The development of bacterial flora of premature neonates.

The sequential acquisition of bacterial flora by premature neonates was studied during a 10 month period. Mean gestational age of the babies was 29.01 weeks and the mean birth weight was 1.728 kg. Escherichia coli and group B streptococci (GBS) colonized the umbilicus of 7 and 6 babies respectively, out of 23 studied, on the first day of life. E. coli and staphylococci were the predominant flora on the 6th day and they colonized 12 and 13 respectively. The oral flora was predominantly Gram-positive cocci, mainly Streptococcus salivarius which was isolated from 17 out of 22 babies on the 6th day, viridans streptococci were isolated from 14 babies, Staphylococcus albus from 16 babies and group D streptococci from 11 babies. Candida spp. also colonized the oral cavities of 17 out of 22 babies on the 6th day. At the end of the first week of life, the faecal flora was predominantly anaerobic represented by Bifidobacterium spp., Bacteroides spp. and Clostridium spp. The commonest facultative faecal flora were E. coli, which was isolated from all the babies, and Strept. faecalis isolated from 20 babies. Early gut colonization by GBS, Bacteroides spp. and Clostridium spp. was noticed in more babies delivered vaginally than by caesarean section where colonization by these bacteria was relatively delayed. The use of prophylactic penicillin plus gentamicin in the special neonatal unit probably prevented systemic spread of any of the potential opportunistic pathogens during the study.     

Development of the normal gastrointestinal microflora of specific pathogen-free chickens

The development of the normal intestinal microflora of the small intestine, caecum and large intestine of specific pathogen-free (SPF) chickens, was studied in the period from hatching to 84 days of age. No bacteria were detected in any of the sites at hatchery (day 1), but by day 3 significant levels of faecal streptococci and coliforms were isolated from all sites. The flora of the small intestine was limited to faecal streptococci and coliforms for the first 40 days and then lactobacilli became established and dominated the flora. A large variety of facultative and strictly anaerobic organisms colonized the caecum. Many of these species were transient and were only present for a limited period; after 40 days the flora stabilized to consist predominantly of faecal streptococci, Escherichia coli, Bacteroides spp. and Lactobacillus sp. The flora of the large intestine was composed of organisms also present in the small intestine or the caecum. These findings differ from previously published studies on conventionally reared chickens in that the number of species isolated and the population levels of organisms are much lower. This probably reflects the absence of continuous environmental challenge to the chickens because of the housing and feeding facilities in which the chickens were maintained.     

Development of the normal gastrointestinal microflora of specific pathogen-free chickens.

The development of the normal intestinal microflora of the small intestine, caecum and large intestine of specific pathogen-free (SPF) chickens, was studied in the period from hatching to 84 days of age. No bacteria were detected in any of the sites at hatchery (day 1), but by day 3 significant levels of faecal streptococci and coliforms were isolated from all sites. The flora of the small intestine was limited to faecal streptococci and coliforms for the first 40 days and then lactobacilli became established and dominated the flora. A large variety of facultative and strictly anaerobic organisms colonized the caecum. Many of these species were transient and were only present for a limited period; after 40 days the flora stabilized to consist predominantly of faecal streptococci, Escherichia coli, Bacteroides spp. and Lactobacillus sp. The flora of the large intestine was composed of organisms also present in the small intestine or the caecum. These findings differ from previously published studies on conventionally reared chickens in that the number of species isolated and the population levels of organisms are much lower. This probably reflects the absence of continuous environmental challenge to the chickens because of the housing and feeding facilities in which the chickens were maintained.     

The bacterial colonization of the large bowel of pre-term low birth weight neonates.

The bacterial colonization of the large bowel of 11 pre-term, low birth weight neonates who were nourished by expressed breast milk was examined by culturing serial faecal samples and compared to that observed in eight breast-fed and seven formula-fed full-term neonates. Pre-term neonates were colonized by high counts of facultatively anaerobic bacteria from the first days of life while bifidobacteria colonized only six babies during the first week and appeared in only one baby before day 5. Bacteroides spp. and clostridia were isolated from seven and six pre-term babies respectively during week 1 and were first observed on day 2. The intestinal colonization of pre-term infants differed from that in full-term breast-fed infants in the high counts of facultatively anaerobic bacteria and late appearance of bifidobacteria, and from both groups of full-term infants in the early stable colonization by Bacteroides spp. It is postulated that the composition of the normal intestinal microflora of pre-term low birth weight babies contributes to their predisposition to neonatal necrotizing enterocolitis. Results are discussed in relation to the effect of infant feeding regimens on intestinal microbial populations.     

