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The role of bacteria as a local defence mechanism in the ear, nose and throat.

The mucosae of the oro-nasopharynx in man are asymptomatically colonised by a commensal flora. This commensal flora consists largely of non-pathogenic bacteria but potentially pathogenic bacteria, such as S. pneumoniae, H. influenzae, M. catarrhalis can also be part of it. The commensal flora can be affected by host factors such as age or antibiotic usage but will in itself also affect its host. In addition to being a source of resistance genes it will also protect the host against exogenous, non-commensal pathogens. This protective effect is the result of three characteristics of the commensal flora. The commensal flora will hinder the establishment of new pathogens on the mucosa (termed colonisation resistance), it will especifically stimulate the immune system and it will induce formation of protective antibodies.

Bacteria, Aerobic↗

Secondary ocular bacterial infection in hypovitaminosis a xerophthalmia.

Extraocular bacterial culture was performed in 100 patients with hypovitaminosis A xerophthalmia. There was corneal ulceration in 29 cases and corneal perforation in 22 cases. Eighty-six percent of the patients harbored frankly pathogenic bacteria (46 patients) and potentially pathogenic bacteria (40 patients). All but two patients with either cornal ulceration or perforation harbored potentially pathogenic or frankly pathogenic bacteria. Pseudomonas aeruginosa, Diplococcus pneumoniae, and Moraxella species were isolated in 37% (19 patients) of cases with corneal ulceration and perforation. I cultured P. aeruginosa from 36% (eight patients) of cases with corneal perforation. The many ocular secondary bacterial infections in the early stages of xerophthalmia seem to suggest that bacterial action plays a major role in causing the corneal ulceration and perforation in hypovitaminosis A xerophthalmia.

Adolescent↗

Quantitative culture of bronchoalveolar lavage fluid in community-acquired lower respiratory tract infections.

To evaluate the diagnostic value of quantitative bacterial culture of bronchoalveolar lavage (BAL) fluid obtained by fibreoptic bronchoscopy, 67 consecutive immunocompetent adult patients admitted to hospital with community-acquired lower respiratory tract infections from September 1997 to May 1998 were investigated. Results were compared to the findings in eight healthy control persons investigated in February 1998. There was no difference between study patients and control persons when quantitative culture of total cumulative bacterial findings or bacteria categorized as members of the oropharyngeal normal flora were compared. The culture of normal flora in bronchial washings probably reflects contamination of the lower airways with secretions from upper arways by the fibreoptic procedure itself, as fractionated sampling showed a 10-fold reduct on in quantitative culture results when a primary bronchial washing was compared to a secondary sampling from the same bronchus in the control group. Twenty-four (36%) of 67 patients were cultured as positive in the study group while all control persons were cultured as negative for bacteria categorized as potential pathogens. With a threshold value for positive culture of 10(4) cfu ml(-1) the specificity of lavage culture of potential pathogenic bacteria in relation to actual lower airway infection was 100%. Therefore, quantitative bacterial culture of potential pathogenic bacteria in BAL fluid is very specific but only positive in about one-third of unselected immunocompetent adult patients with a lower respiratory tract infection.

Adult↗

Filamentous bacteria-induced sludge bulking can alter antibiotic resistance gene profiles and increase potential risks in wastewater treatment systems.

Sludge bulking caused by filamentous bacteria is a prevalent issue in wastewater treatment systems. While previous studies have primarily concentrated on controlling sludge bulking, the biological risks associated with it have been overlooked. This study demonstrates that excessive growth of filamentous bacteria during sludge bulking can significantly increase the abundance of antibiotic resistance genes (ARGs) in activated sludge. Through metagenomic analysis, we identified specific ARGs carried by filamentous bacteria, such as Sphaerotilus and Thiothrix, which are responsible for bulking. Additionally, by examining over 1,000 filamentous bacterial genomes, we discovered a diverse array of ARGs across different filamentous bacteria derived from wastewater treatment systems. Our findings indicate that 74.84% of the filamentous bacteria harbor at least one ARG, with the occurrence frequency of ARGs in these bacteria being approximately 1.5 times higher than that in the overall bacterial population in activated sludge. Furthermore, genomic and metagenomic analyses have shown that the ARGs in filamentous bacteria are closely linked to mobile genetic elements and are frequently found in potentially pathogenic bacteria, highlighting potential risks posed by these filamentous bacteria. These insights enhance our understanding of ARGs in activated sludge and underscore the importance of risk management in wastewater treatment systems.

Sewage↗

Importance of hand germ contamination in health-care workers as possible carriers of nosocomial infections.

