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Questions and Answers
What is the main pathogen in humans discussed in the content?
Pseudomonas aeruginosa is an obligate anaerobe.
False
What color is Stenotrophomonas maltophilia?
Lavender green or gray
What is the drug of choice for treating Stenotrophomonas maltophilia?
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Pseudomonas aeruginosa does not ferment ______.
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Which of the following is a serious pathogen associated with Pseudomonas aeruginosa?
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What are the virulent factors for Pseudomonas aeruginosa?
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Acinetobacter is a glucose fermenter.
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What infection can Pasturella multocida cause from animal bites?
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What is a hallmark of Bacteroides fragilis infections?
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Yersinia species can cause ______ disease in humans.
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What body systems can Pseudomonas aeruginosa infect?
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What type of toxin does Pseudomonas aeruginosa produce that inhibits protein synthesis?
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Which diagnostic method is used for the isolation of Pseudomonas aeruginosa?
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Pseudomonas aeruginosa is only found in hospital environments.
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What is a notable environmental concern caused by Pseudomonas aeruginosa?
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Which of the following treatment options is commonly used for Pseudomonas aeruginosa infections?
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What mechanism does Pseudomonas aeruginosa employ to inactivate penicillins?
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Which treatment strategy is often required due to antibiotic resistance in Pseudomonas aeruginosa?
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Efflux pumps in Pseudomonas aeruginosa help retain antibiotics within the bacteria.
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Study Notes
Pseudomonas aeruginosa
- Common nosocomial pathogen (moist hospital areas)
- Obligate aerobe with distinct sweet, grape-like odor
- Oxidase positive, non-fermenter of glucose and lactose
- Grows at 42°C
- Motile, found in water, plants, and animals
- Causes skin, eye, and ear infections
- Can cause serious infections like ventilated-associated pneumonia (VAP), nosocomial pneumonia, and urinary tract infections (UTIs)
- High risk for neutropenic, burn, cystic fibrosis, and mechanically ventilated patients
- Virulence factors: exotoxin A, pili, lipopolysaccharide, and chronic colonization
- Resistance mechanisms include beta-lactamase production, biofilm formation, and multi-drug efflux pumps
Stenotrophomonas maltophilia
- Distinct lavender green or gray color
- Oxidase negative, oxidizes glucose and maltose, but doesn't ferment lactose
- Associated with hospital-acquired infections
- Treated with Bactrim
Burkholderia
- Causative agent of glanders, a zoonotic disease
Acinetobacter
- Aerobic, non-glucose and non-lactose fermenting, short rod-shaped bacteria commonly found in soil and water
- Significant nosocomial pathogen, causing pneumonia, bacteremia, and wound infections
- Highly resistant, often requiring treatment with colistin
The HACEK Bacteria
- Includes Eikenella corrodens, a small, fastidious, oxidase-positive gram-negative rod
- Found in gingival and bowel flora
Moraxella species
- Coccobacilli associated with bronchitis and pneumonia
Neisseria Species
- Includes Neisseria gonorrhoeae, a sexually transmitted infection causing gonorrhea
- Includes Neisseria meningitidis, a causative agent of meningitis
Pasteurella multocida
- Primarily an animal pathogen, but can be zoonotic
- Causes cellulitis from animal bites
- Non-motile gram-negative coccobacilli, strongly suspected in skin infections from cats and dogs
- Treated with Augmentin
Yersinia species
- Infections from wild rodents, transmissible to humans and other mammals
- Includes Yersinia pestis, the causative agent of the black death (bubonic plague)
- Can be utilized as a biological weapon
Y. enterocolitica and Y. pseudotuberculosis
- Cause diarrheal disease in humans
- Non-lactose fermenting
Haemophilus influenzae type B
- Possesses an antiphagocytic capsule, with type B being the most virulent for humans
- Its major virulence factor is the polyribose phosphate capsule
- Causes non-invasive infections like otitis media, sinusitis, and pharyngitis
- Can cause invasive infections such as pneumonia, septic arthritis, and osteomyelitis
- Preventable with vaccination
Bacteroides fragilis
- Part of the normal intestinal flora, but can be pathogenic in synergy with other bacteria
- Causes polymicrobic infections
- Virulent factor is its capsular polysaccharide
- Facultative anaerobe, known for causing aspiration pneumonia and intra-abdominal abscesses
- Treated with metronidazole or clindamycin
Haemophilus
- Small pleomorphic bacteria requiring enriched chocolate agar (contains no chocolate) for growth
- Requires X (heme) and V (nicotinamide adenine dinucleotide) factors for growth
- Found in normal respiratory flora
- Causes a wide range of diseases
Pseudomonas aeruginosa
- An opportunistic pathogen found in a wide range of environments, including hospitals.
- Frequently infects individuals with compromised immune systems, burn victims, patients with cystic fibrosis, and those with chronic lung diseases.
- Causes infections in diverse areas of the body, such as the respiratory system, urinary tract, bloodstream, and skin.
- Possesses a variety of virulence factors that enable it to evade the host’s defenses and cause harm:
- Produces exotoxins: specifically, exotoxin A inhibits protein synthesis.
- Secretes enzymes: elastase and proteases degrade host tissues, facilitating tissue damage.
- Forms biofilms: enhancing survival in hostile environments, such as the body's immune system.
- Commonly diagnosed by collecting clinical specimens from infected sites (e.g., sputum, wounds, urine) and culturing them on selective media (like cetrimide agar).
- Can be identified using biochemical tests, like the oxidase test, which is positive for Pseudomonas aeruginosa, and tests for its utilization of citrate as its sole carbon source.
- Advanced techniques like PCR and MALDI-TOF provide quicker and more accurate identification.
- A prevalent bacterium in the environment, found in soil, water, and diverse settings, including hospitals.
- Utilized in bioremediation due to its ability to degrade pollutants.
- Known for forming biofilms in aquatic environments, such as pipelines and water systems, contributing to biofouling in industrial processes and natural ecosystems.
- Treatment typically involves the use of broad-spectrum antibiotics like piperacillin-tazobactam, cephalosporins (cefepime), and carbapenems (meropenem).
- Combination therapy might be required due to the prevalence of antibiotic resistance.
- Antibiotic susceptibility testing is crucial to guide treatment selection.
- Alternative treatments, like phage therapy and immunotherapy, are being investigated for their potential to combat Pseudomonas aeruginosa infections.
- Significantly resistant to numerous antibiotics, complicating treatment efforts.
- Several mechanisms contribute to its resistance:
- Production of β-lactamases: these enzymes inactivate penicillins and cephalosporins.
- Efflux pumps: these pumps expel a range of antibiotics from the bacterial cell, preventing them from reaching their target.
- Modifications to target sites: changes in penicillin-binding proteins can obstruct antibiotics from binding and inhibiting bacterial cell wall synthesis.
- Resistance plasmids: these plasmids allow for horizontal gene transfer among bacterial populations, facilitating the spread of drug resistance.
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Description
Test your knowledge on Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Burkholderia. This quiz covers their characteristics, pathogenicity, and clinical significance, particularly in nosocomial infections. Understand their virulence factors and resistance mechanisms to better prepare for medical microbiology scenarios.
