Please enable JavaScript.
Coggle requires JavaScript to display documents.
Gram Negative Rods (The Enterobacteriaceae
Glucose fermenters
Oxidase…
Gram Negative Rods
The Enterobacteriaceae
- Glucose fermenters
- Oxidase negative
- Nitrate positive
Diarrhoeal illness
- Some strains of Escherichia coli with various virulence factors --> diarrhoeagenic
---EHEC (shiga toxin), EPEC, EIEC, ETEC (travelers diarrhoea), EaggEC
- Yersinia enterocolitica, infects lymph nodes if mesentery --> pain
- Salmonella enterica and bongari. Many serotypes. Typhoidal or non-typhoidal
- genus Shigella. Invade bowel wall
---Bacillary dysentery: faeces contain blood and pus due to inflammatory processes
Typhoid fever (enteric fever)
- Salmonella typhi and paratyphi: may invade the bowel wall
- serious systemic disease- not really diarrhoal (blood stream and lymphoreticular tissue
Antibiotic resistant nosocomial infections
- very resistant to antibiotics due to extensive use in hospitals
- Hospital patients susceptible to infections
---Elderly, ill, debilitated, pose operative
---immunocompromised (cancer or drugs)
---innate immunity interfered: IV catheters, endotracheal tubes, urinary catheters, surgery
- Combat by: Hand washing, control antibiotic use, minimize risk factors
- Genera: Enterobacter, Serratia, Klebsiella, Proteus, Morganella, Providencia, E. coli
- Types of infection: Pneumonia, UTI, septicaemia, wound infections, orthopedic infections
Plague
- Black Death- killed 1/3 of Europe RIP
Urinary tract infections
- consist of bladder infections (cystitis) or kidney infections (pyelonephritis)
- Usually due to bacteria of bowel origin --> urethra --> UT
- Enterobacteriaceae are commensals of the bowel
- Strains of Escherichia coli cause most UTIs: virulence factors enable urethral colonisation
- Proteus mirabilis is the second most common cause of UTIs in the community
Miscellaneous, fastidious Gram negative rods
Genus Bordetella
- Bordetella pertussis is the main pathogen. coccobacilli.
- Whooping cough (pertussis). SIgnificant morbidity in children <6mnt
---Catarrhal phase: mild cough, runny nose
---Paroxysmal phase: severe cough attacks, gagging, cyanosis, whooping due to desperate indrawing of breath, vomiting. Apneoa, pneumonia, pneumothorax, haemorrhage, rib fracture, death
---Convalescent phase
- Highly infectious and is transmitted by the aerosol route
- Vaccination against whooping cough is available
- Seen mostly in older primary school students and middle aged adults. Current epidemic
Genus Brucella
- coccobacilli
- Pathogens of animals. Humans get it by contact or contaminated products of sheep, cow, goat, pig, dogs
- uncommon in developed countries, most common zoonosis worldwide.
- Generalised features: fever, night sweats, fatigue, muscle/joint pain, enlarged liver, depression.
- Localised features: Joint infection, orchitis/epididymitis, hepatitis, meningitis, encephalitis, skin rash
Genus Pasteurella
- Pasteurella multocida causes most infections
- Commensal in mouths of cats and dogs.
- May cause severe infection of skin and soft tissue following bite.
- May involve tendons, joints, bone.
Genus Bartonella
- tiny pleomorphic gram -ve rods
Bartonella henselae
- cat scratch disease
---Usually in young children
---Self limiting
---enters the skin from a cat scratch, bite or lick
---small red papule develops at the site of inoculation and over a couple weeks a regional lymph node becomes enlarged and tender (maybe months)
- bacillary angiomatosis
---seen in HIV infected people
---vascular lesion typically involving the skin
---Small red nodules --> raised or pedunculated friable lesions that bleed
- Peliosis
---formation within organs (liver or spleen) of blood filled cavities
Bartonella quintana
- trench fever
- spread by body lice
- homeless people or those with AIDS
- debilitating, bacteraemic febrile illness (days/ weeks)
- May lead to endocarditis.
- may cause bacillary angiomatosis or peliosis in AIDS patients
The HACEK group
- causes of bacterial endocarditis (not as common as aureus or strep), 3% of cases.
- commensals of the human oropharynx. Enter blood stream. adhere to heart valve
- “culture negative” endocarditis
H Haemophilus aphrophilus and H. paraphrophilus
A Actinobacillus actinomycetemcomitans
C Cardiobacterium hominis
E Eikenella corrodens
K Kingella kingae
- Bolded ones now in genus Aggregatibacter
-
The Genus Haemophilus
- commensals of the human upper respiratory tract
Haemophilus influenzae
- Some strains of this species are encapsulated (virulent)
- Serotypes: a, b, c, d, e, f, g. Haemophilus influenzae type B (“Hib”) most common
- Vaccine available.
- Causes meningitis (mainly in <18mo, cause retardation, deafness), epiglottitis (in <18mo, progression to laryngeal obstruction, asphyxiation)
- Non-encapsulated: commensal of upper RT, cause infection of mucosa, otitis media,bronchitis, conjunctivitis, sinusitis, pneumonia.
Haemophilus parainfluenzae
- commensal of the upper respiratory tract
- Same kinda infections
Haemophilus aphrophilus & paraphrophilus
- Aggregatibacter, part of HACEK
- Normal oral flora
- rare cause of endocarditis
Haemophilus ducreyi
- cause of the sexually transmitted disease chancroid
- ulcerative genital lesions and enlarged inguinal lymph nodes
-
-
The Genus Legionella
- ubiquitous inhabitants of aquatic environments (natural and man-made)
- fastidious (need special agar plates)
Legionella pneumophila
- Most disease
- inhale water vapour from a manmade water source
- Legionnaires’ disease: Pneumonia, high fever, GI symptoms, headache, myalgia
- More likely in smokers and the immunocompromised
Legionella longbeachae
- community acquired pneumonia
- acquired from potting mix and compost
- More likely in smokers, immunocompromised