The effect of enterocin A/P dipeptide on growth performance, glutathione-peroxidase activity, IgA secretion and jejunal morphology in rabbits after experimental methicillin-resistant Staphylococcus epidermidis P3Tr2a Infection

The increasing frequency of methicillin-resistant (MR) staphylococci in humans and animals need special attention for their difficult treatment and zoonotic character, therefore novel antimicrobial compounds on a natural base against antibiotic-resistant bacteria are requested. Currently, bacteriocins/enterocins present a new promising way to overcome this problem, both in prevention and treatment. Therefore, the preventive and medicinal effect of dipeptide enterocin EntA/P was evaluated against MR Staphylococcus epidermidis SEP3/Tr2a strain in a rabbit model, testing their influence on growth performance, glutathione-peroxidase (GPx) enzyme activity, phagocytic activity (PA), secretory (s)IgA, and jejunal morphometry (JM). Eighty-eight rabbits (aged 35 days, meat line M91, both sexes) were divided into experimental groups S (SEP3/Tr2a strain; 1.0 × 105 CFU/mL; dose 500µL/animal/day for 7 days, between days 14 and 21 to simulate the pathogen attack), E (EntA/P; 50 µL/animal/day, 25,600 AU/mL in two intervals, for preventive effect between days 0 and 14; for medicinal effect between days 28 and 42), E + S (EntA/P + SEP3/Tr2a; preventive effect; SEP3/Tr2a + EntA/P; medicinal effect) and control group (C; without additives). Higher body weight was recorded in all experimental groups (p < 0.001) compared to control data. The negative influence/attack of the SEP3Tra2 strain on the intestinal immunity and environment was reflected as decreased GPx activity, worse JM parameters and higher sIgA concentration in infected rabbits. These results suggest the promising preventive use of EntA/P to improve the immunity and growth of rabbits, as well as its therapeutic potential and protective role against staphylococcal infections in rabbit breeding.

Hospitalization and colonization by methicillin-resistant Staphylococcus aureus in the surgical department of 03 health facilities in the Ndé division, West-Cameroon

Background

Commensal flora colonization during hospitalization by bacteria is the first step for nosocomial infections while antibiotic resistance reduces therapeutic options. In aim to control this phenomenon, we initiated this study to describe the impact of hospitalization on colonization by methicillin-resistant Staphylococcus aureus in the surgical department of 03 health facilities in the Ndé division, West-Cameroon.

Methods

This study was carried out on patients admitted for surgery in 03 health facilities of the Ndé division, West-Cameroon (District Hospital of Bangangté, Protestant Hospital of Bangwa and Cliniques Universitaires des Montagnes). After obtaining ethical clearance and authorizations, nasal swabs were performed at admission and discharge, with the aim of isolating bacteria and performing their antibiotic susceptibility tests. Informations on each participant's antibiotic therapy were recorded. Laboratory investigations were carried out according to standard protocols (CASFM, 2019).

Results

The most commonly used antibiotics were β-lactams. A total of 104 nasal swabs were performed on 52 patients who agreed to participate to the study. From the analysis, 110 (57 at admission versus 53 at discharge) Staphylococcus isolates were obtained. Overall, susceptibility testing showed that antibiotic resistance rates were higher at discharge than at admission; with significant differences between the susceptibility profiles obtained at admission and discharge for β-lactams and not significant for fluoroquinolones and aminoglycosides. Globally, frequency of nasal carriage of methicillin-resistant Staphylococcus aureus at discharge 16 (30.77%) was significantly higher than at admission 07 (13.46%) with Chi-2 = 4.52 and p = 0.0335.

Conclusion

The high rates of antibiotic resistance of bacteria isolated at discharge compared to those isolated at admission obtained in the present investigation, highlights the important role that hospitalization plays in the selection and dissemination of methicillin-resistant Staphylococcus aureus and colonization by these bacteria in health structures of Ndé division. As a result, further investigations to find the factors that promote this phenomenon should be carried out.

