The Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) is an international, interdisciplinary, nonprofit, standards-developing. The Clinical and Laboratory Standards Institute (CLSI) is a not-for-profit membership CLSI document MS24 (ISBN CLSI MS18 Glossary I CLSI MS18 Glossary I (Part Read more about esbl, clsi, imipenem, resistant, cefepime and mirabilis.

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Ina new set of penicillin breakpoints was published in the CLSI revised guideline, MS18, to define the 1s8 of non-meningeal isolates of Streptococcus pneumoniae. The impact of the change is studied and discussed. Laboratory data on pneumococcal isolates collected from Chang Gung Memorial Hospital during —07 were analysed using the original and modified penicillin CLSI breakpoints.

A total of non-duplicate isolates were identifed, including 43 1.

For non-meningeal isolates, penicillin non-susceptibility was reduced significantly from Ceftriaxone non-susceptibility m10 increased significantly from 2. Higher resistance to penicillin With the implementation of the new breakpoints, clinicians may continue to use penicillin for the treatment of m10 pneumococcal infections in preference to other drug classes. However, as isolates with borderline penicillin MICs are increasing, continued surveillance of pneumococcal susceptibility to penicillin will be needed.

Streptococcus pneumoniae is one of the most frequent causative agents of community-acquired infections, including bacteraemia, pneumonia and meningitis. In the USA, the first case of penicillin-non-susceptible S. To achieve a better therapeutic outcome, broad-spectrum cephalosporins, such as ceftriaxone and cefotaxime, are usually recommended in such a setting.

Higher doses of penicillin were found to saturate the available PBPs, leading to the adequate killing of S. Similar inconsistency between the in vitro data and in vivo effects was also found with broad-spectrum cephalosporins. The relationship between penicillin resistance and increased mortality or treatment failure remains the subject of debate.

M1000 than four decades ago, when penicillin resistance in S8. Definitions of penicillin susceptibility or resistance in S. However, different factors should be considered when treating pneumococcal pneumonia and m1100.

Thus, the definitions of penicillin susceptibility for pneumococcal bacteraemia or pneumonia should be different to reflect the pharmacokinetics of penicillin and its clinical effectiveness. The present report was conducted to assess the impact of the CLSI modified breakpoints on the reporting of antimicrobial susceptibility among clinical isolates of S. To avoid duplication, only the first pneumococcal isolate from each patient was included for statistial analysis.

All pneumococcal isolates were isolated and identified by standard methods. Moxifloxin and levofloxacin were included in the testing panel from andrespectively. Isolates with intermediate or full resistance were classified as non-susceptible in this study. Epi Info software version 6. Data from a total of pneumococcal isolates were collected during the study period and analysed.

The average annual number of isolates was maximum, in The remaining isolates were from normally sterile specimens, including blood Because penicillin and ceftriaxone breakpoints for meningeal isolates are different from those from other sites, antimicrobial susceptibility results for these isolates were analysed separately.

Clzi total of 43 meningeal isolates were found during the study period. Of these, 23 The numbers of meningeal isolates decreased by half, from 8—10 isolates per year before to 1—5 isolates clsk year thereafter. Ceftriaxone non-susceptibility was found in A total of pneumococcal isolates were recovered from non-meningeal specimens.


With the use of the original penicillin breakpoints, the rate of penicillin non-susceptibility increased significantly from an clai of If the modified CLSI breakpoints were applied, m100 penicillin non-susceptibility rate reduced significantly from The decrease was mostly due to a change in the proportion of intermediately resistant isolates now classified as susceptible.

Full resistance to penicillin was found only sporadically 0—6 isolates per year. Annual numbers bars and non-susceptibility rates lines of non-meningeal pneumococcal isolates with various antimicrobial susceptibilities to penicillin a, according to the original CLSI breakpoints; b, according to the CLSI breakpoints or ceftriaxone c, the CLSI breakpoints remained unchanged in In each panel, the numbers of susceptible isolates are indicated by white bars, while black bars represent those of resistant isolates and bars with horizontal lines are the numbers of intermediately resistant isolates.

The non-susceptibility rates of isolates from normally sterile specimens are indicated by bold lines and those for other clsl are indicated by lines with open circles.

Navigating the 2012 Changes to CLSI M100, M02 and M07

With regard to ceftriaxone non-susceptibility, the rate increased significantly from an average z18 2. Full resistance to ceftriaxone was found in less than five isolates per year. With regard to other antibiotics, cpsi rates csli at a low level: The correlation between penicillin and ceftriaxone non-susceptibilities was further analysed. The ceftriaxone resistance of such isolates was mostly In contrast, if the new penicillin breakpoints were applied, the increase in ceftriaxone non-susceptibility from 0.

During —07, the proportion of such ceftriaxone-non-susceptible isolates reached a surprisingly high level of Annual numbers of non-meningeal pneumococcal isolates categorized by their penicillin susceptibilities [ a susceptible, b intermediately resistant and c resistant] according to the original upper panels and lower panels CLSI breakpoints. In each bar clzi numbers of isolates with various ceftriaxone susceptibilities are also indicated white, susceptible; black, resistant; horizontal lines, intermediately resistant.

