Risk factors for anti-MRSA drug resistance

Real-World Experience of Ceftobiprole for Community- and Hospital-Acquired Pneumonia from a Stewardship Perspective

Ceftobiprole is a fifth-generation cephalosporin approved by European and American regulatory agencies for the treatment of community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP). Ceftobiprole administration is useful in severe CAP as well as HAP where the potential is to save other β-lactams including carbapenems or linezolid/vancomycin in clinical practice. The aim of this study was to report the real-world evidence of ceftobiprole in patients with CAP and HAP in a single center. In this retrospective study, we included 159 patients with CAP or HAP: 105 (66%) had CAP and 54 (34%) had HAP. The median age was 70 years (IQR 60-77), the median Charlson Comorbidity Index was 5 (IQR 3-7.5) and baseline INCREMENT ESBL score was 8 (IQR 6-11). Ceftobiprole was mostly given as a combination treatment (77%) or as a carbapenem-sparing strategy (44%). There were no differences in mortality between shorter and longer duration of treatment (<7 days compared with ≥7 days (HR 1.02, C.I. 0.58-1.77, p = 0.93) or between first-line (HR 1.00, C.I. 0.46-2.17, p = 0.989) and second-line therapy. Ceftobiprole use in CAP or HAP in the real world is effective as a first- and second-line treatment as well as a carbapenem-sparing strategy. Further studies are needed to explore the full potential of ceftobiprole, including its real-world use in antimicrobial stewardship programs.

Design, synthesis and biological evaluation of pleuromutilin-Schiff base hybrids as potent anti-MRSA agents in vitro and in vivo

A series of pleuromutilin derivatives with 1,2,4-triazole-3-substituted Schiff base structure were designed and synthesized under mild conditions. The in vitro antibacterial activities of the synthesized derivatives against 4 strains of Staphylococcus aureus (MRSA ATCC 43300, S.aureus ATCC 29213, S.aureus 144 and S.aureus AD3) and 1 strain of E. coli (ATCC 25922) were evaluated by the broth dilution method. Among these derivatives, compound 60 exhibited superior in vitro antibacterial effect against MRSA (MIC = 0.25 μg/mL) than tiamulin (MIC = 0.5 μg/mL), and compound 60 (-2.28 log10 CFU/mL) also displayed superior in vivo antibacterial efficacy than tiamulin (-1.40 log10 CFU/mL) in reducing MRSA load in the mouse thigh infection model. The time-kill study and the post-antibiotic effect study indicated that compound 60 showed a faster bactericidal kinetic and longer PAE time (exposure to 2 × MIC and 4 × MIC for 2 h, the PAE was 4.06 and 4.27 h) against MRSA compared with tiamulin (exposure to 2 × MIC and 4 × MIC for 2 h, the PAE was 1.72 and 2.14 h). Meanwhile, most of these compounds had no significant inhibitory effect on RAW 264.7 cells and HepG2 cells at the concentration of 4 μg/mL. Additionally, the development of resistance study showed that MRSA did not easily develop resistance against compound 60 compared with tiamulin after induction for 8 passages.

Different formulations of vancomycin: In vitro antimicrobial activity against clinical isolates of methicillin-resistant Staphylococcus aureus

We compared in vitro antimicrobial activity of four vancomycin formulations used clinically against clinical isolates of Staphylococcus aureus, including methicillin-resistant and -susceptible (MRSA and MSSA, respectively), using different susceptibility assays. The minimal inhibitory concentrations (MICs) against MRSA clinical isolates were significantly different for some vancomycin formulations by the broth microdilution and agar dilution methods. However, these variations would not compromise their clinical use, since the MICs were within the range recommended by the Clinical and Laboratory Standards Institute. Furthermore, 26.9% of MRSA clinical isolates showed a vancomycin MIC ≥1.5 μg/mL according to the Etest® method but none by broth microdilution. Regarding quality, all formulations were in accordance with United States Pharmacopeia criteria. Our results showed that all vancomycin formulations tested showed similar in vitro antimicrobial activity, making them suitable for clinical use, and that the evaluation method chosen to determine sensitivity to this antimicrobial should be carefully performed, particularly for MRSA.

Healthcare Associated Infections of Methicillin-Resistant Staphylococcus aureus: A Case-Control-Control Study

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most widespread and dangerous pathogens in healthcare settings. We carried out this case-control-control study at a tertiary care hospital in Guangzhou, China, to examine the antimicrobial susceptibility patterns, risk factors and clinical outcomes of MRSA infections.

