Antibiotic resistance and survival of E coli in the alimentary tract

Is there an association between long-term antibiotics for acne and subsequent infection sequelae and antimicrobial resistance? A systematic review

BACKGROUND

Antimicrobial resistance (AMR) is a global health priority. Acne vulgaris is a common skin condition for which antibiotic use ranges from a few months to years of daily exposure.

AIM

To systemically search for and synthesise evidence on the risk of treatment-resistant infections, and other evidence of AMR, following long-term oral antibiotic use for acne.

DESIGN & SETTING

In this systematic review, a literature search was carried out using the databases Embase, MEDLINE, Cochrane, and Web of Science. They were searched using MeSH, Emtree, or other relevant terms, and followed a pre-registered protocol.

METHOD

Search strategies were developed with a librarian and undertaken in July 2019. All searches date from database inception. The primary outcome was antibiotic treatment failure or infection caused by a resistant organism. Secondary outcomes included detection of resistant organisms without an infection, rate of infection, or changes to flora.

RESULTS

A total of 6996 records were identified. Seventy-three full-text articles were shortlisted for full review, of which five were included. Two investigated rates of infection, and three resistance or changes to microbial flora. Three studies had 35 or fewer participants (range 20-118 496). Three studies had a serious or high risk of bias, one moderate, and one a low risk of bias. Weak evidence was found for an association between antibiotic use for acne and subsequent increased rates of upper respiratory tract infections and pharyngitis.

CONCLUSION

There is a lack of high quality evidence on the relationship between oral antibiotics for acne treatment and subsequent AMR sequelae. This needs to be urgently addressed with rigorously conducted studies.

Tetracycline use in the community may promote decreased susceptibility to quinolones in Escherichia coli isolates

We previously found that the hospital use of tetracyclines is associated with quinolone resistance in hospital isolates of Enterobacteriaceae. Tetracyclines are heavily used in the community. Our aim was to assess whether their use in the community favors quinolone resistance in community isolates of Escherichia coli. Monthly data of community antibiotics use and E. coli quinolone resistance in a 1.3 million inhabitant French area were obtained from 2009 to 2014, and were analyzed with autoregressive integrated moving average (ARIMA) models. Quinolone use decreased from 10.1% of the total antibiotic use in 2009 to 9.3% in 2014 (trend, - 0.016; p-value < 0.0001), while tetracycline use increased from 16.5% in 2009 to 17.1% in 2014 (trend, 0.016; p < 0.0001). The mean (95% confidence interval) monthly proportions of isolates that were non-susceptible to nalidixic acid and ciprofloxacin were 14.8% (14.2%-15.5%) and 9.5% (8.8%-10.1%), respectively, with no significant temporal trend. After adjusting on quinolone use, tetracycline use in the preceding month was significantly associated with nalidixic acid non-susceptibility (estimate [SD], 0.01 [0.007]; p-value, 0.04), but not with ciprofloxacin non-susceptibility (estimate [SD], 0.01 [0.009]; p-value, 0.23). Tetracycline use in the community may promote quinolone non-susceptibility in E. coli. Decreasing both tetracycline and quinolone use may be necessary to fight against the worldwide growth of quinolone resistance.

R-Plasmid Transfer to and from Escherichia coli Strains Isolated from Human Fecal Samples

Strains of Escherichia coli recently isolated from human feces were examined for the frequency with which they accept an R factor (R1) from a derepressed fi strain of E. coli K-12 and transfer it to fecal and laboratory strains. Colicins produced by some of the isolates rapidly killed the other half of the mating pair; therefore, conjugation was conducted by a membrane filtration procedure whereby this effect was minimized. The majority of fecal E. coli isolates accepted the R factor at lower frequencies than K-12 F, varying from 10 per donor cell to undetectable levels. The frequencies with which certain fecal recipients received the R-plasmid were increased when its R transconjugant was either cured of the R1-plasmid and remated with the fi strain or backcrossed into the parental strain. The former suggests the loss of an incompatibility plasmid, and the latter suggests the modification of the R1-plasmid deoxyribonucleic acid (DNA). In general, the fecal RE. coli transconjugants were less effective donors for K-12 F and heterologous fecal strains than was the fi K-12 strain, whereas the single strain of Citrobacter freundii examined was generally more competent. Passage of the R1-plasmid to strains of salmonellae reached mating frequencies of 10 per donor cell when the recipient was a Salmonella typhi previously cured of its resident R-plasmid. However, two recently isolated strains of Salmonella accepted the R1-plasmid from E. coli K-12 R or the RE. coli transconjugants at frequencies of 5 x 10 or less.

