Intestinal and pharyngeal microbiota in early neonates: an analysis based on high-throughput sequencing / 中国当代儿科杂志

OBJECTIVES@#To investigate the distribution characteristics and correlation of intestinal and pharyngeal microbiota in early neonates.@*METHODS@#Full-term healthy neonates who were born in Shanghai Pudong New Area Maternal and Child Health Hospital from September 2021 to January 2022 and were given mixed feeding were enrolled. The 16S rRNA sequencing technique was used to analyze the stool and pharyngeal swab samples collected on the day of birth and days 5-7 after birth, and the composition and function of intestinal and pharyngeal microbiota were analyzed and compared.@*RESULTS@#The diversity analysis showed that the diversity of pharyngeal microbiota was higher than that of intestinal microbiota in early neonates, but the difference was not statistically significant (P>0.05). On the day of birth, the relative abundance of Proteobacteria in the intestine was significantly higher than that in the pharynx (P<0.05). On days 5-7 after birth, the relative abundance of Actinobacteria and Proteobacteria in the intestine was significantly higher than that in the pharynx (P<0.05), and the relative abundance of Firmicutes in the intestine was significantly lower than that in the pharynx (P<0.05). At the genus level, there was no significant difference in the composition of dominant bacteria between the intestine and the pharynx on the day of birth (P>0.05), while on days 5-7 after birth, there were significant differences in the symbiotic bacteria of Streptococcus, Staphylococcus, Rothia, Bifidobacterium, and Escherichia-Shigella between the intestine and the pharynx (P<0.05). The analysis based on the database of Clusters of Orthologous Groups of proteins showed that pharyngeal microbiota was more concentrated on chromatin structure and dynamics and cytoskeleton, while intestinal microbiota was more abundant in RNA processing and modification, energy production and conversion, amino acid transport and metabolism, carbohydrate transport and metabolism, coenzyme transport and metabolism, and others (P<0.05). The Kyoto Encyclopedia of Genes and Genomes analysis showed that compared with pharyngeal microbiota, intestinal microbiota was more predictive of cell motility, cellular processes and signal transduction, endocrine system, excretory system, immune system, metabolic diseases, nervous system, and transcription parameters (P<0.05).@*CONCLUSIONS@#The composition and diversity of intestinal and pharyngeal microbiota of neonates are not significantly different at birth. The microbiota of these two ecological niches begin to differentiate and gradually exhibit distinct functions over time.

Evaluación in vitro de la actividad antimicrobiana de un propóleo chileno sobre muestras clínicas de exudados bucofaríngeos y cepas ATCC / In vitro evaluation of the antimicrobial activity of a Chilean propolis on clinical samples of oropharyngeal exudates

Propolis is a substance manufactured by Apis mellifera and has been widely used in folk medicine due to its high concentration of bioactive compounds. The purpose of the following study was to characterize and evaluate in vitro the antimicrobial properties of propolis on clinical samples and ATCC strains. The chemical characterization of propolis presents a concentration of total polyphenols of 247 ± 9 mg EAG g-1 MS, flavones and flavonols 75± 4 mg EQ g-1 MS, flavanonones and flavanonols 118 ± 11 EP g-1 MS. HPLC-DAD identified apigenin, galangin, phenethyl ester of caffeic acid and pinocembrin, in addition to 16 compounds by HPLC MS/MS. Chilean propolis is a natural antimicrobial, showing effectiveness in strains ATCC Staphylococcus aureus, Candida albicans, Trichophyton rubrum and clinical samples of Staphylococcus aureus unlike Escherichia coli. These results demonstrate the antimicrobial effectiveness of the synergy of compounds present in propolis against different human pathogens.