Colonization and infection of mothers and neonates with group B streptococci in three Italian hospitals

In the absence of previous published studies from Italy on the epidemiology of group B streptococci we investigated 1516 mothers at delivery and 1294 neonates in three hospitals. Of mothers in labour, 7.5% were colonized with group B streptococci and 4.9% of their babies. Of the neonates born to a positive mother 45.1% were colonized, whilst only 2.2% of babies born to a negative mother were colonized. For the mothers, the vagina was colonized more often (7.3% of all women) than the cervix (6.0%), the urethral meatus (3.9%) or the rectum (2.9%). For the neonates, the rates of colonization of the throat, external auditory canal, and the umbilicus were 3.2%, 3.0% and 2.6%, respectively. The distributions of the serotypes were similar to that reported from other parts of Europe and the USA and vertical transmission of group B streptococci was demonstrated in most of the mothers and their neonates. Of 30 mother-neonate pairs, 25% of mothers carried group B streptococci intermittently and 58% had persistent carriage until the 90th day postpartum, the rectum being the commonest positive site. Of 20 infants that were positive at birth, only six were still positive on the 15th day and none by the 90th day of life. Of 1294 infants, four (0.3%) developed early-onset sepsis with group B streptococci and one died. The overall incidence of clinical infection amongst colonized infants was 6.2%.     

Spread of Escherichia coli colonizing newborn babies and their mothers

Most babies are colonized by the predominant strains of Escherichia coli present in their own mother''s faecal flora. Those babies who did not acquire their maternal faecal flora acquired strains of E. coli belonging to a small number of the possible serotypes. Moreover, the same serotypes were found in several babies and other mothers, suggesting spread within the ward. These few strains included some of the O groups which had previously commonly been found as urinary pathogens. These strains may have increased potentialities for colonization of human bowel. Antigenic and biochemical variation was observed among the strains.     

A comparison of the levels of faecal indicator bacteria in water and human faeces in a rural area of a tropical developing country (Sierra Leone).

The levels of faecal coliforms (FC), indole-positive FC (presumptive Escherichia coli), faecal streptococci (FS), Streptococcus faecalis and Clostridium perfringens in the natural water sources used by 29 rural settlements in Sierra Leone were investigated. Levels of the same indicators in human faeces were also investigated. The incidence of Salmonella spp. in both habitats and the temperature, pH and conductivity of water sources were also recorded. All water sources were contaminated with the indicator bacteria, mean numbers of which occurred in the relationship FC greater than presumptive E. coli congruent to FS congruent to C. perfringens greater than S. faecalis. FC were also predominant in human faeces, the relationship of means being FC congruent to presumptive E. coli greater than FS greater S. faecalis greater than C. perfringens. The need for confirmation of FC counts obtained from water sources was indicated by the large number of positive tubes produced in the FC multiple-tube dilution test from some samples which could not be confirmed as presumptive E. coli. Salmonella spp. Were isolated from 13 water sources and 6% of faecal samples. Mean water temperature was high (26.2 degrees C), pH low (5.04) and conductivity low (34 microS cm-1). Presumptive E. coli was considered the most appropriate indicator of faecal pollution of the types of water investigated.     

A comparison of the levels of faecal indicator bacteria in water and human faeces in a rural area of a tropical developing country (Sierra Leone)

The levels of faecal coliforms (FC), indole-positive FC (presumptive Escherichia coli), faecal streptococci (FS), Streptococcus faecalis and Clostridium perfringens in the natural water sources used by 29 rural settlements in Sierra Leone were investigated. Levels of the same indicators in human faeces were also investigated. The incidence of Salmonella spp. in both habitats and the temperature, pH and conductivity of water sources were also recorded. All water sources were contaminated with the indicator bacteria, mean numbers of which occurred in the relationship FC greater than presumptive E. coli congruent to FS congruent to C. perfringens greater than S. faecalis. FC were also predominant in human faeces, the relationship of means being FC congruent to presumptive E. coli greater than FS greater S. faecalis greater than C. perfringens. The need for confirmation of FC counts obtained from water sources was indicated by the large number of positive tubes produced in the FC multiple-tube dilution test from some samples which could not be confirmed as presumptive E. coli. Salmonella spp. Were isolated from 13 water sources and 6% of faecal samples. Mean water temperature was high (26.2 degrees C), pH low (5.04) and conductivity low (34 microS cm-1). Presumptive E. coli was considered the most appropriate indicator of faecal pollution of the types of water investigated.     

