Different characteristics of bloodstream infection during venoarterial and venovenous extracorporeal membrane oxygenation in adult patients.

Currently, there is scarcity of data on whether differences exist in clinical characteristics and outcomes of bloodstream infection (BSI) between venoarterial (VA) and venovenous (VV) extracorporeal membrane oxygenation (ECMO) and whether they differ between Candida BSI and bacteremia in adult ECMO patients. We retrospectively reviewed data of patients who required ECMO for > 48 h and had BSIs while receiving ECMO between January 2015 and June 2020. Cases with a positive blood culture result within 24 h of ECMO implantation were excluded. We identified 94 (from 64 of 194 patients) and 38 (from 17 of 56 patients) BSI episodes under VA and VV ECMO, respectively. Fifty nine BSIs of VA ECMO (59/94, 62.8%) occurred in the first 2 weeks after ECMO implantation, whereas 24 BSIs of VV ECMO (24/38, 63.2%) occurred after 3 weeks of ECMO implantation. Gram-negative bacteremia (39/59, 66.1%) and gram-positive bacteremia (10/24, 41.7%) were the most commonly identified BSI types in the first 2 weeks after VA ECMO implantation and after 3 weeks of VV implantation, respectively. Timing of Candida BSI was early (6/11, 54.5% during the first 2 weeks) in VA ECMO and late (6/9, 66.7% after 3 weeks of initiation) in VV ECMO. Compared with bacteremia, Candida BSI showed no differences in clinical characteristics and outcomes during VA and VV ECMO, except the significant association with prior exposure to carbapenem in VA ECMO (vs. gram-negative bacteremia [P = 0.006], vs. gram-positive bacteremia [P = 0.03]). Our results suggest that ECMO modes may affect BSI clinical features and timing. In particular, Candida BSI occurrence during the early course of VA ECMO is not uncommon, especially in patients with prior carbapenem exposure; however, it usually occurs during the prolonged course of VV ECMO. Consequently, routine blood culture surveillance and empiric antifungal therapy might be warranted in targeted populations of adult ECMO patients, regardless of levels of inflammatory markers and severity scores.

Oral-bacterial-induced arterial and venous thrombus in rats: Pathological and immunological studies.

Objectives: Our study investigated the pathological outcome of experimental thrombi that incorporate oral bacteria. Material and methods: A small artery and vein in the rats' groins were injected with a solution containing periodontal bacteria Porphyromonas gingivalis and followed up for 28 days. In all, 18 limbs of nine male rats (500-650 g) were used for the arterial study, and eight limbs of four rats were used for the veins. Two densities of the bacterial solution and two arterial thicknesses sizes were used in the arterial study. Both proximal and distal arteries and veins were ligated loosely using a monofilament nylon suture before bacterial suspensions or control solutions were injected into the ligated vessels. Results: After 7, 14-18, and 28 days, the rats were sacrificed. Pathology and immunohistochemistry were performed. All specimens exhibited thrombus formation and an acute inflammation reaction with granulocytes at 7 days and then settled down to chronic fibrous change with plasma cells or macrophages at 28 days in the arterial thrombus. CD3 (Pan T-cells), CD79a (Pan B cells in the rats), and IgG were observed in the process of the healing of the arterial thrombus. Venous changes showed relatively clear recanalization that appeared at 7 days, which is slightly different from the artery. Granulocytes were present from 7 to 28 days. Conclusions: Periodontal bacteria act as an inflammatory core in the vessels, but not as an infectious agent, in our experiments, because of their low ability to invade tissues.

Systematic Review and Meta-Analysis on the Management of Open Abdominal Aortic Graft Infections.