El propóleos es una substancia fabricada por Apis mellifera y ha sido utilizado ampliamente en la medicina popular debido a su alta concentración de compuestos bioactivos. El propósito del siguiente estudio fue caracterizar y evaluar in vitro las propiedades antimicrobianas del propóleos sobre muestras clínicas y cepas ATCC. La caracterización química de propóleos presenta una concentración de polifenoles totales de 247 ± 9 mg EAG g-1 de MS, flavonas y flavonoles 75 ± 4 mg EQ g-1 de MS, flavanononas y flavanonoles 118 ± 11 EP g-1 de MS. Mediante HPLC-DAD se identificó apigenina, galangina, fenetil éster del ácido cafeico y pinocembrina, además de 16 compuestos mediante HPLC MS/MS. El propóleos chileno es un antimicrobiano natural, observándose efectividad en cepas ATCC Staphylococcus aureus, Candida albicans, Trichophyton rubrum y muestras clínicas de Staphylococcus aureus a diferencia de Escherichia coli. Estos resultados demuestran la efectividad antimicrobiana de la sinergia de compuestos presentes en el propóleos ante diferentes patógenos humanos.

A cross-sectional study assessing the pharyngeal carriage of Neisseria meningitidis in subjects aged 1-24 years in the city of Embu das Artes, São Paulo, Brazil

ABSTRACT Meningococcal carriage is a prerequisite for invasive infection. This cross-sectional study assessed the pharyngeal carriage prevalence in healthy subjects aged 1-24 years in Embu das Artes city, São Paulo, Brazil. Pharyngeal swabs were examined for the presence of Neisseria meningitidis. The isolates were tested for different serogroups using agglutination and polymerase chain reaction. A logistic regression model assessed any independent association between Neisseria meningitidis carriage and various risk factors. A total of 87/967 subjects (9%, 95% Confidence Interval (CI): 7.3-11.0) tested positive for N. meningitidis: 6.2% (95% CI: 3.8-9.4) in 1-4 years, 8.5% (95% CI: 5.1-13.0) in 5-9 years, 12.5% (95% CI: 7.8-18.6) in 10-14 years, 12.6% (95% CI: 7.4-19.7) in 15-19 years and 9% (95% CI: 4.9-14.9) in 20-24 years age groups. Highest carriage prevalence was observed in adolescents 10-19 years old. Serogroup C was predominant (18.4%) followed by serogroup B (12.6%). The 15-19 years age group showed a significant association between number of household members and carriers of N. meningitidis. This cross-sectional study is the first in Brazil to evaluate meningococcal carriage prevalence and associated factors in a wide age range.

Aislamientos bacterianos de muestras respiratorias de pacientes pediátricos con fibrosis quística y su distribución por edades / [Bacterial isolates from respiratory samples of pediatric patients with cystic fibrosis and their distribution by ages].

The bacterial isolates from respiratory samples of 50 pediatric patients with cystic fibrosis, their distribution by ages and antimicrobial resistance pattern as well as the intermittence of isolations and coinfections, were investigated. Staphylococcus aureus was isolated in 72

of patients, followed by Pseudomonas aeruginosa (58

), and the Burkholderia cepacia complex (12

). The frequency of resistance of P. aeruginosa isolates to ß-lactam antibiotics was low (13.8

). Fifty percent of S. aureus isolates was methicillin-resistant, and 57.1

of H. influenza was ampicillin resistant due to ß-lactamase production. In children under 4 years-old, S. aureus was predominant, followed by P. aeruginosa and H. influenzae. This order of predominance was observed in all the groups studied, except in that of children between 10 and 14 years-old. Stenotrophomonas maltophilia and Achromobacter xylosoxidans isolates were intermittent and accompanied by other microorganisms. Finally, we observed a great variety of bacterial species, which imposes stringent performance requirements for microbiological studies in all respiratory samples of these patients.