Linezolid for the treatment of postneurosurgical infection caused by methicillin-resistant Staphylococcus

Background

Postneurosurgical infection (PNSI) is a major problem. Linezolid is a bacteriostatic oxazolidinone antibiotic with a highly activity against Gram-positive cocci resistant to methicillin and a good cerebrospinal fluid penetration. The purpose of this study is to evaluate the efficacy of linezolid in the treatment of PNSI caused by methicillin-resistant Staphylococcus (MRS).

Methods

We conducted an observational study for all patients over 14 years old and diagnosed with MRS PNSI. Demographic, clinical, and laboratory information were collected prospectively.

Results

A total of 10 patients with PNSI (6 meningitis, 2 ventriculitis, and 2 subdural empyema) received linezolid. MRS isolated was Staphylococcus aureus in seven cases and Staphylococcus epidermidis in three cases. All isolated microorganisms were susceptible to vancomycin (minimum inhibitory concentration (MIC) = 2 mg/L) and linezolid (MIC = 1). The rate of microbiologic efficacy was 100% for patients with meningitis or ventriculitis. In the case of subdural empyema, focal infection had improved between 14 and 18 days. No adverse effects occurred during this study.

Conclusion

Our results suggest that linezolid as an alternative to vancomycin for the treatment of PNSI caused by MRS with a high rate of efficacy.

Accuracy of PCR universal primer for methicillin-resistant Staphylococcus and comparison of different phenotypic screening assays

Characterization of methicillin-resistant Staphylococcus (MRS) is a continuous challenge at diagnostic laboratories. The phenotypic methods present heterogeneous results and the occurrence of variants of mecA gene turned this goal even more challenging to achieve. The present study provided an accurate and highly discriminatory screening tool for MRS, improving its detection.

Resistance reported from China antimicrobial surveillance network (CHINET) in 2018

The aim of this study is to investigate the antimicrobial susceptibility of strains isolated from the major hospitals in China. A total of 44 teaching hospitals were involved. Antimicrobial susceptibility testing was conducted by Kirby-Bauer automated systems, and results were interpreted using CLSI criteria. Totally 244,843 strains were isolated in 2018, of which gram-negative bacilli and gram-positive cocci were accounting for 71.8% and 28.2%, respectively. 39.7% of isolates were cultured from lower respiratory tract, 18.8% from urine, 14.8% from blood, 1.3% from cerebrospinal fluid, respectively. Of those, the five major species were most often isolated (65.5%, 63%, 52.3%, and 30.3%). The resistance rate of MRSA to most antimicrobial agents was significantly higher than that of MSSA strains, except for to trimethoprim-sulfamethoxazole in urine specimen. E.coli was still highly susceptible to carbapenem antibiotics, and the resistance rate was less than 5%. Carbapenem resistance among Klebsiella pneumoniae, especially cultured from cerebrospinal fluid, increased significance from 18.6 to 64.1%. The resistance rates of Pseudomonas aeruginosa to carbapenems were nearly 30% in the blood, in urine, and in the lower respiratory tract, but about 60% of that in cerebrospinal fluid. About 80% of Acinetobacter baumannii strains was resistant to imipenem and meropenem, respectively. Bacterial resistance of five major clinical isolates from cerebrospinal fluid to common antibiotics (in particular Carbapenem-resistant Klebsiella pneumoniae) currently shows an increasing trend. It is worth to emphasize the importance of serious control of hospital infection and better management of clinical use of antimicrobial agents.

[Role of ceftaroline in skin and soft tissue infections]

Skin and soft tissue infections (SSTI) are relatively common. Although most of these infections are mild, a few are severe, requiring hospital admission for intravenous antimicrobial therapy and, fairly frequently, surgery. These infections can be produced by any microorganism, but the most frequent is Staphylococcus aureus. Traditionally, the bacteria causing community-acquired SSTI have been sensitive to antimicrobial agents but this situation has changed with the dissemination of community-acquired microbial resistance, as has occurred in many countries with the increase in methicillin-resistant S. aureus (MRSA). These changes complicate empirical therapy and increase the risk of monotherapy being insufficient to cover all the diagnostic possibilities of SSTI. Within this epidemiological framework, ceftaroline, because of its activity against MRSA, can be used as empirical monotherapy for SSTI.