Presence of bacteriuria caused by trimethoprim resistant bacteria in patients prescribed antibiotics: multilevel model with practice and individual patient data

OBJECTIVE

To look for evidence of a relation between antibiotic resistance and prescribing by general practitioners by analysis of prescribing at both practice and individual patient level.

DESIGN

Repeated cross-sectional study in 1995 and 1996.

SETTING

28 general practices in the Ninewells Hospital laboratory catchment area, Tayside, Scotland. SUBJECTS REVIEWED: 8833 patients registered with the 28 practices who submitted urine samples for analysis.

MAIN OUTCOME MEASURES

Resistance to trimethoprim in bacteria isolated from urine samples at practice and individual level simultaneously in a multilevel model.

RESULTS

Practices showed considerable variation in both the prevalence of trimethoprim resistance (26-50% of bacteria isolated) and trimethoprim prescribing (67-357 prescriptions per 100 practice patients). Although variation in prescribing showed no association with resistance at the practice level after adjustment for other factors (P = 0.101), in the multilevel model resistance to trimethoprim was significantly associated with age, sex, and individual-level exposure to trimethoprim (P < 0.001) or to other antibiotics (P = 0.002). The association with trimethoprim resistance was strongest for people recently exposed to trimethoprim, and there was no association for people with trimethoprim exposure more than six months before the date of the urine sample.

DISCUSSION

Analysis of practice level data obscured important associations between antibiotic prescribing and resistance. The results support efforts to reduce unnecessary prescribing of antibiotics in the community and show the added value of individual patient data for research on the outcomes of prescribing.

Developmental microbial ecology of the neonatal gastrointestinal tract

The gastrointestinal tract of a normal fetus is sterile. During the birth process and rapidly thereafter, microbes from the mother and surrounding environment colonize the gastrointestinal tract of the infant until a dense, complex microbiota develops. The succession of microbes colonizing the intestinal tract is most marked in early development, during which the feeding mode shifts from breast-feeding to formula feeding to weaning to the introduction of solid food. Dynamic balances exist between the gastrointestinal microbiota, host physiology, and diet that directly influence the initial acquisition, developmental succession, and eventual stability of the gut ecosystem. In this review, the development of the intestinal microbiota is discussed in terms of initial acquisition and subsequent succession of bacteria in human infants. Intrinsic and extrinsic factors influencing succession and their health significance are discussed. The advantages of modern molecular ecology techniques that provide sensitive and specific, culture-independent evaluation of the gastrointestinal ecosystem are introduced and discussed briefly. Further advances in our understanding of developmental microbial ecology in the neonatal gastrointestinal tract are dependent on the application of these modern molecular techniques.

Screening for antimicrobial resistance in fecal samples by the replica plating method