A survey on pulmonary pathogens and their antibiotic susceptibility among cystic fibrosis patients

OBJECTIVE:This study was performed to investigate frequency and antimicrobial susceptibility of pulmonary pathogens in cystic fibrosis (CF) patients. METHODS: 129 pediatric patients with CF were enrolled in this cross-sectional study. Microbiological cultures were performed based on sputum or pharyngeal swabs. Antibiotic susceptibilities of the isolated bacteria were determined by the disk diffusion method. RESULTS: The main infecting pathogens were Pseudomonas aeruginosa (38.8%), Klebsiella pneumoniae (11.6%) and Staphyloccus areus (9.3%), respectively. The most active antibiotics included rifampin (91.7% susceptibility), vancomycin (85%) and imipenem (83.5%). Emerging resistance against aminoglycosides was observed. CONCLUSION: Regarding in vitro susceptibility results, cyclic treatment of long-term oral azithromycin and inhaled tobramycin could prophylactically be applied, and during exacerbations, imipenem or ceftazidime in combination with an aminoglycoside such as amikacin could be considered the drugs of choice.

Prevalence of biofilm and betalactamase-producing staphylococcus in nasal and throat isolates from healthy volunteers: a medical alert

To study the prevalence of virulence factors such as Biofilm and Beta-lactamase in Staphylococcus isolates residing in nasal and throat mucosa in healthy volunteers. Nasal and throat swabs were taken from 100 healthy volunteers at Gulf Medical University and Gulf Medical College Hospital, Ajman, UAE, and cultured for Staphylococcus isolates on appropriate culture media. The isolate were classified as Staphylococcus aureus or Coagulase Negative Staphylococcus [CoNS] based on the growth characteristics on Mannitol Salt Agar and standard tube coagulase test. They were further tested for Biofilm production by Christensen's tissue culture plate and Congo red agar methods. The positive samples were identified for beta-lactamase by iodometric tube method. Of the 100 Staphylococcus isolates, 41 were Staphylococcus aureus of which 25 [61%] were positive for biofilm production whereas 19 [46.3%] were Beta-lactamase positive. Of the 16 [39%] biofilm negative Staphylococcus aureus isolates, 13 [31.7%] were Beta-lactamase positive. Among the 59 CoNS isolates, 38 [64.4%] were positive for biofilm production and 18[30.5%] were Beta-lactamase positive. Twenty one CoNS samples [35.5%] were negative for both biofilm and Beta-lactamase production. Biofilm production in Staphylococcus aureus and CoNS did not show any significant difference [61% and 64.4%]. Predominance of Staphylococcal isolation was in males between the age group of <20 years, mostly from the nasal site. Biofilm-producing Staphylococcus appear to inhabit the normal flora of the nasal and throat mucosa of healthy individuals. Beta-lactamase production was found to be higher in Staphylococcus aureus positive for biofilm producers as compared to CoNS. Transmission of these biofilm producers with drug resistance factors from the healthy individuals to those at risk, like patients on long term catheterization or with indwelling devices need to be considered

Survey of Mycoplasma pneumoniae in Iranian children with acute lower respiratory tract infections

OBJECTIVES: Mycoplasma pneumoniae is an atypical pathogen, which is one of the major causes of lower respiratory tract infections (LRTIs) worldwide. This study was performed to determine the role of M. pneumoniae in acute LRTIs in children, who were referred to main pediatric hospitals in Shiraz, Iran, with the diagnosis of LRTI. Polymerase chain reaction method on a throat-swab specimen was utilized to detect M. pneumoniae. RESULTS: One hundred patients with acute LRTIs were investigated in this study. There were 10 positive PCR for M. pneumoniae (10 percent), including 6 of 62 hospitalized patients and 4 of 38 outpatients. All patients with LRTIs due to M. pneumoniae had cough. Fever, flu like symptoms, dyspnea, pulmonary rales, wheezing, and conjunctivitis were other common signs and symptoms. CONCLUSIONS: The percentage of cases with M. pneumoniae infection in our population is similar to the reported in other parts of Asia. Precise and early detection of pathogen and appropriate antibiotic therapy are the key points in management of patients with LRTIs.

