Nocardial cerebral abscess cured with imipenem/amikacin and enucleation

Isolated Nocardiosis, an Unrecognized Primary Immunodeficiency?

Nocardiosis is an infectious disease caused by the gram-positive bacterium Nocardia spp. Although it is commonly accepted that exposure to Nocardia is almost universal, only a small fraction of exposed individuals develop the disease, while the vast majority remain healthy. Nocardiosis has been described as an "opportunistic" disease of immunocompromised patients, suggesting that exposure to the pathogen is necessary, but a host predisposition is also required. Interestingly, increasing numbers of nocardiosis cases in individuals without any detected risk factors, i.e., without overt immunodeficiency, are being reported. Furthermore, a growing body of evidence have shown that selective susceptibility to a specific pathogen can be caused by a primary immunodeficiency (PID). This raises the question of whether an undiagnosed PID may cause nocardiosis affecting otherwise healthy individuals. This review summarizes the specific clinical and microbiological characteristics of patients with isolated nocardiosis published during the past 30 years. Furthermore, it gives an overview of the known human immune mechanisms to fend off Nocardia spp. obtained from the study of PIDs and patients under immunomodulatory therapies.

Management of Brain Abscess

Despite recent advances in neuroimaging techniques, brain abscesses can be difficult to diagnose and may often require surgical intervention. The primary sources of infection are often difficult to locate; hence, even if an abscess is suspected, the organisms may remain unknown. In other patients, the location of the lesion may be in a site of the brain where surgical intervention may not be possible. The types of brain abscesses, their pathophysiology including predisposing conditions, and their characteristic radiologic features are discussed in this review, with particular emphasis on the indications and modes of medical management of brain abscesses. It discusses the use of antimicrobial agents that have the best central nervous system penetration and outlines a strategy for treatment of organisms likely to infect the brain with the different types of predisposing conditions. Also discussed are the indications for empirical therapy, and antimicrobial regimens for this purpose are suggested.

Clinical Pathway in the Treatment of Nocardial Brain Abscesses following Systemic Infections

Nocardial infections are commonly encountered in patients with immunocompromised states. Cerebral nocardiosis is an uncommon clinical entity, representing only 2% of all cerebral abscesses. It has a higher mortality rate, especially for multiple cerebral lesions in immunocompromised hosts following systemic infections. However, an optimal treatment policy to deal with these immunocompromised patients in Asia is still lacking. We retrospectively reviewed the subjects with nocardial brain abscesses from 2001 to 2011 at our medical center. All of them had multiple brain abscesses, underlying with immunocompromised state following systemic infections. All cases were under steroid control due to their comorbidities for more than six months. The comorbidities and misdiagnosis often lead to poor prognosis. The change in the environments of the microorganisms caused by immunosuppressive agents and multiple antibiotic uses may play an important role in this critical disorder. Aggressive craniotomy should be performed in time to avoid grievous neurological outcomes. Our conclusion is that early diagnosis and appropriate antibiotic uses should be implemented promptly, and aggressive craniotomy should be performed for nocardial brain abscesses in subjects with systemic infections under an immunocompromised status.

Nocardia farcinica brain abscess: epidemiology, pathophysiology, and literature review

BACKGROUND

Infections caused by Nocardia farcinica are potentially lethal because of the organism's tendency to disseminate and resist antibiotics. Central nervous system involvement has been documented in 30% of infections caused N. farcinica.

METHODS

Case report and review of the literature.

RESULTS

A case of primary brain abscess caused by N. farcinica, identified by 16SrRNA sequencing, is presented, and 39 cases reported previously in the literature are reviewed. Our patient underwent a neuronavigation-guided right frontal craniotomy and was treated with trimethoprim/sulfamethoxazole and amoxicillin-clavulanic acid for 12 mo. He showed marginal improvement in his prior left hemiparesis at the last review 14 months later.

CONCLUSION

Cases of N. farcinica infections are being reported increasingly because of recent changes in taxonomy and diagnostic methodology. This change in epidemiology has implications for therapy because of the organism's pathogenicity and natural resistance to multiple antimicrobial agents, including third-generation cephalosporins. Any delay in starting appropriate antibiotic therapy can have adverse consequences.

Disseminated Nocardia farcinica: literature review and fatal outcome in an immunocompetent patient

BACKGROUND

Nocardia farcinica is a gram-positive, partially acid-fast, methenamine silver-positive aerobic actinomycete. Nocardia spp. are opportunistic pathogens, and N. farcinica is the least common species of clinical importance.