OBJECTIVE: Aortic graft infection (AGI) is a disastrous complication with an incidence of 0.2-6% in operated patients. With little or no high quality evidence, the best treatment option remains unclear. Therefore, the literature on the management of open abdominal AGI was systematically reviewed to determine optimal treatment. METHODS: In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic review and meta-analysis was conducted for AGI. MEDLINE, Embase, and the Cochrane Database of Systematic Reviews were searched. Methodological quality was assessed using the Methodological Index for Non-randomised Studies (MINORS) score. Primary outcomes were 30 day mortality and one year survival. Secondary outcomes were survival, infection recurrence, limb salvage, and graft patency. RESULTS: Of 1574 studies identified, 32 papers were included in the study. The overall quality of the studies was moderate, with an average MINORS score of 11.9. Pooled overall 30 day mortality and one year survival were 13.5% (95% CI 10.5-16.4) and 73.6% (95% CI 68.8-78.4), respectively. The lowest 30 day mortality and highest one year survival were found for in situ repair compared with extra-anatomic repair and for prosthetic grafts compared with venous grafts or arterial allografts. The infection recurrence rate was highest for prosthetic grafts. CONCLUSIONS: There is a lack of well designed, qualitative comparative studies making conclusive recommendations impossible. The current best available data suggests that partial graft removal should be avoided and the lowest 30 day mortality and best one year survival are achieved with in situ repair using prosthetic grafts. Initiatives such as the MAGIC database to collaboratively collect prospective data are an important step forward in obtaining more solid answers on this topic.

Bacterial signatures in thrombus aspirates of patients with lower limb arterial and venous thrombosis.

OBJECTIVE: Increasing data supports the role of bacterial inflammation in adverse events of cardiovascular and cerebrovascular diseases. In our previous research, DNA of bacterial species found in coronary artery thrombus aspirates and ruptured cerebral aneurysms were mostly of endodontic and periodontal origin, where Streptococcus mitis group DNA was the most common. We hypothesized that the genomes of S mitis group could be identified in thrombus aspirates of patients with lower limb arterial and deep venous thrombosis. METHODS: Thrombus aspirates and control blood samples taken from 42 patients with acute or acute-on-chronic lower limb ischemia (Rutherford I-IIb) owing to arterial or graft thrombosis (n = 31) or lower limb deep venous thrombosis (n = 11) were examined using a quantitative real-time polymerase chain reaction to detect all possible bacterial DNA and DNA of S mitis group in particular. The samples were considered positive, if the amount of bacterial DNA in the thrombus aspirates was 2-fold or greater in comparison with control blood samples. RESULTS: In the positive samples the mean difference for the total bacterial DNA was 12.1-fold (median, 7.1), whereas the differences for S mitis group DNA were a mean of 29.1 and a median of 5.2-fold. Of the arterial thrombus aspirates, 57.9% were positive for bacterial DNA, whereas bacterial genomes were found in 75% of bypass graft thrombosis with 77.8% of the prosthetic grafts being positive. Of the deep vein thrombus aspirates, 45.5% contained bacterial genomes. Most (80%) of bacterial DNA-positive cases contained DNA from the S mitis group. Previous arterial interventions were significantly associated with the occurrence of S mitis group DNA (P = .049, Fisher's exact test). CONCLUSIONS: This is the first study to report the presence of bacterial DNA, predominantly of S mitis group origin, in the thrombus aspirates of surgical patients with lower limb arterial and deep venous thrombosis, suggesting their possible role in the pathogenesis of thrombotic events. Additional studies will, however, be needed to reach a final conclusion.

Evaluating Approaches for the Diagnosis of Hemodialysis Catheter-Related Bloodstream Infections.

