Occurrence of Enterococci in Mastitic Cow's Milk and their Antimicrobial Resistance.

INTRODUCTION: The aim of the study was to evaluate the occurrence of enterococci in inflammatory secretions from mastitic bovine udders and to assess their antimicrobial resistance. MATERIAL AND METHODS: A total of 2,000 mastitic milk samples from cows were tested in 2014-2017. The isolation of enterococci was performed by precultivation in buffered peptone water, selective multiplication in a broth with sodium azide and cristal violet, and cultivation on Slanetz and Bartley agar. The identification of enterococci was carried out using Api rapid ID 32 strep kits. The antimicrobial susceptibility was evaluated using the MIC technique. RESULTS: Enterococci were isolated from 426 samples (21.3%). Enterococcus faecalis was the predominant species (360 strains), followed by E. faecium (35 isolates), and small numbers of others. The highest level of resistance was observed to lincomycin, tetracycline, quinupristin/dalfopristin (Synercid), erythromycin, kanamycin, streptomycin, chloramphenicol, and tylosin. Single strains were resistant to vancomycin and ciprofloxacin. All isolates were sensitive to daptomycin. E. faecalis presented a higher level of resistance in comparison to E. faecium, except to nitrofurantoin. CONCLUSION: The results showed frequent occurrence of enterococci in mastitic cow's milk and confirmed the high rate of their antimicrobial resistance.

Evaluation of the amoxicillin concentrations in amniotic fluid, placenta, umbilical cord blood and maternal serum two hours after oral administration.

OBJECTIVES: Amoxicillin is a broad-spectrum beta-lactam antibiotic. Due to its low toxicity, it is commonly used in obstetrics. The objective of this study was to assess amoxicillin concentrations in amniotic fluid, umbilical blood, placenta and maternal serum two hours following oral administration among pregnant women at term and to assess obstetric and non-obstetric factors that might affect amoxicillin's penetration of these tissues. MATERIALS AND METHODS: A total of 30 full-term pregnant women who qualified for elective Caesarean delivery were included in the study. Amoxicillin at a dose of 500 mg was administered prior to surgery. Amoxicillin levels were determined by diffusion microbial assay. RESULTS: The maternal serum, placental, umbilical blood and amniotic fluid levels of amoxicillin two hours after oral administration were 2.18±1.30 µg/g, 1.00±0.71 µg/g, 1.00±0.73 µg/g, and 0.67±0.59 µg/g, respectively (Table 2). Maternal serum levels of amoxicillin were significantly higher compared to other tissues (p<0.05). CONCLUSION: If the target tissues for the use of antibiotic drugs in pregnant patients are the fetus and/or the placenta, the drug should be administered in a higher-than-standard dose than that used to treat infections in non-pregnant patients. Considering that there is a maximum absorbable dose following oral administration, intravenous administration should be considered to prevent failure of antibiotic treatment. A higher dose of amoxicillin should be considered in obese mothers.

Evaluation of the amoxicillin concentrations in amniotic fluid, placenta, umbilical cord blood and maternal serum two hours after intravenous administration.

OBJECTIVES: The aims of this study were to evaluate amoxicillin concentrations in amniotic fluid, placenta, umbilical cord blood and maternal blood two hours after intravenous administration to assess obstetric and non-obstetric factors that could have influences on the penetration of the antibiotic into the examined tissues and to analyze the sensitivity to amoxicillin of the most common pathogens isolated from the genital tract. METHODS: A total of 35 full-term pregnant women who qualified for elective Caesarean delivery were included in the study. Amoxicillin at a dose of 1000 mg was administered prior to surgery. Amoxicillin levels were determined by diffusion microbial assay. RESULTS: The drug concentration was highest in umbilical cord blood compared with amniotic fluid, maternal blood and placenta (4.20±1.06 µg/g versus 3.96±0.79 µg/g, 3.22±0.64 µg/g and 2.81±0.64 µg/g, respectively). Obstetric and non-obstetric factors had no influence on the amoxicillin concentration. The most common bacteria isolated from the genital tracts of pregnant women (Streptococcus agalactiae, Enterococcus faecalis, Escherichia coli) were sensitive to amoxicillin. The MIC for the sensitive strain of Streptococcus agalactiae was seen in the majority of tissues of all of the patients; however, the MICs for E. faecalis and E. coli were not observed in any compartment. CONCLUSIONS: Amoxicillin proved to have good penetration into the fetal tissues and placenta after intravenous administration. The most common bacteria isolated from the genital tracts of pregnant women were sensitive to amoxicillin. Pregnancy complications were not found to have an influence on the amoxicillin concentrations in the examined tissues.

Concentration of amoxicillin in maternal serum, cord blood, amniotic fluid and the placenta after vaginal administration.

OBJECTIVE: The aim of this study was to assess the amoxicillin concentration in maternal serum, cord blood, amniotic fluid and the placenta, 2 h following vaginal administration and the factors influencing the drug level. METHODS: Twenty-eight full-term pregnant women who qualified for elective cesarean delivery were included in the study. Vaginal suppositories containing 250 mg of amoxicillin were administered 2 h prior to the operation. Amoxicillin levels were determined using the diffusion microbial assay. RESULTS: The amoxicillin level in amniotic fluid was significantly higher in comparison to that of maternal serum, cord blood or the placenta. Maternal age positively and gestational weight gain negatively correlated with the amoxicillin concentration in maternal serum. The maternal serum hemoglobin level and red blood cell count were positively correlated with amoxicillin concentration in the amniotic fluid. Neonatal birth weight was positively correlated with maternal serum and cord blood amoxicillin levels. Hypertensive women had significantly higher amoxicillin concentrations in amniotic fluid, and women with thrombocytopenia presented significantly higher cord blood amoxicillin concentrations. CONCLUSIONS: Amoxicillin presented poor concentration in maternal-fetal compartments after vaginal administration, but the factors influencing the drug level in different compartments require further investigation.