Lung Abscess Formation Research Articles

Mediastinal Lymphadenopathy Complicating into a Bronchonodal Fistula and Lung Abscess Formation – Rare Manifestation of Drug-resistant Tuberculosis

Pulmonary tuberculosis (TB) sometimes involves regional lymph nodes like mediastinal lymph nodes. These may resolve spontaneously or on treatment; or they may enlarge and result in various complications such as extrinsic bronchial inflammation, ulceration, or rarely erode through the bronchial wall. This erosion is seen radiologically as mediastinal widening or lymphadenopathy with atelectasis and consolidation termed “epituberculosis.” This is more frequently encountered in infants than older children and extremely rarely in adults. We hereby describe a rare case of a 14-year-old girl with mediastinal lymphadenopathy complicating into a bronchonodal fistula and lung abscess formation. A diagnosis of pulmonary rifampicin-resistant TB was obtained on repeated testing of sputum for GeneXpert. The patient was started on appropriate drug-resistant TB therapy and completed therapy successfully.

One case of severe exogenous lipoid pneumonia complicated with lung abscess caused by diesel inhalation

Exogenous lipoid pneumonia is an inflammatory response to the lungs caused by inhaled lipid substances, which is prone to secondary bacterial infection, resulting in the formation of local abscesses, which can be life-threatening in severe cases. This paper reports a case of a 55-year-old patient with diesel aspiration, secondary to Klebsiella pneumoniae (ESBL positive) and Candida glabrata infection resulting in lung abscess formation. He was treated with a variety of antibacterial drugs for anti-infection, non-invasive ventilator ventilation, bronchoalveolar lavage, glucocorticoids, phlegm and other medical treatments. Finally, he underwent middle lobectomy for improvement and was discharged from the hospital, and he recovered well with regular follow-up.

A 66-year-old Woman of Leukemia with Extramedullary Pulmonary Infiltration Manifesting as Lung Mass

<p>白血病髓外肺浸潤是一種罕見的臨床疾病，因其胸部X光和臨床表徵不具特異性，診斷困難往往延誤適當的治療。本案例為66歲女性，因發燒、咳嗽、活動後呼吸急促就醫，胸部電腦斷層顯示疑似肺膿瘍。因初步診斷為肺膿瘍故行豬尾巴導管置放術併切片檢查，病理報告僅顯示慢性發炎，且以多線抗生素藥物治療。爾後因周邊血液出現芽細胞，經骨髓切片診斷為急性骨髓性白血病，隨著病人發燒未改善，醫療團隊針對肺膿瘍，安排胸腔鏡行右上葉切除、右下葉楔狀切除及肺剝離術，最終肺組織病理報告確診為急性骨髓性白血病併髓外肺浸潤。經此案例予臨床重要省思是當病人反覆發燒且電腦斷層影像疑似肺膿瘍生成，抗生素藥物治療效果不彰，必須將白血病併髓外肺浸潤列入鑑別診斷，且一經確診為白血病髓外肺浸潤，應及早針對白血病疾病治療， 以免誤判病人肺部有感染情形，而延後癌症治療，增加病人死亡風險。</p> <p> </p><p>Acute myeloid leukemia with extramedullary pulmonary infiltration is a rare clinical case. Without specific clinical manifestations and imaging features, the diagnosis is often challenging, leading to a delay in treatment. The case is of a 66-year-old female patient, who visited the emergency department due to cough, fever and exertional dyspnea. Due to recurrent fever, a chest CT scan was performed and revealed lung abscess. Based on the initial diagnosis of lung abscess, pigtail catheter placement and bronchial biopsy were performed. The pathological report showed only chronic inflammation. Thus, the patient was treated with multiple antibiotics and antifungals. Due to the detection of blast cells in the peripheral blood via the complete blood count, bone marrow biopsy was performed and then acute myeloid leukemia was confirmed. However, the recurrent fever continued for one month. The medical team arranged thoracoscopy for right upper lobe resection, right lower lobe wedge resection, and lung pneumonolysis for the lung abscess. Pulmonary histopathological report eventually confirmed acute myeloid leukemia with extramedullary pulmonary infiltration. This case suggested that when a patient has recurrent fever and the CT image shows suspected lung abscess formation, antibiotic treatment may not be effective. Extramedullary infiltration of leukemia should be suspected in the differential diagnosis. Once confirmed as extramedullary pulmonary infiltration of leukemia, leukemia related treatment should be provided as soon as possible. The delay of cancer treatment, which may increase the risk of mortality.</p> <p> </p>

Outcome of Emergency Pulmonary Lobectomy under ECMO Support in Patients with COVID-19.

