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Results for “Asymptomatic carriage”

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At least 19 recordsLinked to original sources
PubMed1995

Asymptomatic carriage of intestinal Cryptosporidium in immunocompetent and immunodeficient children: a prospective study.

Little information is available on asymptomatic carriage of Cryptosporidium in immunocompetent and immunodeficient children. We prospectively studied a group of asymptomatic children, 78 immunocompetent and 50 immunodeficient, to document the incidence of asymptomatic carriage of cryptosporidiosis in such a population. We also investigated whether the treatment of children who carried asymptomatic cryptosporidiosis could help in reducing their risk of gastrointestinal symptoms as well as the shedding of infectious oocysts. The occurrence of multiple infections with common intestinal pathogens including Giardia lamblia was also investigated. Asymptomatic cryptosporidiosis was documented in 6.4% of immunocompetent and 22% of immunodeficient children. In a control symptomatic population Cryptosporidium was found in 4.4% of immunocompetent and 4.8% of immunodeficient children. Asymptomatic carriage of Cryptosporidium was documented in 2 human immunodeficiency virus-infected children, one of whom also carried Giardia asymptomatically. Treatment with spiramycin (100 mg/kg daily for 14 days) reduced significantly the duration of the shedding of potentially infectious oocysts. Finally no gastrointestinal symptoms developed in children treated for asymptomatic infection with Cryptosporidium, whereas children who were not treated developed gastrointestinal symptoms.

Adolescent↗
PubMed2000

Asymptomatic carriage of Clostridium difficile and serum levels of IgG antibody against toxin A.

BACKGROUND: Clostridium difficile infection can result in asymptomatic carriage, mild diarrhea, or fulminant pseudomembranous colitis. We studied whether antibody responses to C. difficile toxins affect the risks of colonization, diarrhea, and asymptomatic carriage. METHODS: We prospectively studied C. difficile infections in hospitalized patients who were receiving antibiotics. Serial stool samples were tested for C. difficile colonization by cytotoxin assay and culture. Serum antibody (IgA, IgG, and IgM) levels and fecal antibody (IgA and IgG) levels against C. difficile toxin A, toxin B, and nontoxin antigens were measured by an enzyme-linked immunosorbent assay (ELISA). RESULTS: Of 271 patients, 37 (14 percent) were colonized with C. difficile at the time of admission, 18 of whom were asymptomatic carriers. An additional 47 patients (17 percent) became infected in the hospital, 19 of whom remained asymptomatic. The baseline antibody levels were similar in the patients who later became colonized and those who did not. After colonization, those who became asymptomatic carriers had significantly greater increases in serum levels of IgG antibody against toxin A than did the patients in whom C. difficile diarrhea developed (P<0.001). The adjusted odds ratio for diarrhea was 48.0 (95 percent confidence interval, 3.4 to 678) among patients with colonization who had a serum level of IgG antibody against toxin A of 3.00 ELISA units or less, as compared with patients with colonization who had a level of more than 3.00 ELISA units. CONCLUSIONS: We find no evidence of immune protection against colonization by C. difficile. However, after colonization there is an association between a systemic anamnestic response to toxin A, as evidenced by increased serum levels of IgG antibody against toxin A, and asymptomatic carriage of C. difficile.

Aged↗
PubMed2003

Limited asymptomatic carriage of Pneumocystis jiroveci in human immunodeficiency virus-infected patients.

Forty-seven bronchoalveolar lavage fluid samples from 16 human immunodeficiency virus (HIV)-infected patients were used to test the latency model of Pneumocystis infection in the human host. Identification of DNA sequence polymorphisms at 4 independent loci were used to genotype Pneumocystis jiroveci from the 35 samples that contained detectable P. jiroveci DNA. Eighteen of those 35 samples came from patients who did not have Pneumocystis pneumonia (PCP) and had confirmed alternative diagnoses. Seven patients had asymptomatic carriage of P. jiroveci over periods of < or = 9.5 months after an episode of PCP, and in all 7 cases, a change in genotype from that in the original episode of PCP was observed. The absence of P. jiroveci DNA in one-fourth of the 47 samples and the observed changes in genotype during asymptomatic carriage do not support the latency model of infection. Asymptomatic carriage in HIV-infected patients may play a role in transmission of P. jiroveci and may even supply a reservoir for future infections.

AIDS-Related Opportunistic Infections↗
PubMed1995

Asymptomatic carriage of Haemophilus ducreyi confirmed by the polymerase chain reaction.

