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What does inoculum effect mean?

What does inoculum effect mean?

Inoculum effect is defined as an increase in the MIC with increasing bacterial inoculum size (Brook, 1989). If there is an inoculum effect, bacteria might appear as a susceptible when the inoculums is standard (105 CFU/ml) but resistant if the inoculum size is increased.

What is cefazolin inoculum effect?

Clinical failures of cefazolin occur most frequently with enzyme types A and C and have been linked to the cefazolin inoculum effect (CIE). This phenomenon is the loss of therapeutic efficacy of cefazolin and other early generation cephalosporin antibiotics when large numbers of organisms are present.

What is meant by inoculum in microbiology?

An inoculum can be defined as the population of microorganisms or cells that is introduced in the fermentation medium or any other suitable medium. From: Comprehensive Biotechnology (Second Edition), 2011.

What is inoculum in plant pathology?

Inoculation. Inoculation is the initial contact of a pathogen with a site of plant where infection is possible. The pathogen(s) that lands on or is otherwise brought into contact with the plant is called the inoculum. The inoculum is any part of the pathogen that can initiate infection.

Is MSSA sensitive to cefazolin?

About 20% of methicillin-susceptible Staphylococcus aureus (MSSA) isolates have a substantial inoculum effect with cefazolin, suggesting that cefazolin treatment may be associated with clinical failure for serious MSSA infections.

Is nafcillin the same as oxacillin?

Summary: Nafcillin and oxacillin, two antibiotics commonly prescribed in hospitals, have been used without preference for one over the other. Costs and effectiveness are similar for both. But a new study suggests that oxacillin is significantly safer than nafcillin.

What does high inoculum mean?

The inoculum effect (IE) is a laboratory phenomenon that is described as a significant increase in the minimal inhibitory concentration of an antibiotic when the number of organisms inoculated is increased. The IE generally occurs with beta-lactam antibiotics in relation to beta-lactamase-producing bacteria.

How can we reduce the level of inoculum?

Reduce the production of initial inoculum by destroying or inactivating the sources of initial inoculum (sanitation, removal of reservoirs of inoculum, removal of alternate hosts, etc.). Protection. Reduce the level of initial infection by means of a toxicant or other barrier to infection.

Is MRSA sensitive to ceftriaxone?

It is highly stable in the presence of beta-lactamases, both penicillinase and cephalosporinase, of gram-negative and gram-positive bacteria. Ceftriaxone does not cover MRSA.

Why is nafcillin better than vancomycin for MSSA?

Growth in the presence of sub-inhibitory nafcillin significantly enhanced LL-37 killing of MSSA compared to vancomycin and antibiotic-free controls. Nafcillin also reduced MSSA production of the golden staphylococcal pigment staphyloxanthin in 39% of pigmented strains vs. 14% for vancomycin.

How is nafcillin different from penicillin?

Basic Chemistry. Nafcillin is a semisynthetic penicillin with an acyl side chain that sterically inhibits the action of penicillinase by preventing the opening of the beta-lactam ring. Nafcillin is a white to yellowish-white powder with a slight characteristic odor Sweetman (2003).

What does inoculum mean in microbiology?

What is inoculum in microbiology?

Why is inoculum important?

The inoculum source had a significant impact on both growth and pH tolerance of the bacterial community in the EL soil. These differences between the EL soil inoculated with UL soil and FL soil were correlated to structural changes, as evidenced by both PLFA and DGGE analyses on the soil.

What is MSSA vs MRSA?

Those that are sensitive to meticillin are termed meticillin-sensitive Staphylococcus aureus (MSSA). MRSA and MSSA only differ in their degree of antibiotic resistance: other than that there is no real difference between them. Having MSSA on your skin doesn’t cause any symptoms and doesn’t make you ill.

Why is vancomycin bad for MSSA?

Vancomycin is associated with higher rates of infection-related mortality, re-infection and bacteriologic failure compared to cloxacillin or cefazolin in the definitive treatment of MSSA bacteremia [9, 12–15].

What class of drug is nafcillin?

Nafcillin injection is in a class of medications called penicillins. It works by killing bacteria. Antibiotics such as nafcillin injection will not work for colds, flu, or other viral infections.

What is the inoculum effect (ie)?

The inoculum effect (IE) is a laboratory phenomenon that is described as a significant increase in the minimal inhibitory concentration of an antibiotic when the number of organisms inoculated is increased. The IE generally occurs with beta-lactam antibiotics in relation to beta-lactamase-producing … Inoculum effect Rev Infect Dis.

What is the inoculum effect in microbiology?

Over 60 years ago, Eagle described an in vitro phenomenon called the “inoculum effect.” This effect has been observed in gram-positive bacteria exposed to β-lactam antibiotics and glycopeptides such as vancomycin (52, 53). This is believed to occur as a result of the cell wall-active agents’ mechanism of action.

Does the inoculum effect affect the virulence of nafcillin-induced infections?

No difference in either outcome was noted with the nafcillin treatment group, regardless of the presence of the inoculum effect, suggesting that there were no differences in virulence between isolates from the two groups. Currently, the only way to detect the CIE is by standard MIC determination at high bacterial inoculum.

Where does inoculum come from?

The inoculum sometimes is present right in the plant debris or soil in the field where the crop is grown; other times it comes into the field with the seed, transplants, tubers, or other propagative organs or it may come from sources outside the field. Outside sources of inoculum may be nearby plants or fields or fields many miles away.