BACKGROUND AND OBJECTIVES: Guideline-recommended diagnostic criteria for hemodialysis (HD) catheter-related bloodstream infections (CRBSIs) are based on data from indwelling central catheters in patients not on HD and non-HD situations, and upon which peripheral vein cultures are the gold standard. We aimed to examine the validity of these criteria in patients on HD. DESIGN, SETTINGS, PARTICIPANTS, & MEASUREMENTS: Adult patients on in-center HD using catheters were prospectively followed from 2011 to 2014 at a large academic-based HD facility (Toronto, Canada). When a CRBSI was suspected, blood culture sets were obtained from four sites (peripheral vein, both catheter hubs, and HD circuit) to determine the guideline-recommended differential time to positivity (DTTP). DTTP criteria were met when catheter hub cultures turned positive ≥120 minutes before peripheral vein cultures. The sensitivity, specificity, and accuracy were first calculated using peripheral vein cultures as the gold standard and then these same calculations were repeated with additional information, including exit site/catheter tip and HD circuit cultures, as the true gold standard. The feasibility of obtaining peripheral vein cultures was determined. RESULTS: Of 178 suspected CRBSIs, 100 had peripheral vein blood cultures. Using the true gold standard, sensitivity, specificity, and accuracy of blood culture results were highest in samples from the HD circuit (93.5%, 100%, and 95%, respectively). The guideline recommended combination of peripheral vein and arterial hub blood cultures was the least sensitive, specific, and accurate (91.7%, 93.1%, and 92.7%, respectively). The diagnostic criteria using measured DTTP were met in less than one third of events. CONCLUSIONS: In patients on HD, blood culture results are the most sensitive, specific, and accurate for diagnosing CRBSIs when taken from the HD circuit and the venous catheter hub, and blood culture results are the least sensitive, specific, and accurate in any combination with peripheral vein cultures. The DTTP does not increase diagnostic accuracy, reducing the necessity for venipuncture and its potential vein damage. Future guidelines should consider the applicability of criterion on specific patient populations and tailor them accordingly.

[Indwelling position and bacterial colonization of peripheral venous indwelling needles in patients with cardiovascular diseases].

OBJECTIVE: To study the characteristics of infections associated with peripheral venous indwelling needles and to explore the best indwelling position in patients with cardiovascular diseases from the perspective of bacteriology. METHODS: A total of 240 hospitalized patients from the Department of Cardiovascular Diseases, Xiangya Hospital, Central South University between November 2009 to July 2010 were randomly selected, and were divided into 3 groups according to the indwelling position and the indwelling time: a back of hand group (n=80), a forearm group (n=80) and a foot group (n=80). The above 3 groups were also divided into 4 subgroups according to the indwelling time (T1: 48 h ≤ t < 72 h; T2: 72 h ≤ t ≤ 96 h; T3: 96 h < t ≤ 120 h; and T4: 120 h < t ≤ 168 h) (20 patients in each subgroup). The bacteria of samples from puncture position of the skin were respectively cultured and identified after skin disinfection, needle pulling out and sample puncture from the indwelling needle catheters, respectively. RESULTS: 1) After the skin disinfection, there was no bacterium in the skin samples of puncture position. 2) When the needles were pulled out, there was bacterial growth in the skin samples of puncture position in 41 patients in the 3 groups, and the bacterium was not detected in samples of the 3 groups at T1 and T2 period. There was no significant difference in the positive rate of bacterial culture in the 3 groups at T3 and T4 period (P<0.05). 3) When the needles were pulled out. There was bacterial growth in the samples of indwelling needle catheters in 10 patients in the 3 groups; no bacterium was detected in the back of hand group and the forearm group at T1, T2, T3 and T4 period. In the foot group, there was no bacterium growth in the samples of indwelling needle catheters at T1 and T2 period, but there was bacterial growth in 4 patients at T3 period and in 6 patients at T4 period. There was significant difference in the positive rate of bacterial culture in the samples of indwelling needle catheters in the 3 groups (P<0.05). CONCLUSION: The best indwelling position for peripheral venous indwelling needles is the forearm in patients with cardiovascular diseases.

Does a species of Rickettsia play a role in the pathophysiology of Buerger's disease?