OBJECTIVE: To investigate asymptomatic carriage of Haemophilus ducreyi by using polymerase chain reaction (PCR) on samples from women at high risk of infection. SUBJECTS: 213 commercial sex workers (CSWs) recruited in The Gambia, West Africa. METHODS: Genital samples (cervical, vaginal and ulcer) were tested for the presence of H ducreyi by PCR with the technique of "one tube nested primer". RESULTS: 12 CSWs were PCR positive for H ducreyi; 8 of these women had genital ulcers on examination. CONCLUSION: Using a simplified PCR technique for detecting H ducreyi we have shown that 2% of CSWs were carrying the organism without clinical symptoms or signs. This has important implications for sexually transmitted disease control programmes in areas with a high prevalence of chancroid.

Base Sequence↗
PubMedDate not supplied

[Methods for analyzing the frequency, prevalence and the duration of asymptomatic carriage of Neisseria meningitidis. Longitudinal study of a school population in Belgium].

In Belgium, during an outbreak of meningococcal disease mainly due to serogroup B, serotype 2 meningococcus, a prospective study of asymptomatic carriage was undertaken in two primary schools. From march 1975 to may 1976, 361 schoolchildren aged 3 to 14 years were surveyed. The result of nasopharyngeal cultures were adjusted to compensate the lack of sensitivity and specificity of the identification techniques. The hypotheses on which the adjustment rules are based were statistically validated. The mean prevalence of meningococcal carriage was 23 p. 100, the incidence rate was 0.02 acquisition for month and for person. The median duration of carriage was estimated at 9.4 months, and the mean duration at 13.6 months. For the first time, the expected relationship between prevalence, incidence, and duration was confirmed for meningococcal carriage.

Adolescent↗
PubMed1984

Rotavirus carriage, asymptomatic infection, and disease in the first two years of life. II. Serological response.

Serological response to rotavirus and virus shedding were prospectively studied in 179 children (neonatal to 24-month-old) upon admission to a hospital during an 11-month period. Analysis of the evolution of IgG and IgM ELISA titers revealed 24 cases of rotaviral disease (serological response and diarrhea), 13 cases of asymptomatic infection (serological response and no diarrhea), 36 cases of virus carriage (absence of a serological response), three cases of past infection, and six possible cases of nosocomial infection. Rotaviral disease was encountered two out of three times and was characterized by diarrhea associated with fever and vomiting. Asymptomatic rotaviral infection and disease, observed from the neonatal period onwards, affected 2% of neonates, 20% of one- to six-month-old children, and 37% of 7-24-month-old children. In contrast, virus carriage occurred in 27%, 19%, and 14% of those children respectively. Altogether these results indicate that during the period 1-24 months of age, when asymptomatic rotaviral infection and disease were prevalent, approximately two of 10 children had rotaviral disease, one of 10 had asymptomatic infection, two of 10 were virus carriers, and five of 10 were not infected with rotavirus.

Aging↗
PubMed1994

Asymptomatic carriage of Neisseria meningitidis in a randomly sampled population.

To estimate the extent of meningococcal carriage in the Norwegian population and to investigate the relationship of several characteristics of the population to the carrier state, 1,500 individuals living in rural and small-town areas near Oslo were selected at random from the Norwegian National Population Registry. These persons were asked to complete a questionnaire and to volunteer for a bacteriological tonsillopharyngeal swab sampling. Sixty-three percent of the selected persons participated in the survey. Ninety-one (9.6%) of the volunteers harbored Neisseria meningitidis. The isolates were serogrouped, serotyped, tested for antibiotic resistance, and analyzed by multilocus enzyme electrophoresis. Eight (8.8%) of the 91 isolates represented clones of the two clone complexes that have been responsible for most of the systemic meningococal disease in Norway in the 1980s. Age between 15 and 24, male sex, and active and passive smoking were found to be independently associated with meningococcal carriage in logistic regression analyses. Working outside the home and having an occupation in transportation or industry also increased the risk for meningococcal carriage in individuals older than 17, when corrections for gender and smoking were made. Assuming that our sample is representative of the Norwegian population, we estimated that about 40,000 individuals in Norway are asymptomatic carriers of isolates with epidemic potential. Thus, carriage eradication among close contacts of persons with systemic disease is unlikely to have a significant impact on the overall epidemiological situation.

Adolescent↗
PubMed2003

Asymptomatic carriage of Pneumocystis jiroveci in subjects undergoing bronchoscopy: a prospective study.