[ prevalence of pharyngeal carriers of group A Beta-hemolytic Streptococcus and antibiotic susceptibility pattern of this bacteria in Zahedan, southeast of Iran]

Group A Beta-Hemolytic Streptococcus [GABHS] is the most important and common bacterial cause of acute pharyngitis in children. Nowadays, cases of resistance to antibiotics have been reported due to unnecessary and extensive usage of antibiotics. The aim of this study was to determine the prevalence of healthy pharyngeal carriers and evaluate the antibiotic susceptibility of GABHS. In this study among guidance school students of Zahedan aged 12 to 14 years, 1092 cases were selected randomly. After culturing the pharyngeal samples, GABHS was isolated and its susceptibility to different antibiotics was examined. Results were statistically analyzed by Chi-square and Exact fisher tests. 76 specimens of GABHS were isolated from 1092 cultivated specimens and the differences in the prevalence of GABHS between different age groups of two sexes and different age groups of each sex were not statistically significant. The antibiotic susceptibility ratios were 98.68% for cephalexin and cefazolin, 97.37% for erythromycin and 92.11% for penicillin and the difference was not statistically significant. The susceptibility to amoxicillin was 80.26%, which was significantly different from susceptibility to cephalexin and cefazolin [p<0.001], erythromycin [p=0.001] and penicillin [p=0.034]. In spite of widespread resistance to antibiotics, penicillin still is the first drug of choice for treatment of GABHS pharyngitis and erythromycin is the best alternative drug for patients sensitive to penicillin

Bacterial contamination in milk kitchens in pediatric hospitals in Salvador, Brazil

Milk may represent an important source of infectious agents to hospitalized pediatric patients. To describe the bacterial microflora isolated from the hands, stools, pharynx of all workers at milk kitchens in pediatric hospitals in the city of Salvador, Brazil, as well as in the formulas prepared by them, we carried out this cross-sectional study with all 91 workers from the 20 milk kitchens of all the public and private hospitals in Salvador, Brazil. Hand and pharynx swabs and stool samples were collected from all workers, as well as samples of the milk and formulas delivered by the kitchens. All samples were cultured for the detection of pathogenic and non-pathogenic bacteria. Pathogenic bacteria were isolated from 20 (22.0 percent) and 8 (8.8 percent) cultures of the hands and pharynx of the workers, respectively. No pathogenic bacteria were isolated from stool samples. Pathogenic bacteria were isolated from 17 (18.7 percent) milk samples. The prevalence of pathogenic bacteria in hand swabs was significantly higher in workers from public (37.8 percent) than from private (6.5 percent) hospitals (prevalence ratio [PR]=5.8; p<0.01). Pathogenic bacteria were isolated from two (4.4 percent) workers from public hospitals and six (13.0 percent) workers from private hospitals (PR=0.38; p=0.27). Pathogenic bacteria were isolated from 11 (24.4 percent) milk samples from public hospitals and 6 (13.0 percent) from private hospitals (PR=1.9; p=0.16). A high prevalence of contamination was found, mainly on the hands of workers on units for manipulation of milk. Preventive efforts should be intensified and focus primarily on effective hand washing and continuous work supervision.

Molecular and conventional studies on staphylococcus aureus isolated from milk of subclinical bovine mastitis cases and associated dairy workers

