Distribution of nocardia species in clinical samples and their routine rapid identification in the laboratory

Nocardia species prevalent in India and their antimicrobial susceptibility profiles

BACKGROUND

Nocardia species causes a wide spectrum of infection mainly in immunocompromised patients. Successful treatment of nocardiosis depends on accurate identification of the species as susceptibility profile varies for different species. In this study we describe the drug susceptibility pattern for different Nocardia species in India.

MATERIALS AND METHOD

We conducted a retrospective study from 2017 to 2022. Nocardia species were identified by Matrix assisted laser desorption ionization time of flight and in vitro susceptibility testing was carried out by broth microdilution against 7 antimicrobial agents.

RESULTS

The most common species isolated was N. cyriacigeorgica (n = 18/62; 29 %). Antimicrobial susceptibility testing was performed on 55 isolates. All tested isolates were susceptible to linezolid and 96 % susceptible to amikacin. Varying susceptibility profile was observed for other drugs for Nocardia species.

CONCLUSION

Antimicrobial susceptibility can vary for different Nocardia spp. and can impact the management of nocardiosis. It remains a priority to identify these patterns for local guidelines.

Metagenomic analysis identifying a polymicrobial pulmonary infection in a non-HIV immunocompromised patient: a case report

BACKGROUND

Polymicrobial pulmonary infections, common in immunocompromised patients, often manifest more severe symptoms than monomicrobial infections. Clinical diagnosis delays may lead to mortality, emphasizing the importance of fast and accurate diagnosis for these patients. Metagenomic next-generation sequencing (mNGS), as an unbiased method capable of detecting all microbes, is a valuable tool to identify pathogens, particularly in cases where infections are difficult to diagnosis using conventional methods.

CASE PRESENTATION

A 50-year-old male patient was admitted due to cough, expectoration and dyspnea. CT scan revealed diffuse inflammatory and cavernous lung lesion, and blood examination suggested a polymicrobial infection. However, no etiology was found by routine examination. mNGS of bronchoalveolar lavage fluid(BALF)simultaneously detected the presence of Pneumocystis jirovecii (P.jirovecii), Aspergillus fumigates (A.fumigates), Nocardia farcinica (N.farcinica), Salmonella enterica subsp. enterica (S.enterica subsp. enterica), and cytomegalovirus (CMV). The patient was successfully treated with compound sulfamethoxazole (SMZ-TMP), cefoperazone/sulbactam (SCF), moxifloxacin (MXF), voriconazole (VCZ), and ganciclovir. The patient recovered after two weeks of anti-infection therapy and maintained good health at a six-month follow-up.

CONCLUSION

For immunocompromised patients with multiple infections and atypical symptoms, mNGS emerged as a reliable approach to pathogen detection and guiding antibiotic therapy.

Discovery of Novel Diagnostic Biomarkers for Common Pathogenic Nocardia Through Pan-Genome and Comparative Genome Analysis, with Preliminary Validation

The aim of this study was to reveal diagnostic biomarkers of considerable importance for common pathogenic Nocardia, utilizing pan-genomic and comparative genome analysis to accurately characterize clinical Nocardia infections. In this study, complete or assembled genome sequences of common pathogenic Nocardia and closely related species were obtained from NCBI as discovery and validation sets, respectively. Genome annotation was performed using Prokka software, and pan-genomic analysis and extraction of Nocardia core genes were performed using BPGA software. Comparative genome analysis of these core genes with the validation-set gene sequences was then performed using BLAT, with a threshold of 30% amino acid coverage and identity, in order to distinguish specific core genes. Finally, candidate gene-specific primers were designed using Snapgene software and DNA samples were obtained from clinical Nocardia strains and closely related species for validation. The analysis identified eighteen core genes specific to Nocardia spp., four core genes specific to N. farcinica, and forty-six core genes specific to N. cyriacigeorgica. After rigorous clinical validation, one gene from Nocardia spp. and five genes from N. cyriacigeorgica were confirmed to have high specificity and therefore can be used as reliable biomarkers for accurate diagnosis of Nocardia infection. This pioneering research reveals diagnostic biomarkers of considerable significance, with the potential to substantially enhance the precise diagnosis of common pathogenic Nocardia infections, thereby laying the groundwork for innovative diagnostic methodologies in subsequent studies.

