Antibiotic resistance in lactic acid bacteria isolated from some pharmaceutical and dairy products.

A total of 244 lactic acid bacteria (LAB) strains were isolated from 180 dairy and pharmaceutical products that were collected from different areas in Minia governorate, Egypt. LAB were identified phenotypically on basis of morphological, physiological and biochemical characteristics. Lactobacillus isolates were further confirmed using PCR-based assay. By combination of phenotypic with molecular identification Lactobacillus spp. were found to be the dominant genus (138, 76.7%) followed by Streptococcus spp. (65, 36.1%) and Lactococcus spp. (27, 15%). Some contaminant organisms such as (Staphylococcus spp., Escherichia coli, Salmonella spp., mould and yeast) were isolated from the collected dairy samples but pharmaceutical products were free of such contaminants. Susceptibility of LAB isolates to antibiotics representing all major classes was tested by agar dilution method. Generally, LAB were highly susceptible to Beta-lactams except penicillin. Lactobacilli were resistant to vancomycin, however lactococci and streptococci proved to be very susceptible. Most strains were susceptible to tetracycline and showed a wide range of streptomycin MICs. The MICs of erythromycin and clindamycin for most of the LAB were within the normal range of susceptibility. Sixteen Lactobacillus, 8 Lactococcus and 8 Streptococcus isolates including all tetracycline and/or erythromycin resistant strains were tested for the presence of tetracycline and/or erythromycin resistant genes [tet(M) and/or erm(B)]. PCR assays shows that some resistant strains harbor tet(M) and/or erm(B) resistance genes.

Antibiotic resistance in lactic acid bacteria isolated from some pharmaceutical and dairy products

A total of 244 lactic acid bacteria (LAB) strains were isolated from 180 dairy and pharmaceutical products that were collected from different areas in Minia governorate, Egypt. LAB were identified phenotypically on basis of morphological, physiological and biochemical characteristics. Lactobacillus isolates were further confirmed using PCR-based assay. By combination of phenotypic with molecular identification Lactobacillus spp. were found to be the dominant genus (138, 76.7%) followed by Streptococcus spp. (65, 36.1%) and Lactococcus spp. (27, 15%). Some contaminant organisms such as (Staphylococcus spp., Escherichia coli, Salmonella spp., mould and yeast) were isolated from the collected dairy samples but pharmaceutical products were free of such contaminants. Susceptibility of LAB isolates to antibiotics representing all major classes was tested by agar dilution method. Generally, LAB were highly susceptible to Beta-lactams except penicillin. Lactobacilli were resistant to vancomycin, however lactococci and streptococci proved to be very susceptible. Most strains were susceptible to tetracycline and showed a wide range of streptomycin MICs. The MICs of erythromycin and clindamycin for most of the LAB were within the normal range of susceptibility. Sixteen Lactobacillus,8 Lactococcus and 8 Streptococcus isolates including all tetracycline and/or erythromycin resistant strains were tested for the presence of tetracycline and/or erythromycin resistant genes [tet(M) and/or erm(B)]. PCR assays shows that some resistant strains harbor tet(M) and/or erm(B) resistance genes.

Epidemiology and antimicrobial resistance of staphylococci isolated from different infectious diseases

A total of 187 isolates from 470 clinical specimens were collected from three hospitals in El-Minia governorate and identified as 132 Staphylococcus aureus strains and 55 coagulase-negative staphylococci (CoNS) strains. Susceptibility of isolates to antimicrobial agents was tested by the agar dilution method. The isolated S. aureus strains showed low resistance to vancomycin (1.5 percent), amikacin (2.3 percent) and gatifloxacin (3.8 percent). Vancomycin was the most effective antibiotic against CoNS. The ampicillin-resistant isolates were tested for â-lactamase production where, 61.7 percent of S. aureus and 42.9 percent of CoNS were positive for â-lactamase enzyme. Beta-lactamase producing strains were screened for their plasmid profile using alkaline lysis method. Some of these strains carried at least one plasmid suggesting plasmid-mediated antibiotic resistance. When cells of these strains were exposed to curing agent ethidium bromide, the production of the â-lactamase was lost. Resistance by efflux was studied by a modified fluorometric assay. Addition of uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) increased norfloxacin accumulation in quinolone resistant S. aureus strains, suggesting endogenous energy-dependent efflux. Combinations of ciprofloxacin with four antimicrobial agents against methicillin resistant S.aureus (MRSA) strains were investigated using decimal assay for additivity (DAA) technique. Synergistic interaction was observed between ciprofloxacin and oxacillin. ciprofloxacin plus cefepime and gentamicin appeared to be additive, while ciprofloxacin plus erythromycin was antagonistic.

Epidemiology and antimicrobial resistance of staphylococci isolated from different infectious diseases.

A total of 187 isolates from 470 clinical specimens were collected from three hospitals in El-Minia governorate and identified as 132 Staphylococcus aureus strains and 55 coagulase-negative staphylococci (CoNS) strains. Susceptibility of isolates to antimicrobial agents was tested by the agar dilution method. The isolated S. aureus strains showed low resistance to vancomycin (1.5%), amikacin (2.3%) and gatifloxacin (3.8%). Vancomycin was the most effective antibiotic against CoNS. The ampicillin-resistant isolates were tested for ß-lactamase production where, 61.7% of S. aureus and 42.9% of CoNS were positive for ß-lactamase enzyme. Beta-lactamase producing strains were screened for their plasmid profile using alkaline lysis method. Some of these strains carried at least one plasmid suggesting plasmid-mediated antibiotic resistance. When cells of these strains were exposed to curing agent ethidium bromide, the production of the ß-lactamase was lost. Resistance by efflux was studied by a modified fluorometric assay. Addition of uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP) increased norfloxacin accumulation in quinolone resistant S. aureus strains, suggesting endogenous energy-dependent efflux. Combinations of ciprofloxacin with four antimicrobial agents against methicillin resistant S.aureus (MRSA) strains were investigated using decimal assay for additivity (DAA) technique. Synergistic interaction was observed between ciprofloxacin and oxacillin. ciprofloxacin plus cefepime and gentamicin appeared to be additive, while ciprofloxacin plus erythromycin was antagonistic.