Presence Of Bacteria In Blood Research Articles

Enterobacteriaceae and Enterococcaceae are the dominant bacterial families translocating to femur heads in broiler chicks

ABSTRACT As a result of rapid growth of broilers, bacterial chondronecrosis with osteomyelitis has emerged in the last decade, with bacterial translocation from the gut to internal organs, including the femur head. In this study, we isolated translocated bacteria in femur heads, blood, and liver, during ageing of broilers, and identified the bacteria using 16S rDNA sequencing. We also provided histopathological descriptions of femur head lesions. Bacteria were isolated from blood, liver, and femoral head samples. In the femoral heads, an age-related presence of bacteria was observed, with high prevalence at 2 days post-hatch, and no bacteria isolated from femoral heads of broilers older than 14 days. Bacterial identification using 16S rRNA gene sequencing demonstrated that bacteria present in blood, liver, and femur belonged to different taxonomic groups. Bacteria isolated from blood and liver samples belonged predominantly to the Enterobacteriaceae, Enterococcaceae, and Staphylococcaceae, while Escherichia/Shigella and Enterococcus spp. were the most prevalent taxa in femoral head samples. No bacteria were isolated from the femoral head of any of the birds with histopathological lesions. All 19-day-old and 22-day-old birds in this study showed cartilage retention in both legs, and had signs of separation between the articular cartilage and the growth cartilage in one or both legs. This study shows that young clinically healthy broilers have a higher prevalence of bacteria in the femoral head compared to older broilers and that presence of bacteria in blood and liver is common during ageing of broilers. RESEARCH HIGHLIGHTS Large number of bacteria isolated from femoral heads of clinically healthy broilers. The prevailing taxa in femoral heads were Escherichia/Shigella and Enterococcus spp. Continuous presence of bacteria in blood and liver of clinically healthy broilers. Enterobacteriaceae, Enterococcaceae, and Staphylococcaceae prevail in blood and liver.

Evaluation of combination therapies with colistin in an experimental mouse pneumonia model induced by carbapenem-resistant Acinetobacter baumannii strain.

The treatment options are limited in Acinetobacter baumannii infections. In this study, the effectiveness of colistin monotherapy and combinations of colistin with different antibiotics were investigated in an experimental pneumonia model induced by carbapenem-resistant A.baumannii strain. Mice in the study were divided into five groups as control (no treatment), colistin monotherapy, colistin + sulbactam, colistin + imipenem, and colistin + tigecycline combinations. The modified experimental surgical pneumonia model of Esposito and Pennington was applied to all groups. The presence of bacteria in blood and lung samples was investigated. Results were compared. In blood cultures, while there was no difference between the control and colistin groups, there was a statistical difference between the control and the combination groups (P = 0.029). When the groups were compared in terms of lung tissue culture positivity, there was a statistical difference between the control group and all treatment groups (colistin, colistin + sulbactam, colistin + imipenem, and colistin + tigecycline) (P = 0.026, P < 0.001, P < 0.001, and P = 0.002, respectively). The number of microorganisms that grew in the lung tissue was found to be statistically significantly lower in all treatment groups in comparison with the control group (P = 0.001). Both monotherapy and combination therapies of colistin were found to be effective in the treatment of carbapenem-resistant A.baumannii pneumonia, but the superiority of combination therapies over colistin monotherapy has not been demonstrated.

Bacterial DNAemia is associated with serum zonulin levels in older subjects

The increased presence of bacteria in blood is a plausible contributing factor in the development and progression of aging-associated diseases. In this context, we performed the quantification and the taxonomic profiling of the bacterial DNA in blood samples collected from forty-three older subjects enrolled in a nursing home. Quantitative PCR targeting the 16S rRNA gene revealed that all samples contained detectable amounts of bacterial DNA with a concentration that varied considerably between subjects. Correlation analyses revealed that the bacterial DNAemia (expressed as concentration of 16S rRNA gene copies in blood) significantly associated with the serum levels of zonulin, a marker of intestinal permeability. This result was confirmed by the analysis of a second set of blood samples collected from the same subjects. 16S rRNA gene profiling revealed that most of the bacterial DNA detected in blood was ascribable to the phylum Proteobacteria with a predominance of the genus Pseudomonas. Several control samples were also analyzed to assess the influence of contaminant bacterial DNA potentially originating from reagents and materials. The data reported here suggest that para-cellular permeability of epithelial (and, potentially, endothelial) cell layers may play an important role in bacterial migration into the bloodstream. Bacterial DNAemia is likely to impact on several aspects of host physiology and could underpin the development and prognosis of various diseases in older subjects.