Replica plating can be used for the detection of antibiotic resistance in normal flora. We have evaluated this application of the replica plating method by comparing it with a five-colony method. The replica plating method uses a single plate for each antibiotic, with a concentration just above that for borderline resistance. By the five-colony method, five colonies per sample were picked, chosen to represent all different colony morphologies present, and MICs were determined by a standard agar dilution method. The gram-negative, aerobic floras of 131 fecal samples were screened for resistance to ampicillin, cefuroxime, nalidixic acid, trimethoprim, sulfamethoxazole, and tetracycline by both methods. The rate of resistance detection by the two methods did not differ statistically for any of the antibiotics tested. The breakpoint concentrations used for the replica plates in the study gave results similar to those produced by the agar dilution method and the breakpoint values of the National Committee for Clinical Laboratory Standards and can thus be recommended. As the only currently used resistance detection method, replica plating facilitates an exact determination of the percentage of resistant colonies/total number of colonies (between 1 and 100%) in a sample. This revealed an uneven distribution, with only 23% of the samples having resistance frequencies in the range of 10 to 85%; usually, the resistant flora either was a small minority or was very dominant in samples with resistance. This phenomenon was present for all of the antibiotics.

Clinical significance of bacterial resistance to tetracyclines in the treatment of periodontal diseases

Tetracyclines are frequently employed during the treatment of clinical infections in medicine and dentistry, however, emergence of resistant bacterial strains has decreased the utility of these drugs. Accordingly, there is concern that indiscriminant administration of tetracyclines during periodontal therapy will further contribute to the development of additional resistant microorganisms which can complicate infectious disease therapy. This review paper briefly discusses the utility of tetracyclines as an antimicrobial agent in the treatment of periodontal diseases. It then focuses on the clinical significance of bacterial resistance to tetracyclines. Patterns of resistance that may be associated with the following scenarios are addressed: short- and long-term antibiotic therapy, individuals with a history of prior tetracycline therapy, patients with refractory periodontitis, and following controlled local drug delivery. It appears that selection and development of bacterial resistant strains is an inevitable consequence of antibiotic therapy. Nevertheless, prudent administration of tetracyclines may help delay or prevent the emergence of resistant microorganisms.

The prevalence of antimicrobial resistance in human faecal flora in South Africa

Between January and March 1992, 361 faecal specimens were collected from the healthy black population in the Transvaal Province of South Africa. Each specimen was examined for the prevalence of antimicrobial resistance in commensal bacteria. Volunteers, from both rural and urban dwellings, were divided into four age groups. The overall carriage rate of resistance varied from 88.6% for ampicillin, 74.2% for trimethoprim, 52.6% for chloramphenicol, 10.2% for nalidixic acid to 7.5% for gentamicin. The carriage of resistance found to each individual antimicrobial agent was slightly higher in the rural population rather than the urban population but there was no correlation between the prevalence of antimicrobial resistance and the age group.

Occurrence of doxycycline resistant bacteria in the oral cavity after local administration of doxycycline in patients with periodontal disease

Topical antimicrobial treatment is appearing as a means of therapy in patients with advanced periodontal disease. The purpose of the present study was to examine the occurrence of doxycycline resistant bacteria in subgingival plaque and oral cavity after local administration of doxycycline. Five patients with advanced marginal periodontitis were scaled, and one approximal pocket in each patient was additionally treated with locally delivered doxycycline. Microbiological samples were obtained from the test site, a contralateral control site and tongue and tonsils before treatment and 3, 13, 26 and 52 weeks after treatment. The occurrence and morphological distribution of doxycycline resistant bacteria was determined after anaerobic cultivation on enriched tryptic soy agar with and without doxycycline incorporated. At the test site and on tongue and tonsils the percentage of doxycycline resistant bacteria increased from less than 1% before treatment to 22% and 35%, respectively, immediately after treatment, but decreased again at week 13. At the control site no increase was observed. Gram-positive cocci constituted the majority of doxycycline resistant bacteria at all 3 sampling sites (73-94%). The morphological distribution of resistant bacteria was not affected by the doxycycline therapy. Thus, local doxycycline therapy resulted only in a transient increase in resistance in the oral microflora.

