STREPTOCOCCUS: Enterococcus faecalis e faecium | Videoaula | Microbiologia | Flavonoide #13

Summary

This video lesson dives into the world of *Enterococcus* bacteria, focusing on *Enterococcus faecalis* and *Enterococcus faecium*. The lecture explains their classification as Gram-positive, catalase-negative cocci, their ability to survive in high salt concentrations, and the tests used to identify them, such as the bile esculin and pirrolidone tests. The instructor highlights key virulence factors, including antibiotic resistance to penicillin and vancomycin. Clinical manifestations, including endocarditis and urinary tract infections, are covered, alongside diagnosis methods. Treatment options, including the use of penicillins, aminoglycosides, and alternative therapies for vancomycin-resistant strains, are discussed.

Takeaways

• 😀 Enterococci are Gram-positive, catalase-negative bacteria commonly found in the gastrointestinal tract.
• 😀 These bacteria can be identified using a 6.5% NaCl tolerance test, which distinguishes Enterococci from other species.
• 😀 Enterococci can hydrolyze esculin, which can be tested using the bile-esculin test, resulting in a black coloration.
• 😀 A distinguishing feature of Enterococci is their resistance to high concentrations of salt and bile.
• 😀 Enterococci can acquire the Van gene, making them resistant to vancomycin, a potent antibiotic.
• 😀 Vancomycin-resistant Enterococci (VRE) are concerning because they are harder to treat and cause serious infections.
• 😀 Enterococci are associated with hospital-acquired infections, particularly in patients with gastrointestinal or genitourinary surgeries.
• 😀 Common infections caused by Enterococci include endocarditis, cholecystitis, and urinary tract infections, especially in patients with catheters.
• 😀 Endocarditis caused by Enterococci can occur when the bacteria spread to the heart, especially in patients with pre-existing cardiovascular conditions.
• 😀 Enterococci can be treated with penicillins, aminoglycosides, and sometimes vancomycin. However, vancomycin-resistant strains may require linezolid or daptomycin.
• 😀 While there is no vaccine for Enterococci, prophylactic antibiotics are recommended for patients undergoing surgeries involving the gastrointestinal or genitourinary systems.

Q & A

What are Enterococci and why are they important in microbiology?

Enterococci are Gram-positive bacteria that belong to the group of cocci (spherical-shaped bacteria). They are important because they can be found in the gastrointestinal tract and are often associated with infections, particularly in hospital environments.

How are Enterococci classified in terms of their hemolytic activity?

Enterococci are considered gamma-hemolytic, meaning they do not break down hemoglobin or do so only minimally. This characteristic helps differentiate them from other groups of streptococci, such as alpha- and beta-hemolytic strains.

What test can be used to differentiate Enterococci from non-Enterococci species?

One key test is the ability to grow in a 6.5% NaCl (salt) solution. If the bacteria can grow in this concentration, it is identified as Enterococcus. Another test is the bile-esculin test, where Enterococci can hydrolyze esculin in the presence of bile, resulting in a black coloration.

What makes Enterococci resistant to certain antibiotics?

Enterococci have inherent resistance to penicillin and some cephalosporins. Additionally, some strains acquire resistance to vancomycin through the acquisition of the vanA gene, which alters the bacterial cell wall, making it resistant to vancomycin's mechanism of action.

What clinical problems can Enterococci cause?

Enterococci can cause a variety of infections, including endocarditis (infection of the heart valves), urinary tract infections, wound infections, and gallbladder inflammation (cholecystitis), especially in hospital settings or in patients with compromised immune systems.

How does the vanA gene affect Enterococci's resistance to antibiotics?

The vanA gene causes Enterococci to modify their peptidoglycan precursors by replacing the D-alanine with D-lactate. This alteration prevents vancomycin from binding to its target, rendering the bacteria resistant to this potent antibiotic.

What types of patients are most at risk for infections caused by Enterococci?

Patients who are hospitalized, particularly those who have undergone gastrointestinal or genitourinary surgeries, have catheter placements, or have cardiovascular problems, are at higher risk. Enterococci infections are also more common in those who have been on long-term antibiotics or have weakened immune systems.

What diagnostic methods are used to identify Enterococci infections?

Enterococci infections are typically diagnosed by isolating the bacteria from blood, urine, or other clinical samples. Techniques like culture, biochemical tests, and sometimes imaging (like echocardiograms for endocarditis) can be used to confirm the presence of the bacteria.

How are Enterococci infections treated?

Enterococci infections can be treated with penicillins like Penicillin G and Ampicillin, often in combination with aminoglycosides (e.g., gentamicin). However, in cases of vancomycin-resistant Enterococci (VRE), other antibiotics like linezolid or daptomycin may be used.

What preventive measures can be taken to avoid Enterococci infections?

Preventive measures include the prophylactic use of antibiotics in high-risk patients (those undergoing surgeries involving the gastrointestinal or genitourinary tract, or those with cardiovascular issues). Also, proper hygiene and infection control practices in healthcare settings can reduce the spread of Enterococci.