MONOCYTE SUBSETS IN HEALTHY ADULTS AND SEPSIS PATIENTS

Monocytes play a key role in the development of immune response in bacterial infection, because of their phagocytic, antigen-presenting and secretory functions. There are three subpopulations of monocytes: “classical” CD14+CD16-, “intermediate” CD14+CD16+, and “nonclassical” CD14+dimCD16+. These monocyte subtypes have different phenotypes and functions. The ratio of appropriate subpopulations varies with development of the antibacterial response. The aim of the present research was to study phenotypes of the monocyte subpopulations in the patients with sepsis, and changes in the monocyte subpopulation ratio, depending on the presence of bacteria in circulating blood of the patients, as well as to estimate contribution of the monocyte subpopulations to the cytokine production. We observed 16 patients with sepsis (10 men and 6 women; mean age, 58±14 years, SOFA 9.4±2.1; a total of 44 blood samples) examined in dynamics. The control group included healthy adults (n = 23, 12 men and 11 women; mean age, 51±13 years). Laboratory studies included bacteriological cultures, determination of absolute and relative numbers of subpopulations of classical, intermediate and non-classical monocytes and their expression of HLA-DR and CD64, determination of IL-6, TNFα, IL-1β, IL-10 concentration in blood serum. Absolute number of monocytes was increased in the sepsis patients, the ratio of classical monocytes was also increased, like as relative and absolute numbers of intermediate cells. Meanwhile, the subpopulation of non-classical monocytes did not change significantly. The monocyte subpopulation ratio depended on the presence of bacteria in blood, i.e., a higher proportion of intermediate cells was observed in the samples positive for bacteria in blood cultures. The ratio of subpopulations was restored after elimination of bacteria from the circulation. The expression density of LPS receptor (CD14), IgG receptors (CD16 and CD64) was found to be increased, especially in the subpopulations of intermediate and nonclassical monocytes. In all subpopulations of monocytes, expression of HLA-DR is reduced, most notably in classical monocytes, least in intermediate cells. There was a significant increase in serum levels of IL-6, IL-1β, TNFα and IL-10 cytokines. Direct correlation between the absolute number of classical monocytes and IL-6 concentration was revealed, as well as intensity of multiple organ dysfunction. Increase in absolute amount of classical monocytes and IL-6 concentration might serve as an indirect criterion for evaluation of endothelial activation, an active producer of IL-6 and myeloid cell growth factors. A direct correlation between the percentage of CD14+CD16+ cells and IL-10 concentration in blood serum indicates to an important role of intermediate monocytes in IL-10 production. IL-10 suppresses the antigen-presenting function of intermediate cells, namely, expression of HLA-DR molecules, as suggested by inverse correlation between the IL-10 concentration and HLA-DR expression density on CD14+CD16+ cells. We have also determined an inverse correlation between the degree of multi-organ dysfunction and relative amount of HLA-DR+ monocytes. The larger was a classical monocyte subpopulation, the more noticeable was a decrease of this index. The studies in ratios of monocyte subpopulations help to understand the mechanisms of antibacterial protection in sepsis. Monitoring of classical monocyte numbers and serum concentrations of IL-6 is necessary for a comprehensive assessment of inflammatory response in sepsis. Determination of HLADR expression on monocytes allows us to evaluate the intensity of immune suppression in critically ill patients.

Post vaccination follow-up of Brucella melitensis in blood stream of sheep by PCR assay

Brucella melitensis is the causative agent of brucellosis in sheep and goats. While there is no treatment of choice for brucellosis, vaccination with Rev1 vaccine in sheep is the only effective procedure to reduce the incidence of brucellosis in many countries. As it has been shown earlier, in cases with brucellosis, the agent enters into the blood stream at first and then localises in the reticuloendothelial system and reproduction organs. For this reason, and in order to determine the duration of presence of bacteria in blood, this research was carried out on 15 female sheep 3 months of age. Ten sheep were vaccinated with Rev1 vaccine and five were used as control (unvaccinated) group. Polymerase chain reaction (PCR) was used for amplification of the 720-bp sequence of immunogenic outer membrane protein gene specific to B. melitensis. Blood samples were taken before the beginning of the experiment and on the first, 7th, 14th, 21st, 28th and 60th days after that. PCR results showed that all animals were negative before the beginning of experiment, but on the first, 7th, 14th, 21st, 28th and 60th days after that, a positive reaction was observed in 50%, 100%, 100%, 90%, 70% and 50% of vaccinated animals, respectively. Also, 40% of the control group showed positive results only on the 14th day after vaccination. Some serological tests such as Rose Bengal test (RBT), serum agglutination test (SAT) and 2-mercapto-ethanol (2ME) were performed on samples which showed that both vaccinated and unvaccinated animals had titres for Brucella antibody in their sera on the 7th day with relative frequency of 70 and 20%, respectively. These findings show that bacteraemia may occur on the first day and prolongs until the end of experimentation with maximum presence on the 7th and 14th days after vaccination. Conversely, this can explain the B. melitensis dissemination ability from vaccinated animals to healthy ones.

Presence of wild-type and attenuated Salmonella enterica strains in brain tissues following inoculation of mice by different routes.

