Characterization of tetracycline and ciprofloxacin resistance lactobacilli isolated from swine and human at western area of Taiwan

• Main Authors: Yi-Chih Chang, 張益銍
• Other Authors: Tung-Ching Chung
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/42031022034932382504

博士 === 國立中興大學 === 獸醫學系暨研究所 === 100 === Lactobacilli are members of the normal microflora existing in the gastrointestinal ( GI ) tract of human and animals. For a long history, the lactobacilli level in intestine was suggested to be an index of animals’ healthy status, from which isolates were generally regarded as safe and usually used as probiotics to promote the health of animals. The most widely documented effects of lactobacilli in humans and animals: improvement of weight and size, promotion of the immune system, reduction of alleragy, prevention of diarrhea, and exclusion of some pathogens. The emergence of tetracycline and ciprofloxacin resistance ( Tet-R and CIP-R ) in this commensal bacteria, after several decades’ indiscriminate use of antibiotics in the fields of medicine and livestock breeding, has created an important public health problem, arousing much attentions in recent years, that this bacteria may act as reservoirs of antibiotic resistance ( AR ) genes and also as vehicles to horizontally transfer AR to opportunistic pathogens within complex microbial communities such as the gut microflora. To investipate the tetracycline resistance ( Tet-R ) condition of lactobacilli in Taiwan, we analyzed 256 pig colons and found that every sample contain typical colonies of Tet-R lactic acid bacteria. From these samples, a total of 159 isolates of Tet-R lactobacilli were obtained and identified as belonging to 11 species, including Lactobacillus reuteri, Lactobacillus amylovorus, Lactobacillus salivarius, Lactobacillus plantarum, Lactobacillus ruminis, Lactobacillus kefiri, Lactobacillus fermentum, Lactobacillus sakei, Lactobacillus coryniformis, Lactobacillus parabuchneri and Lactobacillus letivazi. All isolates had the significant high Tet-R MIC50 and MIC90 values, indicating an ecological distribution of Tet-R lactobacilli mostly with high resistance potency in pig colons. PCR-detection identified 5 tet genes in these isolates, the most predominant one being tet (W), followed by tet (M), (L), (K), and (Q). Their detection rates were 82.0 %, 22.5 %, 14.4 %, 8.1 % and 0.9 %, respectively. Noteworthily, isolates of the same species carrying identical tet gene(s) usually had a wide different MIC values. Furthermore, strain-subtyping of these isolates by REP-PCR demonstrated a notable genotypic biodiversity % ( average 62% ). Consecutively, we investigated the frequency of ciprofloxacin and tetracycline resistance lactobacilli in feces of aboriginal children. After an isolation on lactobacilli-selective medium and the subsequent analysis by the PCR–16S rRNA gene sequencing, a total of 96 isolates of lactobacilli were obtained and identified as belonging to 6 species, including L. plantarum, L. helveticusi, L. salivarius, L. casei, L. fermentum and L. pentosus. Strain-subtyping of these isolates by repetitive extragenic palindromic ( REP )-PCR demonstrated a notable genotypic biodiversity of 65.6 %. Antimicrobial susceptibility of ciprofloxacin and tetracycline had a wide different minimum inhibitory concentration ( MIC ) values in these isolates. The MIC50 and MIC90 of ciprofloxacin both was 64 ug/ml for both, while the MIC50 and MIC90 of tetracycline were 128 ug/ml and 512 ug/ml. These results indicate that high-level resistant activity of ciprofloxacin and tetracycline among Lactobacillus species in indigenous children’s intestines were prevalent in mountain district at the central area of Taiwan.