Probiotics in animal nutrition: a review

The normal microflora colonizing the digestive tract in livestock species at five to six days after birth can be summarized as following: 400 to 500 different bacterial strains for a total count of 10(14) bacteriae. The role of the gut flora is multifarious: fermentation of feed compounds, induction of anatomical and physiological changes in the intestinal cell wall structure, increase in animal resistance against enteropathogenic bacteriae, etc. In the present review, the numerous hypotheses for explaining the beneficial effects of probiotics on zootechnical performances and also the healthy aspects for men and animals are summarized, and the possible mechanisms of bacterial attachment are enumerated. The different assumptions on mode of action and fixation mechanisms of probiotics in the gut are critically discussed, and the required characteristics of the ideal probiotic are listed. Finally, some zootechnical results obtained with lactic acid bacteria are shown for calves, piglets and broilers.

Antibiotic residues and drug resistance in human intestinal flora

The effect of residual levels of ampicillin on the drug resistance of fecal flora was studied in human volunteers given 1.5 mg of ampicillin orally per day for 21 days. This treatment failed to have any significant reproducible effect on the number of resistant Escherichia coli in their feces. The effect of continuous administration of small doses of ampicillin, chlortetracycline, or streptomycin in the drinking water was studied in gnotobiotic mice inoculated with a human fecal flora. In this animal model, which is free of many interfering factors, an increase in the fecal concentration of resistant E. coli was observed when the mice were given 0.5 microgram of ampicillin or chlortetracycline per ml of water. This model is therefore a sensitive system for testing the effect of antimicrobial drugs on the resistance characteristics of the intestinal flora.

Escherichia coli in retail processed food

Four thousand two hundred and forty six samples of retail processed food were examined for the presence of Escherichia coli. Overall 12% of samples contained this organism, cakes and confectionery being more frequently contaminated (28%) than meat and meat based products (9%). Contamination was more frequent in the summer months than in the colder weather and 27% of the contaminated foods contained greater than 10(3) E. coli/g. E. coli from meat and meat based products were more commonly resistant to one or more antibiotics (14%) than were confectionery strains (1%). The significance of these findings in relation to the E. coli population of the human bowel is discussed.

Long-term antibiotic therapy for acne vulgaris: effects on the bowel flora of patients and their relatives

We have studied the effects of long-term tetracycline and erythromycin administration on the fecal flora of patients and their relatives. Tetracycline administration selects for multiply antibiotic-resistant organisms in both patients and relatives. Erythromycin exerts no such selection pressure. The mechanisms by which this may occur are discussed.

Antibiotic resistance and small R plasmids among Escherichia coli isolates from outpatient urinary tract infections in northern Norway

Escherichia coli strains from outpatient urinary tract infections in northern Norway over a period of 1 year were examined for resistance to nine commonly used antibiotics. Strains collected during 4.5 months were examined for R plasmid content by using conjugation and in vitro transformation. Of the E. coli strains, 42% were resistant to one or more antibiotics. Resistance was highest to sulfonamide (20.8% of all strains), nitrofurantoin (14.5%), and tetracycline (10.1%), whereas less than 6% of the strains were resistant to ampicillin, carbenicillin, cephalothin, nalidixic acid, or trimethoprim-sulfamethoxazole. No strain was resistant to gentamicin. Tetracycline resistance was more common in men than in women. Resistance to cephalothin, nalidixic acid, and sulfonamide was higher in strains from older people. Resistance to sulfonamide was more frequent in the urban community. These was no seasonal variation in antibiotic resistance, although the incidence of urinary tract infection varied with seasons. Plasmid-determined resistance to ampicillin, streptomycin, sulfonamide, and tetracycline was found. About 18% of the resistant strains from the urban municipality carried R plasmids, most of which were small plasmids mediating resistance to sulfonamide and streptomycin. The overall frequency of resistance in strains collected from rural areas was similar to the urban frequency, but in the rural strains, R plasmids were found in only 5% of the resistant strains.

