Coli Flora Research Articles

Diversity and antibiotic resistance among Escherichia coli populations in hospital and community wastewater compared to wastewater at the receiving urban treatment plant

Bacterial diversity and antimicrobial resistance patterns among the indicator organism Escherichia coli were monitored in wastewater samples collected over one year from a hospital (HW), a community (CW) and the receiving urban (UW) wastewater treatment plant (WWTP). We compared levels of antibiotic resistance in the different types of wastewater, and identified whether resistant strains were endemic in the wastewater system. If so, implementation of local treatment at certain resistance hotspots (e.g. hospital outlets) could be used to decrease the amount of resistant bacteria in the wastewater. E. coli from HW (n = 2644), CW (n = 2525) and UW (n = 2693) were analyzed by biochemical phenotyping (PhenePlate System) and antimicrobial susceptibility testing to nine antibiotics (AREB System). The phenotypic diversities of the total E. coli populations were similar for all three sites (Simpson's Diversity index, Di = 0.973), however for individual samples, HW showed low diversities (Median Di = 0.800) and the E. coli flora was often dominated by strains that may have originated from the fecal flora of single individuals. The diversities in CW samples was higher (Median Di = 0.936), and UW samples showed similar diversities as the whole collection of isolates (Median Di = 0.971). Resistance to at least one of the nine antibiotics was observed in 45% of the HW isolates, 44% of CW isolates, and 33% of UW isolates. Resistance to gentamicin and chloramphenicol was uncommon (3.2 and 5.3%, respectively), whereas resistance to tetracycline and ampicillin was most common (24% and 31%, respectively). Extended-spectrum beta-lactamase-producing E. coli (ESBL-EC) were more common in HW (11.5%) and in CW (6.9%) compared to UW (3.7%). A high diversity (Di = 0.974) was observed among ESBL-EC isolates from UW (n = 99), indicating absence of any clonal structure among these isolates. Common PhP types of ESBL-EC often dominated in each HW sample, but were not identified across different samples, whereas ESBL-EC in CW showed low diversity (Di = 0.857) and were dominated by a specific PhP type that was found across almost all CW samples. The antibiotic resistance rates were highest in hospital wastewater, but surprisingly they were also high in the studied community wastewater, compared to the urban wastewater. The relative contribution of HW seemed low in terms of dissemination of antibiotic resistant bacteria to the WWTP.

Changes of viability and composition of the Escherichia coli flora in faecal samples during long time storage

Long-time storage of faecal samples is necessary for investigations of intestinal microfloras. The aim of the present study was to evaluate how the viability and the composition of the Escherichia coli flora are affected in faecal samples during different storage conditions. Four fresh faecal samples (two from calves and two from infants) were divided into sub-samples and stored in four different ways: with and without addition of glycerol broth at − 20 °C and at − 70 °C. The viability and the phenotypic diversity of the E. coli flora in the sub-samples were evaluated after repeated thawings and after storage during 1 year. The samples stored for 1 year without thawing were also kept at room temperature for 5 days and subsequently analysed. According to phenotyping (PhP analysis) of 32 isolates per sample on day 0, all four samples contained two dominating strains of E. coli each, and between one and eight less common strains. Samples that were stored at − 70 °C in glycerol broth showed equal or even higher bacterial numbers as the original samples, even after repeated thawings, whereas samples stored at − 20 °C showed a considerably lower survival rate, also with addition of glycerol. Sub-samples containing glycerol broth that were kept at room temperature after storage for 1 year showed a clear increase in the number of viable cells as well as in diversity. The diversities in each sub-sample showed a tendency to decrease after several thawings as well as after storage. Generally, the E. coli populations in samples stored at − 20 °C were less similar to the population of the original sample than that in samples stored at − 70 °C. Samples that had been mixed with glycerol broth had an E. coli flora more similar to that in the original sample than those without glycerol broth. Furthermore, the sub-samples that were kept at room temperature after storage for 1 year generally were more similar to the original samples than if they were processed directly. We conclude that for long time storage of faecal samples, storage at − 70 °C is preferable. If samples have to be thawed repeatedly, addition of glycerol is preferable both for samples stored at − 70 °C and for samples stored at − 20 °C. Our data also have indicated that when E. coli isolates from faecal samples are selected for, e.g. analysis of virulence factors, it is necessary to pick several isolates per sample in order to obtain at least one isolate representing the dominating strain(s).