Not much is known about the results of nonelective anatomical lung resections in coronavirus disease 2019 (COVID-19) patients put on extracorporeal membrane oxygenation (ECMO). The aim of this study was to analyze the outcome of lobectomy under ECMO support in patients with acute respiratory failure due to severe COVID-19. All COVID-19 patients undergoing anatomical lung resection with ECMO support at a German university hospital were included into a prospective database. Study period was April 1, 2020, to April 30, 2021 (first, second, and third waves in Germany). A total of nine patients (median age 61 years, interquartile range 10 years) were included. There was virtually no preexisting comorbidity (median Charlson score of comorbidity 0.2). The mean interval between first positive COVID-19 test and surgery was 21.9 days. Clinical symptoms at the time of surgery were sepsis (nine of nine), respiratory failure (nine of nine), acute renal failure (five of nine), pleural empyema (five of nine), lung artery embolism (four of nine), and pneumothorax (two of nine). Mean intensive care unit (ICU) and ECMO days before surgery were 15.4 and 6, respectively. Indications for surgery were bacterial superinfection with lung abscess formation and progressive septic shock (seven of nine) and abscess formation with massive pulmonary hemorrhage into the abscess cavity (two of nine). All patients were under venovenous ECMO with femoral-jugular configuration. Operative procedures were lobectomy (eight) and pneumonectomy (one). Weaning from ECMO was successful in four of nine. In-hospital mortality was five of nine. Mean total ECMO days were 10.3 ± 6.2 and mean total ICU days were 27.7 ± 9.9. Mean length of stay was 28.7 ± 8.8 days. Emergency surgery under ECMO support seems to open up a perspective for surgical source control in COVID-19 patients with bacterial superinfection and localized pulmonary abscess.

Lung Abscess in Critically Ill Coronavirus Disease 2019 Patients With Ventilator-Associated Pneumonia: A French Monocenter Retrospective Study.

The pulmonary vascular endothelialitis together with the high rate of distal pulmonary embolism or thrombosis extensively reported in critically ill coronavirus disease 2019 patients may impair antibiotic diffusion in the lung parenchyma of coronavirus disease 2019 patients with ventilator-associated pneumonia leading to insufficient antibiotic concentration, thus promoting lung abscess formation. We report that 17 of 119 coronavirus disease 2019 patients (14%) with ventilator-associated pneumonia developed a lung abscess. Proportion of patients receiving corticosteroids did not differ between patients with and without lung abscess. Most of lung abscess were polymicrobial. Enterobacteriaceae, Pseudomonas aeruginosa, and Staphylococcus aureus were the leading causative bacteria. Most of lung abscesses involved the right lower lobe. Three patients had concomitant pulmonary embolism or thrombosis in the territory of lung abscess. Lung abscess was retrospectively visible on chest radiograph in 29% of the patients. As the occurrence of lung abscess impacts the duration of antibiotics therapy, chest CT scan should be easily performed in case of treatment failure of ventilator-associated pneumonia despite adequate antimicrobial therapy.

Apsces pluća kao komplikacija infekcije COVID-19

Introduction/Objective: A lung abscess is a localized purulent inflammation of lung tissue with necrosis and colliquation. We are presenting a rare case of lung abscess formation as a result of the COVID-19 viral infection. Case report: An 81-year-old male patient with typical complaints (fever, malaise, fatigue) was examined at a designated medical centre for COVID patients. A positive PCR test and radiology findings confirmed a COVID-19 infection. Medication was prescribed according to protocol and he was sent home. During the night, 36 hours after the onset of the first symptoms, the patient developed breathing difficulties and a persistent, irritating dry cough. He was admitted to the Covid Hospital Karaburma, where he received treatment for 35 days. On the 22nd day after being released, the patient was examined at the Emergency Medical Centre, Clinical Centre of Serbia, complaining of dyspnoea, occasional hemoptysis and fatigue. The working diagnosis was pulmonary embolism. A multislice CT scan was ordered only to reveal a pulmonary abscess at the base of the left lung. Conclusion: A lung abscess is a rare, but possible complication of a COVID-19 infection. Therefore, patients should be regularly monitored for an extended period of time following hospitalization.