High rates of colonization and antimicrobial resistance of group B streptococcus highlight the need for vaccination even after implementation of guidelines for intrapartum antibiotic prophylaxis

IntroductionIt is estimated that about 11–35% of pregnant women are colonized with Group B streptococcus. Intrapartum antibiotic prophylaxis (IAP) is the primary intervention to decrease the risk of infecting babies born to GBS colonized mothers.MethodsA total of 5,996 pregnant women, who received the Taiwanese universal GBS screening program from 2012 to 2020, were included in this study that investigated GBS colonization, antimicrobial resistance rates and their neonatal incidence of invasive GBS infection.ResultsThe average GBS colonization rate was 18.5%. Older age groups had higher colonization rates than younger age groups. Compared to Taiwanese, immigrant women from Indonesia had a greater positive rate. GBS isolated from Vietnamese women had significant greater resistance to clindamycin relative to Taiwanese women. Rates of resistance to erythromycin increase from 35.5% to 45.5% over the 9 years of measurements. The incidence of invasive GBS disease was about 0.6/1,000 (4/6,204) live births during the study.ConclusionsAlthough relatively low incidence of invasive GBS diseases was observed after implementation of IAP, the colonization of GBS remains high and antimicrobial resistance of GBS is increasing. An effective GBS vaccine holds promise to be a solution for these issues.     

A comparative study of gram-negative aerobic bacilli in the faeces of babies born in hospital and at home.

Examination of the faeces of 50 babies born at home showed that bottle-fed babies carried significantly more Klebsiella, Proteus and Pseudomonas spp. and antibiotic-resistant Escherichia coli than did breast-fed babies. Bottle-fed babies born in hospital had a less mixed faecal flora than bottle-fed babies born at home. The possibility that bacterial contamination of home-prepared feeds may account for these differences requires investigation.     

Bacteroides species in the normal neonatal faecal flora.

Bacteroides spp. were isolated from the faeces of neonates and identified by rapid modifications of established conventional methods. Gram-negative anaerobic bacilli were recovered from 12 out of 16 neonates and a heavy growth of Bacteroides spp. was obtained from all 12 specimens. Twelve representative isolates from each subject were selected for identification; 141 of the 144 Bacteroides isolates belonged to the B. fragilis group and three to the B. melaninogenicus/oralis group. Eight species were represented within the B. fragilis group. B. vulgatus (c. 46%) and B. thetaiotaomicron (c. 30%) were the predominant species. B. fragilis, the type-species of the group, formed only a small proportion of neonatal faecal flora. The proportional representation of individual species were similar to that found in adults but B. asaccharolyticus was not represented.     

The hygienic quality of vegetables grown in or imported into the Netherlands: a tentative survey.

Samples of 61 home grown and 199 imported vegetables of different varieties were examined for Escherichia coli, faecal streptococci and, when E. coli was present, for salmonellas. Eleven per cent of samples contained greater than 10(4) E. coli per 100 g, and 14% greater than 10(6) faecal streptococci per 100 g. Salmonellas were isolated from 23 out of 103 samples examined. Salmonellas were isolated from 8% of 76 samples with E. coli less than 10(4)/100 g, but from 63% of 27 samples with E. coli exceeding 10(4)/100 g; from 6% of 65 samples containing less than 10(6) faecal streptococci/100 g but from 51% of 37 samples containing more than 10(6)/100 g. S. typhi was isolated from one sample of vegetables imported from the tropics. To our knowledge this is the first isolation of S. typhi from food in the Netherlands. Products from tropical countries were found to present the highest level of contamination. The hygienic quality of Dutch products is sometimes inferior to that of similar imported products, although the different seasons of sampling may have influenced the result. For the prevention of risk to the consumer of vegetables, good kitchen hygiene would appear to be the most important factor.     

Faecal colonization with P-fimbriated Escherichia coli between 0 and 18 months of age

A prospective study of faecal colonization with P-fimbriated Escherichia coli between 0 and 18 months of age was conducted in 751 healthy infants. The influence of breast-feeding and treatment with antibiotics on this colonization was studied. Colonization with P-fimbriated E. coli increased with age from 10% at 6 days to 30% at 18 months of age (P less than 0.01). Breast-feeding influenced colonization at 6 weeks of age when breast-fed children harboured fewer bacterial species (P less than 0.001) and fewer P-fimbriated E. coli (P = 0.06) than bottle-fed infants. Treatment with antibiotics increased the colonization rate with P-fimbriated E. coli at the age of 11 months (P less than 0.05). However, this was not true for treatment with ampicillin, which increased colonization rate with Gram-negative species other than E. coli (P less than 0.05). Fifty per cent (378) of all children were colonized and a quarter (183) had pure cultures of P-fimbriated E. coli in at least one faecal sample. The clinical importance of this colonization remains to be shown.     