Rickettsia is an intracellular pathogen that attaches to vascular endothelial cell membranes and its genome integrates into the DNA of the host and thereby inhibits apoptosis of the endothelial cells. Rickettsia can infect the body following a flea/louse bite. Rickettsia was suggested as one etiology of Buerger's disease long ago. We report a patient with Buerger's disease for whom a left below-knee amputation was done. Twenty-five biopsies for DNA extraction were obtained from the arteries, veins and microvasculature of the amputated limb. Three samples were positive for Rickettsia. The finding may explain the proliferation of endothelial cells in the pathology of Buerger's disease, segmental nature of the disease, involving small- and medium-sized vessels, and the prevalence of Buerger's disease among the low socioeconomic class of the society. Understanding the infectious etiology of Buerger's disease would be invaluable, since early antibiotic therapy or even vaccination might have prevented the limb loss in the current and other cases of Buerger's disease. The authors suggest that paraffin blocks of Buerger's disease biopsies be investigated for Rickettsia infection, focusing specifically on the area of endothelial cell proliferation for DNA extraction. These results should be compared with other biopsies from a variety of other peripheral vascular diseases.

[Formation of bacterial biofilm on deep vein catheters in burn patients and its significance].

OBJECTIVE: To observe the biofilm (BF) formation of Staphylococcus aureus (SA), Acinetobacter baumannii (AB) and Pseudomonas aeruginosa (PA) on the surface of deep vein catheters in burn patients after infection. METHODS: The bacteria from deep vein catheters in 20 patients hospitalized from November 2008 to August 2009 were isolated, and were compared with their respective standard stains. Catheters tips were examined with scanning electron microscope (SEM). The semi-quantitative adhesion assay of bacterial BF was performed with modified microtiter-plate test, and the thickness of BF was scanned and measured by confocal laser scanning microscopy (CLSM) after double fluorescence staining, after being cultured in vitro for 12, 24, 48, 72 hours and 5 days, respectively. Data were processed with grouped t test. RESULTS: Six strains of SA, 8 strains of AB, and 6 strains of PA, all drug resistant, were isolated from the deep vein catheters. SEM showed that the BF structures on the inner surfaces of catheters were in diverse in their shape and degree, characterized by adherence and flake formation, and embedded in polysaccharide matrix. BF gathered in clusters, forming three-dimensional structure, in which small amount of red blood cells were found. A small number of bacteria were incompletely embedded, with some bacteria adhered to them. The absorbance values for SA after 24, 48 and 72 hours of culture (PCH) were above the cut-off value, the same for AB at PCH 12, 24, 48 and 72, and PA after PCH 48. Except for PA standard strain, CLSM showed scattered green fluorescence, mainly close to the bottom of plate, while the red fluorescence was observed in full scope at PCH 24 for each strain. At PCH 48 green fluorescence increased obviously and extended upward from the bottom, overlapping partly with red fluorescence, forming yellow fluorescence, and among the bacteria it was most obvious in AB culture, with SA the next. Compared with those of the standard stains, the intensity and quantity of fluorescence from the clinical strains were stronger; at PCH 72 the green fluorescence increased obviously especially for PA and its standard strain, while the yellow fluorescence was full of the scope for other strains. On in vitro culture day 5, the green fluorescence was dispersed and was obvious on the bottom of the plate. BF mature time for AB and SA was PCH 48, and for PA was PCH 72. The BF thickness of AB was (18.2 +/- 3.6) microm at PCH 72, which was thicker than that [(9.4 +/- 2.6) microm] of its standard strain (t = 5.42, P < 0.05), and was also the thickest among the three clinically found strains. CONCLUSIONS: SA, AB and PA, which are commonly found bacteria in burn patients, can form BF in deep vein catheters. Their ability to form BF seems to be stronger than other usually pathogenic strains, especially AB, which is the important pathogen leading to catheter related infection.

Accelerated immunopathological response of mice infected with Mycobacterium tuberculosis disrupted in the mce1 operon negative transcriptional regulator.