An Unusual Case of Sternoclavicular Joint Infection and Lung Abscess

Septic arthritis of the sternoclavicular joint is a rare and serious infection. A delay in the diagnosis may lead to serious complications. The appropriate medical and surgical treatment is crucial to the outcome. This article aims to report our experience in the successful management of sternoclavicular joint infection complicated with a lung infection. The authors present an unusual case of sternoclavicular joint infection extending into lung parenchyma with lung abscess formation in a diabetic patient, with uncontrolled diabetes that was successfully treated. At revaluation, he was asymptomatic with no evidence of relapse. Although sternoclavicular joint infection is a rare condition we highlight the importance of clinician’s awareness for an early diagnosis and treatment with broad-spectrum antibiotics and surgery.

Paenibacillus alvei Multifocal Cavitary Lung Abscesses in an Immunocompetent Man

Abstract Paenibacillus alvei (formerly Bacillus alvei) is infrequently recognized as a pathogenic bacterium in humans. P. alvei has historically been considered a nonvirulent organism found in soil and water sources and most well-described in European foulbrood, a disease of honeybees. Few case reports have been described in humans, none of which include cavitary lung abscess formation. We describe a case of multifocal lung abscesses secondary to P. alvei in an immunocompetent man and review the literature of other case reports in humans. Identification of P. alvei remains challenging, and the biochemical tests to make the diagnosis are reviewed. Treatment is generally guided by in vitro susceptibility patterns, and we will review the clinical case reports that have resulted in successful treatment of this bacterium.

The multistep road to ventilator-associated lung abscess: A retrospective study of S.aureus ventilator-associated pneumonia.

ObjectWe observed some cases of lung abscess (LA) in ICU patients suffering S.aureus ventilator-associated pneumonia (S.aureus-VAP). We aimed to assess which of the host and/or bacteria-related features are associated with LA.MethodsWe conducted a retrospective study from January 2009 to July 2013 in a trauma surgical ICU within a teaching hospital. All adult patients presenting with S.aureus-VAP were included. We compared two groups of patients according to the formation or not of LA concomitantly to S.aureus-VAP.ResultsSeventy-nine S.aureus-VAP patients, predominantly males (85%) of rather young age (mean [SD]: 35yr [21–64]) with severe trauma (initial Simplified Acute Score II = 42 [32–52]) related-ICU admission, were included. Among them, 10 (14%) developed LA. Patient’s characteristics significantly associated with LA development were: a younger age (p = 0.003), road traffic accidents admission (p = 0.017), head injury (p = 0.002), lower Glasgow Coma Scale (p = 0.009), blunt chest trauma (p = 0.01) pneumothorax (p = 0.01) and lung contusions (p = 0.002). No microbiological factors were significantly associated with LA formation. Abscesses were mostly bilateral, ≥5 cm of diameter and with a posterior location.ConclusionsOur results do not favor a specific virulence of S.aureus, but rather highlight the role of multiple insults to the lung, promoting LA formation. Despite a similar severity score, patients with LA had more serious trauma, combining severe both chest and head insults.

First Case of Lung Abscess due toSalmonella entericaSerovar Abony in an Immunocompetent Adult Patient

In healthy individuals, nontyphoidal Salmonella species predominantly cause a self-limited form of gastroenteritis, while they infrequently invade or cause fatal disease. Extraintestinal manifestations of nontyphoidal Salmonella infections are not common and mainly occur among individuals with specific risk factors; among them, focal lung infection is a rare complication caused by nontyphoidal Salmonella strains typically occurring in immunocompromised patients with prior lung disease. We describe the first case of a localized lung abscess formation in an immunocompetent healthy female adult due to Salmonella enterica serovar Abony. The patient underwent lobectomy and was discharged after full clinical recovery. This case report highlights nontyphoidal Salmonellae infections as a potential causative agent of pleuropulmonary infections even in immunocompetent healthy adults.