BACKGROUND: The opportunistic fungus Pneumocystis jiroveci is a common cause of respiratory infection in immunocompromised patients. By contrast, pneumocystis pneumonia (PCP) occurs only rarely in immunocompetent individuals. Asymptomatic colonisation with P jiroveci has recently been described in patients who are either minimally immunosuppressed or who have underlying lung disorders such as bronchiectasis. We sought to determine the prevalence of asymptomatic colonisation by P jiroveci in a cohort of adult patients undergoing diagnostic bronchoscopy. METHODS: A prospective observational cohort study was performed in patients who required bronchoscopy and bronchoalveolar lavage (BAL) as part of their routine clinical assessment. All the samples underwent standard microbiological analysis and a Grocott methenamine silver stain was performed where clinically indicated to detect the presence of P jiroveci. Polymerase chain reaction for detection of P jiroveci specific DNA was also performed. RESULTS: Ninety three consecutive BAL fluid samples were analysed, 17 (18%) of which contained P jiroveci DNA. Of the potential predictors examined, only glucocorticoid use was significantly associated with detectable P jiroveci DNA. Eighteen patients were receiving oral glucocorticoids (equivalent to >20 mg/day prednisolone) at the time of bronchoscopy, of whom eight (44%) had detectable P jiroveci DNA. In contrast, P jiroveci was detected in only nine of 75 patients (12%) who were not receiving glucocorticoids (difference between proportions 32%, 95% CI 8 to 57; p=0.004, two tailed Fisher's exact test). CONCLUSIONS: P jiroveci colonisation, as determined by detection of P jiroveci DNA in BAL fluid, is common in HIV negative patients with primary respiratory disorders undergoing bronchoscopy and BAL. The higher prevalence in patients receiving corticosteroids suggests that oral glucocorticoid therapy is an independent risk factor for colonisation. In contrast, underlying lung cancer or COPD did not appear to be risk factors.

Adult↗
PubMed2004

Screening of glutamate decarboxylase activity and bile salt resistance of human asymptomatic carriage, clinical, food, and environmental isolates of Listeria monocytogenes.

Following consumption, stomach acidity is the first major barrier encountered by the food-borne pathogen Listeria monocytogenes. Analysis of low pH sensitivity and glutamate decarboxylase (GAD) acid resistance system of 14 isolates of L. monocytogenes carried asymptomatically by humans showed that levels of GAD activity were subjected to strain variation. Similar variations were observed for strains responsible for 18 cases of listeriosis, whereas in comparison, 13 strains isolated from food and food-processing plant environments showed lower GAD activity. Following survival of the stomach barrier, L. monocytogenes also has to resist bile salts encountered in the small intestines. Analysis revealed that all strains tested were able to grow in the presence of bile salts with concentrations as high as those encountered in the small intestines and had previously identified bile salt hydrolase (BSH) activity. Strain variation was observed but there was no relationship between the origin of the strains and the ability to degrade bile salts.

Bacterial Proteins↗
PubMed2000

Relationship between asymptomatic carriage of Streptococcus pyogenes and the ability of the strains to adhere to and be internalised by cultured epithelial cells.

This study was undertaken to determine whether the ability of group A streptococci to persist in the throat following antibiotic therapy corresponded with their capacity to adhere to and be internalised by epithelial cells. The study employed a HEp-2 cell model to examine the adherence and internalisation capacities of 42 strains (13 from asymptomatic patients with bacteriological eradication failure and 29 from patients with bacterial eradication). The adherence and internalisation efficiencies of strains from symptomless carriers were significantly higher. The average adherence efficiency of the carriers' strains was 53 (SEM 6)% versus 35 (SEM 5)% in control strains. The average internalisation efficiency of the carriers' strains was 13.4 (SEM 4)% compared with 4.4 (SE 1.6)% in the control group. The results are in agreement with the hypothesis that, in a significant number of cases, streptococcal internalisation might contribute to eradication failure and persistent throat carriage.

Anti-Bacterial Agents↗
PubMed1992

[Asymptomatic carriage of Pestivirus in ruminants].

Pestiviruses are enveloped single-chain ribonucleic acid viruses with a positive polarity. Pestiviruses include the viruses of classical swine fever (hog cholera), Border disease of sheep, mucosal disease of cattle, and isolates obtained from wild animals, such as red deer (Cervus elaphus). Among ruminants, pestiviruses have developed a remarkable strategy for assuring their persistence. Through epigenetic transmission, they lead to the birth of asymptomatic carrier animals harbouring non-cytopathic variants, which become immunotolerant to the strain of virus present. The presence of a small number of asymptomatic carriers enables the virus to circulate within a herd by horizontal transmission, leading to the birth of a new generation of asymptomatic carriers.

Animals↗
PubMedDate not supplied

Asymptomatic carriage of Cryptococcus neoformans in the nasal cavity of dogs and cats.

Nasal washings, obtained from a random source of dogs and cats, were concentrated by centrifugation and plated onto bird seed agar containing antibiotics. Cryptococcus neoformans var. neoformans was isolated from eight of 56 dogs (14%) and three of 45 cats (7%). More than 100 colonies of C. neoformans were present on the plates from seven of the 11 positive animals. Absence of cryptococcal antigen in the serum of these animals, and failure to demonstrate yeast-like organisms or significant pathology in nasal biopsies, suggests that the nasal cavity of these animals was not infected by C. neoformans but rather that blastoconidia and/or basidiospores were carried asymptomatically. These findings are discussed in relation to the likelihood of the upper respiratory tract being the primary site for cryptococcal infection in dogs and cats.