Escherichia coli in infants' intestinal microflora: colonization rate, strain turnover, and virulence gene carriage.

Colonization by Escherichia. coli in infants might have decreased in the last decades, owing to changes in hospital routines and family lifestyle. In this study, the E. coli flora was characterized in 70 healthy Swedish infants followed for the first year of life. E. coli was isolated from rectal swabs obtained at 3 d of age and quantified in fecal samples collected at 1, 2, 4, and 8 wk of age and at 6 and 12 mo of age. Strains were typed using random amplified polymorphic DNA, and their virulence factor genes were identified by multiplex PCR. Colonization by E. coli occurred late; only 61% of the infants were positive by 2 mo of age. The turnover of individual strains in the microflora was slow (1.5 strains per infant during 6 mo, 2.1 during 1 y). Environmental factors, such as siblings, pets, or feeding mode, did not influence colonization kinetics or strain turnover rate. Genes encoding type 1 fimbriae, P fimbriae, and hemolysin were significantly more common in E. coli strains persisting for at least 3 wk in the microflora than in transient strains. The P-fimbrial class III adhesin gene was more common in E. coli from children who had a cat in their homes than in E. coli from children without pets (p = 0.01); this adhesin type is common in E. coli from cats. The late colonization and low E. coli strain turnover rate suggest limited exposure of Swedish infants to E. coli. Our results confirm that P fimbriae and other virulence factors facilitate persistence of E. coli in the human colonic microflora.

The story of live human intestinal bacteria administered orally as a remedy.

The story of live human intestinal bacteria administered orally as a remedy.

The influence of antibacterial agents on the complexity of theEscherichia coliflora of chickens

Abstract Escherichia coli isolates from young chickens were differentiated into strains on the basis of biotype and resistance pattern. The complexity of the faecal E. coli flora varied in birds purchased at different times from the same hatchery. Dosing of the water with ampicillin (Ap), gentamicin (Gm), oxytetracycline (Ot) and trimethoprim (Tm), and also with neomycin (Nm) and streptomycin (Sm) together, but not chloramphenicol (Cm) and Nm, was associated with the selection, during the period of administration, of E. coli strains resistant to the given agent. This increase in incidence of resistance was not associated with a consistent change in the isolation rate of E. coli strains, suggesting that dosing with antibiotics did not have any specific effect on the complexity of the E. coli flora of these animals.

Colonization and persistence of Escherichia coli phenotypes in the intestines of children aged 0 to 18 months.

The aim of the present investigation was to study the intestinal colonization of Escherichia coli in newborn children, and to determine which strains become residential within the human intestine. The E. coli flora of 89 newborn children was studied by repeated sampling during their first 11 or 18 months of life. The E. coli isolates from the samples were subdivided into phenotypes by the aid of biochemical fingerprinting, a method which measures the kinetics of 24 selected biochemical tests as a tool for discriminating bacterial strains. It was found that E. coli strains colonizing children soon after birth persisted longer than strains colonizing them later. Especially those phenotypes which were defined as hospital strains persisted longer. Certain phenotypes were commonly found among the children, and these phenotypes were more persistent and more homogeneous than other phenotypes with respect to their pattern of biochemical activities. They might be specially adapted to colonize the human intestine. It was concluded that the generally long persistence of the first E. coli strains colonizing a newborn child indicates that the first case of bacterial colonization in children may be an event too important to be allowed to happen at random.

The effects of oxytetracycline on the intestinal Escherichia coli flora of newly weaned pigs.

Four recently weaned pigs were dosed orally with oxytetracycline. This caused a rapid increase in the incidence of tetracycline resistance (TcR) among Escherichia coli isolates from the faecal flora. The isolates were differentiated further on the basis of O-serogroup, biotype and resistance pattern. There was no evidence that the administration of the antibiotic selected for a few TcR clones, but rather a relatively large number of TcR strains were identified during the dosing period. Using selective isolation media a proportion of these strains were demonstrated in the minority faecal Esch. coli flora before dosing, while the remainder were recognized for the first time after dosing commenced. The incidence of TcR among Esch. coli isolates also increased after weaning in other pigs which were not dosed with oxytetracycline or any other antibacterial agent. In a proportion of these animals this increase was associated with the dominance of a TcR enteropathogenic serotype (0149:K 91, K 88a, c) in the faecal Esch. coli flora which was probably ingested in small numbers before weaning. The source of other TcR strains was probably the environment in which each pig was placed after weaning.

