Lung ; pathology ; Pneumoconiosis ; microbiology ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa

Bacteremia ; microbiology ; Female ; Humans ; Infant ; Pseudomonas Infections ; pathology ; Pseudomonas aeruginosa

OBJECTIVETo 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.

METHODSThe 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.

RESULTSSix 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.

CONCLUSIONSSA, 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.

Acinetobacter Infections ; microbiology ; Acinetobacter baumannii ; growth & development ; Bacterial Adhesion ; Biofilms ; Burns ; microbiology ; Catheters ; microbiology ; Humans ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; growth & development ; Staphylococcal Infections ; microbiology ; Veins ; microbiology

Pseudomonas aeruginosa is the most common pathogen of burn wound infection. It can encode a variety of virulence factors and is highly pathogenic, which can lead to poor prognosis and high mortality. In order to research a new method to combat Pseudomonas aeruginosa infection, researchers have observed a wide range of interactions between the bacteriophages and the host. Bacteriophages influence and even dominate the structure, movement, and metabolism of host bacteria through a variety of mechanisms, catalyze the evolution of the host, and are also an important factor in host environmental adaptability and pathogenicity. In this paper, the interaction between Pseudomonas aeruginosa bacteriophages and the host is reviewed from the single cell level and the population level. Understanding these interactions could provide new idea for the treatment of Pseudomonas aeruginosa clinical infections, provides a basis for future development of antimicrobial agents and guides the treatment of burn infections.
Bacteriophages ; Burns/therapy* ; Humans ; Pseudomonas Infections/microbiology* ; Pseudomonas Phages ; Pseudomonas aeruginosa ; Virulence Factors

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogenic bacterium with complex pathogenesis and drug resistance mechanisms. It has high morbidity and mortality and can cause acute and chronic infections in immunocompromised individuals, with lung infections, wound infections, and bloodstream infections being the most common. The animal infection model of P. aeruginosa is of great value for in-depth research on the pathogenicity, drug resistance, and therapeutic measures of P. aeruginosa by simulating the pathways of human bacterial infections. This article firstly summarizes the selection, anesthesia, and disposal of experimental animals in the construction of animal models of P. aeruginosa infection, and then reviews the methods of construction, model evaluation, and applications of animal models of P. aeruginosa pulmonary infection, wound infection, and bloodstream infection, in order to provide a reference for scientific research related to P. aeruginosa infectious diseases.
Humans ; Animals ; Pseudomonas Infections/microbiology* ; Models, Animal ; Virulence ; Pseudomonas aeruginosa ; Disease Models, Animal

Coal Mining ; Humans ; Microbial Sensitivity Tests ; Pneumoconiosis ; microbiology ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; drug effects ; enzymology ; Respiratory Tract Infections ; microbiology ; Sputum ; microbiology ; beta-Lactam Resistance

OBJECTIVEThis study sought to analyze the clinical manifestations and intervention of fulminant septic shock in community-acquired Pseudomonas aeruginosa septicemia.

METHODSWe retrospectively reviewed the medical records for diagnosis, antibiotic therapy, clinical course of septic shock, respiratory support, laboratory data etc.

RESULTSEight of nine cases with P. aeruginosa septic shock died. Fever (nine cases) and cough (three cases) or diarrhea (3 cases) were the 2 most common initial symptoms, three cases developed skin gangrenosum later. Pseudomonas aeruginosa infection was not considered in any of the cases before death or blood culture showed positive result. Only 3 cases were initially treated with susceptible antibiotic regimen but no anti pseudomonas combination therapy was applied, susceptible antibiotic monotherapy was applied in 7 cases after transfer to the ICU. The mean latency of shock occurrence was 5.1 hours (range 0 to 21 hours) after admission, the mean duration from the occurrence of shock to death was 13.8 hours (range, 1 - 32 hours). All the patients were transfer red to ICU for shock, the appropriate resuscitation of shock patients was delayed by 49.3 minutes (range 25 - 80 minutes) by transfer. Only two cases were diagnosed and treated for shock on admission; after transferred to ICU, only 5 patients were diagnosed as having shock, and only 3 received anti-shock treatment. Eight of the patients died of persistent shock. In 6 patients who died, mechanical ventilation was not applied until cardiac arrest occurred. All the patients had hypoalbuminaemia, elevated serum C-reactive protein concentration, leukopenia and 6 cases had DIC.

CONCLUSIONThe initial presentation of the cases with community-acquired Pseudomonas aeruginosa septicemia was nonspecific with fever and cough or diarrhea. Clinicians often underestimated the severity of the infection, few patients received effective antimicrobial therapy. The authors suggest that an anti-pseudomonas antibiotic should be included in the initial empiric antibiotic regimen to cover P. aeruginosa high-risk patients; the front-line clinician should be educated for early recognition and aggressive resuscitation of P infection. aeruginosa septicemia.

