Nosocomial methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in Taiwan: Mortality analyses and the impact of vancomycin, MIC = 2 mg/L, by the broth microdilution method

AIM: To determine the distribution of vancomycin MIC and the frequency of S. aureus strains with reduced vancomycin susceptibility among Methicillin-Resistant Staphylococcus aureus (MRSA) isolates. METHODS: MRSA isolates (n = 100) were tested for reduced susceptibility to vancomycin using MIC broth microdilution method (BMD), vancomycin screening agar with different vancomycin concentrations with and without casein, and Vitek 2 system. RESULTS: BMD detected (22%) vancomycin-intermediate S. aureus (VISA) and (78%) vancomycin-susceptible S. aureus (VSSA) but couldn’t detect nine (Heterogeneous VISA) (hVISA) isolates (9%) with MIC ≤ 2 µg/ml that grew on screening agar 4 µg/ml or 6 µg/ml. Adding casein to vancomycin screening agar increased detection rate of VISA by 4.5%. Screening agar with 6 µg/ml vancomycin overall detection rate for VISA was 95.45%. Probable ‘pre-hVISA’isolates (17%) showed growth on vancomycin screening agar 2 µg/ml with casein. Vitek 2 system failed to detect any VISA isolates. CONCLUSION: Vancomycin screening agar; 2 µg/ml and (4 and 6 µg/ml) were able to detect; probable “pre hVISA and (hVISA and VISA) isolates respectively based on their BMD MIC values. Decreased vancomycin susceptibility in MRSA isolates might be related to MIC creep. Analysis of vancomycin MIC values over longer periods is recommended to further study this phenomenon and its impact on vancomycin treatment failure. ABSTRACT Aims: Determine the distribution of vancomycin MIC and the frequency of S. aureus strains with reduced vancomycin susceptibility among MRSA isolates. Methods: MRSA isolates (n =100) were tested for reduced susceptibility to vancomycin using MIC broth microdilution method(BMD), vancomycin screening agar with different vancomycin concentrations with and without casein, and Vitek 2 system. Results: BMD detected (22%) vancomycin intermediate S. aureus(VISA) and (78%) vancomycin susceptible S. aureus(VSSA) but failed to detect nine (Heterogeneous VISA) (hVISA) isolates (9%) with MIC ≤2ug/ml that grew on screening agar 4ug/ml or 6 ug/ml. Adding casein to vancomycin screening agar increased detection rate of VISA by 4.5%. Screening agar with 6 ug/ml vancomycin over all detection rate for VISA was 95.45%. Probable ‘pre-hVISA’isolates (17%) showed growth on vancomycin screening agar 2µg/ml with casein. Vitek 2 system failed to detect any VISA isolates. Conclusion: vancomycin screening agar; 2 µg/ml and (4 and 6 µg/ml) were able to detect; probable “pre hVISA and (hVISA and VISA) isolates respectively based on their BMD MIC values. Decreased vancomycin susceptibility in MRSA isolates might be related to MIC creep. Analysis of vancomycin MIC values over longer periods of time is recommended to further study this phenomenon and its impact on vancomycin treatment failure.

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Antimicrobial Activity of Ceftaroline-Avibactam Tested against Clinical Isolates Collected from U.S. Medical Centers in 2010-2011

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02436-12 ◽

2013 ◽

Vol 57 (4) ◽

pp. 1982-1988 ◽

Cited By ~ 32

Author(s):

Helio S. Sader ◽

Robert K. Flamm ◽

Ronald N. Jones

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Activity ◽

Streptococcus Pneumoniae ◽

Enterobacter Cloacae ◽

Broth Microdilution ◽

Methicillin Resistant ◽

Content Type ◽

Microdilution Method ◽

Medical Centers ◽

Broth Microdilution Method

ABSTRACTCeftaroline-avibactam and comparator agents were tested by the broth microdilution method against 20,089 isolates consecutively collected in 2010 and 2011 from 75 U.S. medical centers. Ceftaroline-avibactam was active againstEnterobacteriaceae(4,908 strains; MIC90, 0.25 μg/ml; highest MIC, 4 μg/ml), including meropenem-nonsusceptibleKlebsiellaspp. and ceftazidime-nonsusceptibleEnterobacter cloacaestrains (MIC90, 1 μg/ml for both). Ceftaroline-avibactam was also active against ceftriaxone-nonsusceptibleStreptococcus pneumoniae(MIC90, 0.25 μg/ml) and methicillin-resistantStaphylococcus aureus(MIC90, 1 μg/ml).

