Prevalence of Antibiotic Resistance in Escherichia coli Fecal Isolates From Healthy Persons and Patients With Diarrhea

Objectives

This study aimed to investigate the prevalence of antibiotic resistance in fecal Escherichia coli isolates from healthy persons and patients with diarrhea.

Methods

E. coli isolates (n = 428) were obtained from fecal samples of apparently healthy volunteers and hospitalized patients with diarrhea. Susceptibility patterns of isolates to 16 antimicrobial agents were determined by agar disc diffusion.

Results

Most E. coli isolates exhibited less than 10% resistance against imipenem, cefotetan, aztreonam, cefepime, cefoxitin, amikacin and netilamicin, although greater than 65% were resistant to ampicillin and tetracycline. No significant difference in resistance rates for all tested antibiotics was found between isolates from the healthy-and diarrheal-patient groups, including for multi-drug resistance (p = 0.22). The highest number of resistant antibiotics was 12 antibiotics. No significant differences in antibiotic resistance were found among the sex and age strata for isolates from healthy individuals. However, antibiotic resistance rates to cefoxitin, cefotaxime, amikacin, and netilamicin were significantly higher in the isolates of men than those of women (p < 0.05) in isolates from patients with diarrhea. Furthermore, isolates from patients with diarrhea older than 40-years of age showed higher resistance to cefepime and aztreonam (p < 0.05).

Conclusion

High resistance to the antibiotics most frequently prescribed for diarrhea was found in isolates from patients with diarrhea and apparently healthy individuals without any significant difference.     

Antibiotic Resistance Pattern of Community Acquired Uropathogens at a Tertiary Care Hospital in Jaipur, Rajasthan

Background:

Urinary tract infections (UTIs) are amongst the most common infections described in outpatients setting.

Objectives:

A study was conducted to evaluate the uropathogenic bacterial flora and its antimicrobial susceptibility profile among patients presenting to the out-patient clinics of a tertiary care hospital at Jaipur, Rajasthan.

Materials and Methods:

2012 consecutive urine specimens from symptomatic UTI cases attending to the outpatient clinics were processed in the Microbiology lab. Bacterial isolates obtained were identified using biochemical reactions. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disc diffusion method. Extended spectrum beta lactamase (ESBL) production was determined by the double disk approximation test and the Clinical and Laboratory Standards Institute (formerly NCCLS) confirmatory method.

Results:

Pathogens were isolated from 346 (17.16%) of the 2012 patients who submitted a urine sample. Escherichia coli was the most frequently isolated community acquired uropathogen accounting for 61.84% of the total isolates. ESBL production was observed in 23.83% of E. coli strains and 8.69% of Klebsiella strains. With the exception of Nitrofurantoin, resistance to agents commonly used as empiric oral treatments for UTI was quite high.

Conclusion:

The study revealed E. coli as the predominant bacterial pathogen for the community acquired UTIs in Jaipur, Rajasthan. An increasing trend in the production ESBLs among UTI pathogens in the community was noted. Nitrofurantoin should be used as empirical therapy for primary, uncomplicated UTIs.     

尿路致病性大肠埃希菌生物膜形成与耐药性的关系

目的研究50株临床分离的尿路致病性大肠埃希菌（UPEC）形成生物膜情况及其对抗菌药物敏感性的影响。方法采用结晶紫染色法检测生物膜阳性菌株,K B纸片扩散法分析UPEC对8种抗菌药物的敏感性,再通过统计学方法分析细菌耐药性与生物膜形成之间的关系。结果50株UPEC中,生物膜阳性34株,占68.00%。UPEC对8种抗菌药物均有不同程度耐药性;经统计学分析,生物膜阳性菌株对氨苄西林和庆大霉素耐药率（76.47%和55.88%）明显高于生物膜阴性菌株（43.75%和18.75%）,差异有统计学意义（P<0.05）。结论UPEC产生物膜现象较普遍,生物膜形成与其对氨苄西林和庆大霉素的耐药性具有相关性。     

Comparison of Antimicrobial Resistance in Escherichia coli Strains Isolated From Healthy Poultry and Swine Farm Workers Using Antibiotics in Korea