Adolescent ; Child, Preschool ; Community-Acquired Infections ; Female ; Humans ; Infant ; Male ; Pseudomonas Infections ; Pseudomonas aeruginosa ; Retrospective Studies ; Shock, Septic ; microbiology

Aged ; Cross Infection ; microbiology ; Female ; Humans ; Intensive Care Units ; Male ; Microbial Sensitivity Tests ; Pneumonia, Bacterial ; microbiology ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; classification ; isolation & purification

BACKGROUNDImplanted medical catheter-related infections are increasing, hence a need for developing catheter polymers bonded to antimicrobials. We evaluated preventive effects of levofloxacin-impregnated catheters in catheter-related Psuedomonas aeruginosa (strain PAO1) infection.

METHODSDrug release from levofloxacin-impregnated catheters was measured in vitro. Levofloxacin-impregnated catheters and polyvinyl chloride (PVC) catheters were immersed in 5 ml 50% Luria Bertani medium containing 10(8) CFU/ml Pseudomonas aeruginosa then incubated for 6, 12, 24 or 48 hours at 37°C when bacteria adhering to the catheters and bacteria in the growth culture medium were determined. Impregnated and PVC catheters were singly implanted subcutaneously in mice, 50 µl (10(7)CFU) of PAO1 was injected into catheters. After the first and fifth days challenge, bacterial counts on implanted catheters and in surrounding tissues were determined microbiologically. Bacterial colonization and biofilm formation on implanted catheters were assessed by scanning electron microscopy.

RESULTSDrug release from levofloxacin-impregnated catheters was rapid. Levofloxacin-impregnated catheters had significantly fewer bacteria compared to PVC in vitro. After first and fifth day of challenge, no or significantly fewer bacteria adhered to impregnated catheters or in surrounding tissues compared to PVC. Scanning electron microscopical images after first day displayed from none to significantly fewer bacteria adhering to impregnated implanted catheters, compared to bacteria and microcolonies adhering to PVC catheters. After the fifth day, no bacteria were found on impregnated catheters, compared to clusters surrounding mucus-like substance and coral-shaped biofilms with polymorphonuclear leukocyte on PVC catheters. After the first day of challenge, secretion occurred in all implanted catheters with surrounding tissues mildly hyperaemic and swollen. After the fifth day, minute secretions inside impregnated catheters and no inflammation in tissues, whereas purulent secretion inside PVC catheters and abscesses in surrounding tissues.

CONCLUSIONLevofloxacin-impregnated catheter is a promising new strategy for prevention of catheter-related Psuedomonas aeruginosa infection.

Animals ; Biofilms ; drug effects ; Catheters, Indwelling ; microbiology ; Female ; Levofloxacin ; therapeutic use ; Mice ; Pseudomonas Infections ; prevention & control ; Pseudomonas aeruginosa ; pathogenicity

In order to investigate the role of the MexA-MexB-OprM efflux pump system in the pathogenesis of Pseudomonas aeruginosa (PA)-induced pulmonary infection, pulmonary infection models were established by intratracheal injection of K767 (wild type), nalB (MexA-MexB-OprM up-regulated mutant), and ΔmexB (knockout) strains, separately. All mice were treated with Meropenem (intraper Δ itoneal injection, 100 mg/kg body weight, twice every day), and strain-related pathology, bacteria count, cytokine level, myeloperoxidase (MPO, indicator of neutrophil recruitment) activity, and macrophage inflammatory protein-2 (MIP-2) expression were evaluated at early (3rd day post-infection) and late (7th and 14th day post-infection) stages of infection. E-test showed that ΔmexB was more significantly Δ sensitive to panipenan (ETP), meropenem (MP) and imipenem (IP) than K767 and nalB strains. There was no significant difference in sensitivity to cefepime (TM) among the three stains. In contrast to the K767 and nalB groups, the ΔmexB group showed decreased bacteria burden over time and less exte Δ nsive pathological change. Additionally, MPO activity and levels of inflammatory cytokines (IL-1b, IL-12, and TNF-α) were increased at the early stage (day 3) and decreased at the later stage (day 14). Serum MIP-2 expression level was steadily increased in all three groups from early to late stages, but significantly higher in ΔmexB group than in K767 and nalB groups ( Δ P<0.05). In conclusion, the MexA-MexB-OprM efflux pump system might play an important role in PA-induced chronic pulmonary infection. High expression of the MexA-MexB-OprM efflux pump could increase antibacterial resistance and promote infection.
Animals ; Bacterial Outer Membrane Proteins ; metabolism ; Lung ; microbiology ; Membrane Transport Proteins ; metabolism ; Mice ; Mice, Inbred BALB C ; Pseudomonas Infections ; metabolism ; microbiology ; Pseudomonas aeruginosa ; metabolism