Animals↗
PubMed2001

Association between asymptomatic carriage and sporadic (endemic) meningococcal disease in an open community.

We analysed a strain collection representative of the overall Neisseria meningitidis population circulating in an open community (46,000 inhabitants, Spain) during an endemic period (30 isolates from patients and 191 from throat cultures of healthy individuals) by both phenotypic and molecular techniques. Almost all patient isolates were assigned to three hyper-virulent lineages (ET-5 complex, ET-37 complex and cluster A4) by both multilocus enzyme electrophoresis (MEE) and pulsed-field gel electrophoresis (PFGE). In contrast, MEE and PFGE assigned 20% and 15% respectively of carrier isolates to the hyper-virulent clones (4% for both methods together). There was also a higher correlation between PFGE and phenotypes associated with virulent clones. These notable differences between the two molecular methods were further observed in more than half the carrier isolates, suggesting that the associations between these strains were distorted by recombination events. However, almost one-third of total endemic strains from symptom-free carriers and almost all patient strains belonged to clones defined by MEE and PFGE, with no known epidemiological connection. These data indicate low transmission and a weak clonal structure for N. meningitidis.

Carrier State↗
PubMed2004

Asymptomatic carriage of verocytotoxin-producing Escherichia coli O157 in farm workers in Northern Italy.

Faecal samples from 350 farm workers on 276 dairy farms and 50 abattoir employees from seven different operations were examined for the presence of Verocytotoxin-producing Escherichia coli 0157 (VTEC O157) by an O157-specific enzyme-linked fluorescent assay followed by immunoconcentration. VTEC O157 was isolated from four (1.1%) of the farm workers. A second stool sample was obtained from the positive farm workers as well as from their household contacts. VTEC O157 was isolated from the wife of one of them. The strains from the same household shared the same Verocytotoxin genes profile, phage type and pulsed-field gel electrophoresis pattern. The VTEC O157-positive subjects had neither intestinal symptoms at the moment of sampling nor a history of bloody diarrhoea or renal failure. Our study seems to confirm the hypothesis that farm residents often develop immunity to VTEC O157 infection, possibly due to recurrent exposure to less virulent strains of VTEC.

Abattoirs↗
PubMed1999

Asymptomatic carriage of Cryptococcus neoformans in the nasal cavity of the koala (Phascolarctos cinereus).

Over a 22-month period, sequential nasal and skin swabs were obtained from 52 healthy captive koalas (Phascolarctos cinereus) from the Sydney region. Cryptococcus neoformans was isolated in 17 koalas from 64 of 262 (24%) nasal swabs and from nine of 262 (3%) skin swabs. Prevalence of nasal colonization varied seasonally from 12% (3/25) to 38% (10/26). Cryptococcus neoformans var. gattii alone was cultured from 37, var. neoformans alone from 22 and both varieties from five nasal swabs. Of 33 koalas sampled on three or more occasions, organisms were isolated persistently from six, occasionally from eight and never from 19. Two koalas were persistently and heavily (>/=100 colonies/plate) colonized by C. neoformans var. gattii and two with var. neoformans. Isolation of C. neoformans var. gattii from the skin was low grade and sporadic. No koalas from which C. neoformans was persistently isolated showed clinical signs of cryptococcosis and all except one had a negative latex cryptococcal antigen test, therefore the nasal cavity was presumed to be colonized by, rather than infected with, C. neoformans. Preliminary observations of koalas from Coffs Harbour indicated a much higher prevalence of colonization by C. neoformans, suggesting that environmental factors influenced the extent of carriage by C. neoformans.

Animals↗
PubMed2001

Asymptomatic carriage of Klebsiella pneumoniae producing extended-spectrum beta-lactamase by patients in a neurological early rehabilitation unit: management of an outbreak.

During 11 months 58 extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-Kp) isolates were grown from 10 patients on a neurological early rehabilitation unit. The patients had no signs of infection but were colonized in the nose and trachea, and unusually only one had colonization in the gut. A single clone of ESBL-Kp was identified by pulse field gel electrophoresis. Strong hygienic precautions similar to those for Methicillin-resistant Staphylococcus aureus patients prevented spread of the bacteria to other wards. However, rehabilitation for patients with severe neurological failures made it very difficult to follow hygienic requirements. Disinfection of mucous membranes was difficult. Eventually the application of a nasal spray containing povidone-iodine proved to be successful.

Anti-Infective Agents, Local↗