METHODS

A total of 57 MRSA patients, 116 methicillin-susceptible Staphylococcus aureus (MSSA) patients and 102 S. aureus negative patients were included in this study. We applied the disk diffusion method to compare the antimicrobial susceptibilities of 18 antibiotics between MRSA and MSSA isolates. Risk factors of MRSA infections were evaluated using univariate and multivariate logistic regression models. We used Cox proportional hazards models and logistic regression analysis to assess the hospital stay duration and fatality for patients with MRSA infections.

RESULTS

The MRSA group had significantly higher resistance rates for most drugs tested compared with the MSSA group. Using MSSA patients as controls, the following independent risk factors of MRSA infections were identified: 3 or more prior hospitalizations (OR 2.8, 95% CI 1.3-5.8, P = 0.007), chronic obstructive pulmonary disease (OR 5.9, 95% CI 1.7-20.7, P = 0.006), and use of a respirator (OR 3.6, 95% CI 1.0-12.9, P = 0.046). With the S. aureus negative patients as controls, use of a respirator (OR 3.8, 95% CI 1.0-13.9, P = 0.047) and tracheal intubation (OR 8.2, 95% CI 1.5-45.1, P = 0.016) were significant risk factors for MRSA infections. MRSA patients had a longer hospital stay duration and higher fatality in comparison with those in the two control groups.

CONCLUSIONS

MRSA infections substantially increase hospital stay duration and fatality. Thus, MRSA infections are serious issues in this healthcare setting and should receive more attention from clinicians.

Study of the anti-MRSA activity of Rhizoma coptidis by chemical fingerprinting and broth microdilution methods

AIM

Methicillin-resistant Staphylococcus aureus (MRSA) is a pathogenic bacterium that causes both hospital- and community-acquired infections, and for which single-drug treatments are becoming less efficient. Rhizoma coptidis has been used for more than two thousand years in China to treat diarrhea, fever, and jaundice. In this study, the anti-MRSA activity of Rhizoma coptidis is examined and its effective components sought.

METHODS

The mecA and norA genes were determined by PCR amplification and sequencing. Drug susceptibility of Staphylococcus aureus ATCC43300 was performed using the VITEK2 compact system. The chemical fingerprint of Rhizoma coptidis was investigated using HPLC and preparative liquid chromatography, and the anti-MRSA activity was determined using an improved broth microdilution method.

RESULTS

The drug susceptibility test revealed that the penicillin-binding protein phenotype of the strain changed in comparison to penicillin-sensitive Staphylococcus aureus. Ten batches of Rhizoma coptidis showed anti-MRSA activity on the norA-negative Staphylococcus aureus strain, as well as the strain that contained a norA gene. The spectrum-effect relationship revealed that the berberine alkaloids were the effective components, within which berberine, coptisine, palmatine, epiberberine, and jatrorrhizine were the major components.

CONCLUSION

This study lays a foundation for in vivo studies of Rhizoma coptidis and for the development of multi-component drugs.

Unexpected Multidrug Resistance of Methicillin-Resistant Staphylococcus aureus in Urine Samples: A Single-Center Study

PURPOSE

Infections of methicillin-resistant Staphylococcus aureus (MRSA) are becoming an increasingly concerning clinical problem. The aim of this study was to assess the development of MRSA in urine cultures in a major public university-affiliated hospital and the therapeutical and hygiene-related possibilities for reducing resistance.

MATERIALS AND METHODS

This study included 243 samples from patients diagnosed with MRSA infection over a period of 6 years. An agar diffusion test measured the effects of antimicrobial agents against bacteria grown in culture. The analyses were based on the guidelines of the Clinical and Laboratory Standards Institute.

RESULTS

A regression analysis was performed, which showed 100% resistance to the following antibiotics throughout the entire testing period: carbapenem, cephalosporin (1st-4th generation), penicillin G, aminopenicillin, β-lactamase, and isoxazolyl penicillin. However, a significant decrease in resistance was found for amikacin, gentamicin, clindamycin, levofloxacin, erythromycin, and mupirocin.

CONCLUSIONS

MRSA showed a decreasing trend of antimicrobial resistance, except against carbapenem, cephalosporin (1st-4th generation), penicillin G, aminopenicillin, β-lactamase, and isoxazolyl penicillin, for which complete resistance was observed.