The importance of hands in the transmission of nosocomial infection has been world wide admitted. However, it is difficult to induce this behavior in health-care workers. The aim of the present work was to point out the importance of hand bacteria colonization, the influence of hand washing and of patient physical examination. One hundred health-care workers were randomly divided in two groups: Group A without hand washing previous to patient physical examination or handling (PPE); group B with hand washing previous to PPE. Direct fingerprint samples in Columbia agar before and after PPE were obtained. The colonies were counted and identified by conventional techniques, and antibiograms according to NCCLS were performed. Before PPE group A participants showed a high number of bacteria regarding group B participants (73.9 Vs 20.7; p < 0.001); 44 out of 50 participants were carriers of potentially pathogen bacteria. No group B participants were carriers of potential pathogen bacteria before PPE. The latter group showed an increase in number of bacteria after PPE (20.7 CFU (before) Vs 115.9 CFU (after); p < 0.001). Sixteen group B participants were contaminated after PPE with potential pathogens such as S. aureus (50% of them methicillin resistant); Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis, half of them multiresistant. We can conclude on the importance of these results to implement educational programs and to provide the health-care workers with the proper commodities to fulfill this practice.

Colony Count, Microbial↗

Is breast milk collected at home suitable for raw consumption by neonates in Brazilian public neonatal intensive care units?

This study was designed to verify if breast milk collected at home is appropriate for raw consumption by neonates in a Brazilian public neonatal intensive care unit (NICU). From May 1998 to February 2000, microbiological characteristics of breast milk samples collected at home were analyzed. The milk samples were considered appropriate for raw consumption if mesophilic bacteria count was < 2500 CFU/mL and potential pathogens were not detected. Of 90 milk samples collected from 32 mothers of hospitalized neonates, 36 (40%) were rejected because of potentially pathogenic bacteria (72.2%), mesophilic bacteria count > or = 2500 CFU/mL (13.9%), and both conditions (13.9%). The most frequent nonpathogenic and potentially pathogenic bacteria isolated were Staphylococcus coagulase negative and Klebsiella pneumoniae, respectively. Using univariate analysis, demographic, socioeconomic, educational, and house characteristics were not found to be associated with milk contamination. Breast milk collected at home may not be appropriate for raw consumption in Brazilian NICUs. Pasteurization could improve its microbiological quality. Further studies are needed.

Adolescent↗

Nasopharyngeal bacteria found on blood agar plates from healthy children in Greenland.

We have systematically studied the aerobic nasopharyngeal bacteria isolated from swabs by unselective subculturing on 5% horse blood agar and chocolate agar in 70 healthy children aged 0-1, 3-5 and 8 years in Nuuk and Sisimiut, Greenland. The purpose was to provide a basis for a better understanding of the infectious pathology and blind antibiotic treatment against potential pathogens thereby improving standard antimicrobial treatment of upper respiratory tract infections (URTI) and otitis media (OM) among children in Greenland. The study serves also as a baseline for future microbiological and immunological research projects. The children were clinically examined for any infectious diseases and a medical history was obtained which allowed for selection of children without a history of severe clinical infection. Nasopharyngeal swabs obtained via the oral route were instantly spread on 5% blood agar and chocolate agar culture plates and incubated aerobically. Subsequently, potentially pathogenic as well as non-pathogenic bacteria were identified by conventional methods. Healthy children in Greenland carry grossly the same aerobic bacterial flora as children in other parts of the world but potentially pathogenic bacteria were found in very high frequency (94%). Staphylococcus aureus, Streptococcus pneumoniae and Moraxella catarrhalis were found in higher frequencies in the youngest children. Haemophilus influenzae non-b was found in high frequencies in all age groups (67-76%). H. influenzae type b was carried by 11.4%. Group A streptococci were found more frequently in older children and in children from Sisimiut. Of M. catarrhalis strains 88% produced beta-lactamase. Neisseria meningitidis, Mycoplasma pneumoniae and chlamydiae were not detected at all. The high carrier frequency of potentially pathogenic bacteria in healthy children in Greenland may be related to the high frequency of URTI's and episodes of OM among children in Greenland.

Bacteria, Aerobic↗

The intestinal bacterial colonisation in preterm infants: a review of the literature.

The aim of this study is to review the normal development of the intestinal microflora of preterm infants and the factors influencing its development. Preterm infants have an increased intestinal permeability, which may lead to bacterial translocation to systemic organs and tissues. In combination with immaturity of the immune system the risk to systemic infections might be increased. Especially potential pathogenic bacteria are able to translocate. The intestinal microflora of breast-fed term infants, dominated by bifidobacteria and lactobacilli, is thought to suppress the growth of potentially pathogenic bacteria. Many attemps have been made to stimulate the presence of bifidobacteria and lactobacilli with changes in the diet and ingredients-like prebiotics and probiotics. After selection, six studies were included reviewing the intestinal bacterial colonisation of preterm infants. In general, these studies show that the intestinal bacterial colonisation with beneficial bacteria is delayed in preterm infants. The number of potentially pathogenic bacteria is high. Antibiotics influence the intestinal colonisation. Many preterm infants receive prophylactic antibiotics at birth. As antibiotics delay the normal intestinal colonisation, caution should be given to the treatment with broadspectrum antibiotics in preterm infants at birth and every attempt has to be made to restrict the period of treatment.