Annual numbers bars, from left to right, —07 of non-meningeal pneumococcal isolates categorized by their MICs of penicillin upper panel. Areas marked with horizontal lines represent the number of ceftriaxone-non-susceptible isolates in the respective bars. S, susceptible; I, intermediately resistant; R, resistant.

The percentage of isolates in each MIC category is indicated by lines in the lower panel. Open squares represent data from and filled circles represent data from Adjacent to this largest group were another two large groups that appeared to have a reverse trend of annual numbers through the years. A similar left-shifting trend was found if only isolates from normally sterile specimens were analysed. Another large group comprised patients in their 60s and 70s.

Age distribution bars, per 5 year interval of patients with non-meningeal pneumococcal infections bars with diagonal lines, invasive infections; open bars, non-invasive infections and rates lines of csli non-susceptibilities among the isolates bold line and penicillin non-susceptibilities among the isolates according to the original line with filled triangles and modified line with filled circles CLSI breakpoints.

Hence, antibiotic breakpoints are used to determine whether m1000 MIC for a bacterium indicates it is susceptible treatableintermediate possibly treatable with higher doses or resistant probably not treatable. Thus, not only may the existing in vitro — in vivo paradox of penicillin for non-meningitis pneumococcal infections be prevented, m010 the effective therapeutic level of penicillin may also be optimized.


In the present study, x18 the application of the modified breakpoints, a striking difference in the penicillin susceptibility among non-meningeal pneumococcal isolates in the past few years was demonstrated.

A recent report indicated a change in the non-susceptibility rate from Moreover, with a continuous analysis across —07, we were able to demonstrate that the penicillin non-susceptibility rate in S. Clinicians may feel more confident in using penicillin for penicillin-susceptible non-meningitis pneumococcal infections. In areas where S. It has been previously demonstrated that ceftriaxone MICs may exceed those of penicillin for the same strains of S.

The application of the modified penicillin breakpoints appeared to provide clinicians with additional options in dealing with pneumococcal infections. Be it at the lower end of resistance MIC range BSAC breakpoints or at the higher end of reduced susceptibility range EUCAST breakpointslaboratories should report MICs of various antimicrobial agents for invasive pneumococcal isolates so that clinicians can make appropriate therapeutic selections.

Dlsi has been shown that S. This difference may be attributed to the higher level of antimicrobial use in the paediatric population. The establishment of the modified non-meningeal penicillin breakpoints in CLSI MS18 would result in a great difference in the reporting of penicillin susceptibilities as well as clinical management of pneumococcal infections.

The modification appears to more accurately reflect the clinical effectiveness of penicillin and, hence, the reduction of cephalosporin use could be expected. Oxford Clsj Press is a department of the University of Oxford. It furthers the University’s objective of excellence in research, scholarship, and education by publishing worldwide.

Navigating the Changes to CLSI M, M02 and M07 – ppt video online download

Sign In or Create an Account. Close mobile search navigation Article navigation. Antimicrobial susceptibility of Streptococcus pneumoniae at a university hospital in Taiwan, — View large Download slide. Multidrug-resistant Streptococcus pneumoniae infections: The in vivo—in vitro paradox in pneumococcal respiratory tract infections. Inhibition of cell wall synthesis and acylation of the penicillin binding proteins during prolonged exposure of growing Streptococcus pneumoniae to benzylpenicillin.

The effect of cephalosporin resistance on mortality in adult patients with nonmeningeal systemic pneumococcal infections. National Committee for Clinical Laboratory Standards. Performance Standards for Antimicrobial Susceptibility Testing: Twelfth Informational Supplement MS Impact of modified nonmeningeal Streptococcus pneumoniae interpretive criteria NCCLS MS12 on the susceptibility patterns of five parenteral cephalosporins: In vitro activities of broad-spectrum cephalosporins against nonmeningeal isolates of Streptococcus pneumoniae: Pneumococcal bacteremia with special reference to bacteremic pneumococcal pneumonia.

Penicillin-resistant pneumococcus and risk of treatment failure in pneumonia. Streptococcus pneumoniae bacteremia in patients with cancer: Impact of penicillin susceptibility on medical outcomes for adult patients with bacteremic pneumococcal pneumonia.

The impact of penicillin resistance on short-term mortality in hospitalized adults with pneumococcal pneumonia: Penicillin resistance not a factor in outcome from invasive Streptococcus pneumoniae community-acquired pneumonia in adults when appropriate empiric therapy is started.

Clinical significance of pneumococcal resistance and factors influencing outcomes. Penicillins for treatment of pneumococcal pneumonia: Does penicillin remain the drug of choice for pneumococcal pneumonia in view of emerging in vitro resistance? Clinical and Laboratory Standards Institute.

Eighteenth Informational Supplement MS