causes gonorrhoeae (pelvic inflammatory disease in woman, urethritis in men)
must be cultured quickly or dies
in females ensure endocervical swab is taken to avoid missing pathogen

Question 17

Moraxella catarrhalis

Answer 17

gram neg coccus
respiratory pathogen
causes exacerbations of chronic bronchitis
causes otitis media in children
more common in people w/ underlying lung pathology
80% strains contain beta-lactamase

Question 18

Vibrio cholerae

Answer 18

gram neg curved bacilli
causes severe diarrhoea in form of cholera
ingested in water contaminated by faeces

Question 19

Neisseria meningitis

Answer 19

gram neg diplococcus
cause of mengiococcal septicaemia and meningitis
meningitis has high mortality and should be treated w/ IV penicillin on presumption of diagnosis
Vaccines - Men A, C, Y, W-135 conjugate & 4 component Men B

Question 20

Campylobacter jejuni

Answer 20

gram neg curved bacilli 
microaerophilic 
source: domestic animals
faecal-oral route
foul smelling then bloody diarrhoea 
commonest cause of gastro-enteritis in UK

Question 21

Enterococcus faecalis

Answer 21

gram positive gut commensal
can cause UTI
vancomicin resistant enterococci (VRE) increase problem in hospitals

Question 22

Staphylococcus saprophyticus

Answer 22

gram positive coagulase negative

cause of UTI in woman of child bearing age

Question 23

Staphylococcus agalactiae

Answer 23

gram positive
group B beta-haemolytic on blood agar
causes neonatal sepsis (meningitis/bacteraemia)
genital tract carriage common (25% in woman)

Question 24

Staphylococcus epidermis

Answer 24

gram positive coagulase negative
ubiquitous on skin
may cause infection of catheters, prostheses, ventricle-peritoneal shunts

Question 25

Streptococcus pyogenes

Answer 25

gram positive group A beta-haemolytic on blood agar cause of sore throats, cellulitis, impetigo post-streptococcal sequelae: acute rheumatic fever, acute glomerulonephritis can also cause necrotising fasciitis treat w/ penicillin

Question 26

Staphylococcus aureus

Answer 26

gram positive, coagulase positive normal flora of skin & nose major pathogen especially of skin - boils, cellulitis, impetigo, endocarditis, osetomyelitis, toxin-mediated food poising, toxic shock syndrome MRSA have altered penicillin binding proteins - resistant to all penicillins & cephalosporus

Question 27

Viridians streptococci

Answer 27

gram positive alpha-haemolytic on blood agar normal oral flora common cause of endocarditis following dental treatment

Question 28

Clostridium tetani

Answer 28

gram positive bacilli spore forming anaerobe cause of tetanus (uncontrolled muscle spasms) due to toxin causing loss of inhibition of NMJ antigenic ally modified toxoid used for immunisation

Question 29

Streptococcus pneumoniae (pneumococci)

Answer 29

gram positive diplococci aplha-haemolytic on blood agar normal flora of upper respiratory tract commonest cause of bacterial lobar pneumonia major cause of meningitis in children/elderly vaccine available

Question 30

Listeria monocytogenes

Answer 30

gram positive rod found in animal and veg products causes meningitis in neonates and elderly bacteraemia in pregnancy

Question 31

Clostridium difficle

Answer 31

gram positive bacilli spore forming anaerobe can be carried asymptomatically in gut of healthy people cause of antibiotic associated diarrhoea Causes psuedomembranous colitis detect antigen and toxin in stool sample by ELISA

Question 32

Clostridium perfringes

Answer 32

gram positive bacilli spore forming anaerobe found in soil and normal commensal in human and animal toxogenic strains cause food poisoning infects serious wounds can cause gas gangrene

Question 33

Clostridium botulinum

Answer 33

``` gram positive bacilli spore forming anaerobe cause of botulism following ingestion of contaminated food most potent neurotoxin known to man rare in UK source of botox - inhibits Ach ```

Question 34

Bacillus cereus

Answer 34

gram positive aerobic rod beta-haemoltic found in soil and food common source of food poisoning from fried rice

Question 35

Bacillus anthracis

Answer 35

gram positive rod | causes anthrax

Question 36

Treponema pallidum

Answer 36

spirochaete causes syphilis does not culture on media diagnosis uses serology and nucleic acid amplification tests (NAAT) management: antibiotics, contact screening, antenatal screening

Question 37

Borrella burgdofen

Answer 37

spirochaete causes Lyme disease organism transmitted from rodent to man by lodes tick presents w/ skin rash (erythema chronic migrans) & arthritis organism difficult to grow, serology used

Question 38

Leptospira interrogans

Answer 38

spirochaete causes leptospirosis (Weil's disease) - febrile illness, systemic upset, renal and liver failure, aseptic meningitis, 10% mortality infects animals and concentrates in kidneys spread via urine/other body fluids sewage workers and people who do water sports at risk

Question 39

Chlamydia trachomatis

Answer 39

miscellaneous obligate intracellular ophthalmic and genital tract infecton - urethritis, cervicitis, PID, lyphogranuloma venereum, neonatal conjunctivitis & trachoma, pneumonia in neonates and immunocompromised culture laborious, infection diagnosed by detecting chlamydia antigen by EIA or chlamydia DNA by amplification test (e.g. PCR)

Question 40

Mycoplasm hominis

Answer 40

miscellaneous may be involved w/ pelvic inflammatory disease and post-pleural fever special media must be used testing not widely available

Question 41

Mycoplasm pneumoniae

Answer 41

miscellaneous important cause of atypical pneumonia appears in 4 year cycles diagnosis usually serological, through appearance of antibody, may be considerably delayed, by detection of specific IgM or rising CFT titre

Question 42

Chlamydia psittaci

Answer 42

``` miscellaneous obligate intracellular cause of psittacosis and ornithosis contracted by contact w/ birds present as pneumonia puts pregnant woman at risk of abortion, they should stay away from sheep during lambing diagnosis involves serology ```

Question 43

Chlamydia pneumoniae

Answer 43

miscellaneous obligate intracellular most recent recognised species culture difficult, serology for antibody best option tests not widely available right now

Question 44

Mycobacterium leprae

Answer 44

alkali and alcohol fast bacilli causes leprosy - attacks PNS cannot be cultured mainly in india, nepal, brazil, parts of africa

Question 45

Mycobacterium tuberculosis

Answer 45

alkali and alcohol fast bacilli causes tuberculosis due to specific straining/culture methods - have to request tests for suspected cases multi-drug resistant TB is big problem in parts of the world immunisation possible w/ live attenuated BCG strain