METHODS

Review of the recent literature and description of a immunocompetent patient with no known risk factors who contracted fatal N. farcinica sepsis.

RESULTS

Positive pre-mortem and post-mortem cultures from the lung and synovium correlated with acute bronchopneumonia and synovitis at autopsy. Colonies of filamentous bacteria, which were not apparent in conventional hematoxylin and eosin-stained sections, were observed with gram and methenamine silver stains, but acid-fast stains were negative. A literature review revealed that disseminated N. farcinica often is associated with an underlying malignant tumor or autoimmune disease (88% of patients). Chemotherapy or corticosteroid treatments are additional risk factors.

CONCLUSIONS

Trimethoprim-sulfamethoxazole typically is the first-line therapy for N. farcinica; treatment with amikacin and imipenem-cilastatin is used less often (7% of patients). Despite aggressive therapy, we observed that the death rate (39%) associated with N. farcinica in recent publications was eight percentage points higher than reported in a review from 2000.

[Case report of nocardia brain abscess that needs to be distinguished from metastatic brain tumor]

We report a 62-year-old woman presenting with nocardia brain abscess that mimics metastatic brain tumor. Six months before admission to our hospital, she presented with persistent hemoptysis, and a friable endobronchial mass was detected at another hospital. However, a definite diagnosis had not been made, and then she presented with hemianopia. Her laboratory analysis results showed that she had no immunological abnormalities. T1-weighted magnetic resonance images of the brain with Gd-DTPA revealed hyperintensive multiple masses with surrounding edema. We suspected this case as metastatic brain tumor of unknown origin, and the patient underwent biopsy of the supraclavicular lymph node. Histopathology results indicated abscess, and gram staining of material obtained from the abscess showed Gram-variable rods, which were determined upon culture as acid-fast Gram-positive branching rods and identified as Nocardia asteroides. Accordingly, we diagnosed the patient as having nocardia brain abscess, and she was treated with an oral antibiotic (TMP-SMX). Four months later, the abscesses disappeared. The patient recovered after prolonged TMP-SMX therapy with no recurrence in over 9 months.

Two cases of multidrug-resistant Nocardia farcinica infection in immunosuppressed patients and implications for empiric therapy

Presented here are two cases of multidrug-resistant Nocardia farcinica infection that occurred in immunocompromised patients. One of the patients developed the infection despite being on trimethoprim/sulfamethoxazole prophylaxis for Pneumocystis jiroveci. These cases demonstrate the propensity of Nocardia spp. to cause disseminated disease and to develop resistance to multiple antimicrobial agents used in the initial treatment of serious Nocardia infection. These factors lead to the conclusion that empiric monotherapy with trimethoprim/sulfamethoxazole may not be sufficient. Treatment with a combination regimen of imipenem and amikacin may be a more promising initial therapy.

Diagnosis and management of brain abscess and subdural empyema

Advances in the diagnosis and treatment of brain abscess and subdural empyema with neuroimaging techniques such as computerized tomography, magnetic resonance imaging, magnetic resonance spectroscopy, the availability of new antimicrobials, and the development of novel surgical techniques have significantly contributed to the decreased morbidity and mortality associated these infections. Determination of point of entry and source of infection is paramount to adequate treatment. A high index of suspicion along with typical clinical presentation of headache, seizures, or focal neurologic signs can lead to early diagnosis so that effective therapy can be instituted as soon as possible. This review discusses etiology and pathology of brain abscess and subdural empyema, neuroimaging techniques useful in the diagnosis, and optimal treatment, including use of antimicrobials and surgical procedures.

Disseminated Nocardia transvalensis infection with osteomyelitis and multiple brain abscesses

A case of Nocardia transvalensis osteomyelitis and cerebral abscesses is described. To the authors' knowledge, the patient described here represents the first reported case of primary N. transvalensis leg abscess with contiguous osteomyelitis of the femur and secondary brain abscesses. The literature on nocardial osteomyelitis and cerebral nocardiosis is reviewed, and treatment of both conditions is discussed. The interactions between the immune system and nocardial organisms are described, as well as the host defense defects in diabetic patients as they relate to pathogenicity of the bacteria. Finally, the patient's paradoxical therapeutic response of resolving brain abscesses with concomitant unresolving osteomyelitis is discussed, as well as its implications for managing similar cases in the future.

Nocardia brain abscess misinterpreted as cerebral infarction

We present the case of a non-immunocompromised man with right-sided hemiparesis and aphasia thought to be caused by cerebral infarction, but which in the later clinical course evolved to be a nocardia brain abscess that needed surgical intervention. Misinterpretation of imaging combined with the absence of clinical signs of infection led to inadequate primary treatment

Treatment and outcome of nocardia keratitis

OBJECTIVE

To report our experience in treatment and outcome ofNocardia keratitis.