Changes in serotype and resistance pattern of the intestinal Escherichia coli flora during travel. Results from a trial of mecillinam as a prophylactic against travellers' diarrhoea

The changes in the intestinal Escherichia coli flora during travel has been studied by serological methods. A group of 74 tourists visiting Egypt and the Far East were given mecillinam or placebo in a randomized double-blind study. In all but 3 participants, 2 in the placebo group and 1 in the mecillinam group, a complete change in the E. coli flora occurred after a few days, and changes continued to occur during the 25 days of travel. The percentage of multiresistant strains rose from 8% in the pretravel samples to 50-60% in the posttravel samples. Less than 5% of the pretravel E. coli strains were resistant to mecillinam, whereas in the posttravel samples 42.9% of the E. coli strains in the mecillinam group and 19.1% in the placebo group were resistant to mecillinam. Of the 30 mecillinam resistant E. coli strains from the diarrhoeal samples only 6 showed transferable mecillinam resistance.

Gastrointestinal endoscopy: infection and disinfection

The past decade has seen the development of an array of complex flexible fibreoptic instruments for gastrointestinal (GI) endoscopy, and an increasing use of these for diagnostic and therapeutic purposes. It has been recognised more recently that the use of contaminated endoscopic equipment can lead to serious and occasionally fatal infections. Infection with a wide variety of micro-organisms has been reported following oesophago-gastroduodenoscopy (OGD) and endoscopic retrograde cholangio-pancreatography (ERCP).

Genetic transfer of antimicrobial resistance and enterotoxigenicity among Escherichia coli strains

To understand the role of enterotoxin (Ent) plasmids in epidemics of enterotoxigenic (ET) Escherichia coli diarrhea in the United States, we studied the genetics of Ent plasmids in relation to E. coli serotypes and R plasmids. Twenty-nine ET E. coli strains, including all epidemic isolates available at the Centers for Disease Control, Atlanta, Ga. (CDC), were assessed for the ability to transfer antimicrobial resistances (if present) by conjugation, to mobilize a nonconjugative R plasmid, and to cotransfer enterotoxigenicity with R determinants. Of the 12 ET E. coli strains isolated in the United States, 5 were able to transfer R plasmids; one strain cotransferred detectable enterotoxigenicity. Another four U.S. isolates were able to mobilize plasmid DNA, but no toxin production was detected in transconjugants. Of 17 resistant ET E. coli from South Asia, 13 were able to transfer R plasmids; 5 of those 13 cotransferred detectable Ent plasmids. In all, 22 ET E. coli strains (76%) were able to initiate conjugation and genetic transfers. Six of these strains (20%) were able to cotransfer enterotoxigenicity with a conjugative R plasmid at a detectable frequency. One of the six strains transferred R and Ent determinants on a single plasmid. These data are addressed in relation to the observed immobility of Ent and R during outbreaks of ET E. coli, the efficacy of prophylactic tetracycline, and the worldwide occurrence of a limited number of ET E. coli serotypes.

Antagonisms among isogenic strains of Escherichia coli in the digestive tracts of gnotobiotic mice

We have observed that antagonisms occur between isogenic strains of Escherichia coli associated with gnotobiotic mice. The strains differed in the carriage of plasmids or in chromosomal mutations. The plasmid-free strains, in general, inhibited the establishment of plasmid-bearing strains in the gastrointestinal tract of mice. The outcome of the interactions between isogenic pairs, however, depended on the order in which the strains were introduced into the mice. Maintaining the bacterial strains in monoassociation with gnotobiotic mice resulted in the "adaptation" of the bacteria to their host. Thus, in all cases, "adapted" strains became the dominant population in the feces of mice, regardless of whether the adapted strains was introduced into mice before or after its isogenic partner which had been cultured in vitro. The ecological advantage disappeared when the adapted strain was cultured in broth. Ultrastructural differences in cell morphology were observed between strains maintained in vivo and in vitro.

The speciation of coliform genera from above and below a sewer outfall and their susceptibilities to antimicrobial agents

The occurrence of coliforms in a small water course was shown to increase by a factor of thirty six below the outfall of a sewage treatment plant. Speciation of the bacteria from above and below the sewer outfall showed that Escherichia coli and Enterobacter species predominated. Drug resistance levels were significant in microorganisms from both sampling sites and the occurrence of a significant number of multiple-resistant microorganisms, particularly E. coli, is reported. Both E. coli and Enterobacter species from below the sewer outfall show a statistically significant increase in resistance to ampicillin and E. coli from below the outfall also shows a statistically significant increase in resistance to sulpha-methoxazole as compared with isolates from above the outfall.