Prevalence of zoonotic agents in dogs visiting hospitalized people in Ontario: implications for infection control

Visitation of hospitalized people by dogs is becoming commonplace, but little is known about the potential health risks of introducing dogs to healthcare settings. This cross-sectional study evaluated the prevalence of zoonotic agents in a group of 102 visitation dogs from a variety of sources across Ontario. Between May and July 2004, owners were interviewed by a standardized questionnaire while dogs underwent a standardized physical examination. One specimen of faeces, hair-coat brushings and one rectal, aural, nasal, oral and pharyngeal swab were collected from each dog and tested for 18 specific pathogens. All dogs were judged to be in good health. Zoonotic agents were isolated from 80 out of 102 (80%) dogs. The primary pathogen was Clostridium difficile, which was isolated from 58 (58%) faecal specimens. Seventy-one percent (41/58) of these isolates were toxigenic. Extended-spectrum beta-lactamase Escherichia coli was isolated from one (1%) dog, extended-spectrum cephalosporinase E. coli was isolated from three (3%) dogs, and organisms of the genus Salmonella were isolated from three (3%) dogs. Pasteurella multocida or Pasteurella canis was isolated from 29 (29%) oral swabs, and Malassezia pachydermatis was isolated from eight (8%) aural swabs. Giardia antigen was present in the faeces of seven (7%) dogs, while Toxocara canis and Ancylostoma caninum were detected in two (2%) dogs and one (1%) dog, respectively. Methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, Campylobacter spp., Microsporum canis, group A streptococci, Pseudomonas aeruginosa and Cryptosporidium spp. were not detected. Further information is needed before the full implications of these findings for infection control can be assessed properly.     

Enteropathogenic bacteria in faecal swabs of young children fed on lactic acid-fermented cereal gruels

The influence of consumption of a lactic acid-fermented cereal gruel togwa with pH < or = 4 on the presence of faecal enteric bacteria such as campylobacter, enterohaemorrhagic Escherichia coli (EHEC:O157), enterotoxigenic Escherichia coli (ETEC), salmonella and shigella was evaluated. Under 5 years old healthy children listed in an ascending order of age were alternatively assigned and given either a lactic-acid fermented cereal gruel togwa (test diet) or an unfermented cereal gruel uji (control diet) once a day for 13 consecutive days. The presence of the enteropathogens was examined in rectal swabs collected from the children at baseline (before feeding session started), on days 7 and 13, and additionally 14 days (follow-up day) after the feeding session had stopped. The swabs were cultured on to different optimal media for respective enteropathogen and confirmed by standard microbiological and serological methods. Campylobacter spp. dominated among the enteropathogens (62% out of total) followed by Salmonella spp., ETEC and Shigella spp. Children with isolated enteropathogens in the togwa group was significantly reduced (P < 0.001) from 27.6% at baseline to 7.8, 8.2 and 12.7% on days 7, 13 and follow-up day, respectively. The effect was more pronounced in those children taking togwa > 6 times during the study period. In the control group, there was a slight decrease from 16.7% at baseline to 11.4% on day 7 and 8.1% on day 13. On the follow-up day, enteropathogens were found in 22.6% of the children, which was significantly higher than in those children taking togwa > 6 times. We conclude, that regular consumption of togwa with pH < or = 4, once a day, three times a week may help to control intestinal colonization with potential diarrhoea-causing pathogens in young children.     

Influence of age on faecal carriage of P-fimbriated Escherichia coli and other gram-negative bacteria in hospitalized neonates

The aerobic faecal flora of 953 infants aged over 5 days was studied on discharge from 22 neonatal wards in Swedish hospitals. Klebsiella/enterobacter was isolated from 74% of infants and dominated the aerobic gram-negative flora in 19 wards. Escherichia coli was carried by 42% and showed a slight dominance in two wards. Initially klebsiella/enterobacter dominated the flora but became increasingly mixed with and taken over by E. coli, carriage increasing from 21% in infants discharged after 5-7 days to 57% after 3 weeks or later. Among infants with E. coli, P-fimbriated strains were demonstrated in 23% (range 0-67) and were independent of age. Occasional clustering of such strains was observed in 3/22 wards during the study period. It is postulated that the general and local colonization patterns observed reflect differences between individual strains of E. coli and klebsiella in both their capacity for transmission and their persistence in the newborn gut. The role of P-fimbriae in intestinal colonization of neonates by E. coli was, however, not supported.     