METHODS

Medical and microbiology records of seven cases of culture-provenNocardia keratitis seen between January 1997 and March 1999 were reviewed retrospectively. In all patients, corneal scrapings were obtained for direct microscopic evaluation and culture. Drug sensitivity was determined by the Kirby-Bauer disk-diffusion method. The minimum inhibitory concentration of ciprofloxacin and amikacin for these isolates was determined by agar dilution method. Response to medical therapy and the end result were analyzed.

RESULTS

By the in vitro Kirby-Bauer disk-diffusion techniques, all isolates were sensitive to amikacin; six of these isolates were sensitive to gentamicin and four were sensitive to ciprofloxacin. The minimum inhibitory concentration (MIC) of amikacin for all isolates by the agar-dilution technique was well below the MIC breakpoint forNocardia resistance, whereas the MIC of ciprofloxacin was above the MIC breakpoint forNocardia resistance. All patients responded to medical therapy. The corneal infection resolved in three patients after treatment with ciprofloxacin, in one patient after fortified gentamicin, and in three patients after fortified amikacin. Outcome details were available for six patients. There was good visual recovery in four patients, with visual acuity of 20/25 or better in three. The cornea of two patients developed nonvascularized scars, and in four patients in whom the infiltrates were peripheral, vascularization was seen.

CONCLUSIONS

Although patients ofNocardia keratitis may respond to other antibiotics, amikacin appears to be a drug of choice. In this small series, when appropriate therapy was initiated,Nocardia keratitis resolved promptly with good visual recovery.

In vitro activities of linezolid against multiple Nocardia species

Linezolid was tested by broth microdilution against 140 clinical Nocardia isolates belonging to seven species. The MIC at which 50% of the strains are inhibited (MIC50) and MIC90 for all species other than Nocardia farcinica were 2 and 4 microg/ml. Linezolid is the first antimicrobial agent demonstrated to be active against all Nocardia species.

Carbapenems and monobactams: imipenem, meropenem, and aztreonam

Imipenem and meropenem, members of the carbapenem class of beta-lactam antibiotics, are among the most broadly active antibiotics available for systemic use in humans. They are active against streptococci, methicillin-sensitive staphylococci, Neisseria, Haemophilus, anaerobes, and the common aerobic gram-negative nosocomial pathogens including Pseudomonas. Resistance to imipenem and meropenem may emerge during treatment of P. aeruginosa infections, as has occurred with other beta-lactam agents; Stenotrophomonas maltophilia is typically resistant to both imipenem and meropenem. Like the penicillins, the carbapenems have inhibitory activity against enterococci. In general, the in vitro activity of imipenem against aerobic gram-positive cocci is somewhat greater than that of meropenem, whereas the in vitro activity of meropenem against aerobic gram-negative bacilli is somewhat greater than that of imipenem. Daily dosages may range from 0.5 to 1 g every 6 to 8 hours in patients with normal renal function; the daily dose of meropenem, however, can be safely increased to 6 g. Infusion-related nausea and vomiting, as well as seizures, which have been the main toxic effects of imipenem, occur no more frequently during treatment with meropenem than during treatment with other beta-lactam antibiotics. The carbapenems should be considered for treatment of mixed bacterial infections and aerobic gram-negative bacteria that are not susceptible to other beta-lactam agents. Indiscriminate use of these drugs will promote resistance to them. Aztreonam, the first marketed monobactam, has activity against most aerobic gram-negative bacilli including P. aeruginosa. The drug is not nephrotoxic, is weakly immunogenic, and has not been associated with disorders of coagulation. Aztreonam may be administered intramuscularly or intravenously; the primary route of elimination is urinary excretion. In patients with normal renal function, the recommended dosing interval is every 8 hours. Patients with renal impairment require dosage adjustment. Aztreonam is used primarily as an alternative to aminoglycosides and for the treatment of aerobic gram-negative infections. It is often used in combination therapy for mixed aerobic and anaerobic infections. Approved indications for its use include infections of the urinary tract or lower respiratory tract, intra-abdominal and gynecologic infections, septicemia, and cutaneous infections caused by susceptible organisms. Concurrent initial therapy with other antimicrobial agents is recommended before the causative organism has been determined in patients who are seriously ill or at risk for gram-positive or anaerobic infection.