Staphylococcus aureus [S.aureus] is the world over pathogen that causes a variety of infections in man and animals. Detection of S. aureus in collected milk samples from apparently normal animals and comparing their genotypic traits with those isolated from hands of dairy workers. A total of 160 apparently normal quarter foremilk samples, collected from 40 machine milking Friesian lactating cows from Aswan governorate, were cultivated on Baird Parker media. 40 swabs collected from dairy workers' hands or faces were streaked on mannitol salt egg yolk agar [MSEY agar]. Isolated Staphylococcus aureus strains were examined for coagulase slide test, Catalase and DNAase test. Staphylococcus aureus isolated were tested by a two multiplex PCR assays one of them was to detect 16SrRNA gene and coagulase [coa] gene. The second multiplex PCR was to clarify presence of Staphylococcus aureus entertoxins type A [SEA] and B [SEB] in positive coagulase S.aureus. For bovine milk, A prevalence rate of 40.6% and 45.0% of California mastitis test [CMT] and Somatic cell count [SCC] was detected respectively. Whereas, coagulase test was positive in 54.4% and 61.1% of bovine milk and dairy workers in the same sequence. 16Sr-RNA gene was positive in 100% of both bovine milk and dairy workers. But coagulase [Coa] gene was positive in 63.4% and 72.2% of milk and dairy workers respectively. SEA was positive in 21.8% and 38.8% of milk and dairy workers respectively, while SEB was positive in 30.1% and 50% in the same sequence. Testing milk [by CMT, SCC microbial isolation] for detection of subclinical mastitis is an essential part of daily evaluation record of each dairy farm. Detection of Staphylococcus aureus by PCR as well as entertoxins identification was found to be rapid, sensitive and accurate. Special concern should be directed to elucidate the kinetic transfer of Staphylococcus aureus between animals and human. Detection of Staphylococcus aureus entertoxin A and B was found to be easy and rapid by using PCR

Rhinosporidiosis in Raipur, Chhattisgarh: a report of 462 cases.

Rhinosporidiosis is endemic in the state of Chhattisgarh. 462 cases were encountered during the period of 12 years from January 1994 to December 2005. Maximum incidence was seen in men in the age group of 21-30 years. Nose and nasopharynx were the commonest site (81.1%), followed by ocular tissue (14.2%). Many rare sites of involvement were encountered. Seven cases of generalized rhinosporidiosis were seen. Rhinosporidium seeberi could be easily identified in Haematoxylin and eosin stained sections. Sporangias and spores are better delineated by periodic Acid Schiff, Mayer's mucicarmine, Verhoff's vonGieson and Grocott Gomori methamine silver stain.

Presencia de ADN bacteriano en el tejido valvular de pacientes con cardiopatía reumática crónica / Presence of bacterial DNA in valvular tissue of patients with rheumatic heart disease

Background: Rheumatic heart disease (RHD) is a delayed consequence of a pharyngeal infection with Group A streptococcus (GAS), usually ascribed to a cross-reactive immune response to the host cardiac tissues. Acute rheumatic fever (ARF) and its ensuing valvular sequelae are thus considered the prototype of a post-infectious autoimmune disease, with no direct evidence of residual streptococcal antigen in diseased valvular tissues. However, recent studies concerning the antigenic specificity and clonality of intralesional lymphocytes have revealed oligoclonal expansions characteristic of an antigen specific response, that might be related to GAS. Aim: To search for bacterial DNA in valvular tissue from RHD patients and controls. Material and methods: We extracted DNA from surgically excised valve specimens from 15 RHD patients and 6 non RHD controls and tested for the presence of bacterial DNA by Polymerase Chain Reaction (PCR) with primers for 16S rRNA. Results: Eighty percent (12/15) of valve specimens from RHD patients were positive for bacterial DNA, as opposed to none of the valves (n =6) from non RHD controls. Conclusions: These results suggest that GAS might persist in valvular tissue in patients with ARF and contribute to the inflammatory scarring lesion that leads to cardiovascular sequelae.