Waterfowl and the bacteriological quality of amenity ponds

This study investigated the impact of waterfowl on the bacteriological quality of village ponds in East Yorkshire, north-east England. Water and sediment samples were collected from ponds with and without resident ducks and geese; faecal indicator and potentially pathogenic bacteria were assayed by membrane filtration and by selective enrichment. Escherichia coli, faecal streptococci and, to a degree, Clostridium perfringens were more abundant in ponds with waterfowl; Salmonella was isolated in June-August from the sediment of a pond with waterfowl. The results suggested that the bacteriological quality of village ponds might be adversely affected by waterfowl. All water samples from ponds with waterfowl had faecal indicators at higher concentrations than EU requirements for bathing waters. Although these ponds are not bathing waters we suggest skin contact and accidental ingestion of water should be avoided.     

Microbial indicators and fresh water quality assessment

Traditionally, the microbiological quality of waters has been measured by the analysis of indicator microorganisms. The article reviews the sanitary significance of traditional indicators of faecal contamination (total coliforms, faecal coliforms and faecal streptococci) and points out their limits. For some characteristics Escherichia coli may be considered a more useful indicator then faecal coliforms and recently it has been included in all recent laws regarding fresh, marine and drinking water. A clearer taxonomic definition of faecal streptococci evidenced the difficulty into defining a specific standard methodology of enumeration and suggested the more suitable role of enterococci as indicator microorganisms. Several current laws require the detection of enterococci. The resistance of Clostridium perfringens spores may mean that they would serve as a useful indicator of the sanitary quality of sea sediments.     

Association between functional antibody against Group B Streptococcus and maternal and infant colonization in a Gambian cohort

BackgroundVertical transmission of Group B Streptococcus (GBS) is a prerequisite for early-onset disease and a consequence of maternal GBS colonization. Disease protection is associated with maternally-derived anti-GBS antibody. Using a novel antibody-mediated C3b/iC3b deposition flow cytometry assay which correlates with opsonic killing we developed a model to assess the impact of maternally-derived functional anti-GBS antibody on infant GBS colonization from birth to day 60–89 of life.MethodsRectovaginal swabs and cord blood (birth) and infant nasopharyngeal/rectal swabs (birth, day 6 and day 60–89) were obtained from 750 mother/infant pairs. Antibody-mediated C3b/iC3b deposition with cord and infant sera was measured by flow cytometry.ResultsWe established that as maternally-derived anti-GBS functional antibody increases, infant colonization decreases at birth and up to three months of life, the critical time window for the development of GBS disease. Further, we observed a serotype (ST)-dependent threshold above which no infant was colonized at birth. Functional antibody above the upper 95th confidence interval for the geometric mean concentration was associated with absence of infant GBS colonization at birth for STII (p < 0.001), STIII (p = 0.01) and STV (p < 0.001). Increased functional antibody was also associated with clearance of GBS between birth and day 60–89.ConclusionsHigher concentrations of maternally-derived antibody-mediated complement deposition are associated with a decreased risk of GBS colonization in infants up to day 60–89 of life. Our findings are of relevance to establish thresholds for protection following vaccination of pregnant women with future GBS vaccines.     

High turnover rate of Escherichia coli strains in the intestinal flora of infants in Pakistan

The Escherichia coli flora of infants in developed countries is dominated by one or a few strains which persist for prolonged periods of time, but no longitudinal studies have been performed in developing countries. To this end, we studied the rectal enterobacterial flora in 22 home-delivered Pakistani infants during their first 6 months of life. Three colonies were isolated and species typed on each of 11 sampling occasions. E. coli isolates were strain typed using electromorphic typing of cytoplasmic enzymes, and their O serogroups were determined. There was a very rapid turnover of enterobacterial strains in the rectal flora of individual infants. On average, 8.5 different E. coli strains were found per infant, and several biotypes of other enterobacteria. Less than 50% of the infants were colonized with E. coli from their mothers, but strains of maternal origin were four times more likely to persists in the infants' flora than other E. coli strains. Enterobacteria other than E. coli were always of non-maternal origin, and Enterobacter cloacae and Klebsiella pneumoniae biotypes recovered from contaminated feeds were later identified in the infants' rectal flora. An early colonization with klebsiella or enterobacter was significantly associated with diarrhoea during the neonatal period, although these bacteria were not likely to be the cause of the disease. The results suggest that poor hygienic conditions result in an unstable and diverse enterobacterial flora, which may influence infant health.