Inoculum effect of methicillin-susceptible Staphylococcus aureus against broad-spectrum beta-lactam antibiotics

Song, Kyoung Ho; Jung, Sook-In; Lee, Shinwon; Park, Sohee; Kim, Eu Suk; Park, Kyung‐Hwa; Park, Wan Beom; Choe, Pyoeng Gyun; Kim, Young Keun; Kwak, Yee Gyung; Kim, So Hyun; Jang, Hee-Chang; Kiem, Sungmin; Kim, Hyein; Kim, Hong Bin

doi:10.1007/s10096-018-3392-6

Cited by 19 publications

(16 citation statements)

References 28 publications

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“…In accordance with this, the MIC results of ampicillin and piperacillin against S. aureus showed clear inoculum effect according to the inoculum size (Table 1). This corresponds with the findings of several other experiments [20,21]. However, although cefotaxime is one of the β-lactam antibiotics, it did not show any inoculum effect in S. aureus in IBAST, which is in agreement with other previous experiments [22,23].…”

Section: Discussionsupporting

confidence: 93%

Microscopic Analysis of Bacterial Inoculum Effect Using Micropatterned Biochip

2021

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Antimicrobial resistance has become a major problem in public health and clinical environments. Against this background, antibiotic susceptibility testing (AST) has become necessary to cure diseases in an appropriate and timely manner as it indicates the necessary concentration of antibiotics. Recently, microfluidic based rapid AST methods using microscopic analysis have been shown to reduce the time needed for the determination of the proper antibiotics. However, owing to the inoculum effect, the accurate measurement of the minimal inhibitory concentration (MIC) is difficult. We tested four standard bacteria: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis, against five different antibiotics: piperacillin, cefotaxime, amikacin, levofloxacin, and ampicillin. The results showed that overall, the microfluidic system has a similar inoculum effect compared to the conventional AST method. However, due to the different testing conditions and determination protocols of the growth of the microfluidic based rapid AST, a few results are not identical to the conventional methods using optical density. This result suggests that microfluidic based rapid AST methods require further research on the inoculum effect for practical use in hospitals and can then be used for effective antibiotic prescriptions.

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Section: Discussionsupporting

confidence: 93%

Microscopic Analysis of Bacterial Inoculum Effect Using Micropatterned Biochip

2021

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“…The inoculum effect describes the phenomenon that a high number of bacteria (high inoculum) leads to an increase in MICs, to values even above the breakpoint. This has been reported for β-lactam antibiotics like piperacillin/tazobactam, ampicillin/sulbactam, and, to some degree, oxacillin, whereas cephalosporins and meropenem were less influenced by the inoculum effect (Song et al, 2019). The inoculum effect is likely to also contribute to the reduced antibiotic effect in case of IE.…”

Section: S Aureus E Faecalismentioning

confidence: 63%

“…The density of the bacterial aggregates and the exceptionally high number of bacteria inside the vegetations also lead to an inoculum effect of the bacteria against different antibiotics (Song et al, 2018). The inoculum effect describes the phenomenon that a high number of bacteria (high inoculum) leads to an increase in MICs, to values even above the breakpoint.…”

Section: S Aureus E Faecalismentioning

confidence: 99%

Anti-biofilm Approach in Infective Endocarditis Exposes New Treatment Strategies for Improved Outcome

Lerche

Schwartz

Theut

et al. 2021

Front. Cell Dev. Biol.

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Infective endocarditis (IE) is a life-threatening infective disease with increasing incidence worldwide. From early on, in the antibiotic era, it was recognized that high-dose and long-term antibiotic therapy was correlated to improved outcome. In addition, for several of the common microbial IE etiologies, the use of combination antibiotic therapy further improves outcome. IE vegetations on affected heart valves from patients and experimental animal models resemble biofilm infections. Besides the recalcitrant nature of IE, the microorganisms often present in an aggregated form, and gradients of bacterial activity in the vegetations can be observed. Even after appropriate antibiotic therapy, such microbial formations can often be identified in surgically removed, infected heart valves. Therefore, persistent or recurrent cases of IE, after apparent initial infection control, can be related to biofilm formation in the heart valve vegetations. On this background, the present review will describe potentially novel non-antibiotic, antimicrobial approaches in IE, with special focus on anti-thrombotic strategies and hyperbaric oxygen therapy targeting the biofilm formation of the infected heart valves caused by Staphylococcus aureus. The format is translational from preclinical models to actual clinical treatment strategies.

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“…Отдельные штаммы MSSA проявляют так называе мый инокулюмэффект к цефазолину. Он выражается в повышении МПК антибиотика в 4 и более раз в случаях, когда патоген присутствует в среде в высокой концен трации [5,6]. Распространенность инокулюмэффекта наиболее изучена среди MSSA, выделенного при бак териемии, и в зависимости от региона составляет от 3% до 58% [3,7].…”

Section: Introductionunclassified

Cefazolin inoculum effect among methicillinsusceptible Staphylococcus aureus isolated from patients with skin infections

Vaganova

Борисенко

Nesterova

et al. 2021

CMAC

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Objective. To evaluate frequency and intensity of cefazolin inoculum effect among methicillin-susceptible staphylococci isolated from patients with skin infections. Materials and Methods. A total of 80 methicillin susceptible isolates of Staphylococcus aureus were identified by cefoxitin disk-diffusion test and negative results of real-time PCR for mecA gene. Inoculum effect was measured by broth microdilution test with two inocula with concentrations of 5 × 105 CFU/mL and 5 × 107 CFU/mL. The disk-diffusion test with cefoxitin was also performed. Penicillin susceptibility was determined by disk-diffusion method. Beta-lactamase blaZ gene was identified by real-time PCR. Results. The frequency of cefazolin inoculum effect in tested isolates was 30% which is consistent with data from different countries. The MIC values for concentrated inoculum reached CLSI breakpoint for cefazolin resistance in 2.5% of isolates. The isolates with inoculum effect and those without it had the similar MIC values for cefazolin in broth microdilution test for standard inocula and similar diameters of inhibition zone in disk-diffusion test with cefazolin. Penicillin resistance was more frequent in inoculum effect-positive isolates. Beta-lactamase activity is considered as a main cause of cefazolin inoculum effect in staphylococci. The beta-lactamase blaZ gene was identified in the majority of isolates with cefazolin inoculum effect, but it was also prevalent among inoculum effect-negative isolates. Conclusions. Up to 30% of MSSA isolates from skin lesions in dermatological patients from SaintPetersburg are positive for cefazolin inoculum effect. Those isolates are usually characterized by penicillin resistance. Most of the cefazolin inoculum effect-positive isolates also carry beta-lactamase blaZ gene.

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Inoculum effect of methicillin-susceptible Staphylococcus aureus against broad-spectrum beta-lactam antibiotics

Cited by 19 publications

References 28 publications

Microscopic Analysis of Bacterial Inoculum Effect Using Micropatterned Biochip

Microscopic Analysis of Bacterial Inoculum Effect Using Micropatterned Biochip

Anti-biofilm Approach in Infective Endocarditis Exposes New Treatment Strategies for Improved Outcome

Cefazolin inoculum effect among methicillinsusceptible Staphylococcus aureus isolated from patients with skin infections

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