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In VitroAntistaphylococcal Effects ofEmbelia schimperiExtracts and Their Component Embelin with Oxacillin and Tetracycline

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2015/175983 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

Johana Rondevaldova ◽

Olga Leuner ◽

Alemtshay Teka ◽

Ermias Lulekal ◽

Jaroslav Havlik ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Medicinal Plants ◽

Bacterial Infections ◽

Inhibitory Concentration ◽

Developed Countries ◽

Positive Interactions ◽

Fractional Inhibitory Concentration ◽

Broth Microdilution ◽

Microdilution Method ◽

Broth Microdilution Method

Bacterial infections are in less-developed countries traditionally treated by remedies prepared from medicinal plants.Embelia schimperi(Vatke) is a plant used as a taenicide or disinfectant in Ethiopia, very often taken mixed with another plant species. In the present study, we examined two extracts prepared from seeds and twigs with leaves ofE. schimperiand its main present secondary metabolite embelin for their antibacterial combinatory effect with oxacillin and tetracycline against sensitive and resistantStaphylococcus aureusstrains. Minimum inhibitory concentrations were determined through the broth microdilution method, whereas the combinatory effect was evaluated through fractional inhibitory concentration sum (ΣFIC) indices. Results show many positive interactions and synergy occurring in embelin and oxacillin combinations against 4 out of 9 strains (ΣFIC 0.203–0.477) and for embelin and tetracycline combination against 3 out of 9 strains (ΣFIC 0.400–0.496). Moreover, the resistance to oxacillin has been overcome in 2 strains and to tetracycline in 3 strains. According to our knowledge, this is the first study showing antimicrobial combinatory effect ofE. schimperias well as of embelin. These findings can be used for the further research targeted on the development of new antistaphylococcal agents.

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Anti-methicillin resistant Staphylococcus aureus (MRSA) activity of an acetone extract from the leaves of Canarium odontophyllum (Miq.)

The Journal of Phytopharmacology ◽

10.31254/phyto.2018.7301 ◽

2018 ◽

Vol 7 (3) ◽

pp. 225-229

Author(s):

Nur Amira Mohd Shamsuddin ◽

◽

Dayang Fredalina Basri ◽

Keyword(s):

Staphylococcus Aureus ◽

Methicillin Resistant Staphylococcus Aureus ◽

Acetone Extract ◽

Health Concern ◽

Antimicrobial Drugs ◽

Methicillin Resistant ◽

Bacteriostatic Action ◽

Broth Microdilution Method ◽

Canarium Odontophyllum ◽

Time Kill

Methicillin-resistant Staphylococcus aureus (MRSA) is a global health concern that has caused nosocomial and community infections over the past decade. The emergence of multi-drug resistant strains and limitations of present antimicrobial drugs have led to continuous search for natural products as curative agents for MRSA infections. Canarium odontophyllum Miq., locally known as dabai, has been considered an alternative phytotherapeutic treatment for MRSA. The aim of this study was to evaluate the bacteriostatic activity of an acetone extract from C. odontophyllum leaves against MRSA. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract against the ATCC 33591 and Mu50 strains were determined using the broth microdilution method, and a time-kill assay was employed to assess the type of bacteriostatic action of the extract against the Mu50 strain only. The MIC and MBC values of the extract against Mu50 were 312.5 µg/ml and 625 µg/ml, respectively, whereas the MIC and MBC values for ATCC 33591 were 625 µg/ml and 1,250 µg/ml, respectively, confirming the bacteriostatic effect against both MRSA strains. A time-kill assay showed that the acetone extract of C. odontophyllum leaves exhibited concentrationdependent bacteriostatic action against the Mu50 strain at 1/2× MIC, 1× MIC and 2× MIC. However, the extract was bactericidal only at the highest concentration (4× MIC) with a reduction in cell viability of more than 3 log10 within 24 hours. These findings confirm that an acetone extract from C. odontophyllum leaves inhibited growth of MRSA at low concentration and could be utilised as an alternative anti-MRSA agent in immune uncompromised hosts

