WCVD Lloyd lectures Flashcards
What are the three species that comprise the Staphylococcus intermedius group?
S. intermedius, S. pseudintermedius, S. delphini
What technique(s) for bacterial identification depends on chromatography and mass spectrometry?
matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), electrospray-ionization mass spectrometry, Fourier transform infrared spectroscopy, Raman spectroscopy and electrokinetic separation
T/F: Sequencing of 16S ribosomal RNA is a useful technique for bacterial identification because the genes are highly conserved.
True - and a large database of specific sequences is available
What technique for bacterial identification has been used for defnining the skin microbiome?
16s ribosomal RNA sequencing
What coagulase negative staphylococci have been reported to cause infection in dogs, cats, and small mammals?
S. schleiferi schleifer, S. felis, S. lugdunensis
What are risk factors for infection with coagulase negative staphylococci?
recent steroid administration, male animals more often affected
Characteristics of Macrococcus: Gram + or -? Coagulase + or -? Major species?
Gram positive cocci, coagulase variable (+ or -); M. caseolyticus, M. canis
Macrococcus spp. can carry which resistance genes, conferring resistance to all beta-lactam antibiotics, includings those with a beta-lactamase inhibitor?
mecB and mecD –> may be multi-drug resistant
T/F: Bacteria of the genus Cutibacterium are commensals of canine skin and there is no report of pathogenicitiy in skin.
True - inhabit hair follicles; single case report of a UTI
Bacteria from the genus Trueperella are most commonly associated with what type of infections?
abscesses and bite wounds (cats > dogs), purulent disease in livestock
Characteristics of Neisseria: Gram + or -? Common location on body? Major species?
gram negative coccoid bacteria; oral inhabitants of dogs & cats; Neisseria dumasiana, Neisseria canis
Characteristics of Burkholderia spp: Gram + or -? Major species?
Gram negative rods; Burkholderia cepacia, Burkholderia pseudomallei
This is a ubiquitous, gram negative rod, found in water, moist soil and contaminated environments, and can adhere to plastic. It can cause life-threatening opportunistic infections in immunocompromised humans as well as dogs treated with cyclosporine.
Burkholderia spp. (Burkholderia cepacia & pseudomallei)
T/F: Burkholderia cepacia is often multi-drug resistant.
True - culture and sensitivity tests should be carried out to determine treatment options
Causative agent of melioidosis in humans and animals (glanders)
Burkholderia pseudomallei
Burkholderia pseudomallei is found in water and soil and contaminated environments in what regions of the world?
Southeast Asia, Northern Australia, South Pacific; emerging in Africa and the Americas
Burkholderia pseudomallei has been isolated from what animals in the Europe and USA
green iguanas
How is Burkholderia pseudomallei typically acquired?
opportunistic infecton in immunocompromised individuals through wounds, inhalation, or ingestion
What organism causes the disease Buruli ulcer?
Mycobacterium ulcerans
What are the three most common mycobacterial species in human diseases?
Mycobacterium tuberculosis, Mycobacterium leprae, Mycobacterium ulcerans
What disease does Mycobacterium ulcerans cause?
Buruli ulcer – results in necrotising ulcers with undermining edges
What species of Mycobacterium have been associated with leprosy?
Mycobacterium lepromatosis and leprae
T/F: Leprosy is a zoonotic disease.
True - reported to be transmitted from armadillos to humans
What two types of bacteria that lack cell walls may be involved in cutaneous infections?
Mycoplasma spp. And L-forms
T/F: Mycoplasma spp. are normal members of the oral and upper respiratory tract flora in dogs and cats.
True - have also been found in canine axillary skin in microbiome studies
To what antibiotics are Mycoplasma spp. Intrinsically resistant? Why?
beta-lactams and other agents that target the cell wall –> they do not have a cell wall.
What are good empirical choices for treatment of Mycoplasma spp.?
macrolides, lincosamides, tetracyclines, fluoroquinolones
T/F: Mycoplasma spp. are difficult to isolate in culture.
True - may be readily obscured by other bacteria; need special sampling transport media and special isolation techniques
T/F: L-forms lack cell walls.
False - they are partially cell wall deficient, and originate from bacteria with cell walls, they may be able to revert to parental type.
Why are L-forms difficult to diagnose?
difficult to demonstrate with light microscopy (require electron microscopy of fresh tissue); cannot be cultured and identified by routine techniques
L-forms usually cause infections in what location of the body?
polyarthropathies; cutaneous lesions are typically feline draining abscesses over joints
Cytology of infections due to L-form bacteria usually demonstrates what?
non-toxic neutrophils (may contain granules) and macropahges
L-form bacteria usually respond to treatment with what antibiotics?
tetracyclines, macrolides, chloramphenicol
T/F: Staph aureus MSCRAMMs (microbial surface components recognizing adhesive matrix molecules) are adhesions (lectins) that bind to the extracellular matrix.
TRUE
Lectins such as Staph aureus MSCRAMMs (microbial surface components recognizing adhesive matrix molecules) bind via what receptors on host cells?
carbohydrate-recognition domains to glycan receptors on host cells – either terminal sugar residues or internal sequences found in oligosaccharide chains
T/F: Sugars are found in secretions such as saliva and tears that can antagonize the lectin binding sites and prevent colonization of staph aureus.
TRUE
What is quorum sensing? What manages quorum sensing?
ability of bacterial species to alter their mode of behavior from a non-aggressive to an aggressive phenotype; involves secretion by the bacteria of peptide signalling molecules which are detected by the other bacteria; managed by the accessory gene regulator (agr) system
Is biofilm formation a characteristic of a non-aggressive phenotype or an aggressive phenotype of bacteria?
non-aggressive: bacterial cells are protected fom host attack and other substances (including antimicrobials) by embedding themselves in a polysaccharide matrix formed by capsular material
Biofilm formation is promoted by what factors?
stress factors – including exposure to subinhibitory concentrations of antimicrobials
What is secreted by an aggressive phenotype of bacteria?
exotoxins, haemolysins, leucocidins – provoke more acute disease
____ are the most abundant mobile genetic elements of bacteria, which are variable in size and can replicate independently from chromosomal DNA but can integrate into chromosomal DNA.
Plasmids
_____ are mobile genetic elements of bacteria that MUST integrate into plasmids or chromosomal DNA to replicate, carrying their genetic material into these structures.
Transposons
______ are the smallest mobile genetic elements that usually only carry a single resistance gene.
Gene cassettes
These are large mobile genetic elements that have site-specific integration into chromosomal DNA and are typically accompanied by other resistance genes?
Integrative and conjugative elements – e.g. Staphylococcal Cassette Chromosome mec (SCCmec)
Resistance problems have particularly occurred within a small group of pathogens that are commonly associated with nosocomial infections: ESKAPE pathogens. What are they?
Enterococcus faecium, Staph aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterbacter spp., Escherichia coli
_____ is resistance to 3 or more antimicrobial classes.
multidrug-resistance (MDR)
_____ is resistance to all but one or two classes of antimicrobials.
extensive drug-resistance (XDR)
_____ is resistance to all classes of antimicrobials.
pandrug-resistance (PDR)
T/F: Classical MRSA infection in dogs and cats is caused by clones that are associated with community-acquired infections.
False - human hospital infections