Gingipains: Critical Factors in the Development of Aspiration Pneumonia Caused by Porphyromonas gingivalis

Aspiration pneumonia is a life-threatening infectious disease often caused by oral anaerobic and periodontal pathogens such as Porphyromonas gingivalis. This organism produces proteolytic enzymes, known as gingipains, which manipulate innate immune responses and promote chronic inflammation. Here, we challenged mice with P. gingivalis W83 and examined the role of gingipains in bronchopneumonia, lung abscess formation, and inflammatory responses. Although gingipains were not required for P. gingivalis colonization and survival in the lungs, they were essential for manifestation of clinical symptoms and infection-related mortality. Pathologies caused by wild-type (WT) P. gingivalis W83, including hemorrhage, necrosis, and neutrophil infiltration, were absent from lungs infected with gingipain-null isogenic strains or WT bacteria preincubated with gingipain-specific inhibitors. Damage to lung tissue correlated with systemic inflammatory responses, as manifested by elevated levels of TNF, IL-6, IL-17, and C-reactive protein. These effects were unequivocally dependent on gingipain activity. Gingipain activity was also implicated in the observed increase in IL-17 in lung tissues. Furthermore, gingipains increased platelet counts in the blood and activated platelets in the lungs. Arginine-specific gingipains made a greater contribution to P. gingivalis-related morbidity and mortality than lysine-specific gingipains. Thus, inhibition of gingipain may be a useful adjunct treatment for P. gingivalis-mediated aspiration pneumonia.

Aspiration-related lung diseases.

Aspiration is a common but underrecognized clinicopathologic entity, with varied radiographic manifestations. Aspiration represents a spectrum of diseases, including diffuse aspiration bronchiolitis, aspiration pneumonitis, airway obstruction by foreign body, exogenous lipoid pneumonia, interstitial fibrosis, and aspiration pneumonia with or without lung abscess formation. Many patients who aspirate do not present with disease, suggesting that pathophysiology is related to a variety of factors, including decreased levels of consciousness, dysphagia, impaired mucociliary clearance, composition of aspirate, and impaired host defenses. In this pictorial essay, we will review the different types of aspiration lung diseases, focusing on their imaging features and differential diagnosis.

Esophageal cancer complicated by esophagopulmonary fistula and lung abscess formation: A surgical approach.

Esophageal cancer is an aggressive malignancy with an unfavorable prognosis and an increasing incidence worldwide.1 Locally advanced esophageal carcinoma might eventually be complicated by esophagorespiratory fistula, which is predominantly palliated by endoscopic stent placement. A subgroup of these patients present with direct tumor invasion of the adjacent pulmonary tissue, resulting in esophagopulmonary fistula and subsequent pulmonary abscess formation.2 Despite stent placement, the prognosis of esophagopulmonary fistula is grim. Most of these patients suffer from persistent pulmonary abscess formation leading to deterioration in their clinical condition and a fatal outcome within a short time.2,3 Therefore, the therapy of patients with esophagopulmonary fistulas should be focused on pulmonary abscess formation, which requires a different approach than that used for patients with uncomplicated esophagorespiratory fistulas. Surgical treatment with resection of the esophageal lesion and the involved pulmonary lobe might be a more promising option than conventional stent placement because this strategy enables the removal of all inflammatory tissue and might significantly prolong the survival time of these patients.4–6 Despite the potential benefits, it seems that most surgeons are rather reluctant to perform major surgery in these patients, who generally present in poor health.7 To our knowledge, there are no current reports addressing the issue of surgery for esophagopulmonary fistulas, apparently reflecting the widespread nihilistic attitude towards this life-threatening condition. Not only is the incidence of esophageal cancer constantly rising, but neoadjuvant radio-chemotherapy protocols are also being used more frequently, and these have been previously associated with the formation of esophageal fistulas.8 Consequently, the number of patients presenting with intractable esophagopulmonary fistulas is likely to increase, challenging the treatment modalities available. In our view, this problem is not adequately reflected in the current literature. Therefore, we report our experience with the surgical treatment of two consecutive patients presenting with malignant esophagopulmonary fistulas, who underwent simultaneous esophageal and pulmonary resection.

Lung Bullae, Cavitation and Right Ventricular Thrombus Formation with Saprophytic Aspergillus Colonisation: A Rare Presentation of Idiopathic Pulmonary Embolism

Pulmonary Embolus (PE), in association with Deep Vein Thrombosis (DVT) is one of the three major cardiovascular causes of death. There are several risk factors for PE but still many cases are idiopathic. Cavity, bullae and lung abscess formation are unusual finding in PE. Right Ventricular (RV) thrombus secondary to PE itself is also rare. Here, we present a case of a young male patient with no prior risk factors, who came to us with a large bullae and cavitation in lung which was secondary to PE. Later he developed RV thrombus and saprophytic fungal colonisation of affected lung which was all attributed to PE. Patient was managed conservatively with anticoagulation and his repeat echo after two months showed clearance of RV thrombus.