Adhesion of commensal bacteria to the large intestine wall in humans

Biopsies taken during colonoscopic examination of the human large bowel were used to examine the relationship of the commensal bacterial to the mucosal epithelial cell surface. Bacteria were seen adhering to the exposed epithelial cell surface and also to the mucus sheet. Isolation of aerobic organisms showed that Escherichia coli are closely associated with the gut wall throughout the large intestine. One strain of E. coli predominated in each biopsy, and this strain was present along the whole length of bowel. Adhesion of bacteria to the gut wall does occur in vivo and may be one of the factors involved in the ability of an organism to colonize and persist.

Spread of a single plasmid clone to an untreated individual from a person receiving prolonged tetracycline therapy

The aerobic gram-negative intestinal flora of two individuals living in close proximity was followed for 17 months. One of these persons was receiving a prolonged tetracycline treatment for acne vulgaris and was colonized by tetracycline-resistant Escherichia coli strains throughout the survey. The other person studied received no antibiotics during the period in question, but was frequently found to excrete a number of E. coli strains harboring tetracycline-resistant plasmids. The two E. coli strains (O75.H7 and O23.H16) excreted from both persons most frequently were indistinguishable, and so were the R-plasmids they carried. This suggests that R-plasmid-carrying E. coli may spread from individuals under treatment to close relatives that have not been treated.

Selection of multiresistant coliforms by long-term treatment of hypercholesterolaemia with neomycin

Patients with hypercholesterolaemia are often treated with the antimicrobial agent neomycin. Such treatment is potentially dangerous, however, as it may favour the emergence of multiresistant, R-factor-carrying, enteric bacteria among the intestinal flora. In 11 out of 14 patients who had received neomycin for three months to eight years most of the faecal coliforms were resistant to at least four antimicrobial drugs and capable of transferring this resistance to others. In contrast, only one out of nine patients who were treated with other lipid-lowering drugs had resistant bacteria in their faeces. Neomycin may cause multiresistant strains to emerge because, like tetracycline, it forms high concentrations in the gut. Long-term treatment of non-infectious conditions like hypercholesterolaemia with neomycin is potentially dangerous not only to the patient but also to the community because of the creation of a reservoir of multiresistant organisms.

R-plasmid transfer in vivo in the absence of antibiotic selection pressure

The persistence of an O18 Escherichia coli strain resistant to tetracycline, streptomycin, and sulfonamide has been followed in the fecal flora of a single individual over a period of 9 months. The strain in question carrying an R plasmid was detectable from the beginning of the survey, but it was only after a 10-day period of tetracycline therapy that it reached an all but permanent dominance in the fecal flora. No transfer of the R plasmid carried by the strain to any other coliform could be detected for 202 days after the end of tetracycline treatment. At this point, however, an O88 E. coli carrying the same plasmid as the O18 strain appeared briefly as a predominant component of the flora. The two plasmids isolated from the O18 and the O88 E. coli strains have been characterized in molecular terms and found to be similar. This suggests that R-plasmid transfer between two E. coli strains occurred in an individual who was living a normal daily life and who was not receiving antibiotics.

The effect of long term tetracycline treatment for acne vulgaris on the occurrence of R factors in the intestinal flora of man

R factors are known to be the most important mechanism of antimicrobial resistance of intestinal flora. Short courses with therapeutic doses (1000 mg/day) of tetracycline select for strains containing transferable resistance factors to more than one antimicrobial agent. In this report we show that long term treatment with very low doses (100 mg/day) of tetracycline for acne vulgaris has an equally strong effect favouring establishment of resistent strains and R factors in the intestinal flora of patients.