Effect of laryngoscope blade cover on bacterial contamination of pharynx and post-operative sore-throat

Laryngoscope blades are in contact with mucous membrance and can pissiblily contaminated with transmissible microgranisms. The cover for the blade of the laryngoscope may be can prevent the cross infection. The aim of this study was to evaluate the effect of use of disposable nylon sheath over laryngoscope blade on bacterial contamination of pharynx and post operative sore throat. 66 patients undergoing general anesthesia were included in this study. In case group [n=32] a translucid nylon cover enclosing the blade of laryngoscope. In control group [n=34] the blade used without cover. Before induction of anesthesia, in both groups the samples from blade, and before induction of anesthesia and 24hr after operation the sample from patients pharynx were obtained and sent for aerobic and anaerobic bacterial culture. Frequency of positive culture and post operative sore throat were determined. The intensity of post operative sore throat was assessed at 24hr after operation using visual analogue scale [VAS]. Data were ananlyzed using chi-square, Fisher exact, McNemar and t-tests. The frequency of positive culture of pharynx before induction of anesthesia in case and control groups was 89.3% and 94.1% respectively [P > 0.05]. This frequency was 43.7% and 61.8% at 24 hr after operation [P > 0.05]. In 6 samples of laryngoscope blade, bacterial culture was positive. The occurence of post operative sore throat in both groups was 62.5% and 52.9% respectively [P > 0.05]. There were no correlation between pharyngeal cultures and post operative sore throat. The bacteriological study of laryngoscope blades showed that the routine cleaning and sterilization of blades in our hospital is effective. Laryngoscope blade cover has no effects on bacterial contamination of pharynx and post operative sore throat

effect of 23-valent pneumococcal polysaccharide vaccine on pharyngeal colonization in healthy children under 5 years of age

Streptococcal pneumonia is one of the most common pathogens that cause otolaryngological diseases [otitis media, sinusitis, tonsillitis] and other invasive diseases such as pneumonia, so that decreasing the pharyngeal carriage of pneumococci will eventually decrease the occurrence of these common diseases and hence decrease the morbidity and mortality associated with these diseases. Are to evaluate the pharyngeal carrier rate of pneumococci in healthy children and to demonstrate the effect of 23-valent pneumococcal polysaccharide vaccine on pneumococcal pharyngeal carriage. This prospective study was carried on 100 healthy children under 5 years of age. They were divided into two groups, the control group consisting of 65 children, throat swabs were taken for them, and the vaccinated group consisting of 35 children which received 23-valent pneumococcal polysaccharide vaccine and throat swabs were taken 1 and 6 months after vaccination. The pharyngeal carriage of pneumococci in the control group was 60% while in the vaccinated group was 8.6%. 23-valent pneumococcal polysaccharide vaccine is significantly effective in decreasing the pharyngeal carriage of pneumococci

Microbial study of hospital environment and carrier pattern study among staff in Nepal Medical College Teaching Hospital.

The present study was done to see the microbial flora in the environment (air and surface) of Nepal Medical College Teaching Hospital and the staffs working in the hospital. Altogether 160 environmental (air n = 43, surface n = 117) samples were collected and studied from different wards. Similarly 150 samples (48 nasal swabs, 48 throat swabs and 54 hand samples) from the staffs were collected and studied following the standard microbiological protocols. Gram +ve cocci were the most predominant ones among the bacterial isolates from the environment followed by gram +ve bacilli and gram -ve bacilli. Among fungal isolates, yeast were the most common isolates while Aspergillus spp. were the most frequently occurring mold. Out of 150 samples collected for the study of carrier pattern, 32 out of 54 samples collected were found to have Staphylococcus aureus in their hands, 1 had Escherichia coli. Other isolates were Bacillus spp., Micrococci and coagulase negative staphylococci. Similarly 21 (43.8%) out of 48 nasal samples were found to have S. aureus while none of the staffs were found to have beta-hemolytic streptococci in their throat. In the study, 1.6% environmental isolates and 5.7% carrier isolates of S. aureus were found to be Methicillin resistant.

Pharyngeal carriage of group A streptococci in school children in Chennai.