Absceso pulmonar y empiema fulminante por Pseudomonas aeruginosa

We report the case of a 27-year-old man with a history of diabetes mellitus who presented with conscious disturbance, fever, and stiff neck after upper respiratory tract infection. Following diagnosis of meningoencephalitis, antibiotic therapy and deamethasone was initiated. He received endotracheal tube intervention under mechanical ventilation in the intensive care unit, and underwent successful weaning on day 4. One week later, he was diagnosed with pneumonia and a rapidly progressing lung empyema with abscess formation was noted. Microbiological culture of the pleural fluid revealed the presence of Pseudomonas aeruginosa. Nosocomial pneumonia is often caused by Staphylococcus aureus and P. aeruginosa; however, the latter often causes bronchopneumonia rather than fulminant empyema or lung abscess formation. The underlying diabetes mellitus and the history of steroid therapy may explain the present condition of this patient. The possibility of P. aeruginosa being the causative agent should be considered during differential diagnosis in patients presenting with fulminant lung empyema, especially in immunocompromised patients.

Lung Abscess due to Clostridium baratii Infection in a Patient with Invasive Pulmonary Aspergillosis

Clostridial pleuropulmonary infections are rare; most of these infections are attributed to Clostridium perfringens (1), and none involving C. baratii have been reported. We describe here a fatal case of C. baratii lung abscess superimposed on invasive pulmonary aspergillosis. A 47-year-old man was diagnosed with myelodysplastic syndrome with refractory anemia and excess blasts in December 2005. The disease course was complicated by disseminated Mycobacterium avium complex infection and invasive pulmonary aspergillosis. The patient underwent allogeneic hematopoietic stem cell transplantation in May 2006. One year later, he was admitted for leukemia relapse associated with febrile neutropenia. Chest radiography and computed tomography (CT) displayed multiple small opacities on the right upper and lower and left upper lung fields. Compared with chest CT results seen 1 year before, only the lesion on the left upper lung had increased in size (Fig. ​(Fig.1A).1A). Low-grade fever persisted despite treatment with imipenem and voriconazole. Serum Aspergillus antigen results (Platelia Aspergillus enzyme immunoassay; Bio-Rad Laboratories) were negative. The lesion on the left lung progressed rapidly within 1 month (Fig. ​(Fig.1B).1B). Follow-up chest CT results showed an abscess with a thick wall (Fig. 1C and D). In August 2007, the patient was admitted to an intensive care unit (ICU) because of acute respiratory failure. A sonography-guided transthoracic lung biopsy was performed on the second ICU day. Pathology examination of the lung biopsy sample disclosed narrow, dichotomous, and septated hyphae compatible with Aspergillus spp. Cultures of the lung biopsy sample and aspirates of the lung abscess as well as blood cultures all yielded C. baratii that was susceptible to penicillin, chloramphenicol, metronidazole, and cefmetazole but was resistant to clindamycin by a disk diffusion test. The patient's hemodynamics deteriorated, and the patient died of multiple organ failure on the twelfth ICU day. FIG. 1. (A) CT scan of the chest on admission, showing a small faint patch at the left upper lung field (LULF) and old fibrotic changes at the right upper lung field. (B to D) Follow-up chest radiography 1 month later disclosed a mass lesion at the LULF (B), ... The genus Clostridium has more than 150 species, but fewer than 20 are associated with human diseases (5, 7). Members of the genus are mainly natural inhabitants of the human intestinal tract, and their disease spectra in humans are broad (7). C. baratii has attracted limited attention because of its lack of overt pathogenesis and failure to produce lethal toxin. Its most striking clinical feature is its neurotoxogenesis, type F botulism in infants (4) and in adults (3, 4). However, C. baratii pulmonary infection in adults has never been previously reported in the literature. We speculate that the development of a lung abscess caused by C. baratii in this case may be closely related to the patient's leukemia relapse with persistent neutropenia and invasive pulmonary aspergillosis. The hyphae of Aspergillus species tend to invade blood vessels, which in turn leads to local thrombosis and tissue infarction (2, 6). Simultaneously, clostridial bacteremia originating from the disruption of the gastrointestinal mucosa results in seeding into the lung, with subsequent formation of lung abscess. The infection is refractory to antimicrobials in the face of tissue infarction despite the use of antimicrobial agents with in vitro activity against C. barati. In conclusion, among high-risk hosts, the rapid progression of fungal pneumonia into lung abscesses may suggest the presence of a superimposed infection due to an anaerobic bacterial species such as C. barati.