ObjectivesThe aim of this study is to compare the antibiotic resistance of Escherichia coli isolates from faecal samples of workers who often use antibiotics.MethodsA total of 163E coli strains isolated from faecal samples of livestock workers (poultry and swine farm workers) and restaurant workers in the same regions as a control group were analyzed by agar disc diffusion to determine their susceptibility patterns to 16 antimicrobial agents.ResultsMost of the tested isolates showed high antimicrobial resistance to ampicillin and tetracycline. The isolates showed higher resistance to cephalothin than other antibiotics among the cephems. Among the aminoglycosides, the resistance to gentamicin and tobramycin occurred at higher frequencies compared with resistance to amikacin and netilmicin. Our data indicated that faecal E coli isolates of livestock workers showed higher antibiotic resistances than nonlivestock workers (restaurant workers), especially cephalothin, gentamicin, and tobramycin (p < 0.05). Moreover, the rates of the livestock workers in the association of multidrug resistance were also higher than the rates of the restaurant workers.ConclusionThis study implies that usage of antibiotics may contribute to the prevalence of antibiotic resistance in commensal E coli strains of humans.     

Resistance to Fluoroquinolone by a Combination of Efflux and Target Site Mutations in Enteroaggregative Escherichia coli Isolated in Korea

ObjectivesEnteroaggregative Escherichia coli (EAEC) was recently reported as a major diarrheagenic pathogen in infant and adult travelers, both in developing and developed countries. EAEC strains are known to be highly resistant to antibiotics including quinolones. Therefore in this study we have determined the various mechanisms of quinolone resistance in EAEC strains isolated in Korea.MethodsFor 26 EAEC strains highly resistant to fluoroquinolone, minimal inhibitory concentrations for fluoroquinolones were determined, mutations in the quinolone target genes were identified by PCR and sequencing, the presence of transferable quinolone resistance mechanism were identified by PCR, and the contribution of the efflux pump was determined by synergy tests using a proton pump inhibitor. The expression levels of efflux pump-related genes were identified by relative quantification using real-time PCR.ResultsApart from two, all tested isolates had common mutations on GyrA (Ser83Leu and Ser87Gly) and ParC (Ser80Gln). Isolates EACR24 and EACR39 had mutations that have not been reported previously: Ala81Pro in ParC and Arg157Gly in GyrA, respectively. Increased susceptibility of all the tested isolates to ciprofloxacin and norfloxacin in the presence of the pump inhibitor implies that efflux pumps contributed to the resistance against fluoroquinolones. Expression of the efflux pump-related genes, tolC, mdfA, and ydhE, were induced in isolates EACR 07, EACR 29, and EACR 33 in the presence of ciprofloxacin.ConclusionThese results indicate that quinolone resistance of EAEC strains mainly results from the combination of mutations in the target enzyme and an increased expression of efflux pump-related genes. The mutations Ala81Pro in ParC and Arg157Gly in GyrA have not been reported previously; the exact influence of these mutations should be investigated further.     

Global Incidence of Carbapenemase-Producing Escherichia coli ST131

We characterized Escherichia coli ST131 isolates among 116 carbapenemase-producing strains. Of isolates from 16 countries collected during 2008–2013, 35% belonged to ST131 and were associated with bla_KPC, H30 lineage, and virotype C. This study documents worldwide incidents of resistance to “last resort” antimicrobial drugs among a common pathogen in a successful sequence type.     

A systematic review of experimental infections with enterotoxigenic Escherichia coli (ETEC)

Volunteer challenge with enterotoxigenic Escherichia coli (ETEC) has been used for four decades to elucidate the pathogenesis and immune responses and assess efficacy of various interventions. We performed a systematic review of these studies and a meta-analysis of individual patient-level data (IPD) from a subset of studies using standard methodology.We identified 27 studies of 11 ETEC strains administered to 443 naive subjects at doses from 1 × 10⁶ to 1 × 10¹⁰ colony forming units (cfu). Diarrhea attack rates varied by strain, dose and enterotoxin. Similar rates were seen at doses of 5 × 10⁸ to 1 × 10¹⁰ cfu with the three most commonly used strains B7A, E24377A, H10407. In IPD analysis, the highest diarrhea attack rates were seen with strains B7A, H10407 and E24377A. The H10407 induced significantly higher stool output than the other strains. Additionally, the rate of output was different across strains.The risk of diarrhea, abdominal cramps, nausea and headaches differed significantly by ETEC strain. An increased risk of nausea, abdominal cramps and headaches was seen for females. Baseline anti-LT IgG titers appeared to be associated with a decrease risk of diarrhea outcomes, a trend not seen with anti-LT IgA or seen consistently with anti-colonization factor antibodies. Neither early antibiotic treatment nor diarrhea duration significantly affected the frequency or magnitude of serologic responses.These studies have served as an invaluable tool in understanding disease course, pathogenicity, innate immune responses and an early assessment of product efficacy. When designing and planning experimental ETEC infection studies in this age of increased ethical scrutiny and growing appreciation of post-infectious sequelae, better understanding of available data is essential.     