Injury-induced physiological events that may modulate gene expression in neurons and glia

Damage to the brain triggers a host of reactive responses in neurons and glia which are seen at sites of focal injury as well as at sites that are at a distance from the injury. Although many of these responses have been studied extensively, the signals that initiate the different responses have not been fully characterized, and it is still not understood how focal injury affects neurons and glia in distant sites. The present review summarizes recent findings that suggest that physiological events that occur at the time of the injury or during the early postlesion period can play an important and variable role in modulating neuronal and glial responses to injury. We focus on the events that occur in the hippocampal formation following unilateral lesions of the entorhinal cortex - a model system that has been used extensively for studies of cellular responses following focal brain injury. This lesion destroys the cells of origin of a massive excitatory projection to the dentate gyrus and hippocampus proper. Over time, the denervated neurons in the hippocampal formation are almost completely reinnervated as a result of local sprouting of systems that survive the lesion. Thus, this model system has been useful for studying cellular responses to both denervation and reinnervation. We summarize the information that this injury triggers physiological events that can strongly modulate gene expression in neurons and glia, including episodes of spreading depression that occur at the time of the injury, seizures that occur during the early postlesion period, the loss of afferent drive which leads to decreases in postsynaptic activity, and the restoration of activity that occurs in conjunction with reinnervation. We describe recent studies which suggest that some of these physiological events occur to a variable extent in different animals, especially the episodes of spreading depression and the recurrent seizures. Thus, the spatial pattern and temporal dynamics of altered gene expression following this "model" experimental injury may vary from animal to animal. The fact that physiological events strongly modulate the reactive changes in gene expression that occur following injury has important implications for understanding the sequelae of injury, and offers new opportunities for experimental and therapeutic interventions that may improve cellular repair, regeneration, and recovery of function.

First reported Nocardia otitidiscaviarum infection in an AIDS patient in Italy

Nocardiosis is a well-described infection in immunocompromised patients, and has been rarely documented in patients with AIDS. Nocardia asteroides is the most frequently isolated etiologic agent. Rare cases are due to N. brasiliensis and N. otitidiscaviarum. This work describes the first case of nocardiosis in Italy caused by N. otitidiscaviarum in an AIDS patient. A 31 year-old intravenous drug abuser with a diagnosis of full-blown AIDS, presented with high fever and lymphadenitis with a fistula draining copious purulent discharge. Broad-spectrum antibiotic therapy was initiated, but the patient did not shown any improvement. Direct examination of the pus revealed numerous gram positive rods. When cultured N. otitidiscavarium was isolated and identified by morphological and biochemical tests.

Nocardia species: host-parasite relationships

The nocardiae are bacteria belonging to the aerobic actinomycetes. They are an important part of the normal soil microflora worldwide. The type species, Nocardia asteroides, and N. brasiliensis, N. farcinica, N. otitidiscaviarum, N. nova, and N. transvalensis cause a variety of diseases in both normal and immunocompromised humans and animals. The mechanisms of pathogenesis are complex, not fully understood, and include the capacity to evade or neutralize the myriad microbicidal activities of the host. The relative virulence of N. asteroides correlates with the ability to inhibit phagosome-lysosome fusion in phagocytes; to neutralize phagosomal acidification; to detoxify the microbicidal products of oxidative metabolism; to modify phagocyte function; to grow within phagocytic cells; and to attach to, penetrate, and grow within host cells. Both activated macrophages and immunologically specific T lymphocytes constitute the major mechanisms for host resistance to nocardial infection, whereas B lymphocytes and humoral immunity do not appear to be as important in protecting the host. Thus, the nocardiae are facultative intracellular pathogens that can persist within the host, probably in a cryptic form (L-form), for life. Silent invasion of brain cells by some Nocardia strains can induce neurodegeneration in experimental animals; however, the role of nocardiae in neurodegenerative diseases in humans needs to be investigated.

Use of imipenem in the treatment of pulmonary nocardiosis

A case of pulmonary nocardiosis with empyema in a 55-year-old man with macroglobulinemic lymphoma is presented. Treatment with imipenem followed by oral trimethoprim-sulfamethoxazole (TMP-SMX) resolved his symptoms and cleared the roentgenographic abnormalities. This case illustrates the clinical potential of imipenem against Nocardia.

Successful treatment of concomitant pulmonary nocardiosis and aspergillosis in an immunocompromised renal patient

A case is reported of rapid onset concomitant pulmonary infection with Nocardia and Aspergillus fumigatus in a patient six weeks after the institution of immunosuppressive therapy for renal vasculitis. Pulmonary lesions completely resolved on treatment with a combination of imipenem, cotrimoxazole and a prolonged course of itraconazole.