Mycobacterium tuberculosis causes a variety of clinical outcomes determined by host as well as bacterial factors. M. tuberculosis disrupted in the mce1 operon causes increased mortality in immunocompetent mice. This operon is negatively regulated by mce1R (Rv0165c). We studied the role of mce1R in infection outcome in mice. At 5 x 10(4) tail vein infectious dose, the median survival time (MST) of mice infected with the mce1R mutant M. tuberculosis H37Rv was 293 days, while mice infected with the wild-type H37Rv survived more than 350 days (P < 0.0001). At a higher dose (5 x 10(6)), the MST of mutant-infected mice was 32 days, compared with 127 days for wild type-infected mice (P < 0.0001). With either tail vein or aerosol infection, mutant-infected mice developed larger granulomatous lesions in their lungs than mice infected with the wild type. Mutant-infected mice were unable to control the bacterial burden in the first 4 weeks of infection, but even after achieving control later, these mice succumbed to granulomatous pneumonia. These observations suggest that the early deregulated expression of the mce1 operon products determines later granulomatous tissue response. mce1 operon may homeostatically regulate the cell wall architecture in vivo that elicits a steady-state granuloma tissue response permitting M. tuberculosis to establish a long-term infection.

Evidence of Rickettsia spp. infection in Sweden: a clinical, ultrastructural and serological study.

Sweden is an area potentially endemic for spotted fever rickettsioses. Rickettsia helvetica has been isolated from its tick vector Ixodes ricinus, and in a handful of cases linked to human disease. This study demonstrates for the first time in Sweden the transmission of rickettsial infection after a tick bite and the attack rate in an endemic area. We present three cases of documented rickettsial infection and a prospective serological study of Swedish recruits who were trained in the area where the patients lived and showed seroconversion to spotted fever rickettsiae. All patients showed a four-fold increase in antibody titer to the spotted fever rickettsia, R. helvetica, and immunohistochemical examination revealed rickettsia-like organisms in the walls of skin capillaries and veins. Electron microscopy showed organisms resembling R. helvetica and immunogold labeling with two anti-rickettsial antibodies demonstrated specific labeling of the rickettsial organisms in the skin biopsy specimens. Eight of the thirty-five recruits showed a four-fold increase in IgG titer reflecting a high rate of exposure. The results of this study demonstrate that spotted fever rickettsioses should be taken into consideration in the diagnosis of tick-transmitted infections in Sweden.

The relationship between the thrombotic and infectious complications of central venous catheters.

OBJECTIVES: To assess the frequency of thrombotic and infectious complications of long-term use of vascular catheters in cancer patients and to determine whether the two types of complication are related. DESIGN: Case series. SETTING: A 500-bed tertiary cancer center. PATIENTS: Seventy-two cancer patients. INTERVENTIONS: During a 16-month period, postmortem examinations of catheterized veins and contralateral uncatheterized veins were done on all patients with indwelling central venous catheters who met study criteria. MAIN OUTCOME MEASURES: Catheter-related septicemia determined by clinical and microbiological data as well as postmortem pathology; venous pathological changes such as mural hemorrhage, thrombosis, calcification, ulceration, and inflammation. RESULTS: Premortem clinical and microbiological data were obtained retrospectively on all patients. Pathological changes were noted in 35 catheterized veins (49%) compared with five contralateral control veins (9.2%) (P < .001). Mural thrombi were noted in 27 catheterized veins (38%) compared with only one contralateral control vein (1.4%) (P < .001). Other pathological changes consisted of four central venous catheter-related mural thrombi (5.6%) in the right atrium and four instances (5.6%) of nonbacterial thrombotic endocarditis, three involving the tricuspid and one the mitral valves. Seven patients had catheter-related septicemia. Of the 31 patients with mural thrombosis of the catheterized vein or right atrium, seven developed catheter-related septicemia, whereas none of the 41 patients with normal catheterized veins and atria developed catheter-related septicemia (P < .01). CONCLUSIONS: Thrombotic complications are common in catheterized veins and are often associated with catheter sepsis.

[Pathomorphologic features in several phlebopathies associated with virus, rickettsia, chlamydia, and mycoplasma infections]. / Aspects pathomorphologiques dans quelques phlébopathies associées à des infections chroniques à virus, à rickettsies, à chlamydies et à mycoplasmes.