Anti-Bacterial Agents↗

Colonization resistance of the digestive tract--mechanism and clinical consequences.

Potentially pathogenic bacteria and yeasts meet a number of resistance factors. These colonization resistance (CR) determining factors control the growth density of potentially pathogenic microorganisms in the various parts of the alimentary canal. The CR of the digestive tract is to be seen partially of host origin but to a greater extent due to direct and indirect activity of the (anaerobic) indigenous microflora. This implies that the CR mechanism is vulnerable to antibiotics which affect the indigenous flora during treatment. A decreased CR enhances colonization by microorganisms that are resistant to the antibiotic(s) used for therapy. Increased population densities of potentially pathogenic bacteria ("overgrowth") may correlate with invasion of the mucosal tissues often followed by translocation to remote lymphatic organs. Overgrowth also may correlate with development or acquisition of resistance to the antibiotic applied. By screening in experimental animals antibiotics have been selected which do not affect the CR. Such antimicrobial drugs have successfully been used to selectively eliminate potentially pathogenic bacteria and yeast in neutropenic patients.

Animals↗

Rare occurrence of heterotrophic bacteria with pathogenic potential in potable water.

Since the discovery of Legionella pneumophila, an opportunistic pathogen that is indigenous to water, microbiologists have speculated that there may be other opportunistic pathogens among the numerous heterotrophic bacteria found in potable water. The US Environmental Protection Agency (USEPA) developed a series of rapid in vitro assays to assess the virulence potential of large numbers of bacteria from potable water to possibly identify currently unknown pathogens. Results of surveys of potable water from several distribution systems using these tests showed that only 50 of the approximately 10,000 bacterial colonies expressed one or more virulence characteristics. In another study, 45 potable water isolates that expressed multiple virulence factors were tested for pathogenicity in immunocompromised mice. None of the isolates infected mice that were compromised either by treatment with carrageenan (CG), to induce susceptibility to facultative intracellular pathogens, or by cyclophosphamide (CY), to induce susceptibility to extracellular pathogens. These results indicate that there are very few potential pathogens in potable water and that the currently developed in vitro virulence screening tests give an overestimation of the numbers of heterotrophic bacteria that may be pathogens. Current efforts are focused on using the animal models to screen concentrated samples of waters known to contain large numbers of heterotrophic bacteria and newly discovered Legionella-like organisms that parasitize amoebae.

Animals↗

Unveiling microbial risks in Chinese household dust: a comprehensive analysis from absolute abundance to virulence unit.

BACKGROUND: People spend the majority of their lives indoors, yet the risk and virulence potential of household microbiota remain largely unexplored, particularly in developing countries. RESULTS: Here, we conducted a nationwide survey on both dust samples and health information across 118 Chinese households. The microbiota composition and its functional units were analyzed using absolute 16S rRNA/ITS sequencing, metagenomics, and metaproteomics. Cross-domain network analysis of the core microbial communities revealed robust co-occurrence patterns in household dust. The mean absolute abundance of potentially pathogenic bacteria and fungi in households was 2.39&#x2009;&#xd7;&#x2009;105 and 2.83&#x2009;&#xd7;&#x2009;106 DNA copies/g dust. The potentially pathogenic community was primarily influenced by latitude, relative humidity, and average temperature. Although total absolute abundance was substantially lower in urban areas, the relative abundance of potentially pathogenic bacteria was markedly higher compared to rural environments. While urban-rural differences existed, the underlying statistical drivers were the environmental variables. The absolute abundance of potential pathogens was significantly associated with the prevalence of rhinitis, wheeze, and dermatitis in 266 participants. Children were identified as the highest-risk group from inhalation exposure of average daily dose. A total of 170 bacterial, 223 fungal virulence factors (VFs), and 370 antibiotic resistance genes (ARGs) were detected in dust and dust extracellular vesicle (EV)-associated DNA. EV-associated cargoes contributed 47.13% to the bacterial VF profiles, 11.90% to fungal VF&#xa0;profiles, and 44.45% to ARG profiles. Metaproteomic analysis confirmed the presence of VF profiles in dust EVs, which was further verified by curated proteomics data from 35 household pathogens. CONCLUSIONS: This study provides a comprehensive, quantitative framework linking indoor microbial exposure to health risks, highlighting EVs as a non-negligible, novel, extracellular mechanistic pathway for health impact in household environments. Video Abstract.

Child↗

Isolation of pathogenic bacteria from the nasopharynx of children with respiratory syncytial virus infection. Predictive value of chest roentgen examination and laboratory tests.