Salmonella enterica serovar Typhi and Typhimurium vaccine candidates elicit significant immune responses in mice by intranasal (i.n.) immunization. Because of the proximity of the cribriform plate of the ethmoid bone, we were concerned that Salmonella bacteria delivered i.n. might access the brain. Accordingly, wild-type and attenuated (by single and double mutations) strains of S. enterica serovars Typhimurium and Typhi were recovered at low numbers initially from the olfactory lobe and then from the brain for 3 to 4 days after i.n. immunization. This was independent of invA gene function. Although the presence of bacteria in blood 1 to 3 h after i.n. inoculation was sometimes observed, this was infrequent compared to the frequency of bacteria detected in brain tissues. In confirmation of recent observations by Wickham et al. (M. E. Wickham, N. F. Brown, J. Provias, B. B. Finlay, and B. K. Coombes, BMC Infect. Dis. 7:65, 2007) that oral inoculation with wild-type S. enterica serovar Typhimurium strains lead to bacteria in blood with subsequent colonization of brain tissues with neurological symptoms of disease, we found similar results by using the i.n. and intraperitoneal (i.p.) routes of inoculation for wild-type but not for attenuated strains of S. enterica serovar Typhimurium. In contrast, a highly modified attenuated S. enterica serovar Typhimurium strain was not present in brain tissues when administered at higher doses by the oral, i.n., and i.p. routes than the wild-type strain even though the presence of bacteria in blood was detectable 1 to 3 h after inoculation by each of the three routes. Our results indicate that i.n. and possibly even oral delivery of live Salmonella vaccines may be unsafe although it is possible to reduce this risk by appropriate genetic modifications.

Inactivation of Gram‐negative and Gram‐positive bacteria in red cell concentrates using INACTINE PEN110 chemistry

The risk of transfusion-transmitted bacterial infections as a result of the presence of bacteria in blood is one of the major concerns in transfusion medicine. The purpose of this study was to investigate whether bacteria inoculated into red blood cell concentrates can be inactivated by the INACTINE PEN110 pathogen-reduction process. Four bacterial species were chosen for the study: anaerobic Gram-positive Clostridium perfringens and Propionibacterium acnes, known to be transfusion-transmitted; and two Gram-negative species, Acinetobacter johnsonii and Acinetobacter lwoffii, recently reported to be a common cause of transfusion-associated infections in Europe. Identical units of leucoreduced red cell concentrates were inoculated with A. johnsonii, A. lwoffii, C. perfringens, or P. acnes. The 4 degrees C control units were put on storage immediately after receiving the spike. The test units were subjected to PEN110 treatment and then stored. The bacterial titre in all units was monitored during a 6-week storage period. The PEN110 inactivation of all tested bacterial strains was time- and titre-dependent. For A. johnsonii and A. lwoffii, no viable bacteria were detected in the units spiked with up to 10(4) colony-forming units (CFU)/ml and treated with PEN110. For red cell units spiked with 10(4)-10(5) CFU/ml of C. perfringens and P. acnes, no viable bacteria were detected in the units treated with PEN110. In control units, there was a gradual decrease in A. johnsonii, A. lwoffii and C. perfringens titres during cold storage, while P. acnes titres remained stable. The PEN110 pathogen-reduction process was demonstrated to inactivate high titres of A. johnsonii, A. lwoffii, C. perfringens and P. acnes in red cell concentrates.

Detection and identification of bacterial DNA in patients with cirrhosis and culture-negative, nonneutrocytic ascites

The current pathogenic theory of spontaneous bacterial peritonitis (SBP) in patients with cirrhosis and ascites suggests that repeated episodes of bacterial translocation (BT) from intestinal lumen to mesenteric lymph nodes followed by systemic seeding are the key steps for the final development of infectious events. However, most of the episodes of systemic bacterial circulation remain undetected. Therefore, we investigated the hypothetical presence of bacteria in blood and/or ascitic fluid (AF) from patients with cirrhosis and sterile (culture negative) AF by means of bacterial DNA (bactDNA) detection and identification. Twenty-eight consecutively admitted patients with cirrhosis and presence of AF were included in the study. BactDNA was detected using a polymerase chain reaction (PCR)-based method. The corresponding bacteria were identified by nucleotide sequencing of purified PCR products. BactDNA was detected simultaneously in blood and AF in 9 patients (32.1%). DNA sequencing allowed the identification of Escherichia coli (n = 7) and Staphylococcus aureus (n = 2). In all cases, the similarity between the sequence found in AF and blood indicated that the bactDNA present in both locations originated from a single clone (single translocation event). Child-Pugh score and basic hemodynamic, clinical, endoscopic, and biochemical characteristics were similar among patients with or without the presence of bactDNA. In conclusion, we have detected bactDNA in serum and AF in 32% of all patients studied, and this likely represents single clone episodes of translocation and systemic seeding. E. coli is the most frequently identified bacteria. (H EPATOLOGY 2002;36:135-141.)