The ecology of Escherichia coli in market calves fed a milk-substitute diet.

Dynamic changes in the Escherichia coli population in the calf gut were studied over 21 days in a group of 18 intensively-reared market calves. Isolates were identified by O-serogrouping, biotyping and resistogram patterns. Seventy O-serogroups were identified among nearly 3000 E. coli isolates examined and these were subdivided into 416 strains by means of their biotype and resistogram. Seventy-five per cent of these strains were detected only once or twice, which points to the continual replacement of the E. coli flora with strains that showed low persistence in the gut. The rise in the frequency of antibiotic resistance observed during the study was not due to a change in the proportion of resistant to sensitive strains in the gut flora. It was a consequence of the displacement of the original flora by multiply-resistant strains, which presumably originated from the calves' environment.

Resident, transient and uropathogenicE.coli strains in the intestinal tract of healthy and hospitalized adults

Samples of faeces were obtained at weekly intervals from 12 patients in a traumatology ward. Each time 20 colonies ofE.coli were typed. The results were compared with those of similar investigations in 10 healthy adults. No difference was found between the two groups as regards changes in the residentE. coli flora, nor in the frequency of occurrence of strains often associated with urinary tract infection.

Acute undifferentiated human diarrhea in the tropics. II. Alterations in intestinal fluid and electrolyte movements.

The nature and magnitude of fluid and electrolyte loss into the small intestine were defined by the marker perfusion technique in patients with acute undifferentiated diarrhea (AUD) in the tropics. The patients were divided into two groups according to their small bowel bacteriologic findings, namely those with a predominant Escherichia coli flora and those with a mixed flora. 11 normal subjects served as controls. Net jejunal fluid secretion occurred into the lumen in four of seven patients with E. coli flora and three of seven with a mixed flora. The magnitude of secretion in the jejunum was greater in the E. coli flora patients than in those with a mixed flora. Four E. coli patients and one mixed flora patient had net fluid secretion in the ileum, although the magnitude of secretion in this area was less than in the jejunum. Intestinal fluid had higher bicarbonate concentration in the ileum than in the jejunum but was isotonic in both regions. It resembled in composition fluid from the same region of intestine in normal individuals. Recovery of normal fluid and electrolyte absorptive function was usually complete in both jejunum and ileum by 6-8 days after onset of the disease. Increase in unidirectional flux rates for H(3)O and (24)Na occurred in acute E. coli flora diarrhea and returned to normal levels in recovery: increase in J(beta) (plasma to lumen flux) primarily accounted for the increase in fluid loss. Intestinal biopsy revealed no alterations in villous architecture.A relationship between small bowel fluid production and the presence of toxigenic strains of E. coli within the small bowel has been found for E. coli flora patients. In many respects this disease resembles acute cholera. The mixed flora group represents a less defined entity which requires further study.

RELATIONSHIP OF INFECTING URINARY ORGANISM TO THE FÆCAL FLORA IN PATIENTS WITH SYMPTOMATIC URINARY INFECTION

In a study of patients with acute symptomatic urinary infection in domiciliary practice, the urinary strain Escherichia coliwas isolated from the rectal, vaginal, and periurethral flora in nearly all cases. The urinary type has been found to predominate in the E. coli flora in all three sites. Although chemotherapy may eradicate the infecting organism from the urinary tract it did not usually eradicate it from the rectum, vagina, or periurethral skin.

Clinical studies on the antibody response to E coli O-antigens in infants and children with urinary infection, using a passive haemagglutination technique.