Potentially pathogenic bacteria were isolated from the nasopharynx in 33/66 hospitalized infants and children with verified respiratory syncytial virus (RSV) infection. The value of chest roentgenograms and blood counts for the prediction of concomitant bacterial infection was evaluated. Abnormal chest roentgenograms were found in 89% whether pathogenic bacteria were present or not. The most common finding was general hyperinflation of the lungs, with or without infiltrates. This occurred more frequently in the group with isolated RSV infection. Fever, leucocytosis and an elevated ESR were found during the illness in more than half the cases. These findings were more frequent in children who harboured potential pathogenic bacteria, though the difference was not significant. For optimal evaluation of a case all available information about it should be taken into consideration.

Bacterial Infections↗

[Itching in the external ear--a side effect of ear plugs].

The object of this investigation was to assess the frequency of itching in the external auditory meatus in individuals who use hearing aid ear plugs (OP) and, simultaneously, to assess the cause of the itching. Seventy-six of the patients examined consecutively in the audiological department (ages 34-89 years) were questioned about itching and were submitted to an objective ear, nose and throat examination, audiometry and culturing from the external meatus for bacterial and fungal growth. In 20 patients, patch tests were made for allergic reactions from which the ear plugs were made (heat polymerized methyl methacrylate). None of the 20 patients had become sensitized. Itching in the external auditory meatus was found to be a side effect of employment of ear plugs with an incidence of 39% as opposed to only seven in ears without ear plugs (p less than 0.05). The incidence of itching was not reduced in ears with a ventilation channel in the ear plug. In 38% of the itching ears no objective changes were observed and, in the remaining cases, the changes were frequently limited. Potentially pathological bacterial growth was found to be significantly more in ears with ear plugs (1- greater than 16%, p less than 0.05) and in itching ears (4- greater than 24%, p less than 0.05). In ears with potentially pathogenic bacteria, objective changes were nearly always found. In the vast majority of cases, the potentially pathogenic bacteria were Gram-negative, corresponding to the findings in external otitis in the tropics and mixed infections with fungi were frequently present.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Spiramycin fermentation residue-derived biochar regulates soil nutrient cycling, microbial communities, and antibiotic resistance gene dynamics.

Spiramycin fermentation residues (SFR) are hazardous wastes enriched with residual antibiotics, yet they can serve as potential feedstocks for resource recovery after appropriate treatment. In this study, SFR-derived biochar (SFR-BC) was produced by pyrolysis and applied to agricultural soil to evaluate its effects on soil properties, microbial communities, potential pathogenic bacteria, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs). A 60-day soil incubation experiment was conducted with one control and three SFR-BC application rates of 0.5%, 1.0%, and 2.0%. SFR-BC improved soil physicochemical properties, nutrient status, enzyme activities, and microbial alpha diversity. Metagenomic analysis showed that SFR-BC altered the abundance of functional genes associated with carbon and nitrogen cycling, indicating shifts in microbial functional potential. SFR-BC also changed bacterial co-occurrence patterns, with the high-dose treatment showing a more complex and highly connected network structure during incubation. In addition, high-dose SFR-BC reduced several potential pathogenic bacteria, including major plant pathogenic taxa. SFR-BC decreased soil ARG abundance by 9.38%-33.67% and MGE abundance by 6.49%-27.89% relative to the control, showing a dose-dependent reduction in antibiotic resistance-related genetic elements. Network and PLS-PM analyses further indicated that ARG variation was statistically associated with soil physicochemical properties, microbial diversity, potential bacterial hosts, and MGEs. Overall, these results suggest that SFR-BC can improve short-term soil nutrient status and reduce ARGs, MGEs, and several potential pathogenic taxa under controlled incubation conditions, providing useful evidence for the potential valorization of antibiotic fermentation residues through pyrolysis.

Charcoal↗

Isolation of gram-negative bacteria from cockroaches trapped from urban environment.

Three different areas--hospital, food-handling establishments and human dwellings, were surveyed for pathogenic gram-negative bacteria carried on the cuticles of cockroaches. Fifty species of bacteria were identified from all cockroaches. Escherichia coli, Klebsiella pneumoniae, Citrobacter freundii and Enterobacter cloacae were the most frequently found. Pathogenic and potentially pathogenic bacteria represented 58% of all bacteria identified. The numbers of pathogenic and potentially pathogenic bacteria were similar in hospital areas and food-handling establishments, while, human dwellings possessed a poorer bacterial flora. E. coli, K. pneumoniae and E. cloacae were dominant species in hospital areas, while in food-handling establishments and human dwellings, E. coli, K. pneumoniae and C. freundii predominated. Therefore, cockroaches can play a role in bacterial transmission, due to the bacteria carried on their cuticles.

Animals↗