The species distribution and antimicrobial resistance profiles of Nocardia species in China: A systematic review and meta-analysis

BACKGROUND

Nocardia species can cause local or disseminated infection. Prompt diagnosis and appropriate treatment of nocardiosis are required, because it can cause significant morbidity and mortality. Knowledge of local species distribution and susceptibility patterns is important to appropriate empiric therapy. However, knowledge on the epidemiology and antimicrobial susceptibility profiles of clinical Nocardia species remains limited in China.

METHODS

The data of isolation of Nocardia species were collected from databases such as Pubmed, Web of Science, Embase as well as Chinese databases (CNKI, Wanfang and VIP). Meta-analysis was performed using RevMan 5.3 software. Random effect models were used and tested with Cochran's Q and I2 statistics taking into account the possibility of heterogeneity between studies.

RESULTS

In total, 791 Nocardia isolates were identified to 19 species levels among all the recruited studies. The most common species were N. farcinica (29.1%, 230/791), followed by N. cyriacigeorgica (25.3%, 200/791), N. brasiliensis (11.8%, 93/791) and N. otitidiscaviarum (7.8%, 62/791). N. farcinica and N. cyriacigeorgica are widely distributed, N. brasiliensis mainly prevalent in the Southern, N. otitidiscaviarum mainly distributed in the east coastal provinces of China. Totally, 70.4% (223/317) Nocardia were cultured from respiratory tract specimens, 16.4% (52/317) from extra-pulmonary specimens, and 13.3% (42/317) from disseminated infection. The proportion of susceptible isolates as follows: linezolid 99.5% (197/198), amikacin 96.0% (190/198), trimethoprim-sulfamethoxazole 92.9% (184/198), imipenem 64.7% (128/198). Susceptibility varied by species of Nocardia.

CONCLUSIONS

N. farcinica and N. cyriacigeorgica are the most frequently isolated species, which are widely distributed in China. Pulmonary nocardiosis is the most common type of infection. Trimethoprim-sulfamethoxazole can still be the preferred agent for initial Nocardia infection therapy due to the low resistance rate, linezolid and amikacin could be an alternative to treat nocardiosis or a choice in a combination regimen.

Pulmonary nocardiosis: Risk factors and species distribution from a high burden centre

Nocardiosis is a clinical and diagnostic challenge. This was a retrospective study carried out on cases of pulmonary nocardiosis presenting over 15 years. Clinical data was retrieved using the electronic patient records. Vitek MS 3.2 (MALDI TOF MS) was carried out on 22 isolates and sequencing on another 9 isolates. Of 71 patients presenting with pulmonary nocardiosis, 58 (81.6%) were on immunosuppressant therapy, 26 (46%) had a previous lung pathology, 11 (8%) were HIV associated. Disseminated disease was seen in 6 (8.4%). There were 8 (11.26%) deaths in this cohort of patients. Of 31/71 identified to species, the most common were Nocardia cyriacigeorgica (n ​= ​11) followed by Nocardia farcinica (n ​= ​9).

Identification and antimicrobial susceptibility of referred Nocardia isolates in Victoria, Australia 2009-2019

Introduction. Nocardia is an opportunistic pathogen that can cause significant morbidity and mortality, particularly in the immunocompromised host. Antimicrobial susceptibility profiles vary across Nocardia spp. and vary within Australia as well as worldwide. Knowledge of local susceptibility patterns is important in informing appropriate empiric antimicrobial therapy.Gap Statement. This is the largest study to date in Australia that correlates antimicrobial susceptibility profiles with molecular identification of Nocardia species. It is the first study that examines isolates from multiple institutions across the state of Victoria, Australia.Aim. To investigate the species distribution and antibiotic susceptibility of Nocardia spp. isolates referred to the Mycobacterial Reference Laboratory (MRL) in Victoria, Australia from 2009 to 2019.Methodology. We conducted a retrospective review of Nocardia spp. isolates which were identified using molecular sequencing. Antimicrobial susceptibility testing was performed using standardized broth microdilution method with Sensititre RAPMYCO1 plates. Species distribution and antibiotic susceptibility profiles were analysed.Results. In total, 414 Nocardia isolates were identified to 27 species levels, the majority originating from the respiratory tract (n=336, 81.2 %). N. nova (n=147, 35.5 %) was the most frequently isolated, followed by N. cyriacigeorgica (n=75, 18.1 %). Species distribution varied by isolate source, with N. farcinica and N. paucivorans found more commonly from sterile sites. Linezolid and amikacin had the highest proportion of susceptible isolates (100 and 99% respectively), while low susceptibility rates were detected for ceftriaxone (59 %) and imipenem (41 %). Susceptibility to trimethoprim sulfamethoxazole varied by species (0-100 %).Conclusion. This is the largest study to date in Australia of Nocardia species distribution and antimicrobial susceptibility patterns. N. farcinica and N. paucivorans were more likely to be isolated from sterile sites, while N. brasiliensis and N. otitidiscvarium were more likely to be isolated from skin and soft tissue. First line therapeutic antimicrobial recommendations by local guidelines were not necessarily reflective of the in vitro susceptibility of Nocardia isolates in this study, with high susceptibility detected for linezolid and amikacin, but poor susceptibility demonstrated for ceftriaxone and imipenem. Profiles for trimethoprim-sulfamethoxazole varied across different Nocardia species, warranting ongoing susceptibility testing for targeted clinical use.