SummaryEarlier investigations have shown that the passive haemagglutination reaction is a specific and reliable tool in demonstrating humoral antibodies to different bacterial species.In the first part of this survey some methodologic investigations are presented. It was found that the antibodies in the sera were partly or completely inactivated during storage at +4°C for about a month, while the activity was unchanged after at least six months at ‐20°C. The limiting concentration, necessary for sensitization of the erythrocytes used in the reaction, was found to be around 60 million bacteria for different 0‐antigens.Four different sources of antigen were used during this investigation. Originally the infecting urinary bacteria from the patients were employed. Further studies compared this source with the faecal coli flora, with Kunin's common enterobacterial antigen and with a polyvalent antigen, consisting of a mixture of the eight E. coli 0‐types most frequently encountered in urinary tract infections. The reason for these investigations were partly that some source other than urinary bacteria had to be used in the controls and in suspected cases of pyelonephritis without urinary excretion of bacteria, and partly that the preparation of individual antigens for each patient makes the method too complicated and time‐consuming for use as a clinical routine procedure.These studies revealed, that the faecal bacterial antigens gave results similar to the urinary ones in about half of the cases. The common enterobacterial antigen could not be used as a substitute for the homologous homologous antigens since practically no antibodies were observed to this antigen in the sera. The polyvalent antigen was found to be a valuable substitute for the infecting strains, as equal titres could be demonstrated in those cases, where the homologous urinary strains belonged to one or another of the types, included in the antigen pool. By means of this antigen it was also found that some patients, lacking antibody response to the bacterial strains, found in their urine, did have antibodies in elevated titres against the polyvalent antigen. This might be due to a continuous antigen stimulation from earlier infections. If this is proved, the finding indicates that determination of the coli antibody titre is a valuable tool in the detection of occult chronic pyelonephritis. However, further studies are necessary to permit definite conclusions.A material of controls was studied and it was found, that almost all children above the age of about two months have agglutinating antibodies to E. coli in their serum.A series of patients with uncomplicated first‐time urinary tract infections with and without renal involvement were followed longitudinally. The findings showed that almost all of the patients above the age of three months with pyelonephritis had a sharp increase in the antibody titre, while those without functional impairment of the kidneys had titres within the limit of the control cases. It is thus possible to differentiate between cases of pyelonephritis and cases of lower urinary tract infections by means of this method. Elevated coli antibody titres were not found in pyelonephritic patients below the age of two months. The reason for this is discussed.A comparison between the antibody titre courses in patients with and without recurrences after their first episode revealed that the initial antibody response in the former group was not less than in the latter group.The rapid decrease (within 90 days) of the antibody titres found in most of the patients after treatment of the infections indicates that the homologous antigens were effectively eliminated by the treatment.Determinations of the coli antibody titre were performed in some patients, whose clinical symptoms were suggestive of pyelonephritis, but in whom the usual urinary findings were absent or inconclusive. In eight out of thirteen of these a course of the antibody titre, similar to that observed in patients with overt pyelonephritis, was demonstrated and it is therefore regarded as most likely, that these patients were in fact suffering from pyelonephritis.Further, the clinical use of antibody titrations in different types of urinary tract infections or their sequelae are illustrated by patients with recurrent urinary tract infection, renal hypertension and asymptomatic bacteriuria. The findings in some of these patients may indicate, that determination of antibodies to E. coli is a useful instrument in the detection of some of those patients who are at risk for contracting chronic pyelonephritis.

The Behaviour of Intestinal Coli Flora in Newborns and Inf ants under the Administration of Antibiotics

The Behaviour of Intestinal Coli Flora in Newborns and Inf ants under the Administration of Antibiotics

A Bacteriophage Feces Media

It became desirable in the course of some investigations to develop a media to determine the relative biological stability of fecal B. coli strains to bacteriophage. The relative sensitiveness of the B. coli flora can be altered by diet. The isolation of colonies and testing their phage-sensitiveness is too involved for practical purposes. We wished to develop a media on which we could plate our fecal specimens and read directly the percent of B. coli flora resistant and susceptible to bacteriophage.Endo, Eosin Methylene Blue, Conradi-Drigalski and Teagues media were used. Fifty cc. of these various agar media were put in flasks and sterilized. After cooling to 50°C. Coli-phage was added in amounts varying from 0.1 cc, 0.3 cc, 0.5 cc, 0.7 cc, 1 cc and 2 cc. and poured into petri dishes. The surface was seeded and smeared with spreader, then incubated for 21 hours. The best results were obtained when 0.3 cc and 0.5 cc. was added to the 50 cc agar media. Increase in concentration of phage causes inhibition ...