BACKGROUND & OBJECTIVES: Asymptomatic pharyngeal carriage of group A streptococci (GAS) in children may lead to spread of respiratory infections in the community. Data on healthy GAS carriers in the community are therefore important. We carried out this preliminary study to screen the school children from various parts of Chennai city, south India to detect pharyngeal carriage of GAS. METHODS: Throat swabs were collected from 1,173 school children aged 5 to 17 yr from different locations in Chennai. The isolates of beta haemolytic streptococci were serogrouped by agglutination tests using specific antisera. RESULTS: Beta haemolytic streptococci were isolated from 16.3 per cent of 1,102 asymptomatic children. 71 children of the study group had untreated tonsillitis positive for beta haemolytic streptococci. The percentage of asymptomatic GAS carriers was 8.4 per cent. INTERPRETATION & CONCLUSION: The high carriage rate of beta haemolytic streptococci seen in children poses a threat to the community and should be checked. Regular screening needs to be done in various parts of the country.

Portación faríngea de Mycoplasma pneumoniae en niños chilenos / Asymptomatic pharyngeal carriage of Mycoplasma pneumoniae in Chilean children

La reacción de polimerasa en cadena (RPC) ha demostrado ser una alternativa sensible para el diagnóstico de enfermedad por M. pneumoniae proporcionando resultados en forma oportuna. Sin embargo, no se conoce bien la frecuencia de portación o la persistencia de este microorganismo en la faringe luego de una enfermedad respiratoria en niños, factores que podrían limitar la utilidad de este procedimiento de diagnóstico. Con el objeto de conocer la frecuencia de portación silenciosa de M. pneumoniae en niños, se estudiaron mediante RPC muestras faríngeas de 185 niños sin signos ni síntomas de infección respiratoria, enrolados en dos consultorios de la Región Metropolitana, Chile, entre septiembre de 2002 y agosto de 2003. M. pneumoniae fue detectado en 4 (2,16%) niños. Las muestras positivas podrían representar portación o persistencia post enfermedad de M. pneumoniae.

Microbiota indígena de seres humanos / Indigenous microbiota of human beings

As superfícies do corpo humano são colonizadas por uma comunidade de organismos, principalmente bactérias, que constitui a microbiota indígena. A composição desta microbiota se altera ao longo da vida e é influenciada por diversos fatores, tais como dieta e status imunológico do hospedeiro. A microbiota pode agir de maneira benéfica ou, em algumas situações, pode ser prejudicial para o indivíduo. Podem ser distinguidas a microbiota residente, constituída por organismos específicos, encontrados, freqüentemente, em determinadas áreas e a microbiota transitória, que consiste de microrganismos provenientes do ambiente, que habitam a pele e as superfícies mucosas por horas ou poucas semanas. Trato gastrointestinal, vagina, cavidade oral e pele possuem a microbiota mais rica e diversificada do corpo humano. O conhecimento da constituição da microbiota indígena é extremamente relevante para os médicos, principalmente para orientar a interpretação de resultados de exames microbiológicos e a escolha da terapia antimicrobiana empírica mais adequada. Deve-se salientar que a microbiota geralmente é benéfica. Por esse motivo, é fundamental que se tenha consciência dos riscos do rompimento da homeostasia entre microbiota e hospedeiro.

Body surfaces are colonized by a community of organisms that are recognized as indigenous microbiota, that is mainly constituted by bacteria. Its constitution changes with time and is influenced by several conditions such as diet and the immune status of the individual, among others. There are now evidences that the microbiota could be beneficial or, in some instances, dangerous to human health. It could be classified as resident, composed by fixed organisms, frequently found in certain areas, or as transitory, consisting of organisms from the environment that inhabits skin and mucosa for hours to few weeks. The gastrointestinal tract, vagina, oral cavity and skin show the richest and most diverse microbiota of the human body. The knowledge of the constitution of the indigenous microbiota is extremely important for clinicians, mainly because it can help them to interpret results of microbiological tests and to choose appropriate empirical therapy. It should be pointed out that microbiota is, in general, harmless and beneficial; for these reason, physicians must keep in mind that the disruption of the homeostasis between microbiota and host should be avoided.