Seventy-six venous specimens were examined by indirect immunofluorescence and histological techniques. 80.26% out of them gave negative I.F. reactions. The following causal agents were found on the I.F. positive preparations: Rickettsia burneti, Chlamydia, Mycoplasma, parainfluenza type 3 and adenoviruses, alone or associated. The most frequent lesion noted in I.F. positive specimens was of the inflammatory-dystrophic type. In I.F. negative preparations the dominant lesion was the hyalinosis of the tunica media.

Spiral modiolar vein: its importance in viral load of the inner ear.

Guinea pig-specific cytomegalovirus and Sendai virus were inoculated into the cochleas of seronegative guinea pigs to study the route of entry of cells participating in inner ear inflammation. Inflammatory cells accumulated around the spiral modiolar vein and appeared to be streaming from this vein into the scala tympani via a collecting venule. Inactivated virus inoculated into the cochlea and normal control cochlea failed to show inflammatory cell infiltrates. The spiral modiolar vein appears to play an important role in the movement of cells from the systemic circulation into the inner ear as part of the host's normal defense against invading pathogens such as viruses.

Ultrastructure of leprous phlebitis.

An ultrastructural study on vein biopsies from six lepromatous leprosy patients was carried out. The results showed that a) the lumen-lining bacillated cells were endothelial in origin due to the presence of specific Weibel-Palade endothelial cell granules; b) endothelial cells released Mycobacterium leprae into the lumen by exophagocytosis; c) M. leprae were able to grow and multiply in the endothelial and smooth muscle cells; and d) smooth muscle cells did not show any evidence of reaction due to the presence of M. leprae in their cytoplasm.

Anastomosis of small veins with suture or Nakayama's apparatus. A comparative study.

In controlled experiments, the posterior facial veins in the rabbits neck (diameter 1.5-2.0 mm) were repaired, either by manual suture with 10-0 nylon or by the use of Nakayama's ring pin stapler. The so-called Nakayama "animal" rings, made from metal alloy, as well as the "human" rings, made from tantalum, were employed. A Nakayama anastomosis was performed in only one-third of the time required to complete a suture anastomosis. Evaluation of anastomotic patency was carried out after 7 days, and the vessels were examined histologically in serial sections. Veins anastomosed by the Nakayama technique had a statistically significant lower rate of early thrombosis than the sutured veins, while no difference was found in the occurrence of late thrombosis. The histological analysis showed a perfect endothelium-to-endothelium coaptation in the Nakayama anastomoses, and endothelium covered the anastomotic site in one week. In suture anastomoses the histological picture was more complex, with disintegration of the layers of the vessel wall and hyaline degeneration betweeen sutures. The "animal" rings almost constantly caused local phlebitis, but these changes were not reflected in the patency rates at one week.

Parainfluenza virus Sendai infection in macrophages, ependyma, choroid plexus, vascular endothelium and respiratory tract of mice.

Immunofluorescent observations showed that after intranasal instillation of parainfluenza 1 (Sendai) virus into adult mice, infection is confined to the epithelial lining of the larger airways. Alveolar macrophages were not significantly involved, although they could be infected in vitro. In suckling mice, the infection was more acutely lethal and extended into the terminal air spaces. The intranasal susceptibility of adult mice was not reproducibly affected by treatment with potent antithymocyte serum, and there were no obvious pathogenic effects when heterologous antiserum was instilled intranasally into infected mice. Peritoneal macrophages were infected by intraperitoneally injected Sendai virus, with production of a highly viscous peritoneal exudate. Kupffer cells of the liver and endothelial cells in large veins and auricles were infected by intravenously injected virus. When injected intracerebrally, Sendai virus infected ependyma and choroid plexus epithelium. Adult mice often survived, in spite of ependymal destruction and changes in ventricular morphology. Astrocytes were activated but not infected.