Imaging Study Of Lung Opportunistic Infections In Immunosuppressive Host

[Background]Recent years, as people aging becoming a aggravating problem, chronic and wasting diseases such as blood disease, tumor, AIDS increasing, the widely use of broad-spectrum antibiotic, GC and immune depressant, immunosuppressive crowds have grown year by year, Opportunistic infections especially lung opportunistic infections has a tendency of persistent increasing. Fungi are important pathogenic microorganism to result in opportunistic infections. Patients with lung mycotic infection often have serious pathogenetic condition, symptoms objective sign and course of disease are often covered by underlying diseases and adopting medicines so that have no specificity, sputum cultures also can not be the evidence of invasive infections. The biopsy methods which can cause damage such as lung puncturation, bronchoscope examination, exploratory thoracotomy and so on, bring great distress and high risk to patients, so seldom apply clinically. Chest CT scan especially HRCT can find tiny abnormity that can not be displayed by radiology, and also describe the character and scope of lesions accurately, helping guide the pathway of biopsy, so as to play a important role in early diagnosis of lung opportunistic infections. But imaging study of pulmonary infection particularly lung mycotic infection are very insufficient at present, specific signs that can identify infectious types of different causative organisms are very rare, therefore, animal experiment part of our study chose Candida albicans which is one of the most common opportunistic infectors to establishment animal model of pulmonary infection, and research the imaging appearances of that; in clinical part, we chose patients after LT as the object in immunosuppressive crowds, retrospectively analyze the epidemiologic feature and imaging appearances, in order to enhance the recognition of lung opportunistic infections in immunosuppressive host in different ways, and raise accuracy of early diagnosis finally.PartⅠThe Animal Experimentation of Pulmonary candidiasis—CT appearances and Pathology Control Study[Objective]Through establish the animal model of pulmonary candidiasis in New Zealand rabbits, to analyze the appearances of chest CT scanning and control with pathology, enhance the cognition to imaging appearances of pulmonary candidiasis. [Methods]Twenty four New Zealand rabbits, no matter male or female, weight 1.5kg-2.5kg, divided into experimental group and control group randomly, experimental group included 21 rabbits, and control group included 3 rabbits. Experimental group rabbits were treated with Cytarabine, 440mg/m~2, intravenous injection every day from first day and every other day from sixth day for maintaining low immune state. Blood routine examination was performed at the first day and the six day respectively to contrast . For prevention from bacterium infections, experimental group and control group were all treated with Vancomycin, 15mg/kg, ceftazidime, 150mg/kg, every day, and Gentamicin, 5mg/kg every other day from forth day.The experimental strain was Candida albicans type strain ATCC10235. After strainresuscitation, prepare the suspension with the density of 5.0×10~8 cfu / ml at the day of inoculations.All experimental group rabbits were inoculated with the way of percutaneous trache puncture at the sixth day. After anesthesia the rabbits were fixed on the consple, held trache , injected 0.2ml suspension with the sterile injector of 1ml volume, then reversed trendelenburg position immediately . The control group were injected with normal sodium 0.2ml with the same way.From the first day after inoculations, set 14 days observation period, Chest CT scan was performed every other day from the second day . Execute one rabbit with abnormal CT appearance at the third and eighth day respectively, execute all alive rabbits at the last day. Take the lung samples of all death rabbits to biological culture and pathological examinations(HE staining and PAS staining).[Results]All 19 rabbits' lung samples were found Candida albicans only when done biological culture. 13 cases had abnormal CT appearances, the first time of occurrence was from the second day to tenth day differently. 9 cases belong to the type of consolidation as the only or main sign, including sublobe consolidation(n=6) which often distribute under pleural membrane, and lobe or section consolidation(n=3) which often distributed in the low department of unilateral or bilateral lung.2 cases belonged to the type of nodules as the only or main sign, mainly found nearly bronchovascular bundle. Ground-glass attenuation was the only appearance in 2 cases, often asymmetrical distributed in bilateral lung. Histopathologic findings(HE stain)displayed areas of exudative or proliferative phase of diffuse alveolar damage in 12 cases, including interstitial fibroblastic proliferation and lymphocytic infiltration or hyperemia, and intraalveolar exudates; lamellar necrosis in 4 cases, well defined, alveolar structure still existed in 3 cases, organizations can found in cavity, alveolar structure destroyed in lcase,displaying large necrotic tissue with no structure.. 2 cases foung embolization in lung Small vessels with spores and mycelia. Well-defined granulomas were found in 2 cases, the center of which were nonfixiform necrosis consisting of localized Candida organisms, surrounding by a great quantity of leukomonocytes and macrophagus, epithelioid cells, MGC dispersedly.[Conclusions]1 Adopt Candida albicans type strain to infect New Zealand rabbits at the condition of immunity suppression through respiratory tract, can establish the animal model of pulmonary candidiasis successfully, and sometimes form latent infection of pulmonary, achievement ratio relate to the extent of immunity suppression.2 A week after inoculation is the period of high danger for pulmonary candidiasis to happen, MSCT chest scan can find abnormity at the early time.3 Consolidation is the most common CT appearances of pulmonary candidiasis in rabbits, Ground-glass attenuation and nodules to follow, different signs can occur at the same time, but none has specificity.PartⅡImaging Study of Pulmonary Infections after Liver Transplantation[Objective]To investigate epidemiology feature and imaging appearance characteristics of pulmonary infections after liver transplantation(LT), in order to offer evidences for early diagnosis.