Oesophageal perforation with asymptomatic lung abscess formation

In November, 2005, a 58-year-old man presented to the emergency department with retrosternal chest pain, which he described as “cutting and stabbing”. The pain was accompanied by the development of dysphagia to solids. Clinical examination was unremarkable, with a normal oropharynx and neck. Chest radiography was normal with no visible foreign body. The patient was admitted overnight. The pain had settled and the dysphagia had improved by the next morning, and he was therefore discharged with an urgent outpatient appointment for oesophagogastroduodenoscopy (OGD).

Surgical management of congenital lung anomalies

Prenatal diagnosis allows for insight into the evaluation of fetal lung anomalies. Serial ultrasonographic studies of fetuses helped in evaluation and definition of the natural course of these lesions as well as necessity for fetal therapy. It has been found that the overall prognosis depends on the size of the lung mass and the secondary derangement of normal lung tissue and cardiovascular system. Although much is known about the prenatal course of these anomalies, little is known about the postnatal course of asymptomatic patients. Infants who are symptomatic at birth require early surgical treatment. During the period from 1984-2003, 23 patients with congenital lung anomalies were treated, out of whom 19 were diagnosed postnatally and 4 prenatally. All postnatally diagnosed patients (9 congenital lobar emphysema, 5 congenital cystic adenomatoid malformations, 3 pulmonal cysts, 1 bronchopulmonary sequestration and 1 arteriovenous malformation) underwent surgical excision (lobectomy or sequestrectomy) after becoming symptomatic (main symptoms were infection or respiratory distress). Prenatally diagnosed patients (2 bronchopulmonary sequestrations and one enteric mediastinal cyst) underwent elective surgical interventions (sequestrectomy and excision of the cyst) in infancy. Postoperative course was uneventful in all patients. One patient probably had spontaneous involution of the mass. We believe that elective resection is indicated in asymptomatic neonates with congenital lung anomalies, because of the potential risk of infection and occult malignant transformation. Early resection also maximizes compensatory lung growth. This approach eliminates any risk of pulmonary infection, lung abscess formation or malignant transformation. In addition, subsequent exposure to radiation will be avoided.

An unusual foreign body in the bronchus

Foreign body aspiration can be the cause of both upper and lower airway obstruction and can occur both in adults and children. Children are likely to aspirate toys, coins and hard candy; while adults more commonly aspirate food particles like meat bones and dental appliances. Inhaled or aspirated foreign bodies are known to cause acute upper airway obstruction, laryngeal edema, central obstructive collapse and obstructive emphysem. If the obstruction is severe and acute it can even lead to sudden death, sub acute and chronic complications including post obstructive pneumonia, lung abscess formation, bronchiectasis and foreign body granuloma. Immediate removal of foreign body and prompt resuscitation can often be life saving [1]. One of the earliest uses of bronchoscope was for removal of aspirated foreign bodies. In the present day, both rigid and fibreoptic bronchoscopes have been widely used for this purpose. The ingenuity of the bronchoscopists has resulted in the invention of various modified devices to remove foreign bodies from the tracheobronchial tree [2]. We report one such case of an unusual foreign body in a distal bronchus that was retrieved successfully.

Bacterial pneumonia in immunocompromised patients.

Immunocompromised patients develop infections resulting from a wide range of organisms. The most commonly encountered type of infection is bacterial in origin. Many of the infections are community-acquired pneumonias in which most of the infections are caused by organisms that typically produce disease in the healthy person. Hospital-acquired pneumonias are particularly serious, being caused by the highly virulent gram-negative bacilli and Staphylococcus aureus. Immunocompromised patients frequently have indwelling intravascular catheters. These catheters may become infected and seed the lung with septic emboli, producing a hematogenous pneumonia. Underlying conditions and therapy increase the risk for aspiration in the immunocompromised patient. These aspirations can result in the development of an aspiration pneumonia and lung abscess formation. The majority of pneumonias resulting from Legionella and Nocardia occur in immunocompromised patients.