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Evaluation of Synergistic Antibacterial Effect of Combined Scrophularia striata Extract and Antibiotics Against Pseudomonas aeruginosa and Methicillin -Resistant Staphylococcus aureus

Iraqi Journal of Pharmaceutical Sciences ( P-ISSN 1683 - 3597 E-ISSN 2521 - 3512) ◽

10.31351/vol30iss2pp219-224 ◽

2021 ◽

Vol 30 (2) ◽

pp. 219-224

Author(s):

Pari Tamri ◽

Shabnam Pourmoslemi ◽

Shirin Moradkhani ◽

Sahar Foroughinia

Keyword(s):

Staphylococcus Aureus ◽

Antibacterial Activity ◽

Synergistic Effect ◽

Methicillin Resistant Staphylococcus Aureus ◽

Folk Medicine ◽

Additive Effects ◽

Methicillin Resistant ◽

Microdilution Method ◽

Scrophularia Striata ◽

New Compounds

Scrophularia. striata from Scrophulariacea family has been used in Iranian folk medicine for the treatment of infectious diseases. In this study we evaluated the synergistic effect of S. striata hydroalcoholic extract (SSE) and commercially available antibiotics against P. aeroginosa and Methicillin- resistant Staphylococcus aureus (MRSA). The resazurin-based microdilution method was used to determine the minimum inhibitory concentration (MIC) values of plan extract and standard antibiotics. The interaction between standard antibiotics and SSE was evaluated by using checkerboard method. The results of this study revealed that SSE enhance the antibacterial activity of antibiotics. The combination of SSE and Vancomycin had synergistic to additive effects against MRSA. SSE in combination with Gentamicin had synergistic to additive effects against P. aeruginosa. The interaction between Ceftazidime and SSE was additive against P. aeruginosa. The best result was the synergistic effect between SSE and Piperacillin-Tazobactam against P. aeruginosa. In conclusion the results of this research indicated that S. striata has the potential to enhance the antibacterial activity of antibiotics and could be a source to the designing new compounds with synergistic effect in combination with standard antibiotics.

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Pharmacist‐Driven Methicillin‐Resistant Staphylococcus aureus Screening Protocol and the Impact on Vancomycin Exposure in Hospitalized Patients with Pneumonia

Journal of the American College of Clinical Pharmacy ◽

10.1002/jac5.1530 ◽

2021 ◽

Author(s):

Will Evans ◽

Kristen Paciullo ◽

Ronald Trible

Keyword(s):

Staphylococcus Aureus ◽

Methicillin Resistant Staphylococcus Aureus ◽

Hospitalized Patients ◽

Methicillin Resistant ◽

Screening Protocol ◽

The Impact

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Antibacterial Triterpenoids from the Bark of Sonneratia alba (Lythraceae)

Natural Product Communications ◽

10.1177/1934578x1501000215 ◽

2015 ◽

Vol 10 (2) ◽

pp. 1934578X1501000

Author(s):

Harizon ◽

Betry Pujiastuti ◽

Dikdik Kurnia ◽

Dadan Sumiarsa ◽

Yoshihito Shiono ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Antibacterial Activity ◽

Mass Spectrometric ◽

Broth Microdilution ◽

Mass Spectrometric Data ◽

Spectrometric Data ◽

Gram Positive Bacteria ◽

Microdilution Method ◽

Sonneratia Alba ◽

Broth Microdilution Method

The new lupane-type triterpenoid, 3β-hydroxy-lup-9(11), 12-diene, 28-oic acid (1), along with two known lupane-type triterpenoids, lupeol (2) and lupan-3p-ol (3), were isolated from the bark of Sonnetaria alba. The structure of the new compound was elucidated on the basis of spectroscopic and mass spectrometric data analysis. Using the broth microdilution method, all compounds exhibited antibacterial activity against the Gram-positive bacteria Staphylococcus aureus ATCC 6538 and Streptococcus mutans ATCC 25175, with minimum inhibitory concentrations ranging from 15-33 to 35-55 ng/mL, respectively.

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