[Methods]1 Patients information:To collect the information of liver transplantation receptors from 2001 August to 2007 June, there are 529 cases in all, including 454 men and 75 women, aging from 8-77.Ground diseases include 233 cases of primary hepatic carcinoma,191 cases of liver cirrhosis caused by all kinds of etiological factors , 78 cases of acute or chronic serious hepatitis,12 cases of failure function liver after LT,8 cases of hepatolenticular degeneration,6 cases of out-burst Hepatic failure,and 1cases of Hepatic leiomyosarcoma. Routine immunosuppressive therapy is adopted,and prevent bacterial infection using cefepime and teicoplanin, precaut mycotic infection using fluconazol in the early period after LT.2 Diagnostic criteria of pulmonary infection after LT:A11 diagnosis are consistent with "Hospital infection diagnostic criteria" formulated by Chinese Department of Health in 20013 The method of computer tomography examination:Collect CT checking information of patients with final diagnosis of pulmonary infection,the CT machine type include Marconi Mx8000,16-slice MDCT scanner(TOSHIBA Acquilion) or 64-slice MDCT scanner(GE LightSpeed VCT),scanning from the apex of lung to the base of lung with routine exposure dosage.CT enhancement:a total dosage of 70～90ml non-ion iodine agent was administered at a rate of 5ml / sec into opisthenar vein,scanning time are 25～45 and 2～4min after injecting.4 CT image analysis:2 thoracic radiological diagnosis analyze the image together,if opinions are different, we reach coincidence after negotiate.The evaluating contents including the scope, distribution and appearance of the main pathological changes.5 Statistical treatment:Do statistical analysis by SPSS16.0 software[Results]1Epidemiological statistics(1)The incidence rate of pulmonary infections after LT is 34.2%, the mortality is 9.8%.The incidence of bacterial infection, mycotic infection,virus infection and the mixed infection of different kinds of etiological agents is 17.2%,5.1%,1.1%,10.8% respectively and constituent ratio is 50.3%,14.9%,3.3%,31.5% respectively,single bacterial infection occupy 12.7% in all infections,and multiple bacterial infection 37.6%,single mycotic infection 12.1%,multiple mycotic infection 2.8%;mixed infection involving fungus 9.6%,not involving fungus 1.1%.(2)Gram-Negative bacillus occupied 69.8%, and Klebsiella pneumoniae was the most common, Gram-Positive coccus occupied 30. 2%, and Staphylococcus epidermidis was the most common, fungus occupied 21.4% of all pathogenic bacterium, of which Candida albicans was the most common.(3)The infected time is divided into three stages which are 30 days since LT end, 31-90 days and after 90 days to follow. The constituent ratio of pulmonary infections in these three stages is 64.7%,28.7%,6.6%. Bacterial infection's ratio in these three stages is 56.0%,37.4%,6.6% and the constituent of mycotic infection or mixed infection including fungus is 78.2%,20.5%,1.3%.2 Thoracic CT appearances(1) Common CT signs: ground-glass attenuation(n=22), 12 cases distribute in bilateral ,other 10 cases in single side,4 in left and 6 in right; distribute in middle or upper lobe in 6 cases, in lower lobe in 8 cases ,diffuse distribute in 8 cases; consolidation(n=32), 10 cases distribute in bilateral ,other 22 cases in single,4 in left and 18 in right; distribute in middle or upper lobe in 5 cases,and other 27 cases in lower lobe; nodules or masses(n=10), was all multiple and bilateral,the diameter was all less than 3cm and even less than lcm(n=7),diffuse distributing nodules of pulmones(n=7) were among the total,3 cases have cavitation ,4 cases do enhancement scanning,only one was enhance;graticules or lines(n=4), two in both upper lobe and two generally in every lobe, two mainly distribute in bilateral peripheral zone;a small or middle quantity pleural effusion(n=31),3 in left and 15 in right,13 in both sides, pleural thickening(n=23), 2 in left and 11 in right,10 in both sides.(2) The comparison of different types of pulmonary infections: The most common CT finding of Lung bacterial infection after LT was consolidation,the incidence rate is 80%(16/20) , consolidation, ground-glass attenuation and nodules aer all often appear in pulmonary mycotic infection, pear in pulmonary mycotic infections, the incidence rate is 50% (4/8) ,62.5% (5/8) ,50% (4/8) respectively. Each appearance does not have statistics difference in compare its incidence rate in bacterial infection with that in mycotic infection(p>0.05).[Conclusions]1 The incidence and mortality in pulmonary infection after LT are both high, bacterial infection is most common, the ratios of mycotic infection and mixed infection are high,30days immediately after LT is the period with high danger to pulmonary infection,this is more apparent in mycotic infection.2 Gram-Negative bacillus was the most detected bacterium in the sputum cultures of this group,of which Klebsiella pneumoniae occupy the majority, Staphylococcus epidermidis was the most in Gram-Positive coccus, Candida was found most in fungus.3 Chest CT scan can display the ranges and affection quality of pulmonary infection at early time accurately, consolidation was the most common, often marked in the right or lower lung zones, ground-glass attenuations and nodules were to follow, nodules were all multiple and bilateral, but no distributing features were found.4 The most common CT finding of Lung bacterial infection after LT was consolidation.In pulmonary mycotic infection, consolidation,ground-glass attenuation and nodules were all often appear. No above sighs can be used to identify the two infected types .