High Prevalence of Class 1 to 3 Integrons Among Multidrug-Resistant Diarrheagenic Escherichia coli in Southwest of Iran

Objectives

Horizontal transfer of integrons is one of the important factors that can contribute to the occurrence of multidrug-resistant (MDR) bacteria. This study aimed to determine the prevalence of integrons among MDR Escherichia coli strains isolated from stool specimens and investigate the associations between the existence of integrons and MDR properties in the southwest of Iran.

Methods

There were 164 E. coli strains isolated from January 2012 to June 2012. Fecal specimens identified as E. coli by the conventional methods. Subsequently the antibiotic resistance was assessed using Clinical and Laboratory Standard Institute criteria. The presence of class 1–3 integrons and embedded gene cassettes was verified using specific primers by multiplex polymerase chain reaction assay.

Results

Among a total of 164 studied samples, 69 (42.07%) isolates were multidrug resistant. Class 1 and class 2 integrons were present in 78.26% and 76.81% MDR isolates, respectively. For the first time in Iran, class 3 integron was observed in 26.09% MDR isolates. Significant correlations were identified between: class 1 integron and resistance to amikacin, gentamicin, chloramphenicol, ampicillin, tetracycline, nalidixic acid, and co-trimoxazole; class 2 integron and resistance to aminoglycosides, co-trimoxazole, cefalexin, ampicillin, and chloramphenicol; and class 3 integron and resistance to gentamicin, kanamycin, and streptomycin.

Conclusion

Our results indicate that integrons are common among MDR isolates and they can be used as a marker for the identification of MDR isolates. Therefore, due to the possibility of a widespread outbreak of MDR isolates, molecular surveillance and sequencing of the integrons in other parts of the country is recommended.     

Comparative evaluation of a vaccine candidate expressing enterotoxigenic Escherichia coli (ETEC) adhesins for colibacillosis with a commercial vaccine using a pig model

In this study, a comparative evaluation of a novel live vaccine candidate expressing enterotoxigenic Escherichia coli (ETEC) fimbriae and a commercial ETEC vaccine was carried out in suckling to weaned piglets. The E. coli K88ab, K88ac, K99, FasA and F41 fimbrial genes were individually inserted into an expression/secretion plasmid, pBP244. These plasmids were subsequently transfected into attenuated Salmonella, which were used as the vaccine candidate. Eighteen pregnant sows and 107 of their piglets were used in this comparative study. All the vaccinated groups of sows and piglets exhibited significantly increased antibody levels relative to specific antigens when compared with those in the unimmunized control. The experimental piglets with the vaccine candidate did not experience diarrhea following challenge with the virulent ETEC strains. However, diarrhea was observed in 36.8% of the piglets in the group immunized with the commercial vaccine and in 50% of the control group after challenge with the ETEC strains. These findings indicate that immunization of sows with the candidate vaccine can effectively protect their young pigs against colibacillosis.     

Effect of St. John's Wort (Hypericum perforatum) on obesity,lipid metabolism and uterine epithelial proliferation in ovariectomized rats

BACKGROUND/OBJECTIVES

This study was conducted to assess the potential of St. John''s Wort (Hypericum perforatum) to prevent obesity and abnormalities in lipid metabolism induced by ovariectomy in a rat model without stimulatory activity on uterus.

MATERIALS/METHODS

Ovariectomized (OVX) rats were treated for 6 weeks with 70% ethanol extracts of Hypericum perforatum [HPEs: whole plant (WHPE) and flower and leaves (FLHPE)], β-estradiol-3-benzoate at a dose of 50 µg/kg/day (E2) or vehicle (distilled water).

RESULTS

As expected, OVX increased body weight gain and adiposity and showed higher food efficacy ratio. OVX also increased the serum cholesterol as well as insulin resistance, while reducing uterus weight and uterine epithelial proliferation rate. HPEs (WHPE and FLHPE) showed estrogen-like effect on body weight gain, adipose tissue weight and food efficacy ratio in OVX rats. HPEs prevented hypercholesterolemia induced by OVX more effectively than E2. E2 increased uterus weight and epithelial proliferation rate in OVX rats, while HPEs maintained them at the level of the sham-operated animals.

CONCLUSIONS

Our finding demonstrates that HPEs can be considered as an effective agent to prevent OVX-induced obesity without stimulatory activity on uterus.