Misdiagnosed tuberculosis being corrected as Nocardia farcinica infection by metagenomic sequencing: a case report

Background

Disseminated nocardiosis is liable to be misdiagnosed owing to the non-specific clinical manifestations and laboratory/imaging findings. Metagenomic next-generation sequencing (mNGS) is a culture-independent and rapid method for direct identification of all microorganisms in clinical specimens.

Case presentation

A 72-year-old man was admitted to our hospital on February 20, 2019 with a history of recurrent cough, expectoration, fever, and diarrhea since 1 month, and unconsciousness since 1 week. Contrast-enhanced magnetic resonance imaging of head showed multiple lesions in the bilateral cerebral hemispheres, brainstem, and cerebellar hemispheres. The presumptive diagnosis was disseminated tuberculosis, although all tests for mycobacterium were negative. However, the patient did not benefit from antituberculosis treatment. Repeat MRI showed multiple abnormal signals in the brain and progression of meningeal thickening. Cerebrospinal fluid and bronchoalveolar lavage fluid specimens were subsequently sent for PMSeq metagenomics sequencing; the results indicated Nocardia. farcinica as the predominant pathogen. The anti-TB treatment was stopped and the patient was prescribed sulphamethoxazole in combination with linezolid and meropenem for nocardiosis. He showed gradual neurological improvement and was transferred to Huashan Hospital. He was discharged from the hospital on April 19, 2019, but died of persistent diarrhea on May 26, 2019.

Conclusions

Patients with suspected nocardiosis do not always respond to conventional treatment; therefore, mNGS can facilitate diagnosis and timely treatment decision-making.

Invasive Nocardiosis in Transplant and Nontransplant Patients: 20-Year Experience in a Tertiary Care Center

Objective

To present the clinical characteristics and outcome of transplant and nontransplant patients with invasive nocardiosis.

Patients and Methods

We conducted a retrospective chart review of 110 patients 18 years and older diagnosed with culture-proven invasive nocardiosis (defined as the presence of clinical signs and/or radiographic abnormalities) between August 1, 1998, and November 30, 2018. Information on demographic, clinical, radiographic, and microbiological characteristics as well as mortality was collected.

Results

One hundred ten individuals with invasive nocardiosis were identified, of whom 54 (49%) were transplant and 56 nontransplant (51%) patients. Most transplant patients were kidney and lung recipients. The overall mean age was 64.9 years, and transplant patients had a higher prevalence of diabetes and chronic kidney disease. A substantial proportion of nontransplant patients were receiving corticosteroids (39%), immunosuppressive medications (16%), and chemotherapy (9%) and had chronic obstructive pulmonary disease (20%), rheumatologic conditions (18%), and malignant neoplasia (18%). A higher proportion of transplant patients (28%) than nontransplant patients (4%) received trimethoprim-sulfamethoxazole prophylaxis. In both groups, the lung was the most common site of infection. Seventy percent of all Nocardia species isolated were present in almost equal proportion: N brasiliensis (16%), N farcinica (16%), N nova (15%), N cyriacigeorgia (13%), and N asteroides (11%). More than 90% of isolates were susceptible to trimethoprim-sulfamethoxazole, linezolid, and amikacin. There was no significant difference in mortality between the 2 groups at 1, 6, and 12 months after the initial diagnosis.

Conclusion

The frequency of invasive Nocardia infection was similar in transplant and nontransplant patients and mortality at 1, 6, and 12 months was similar in both groups. Trimethoprim-sulfamethoxazole prophylaxis failed to prevent Nocardia infection.

Revisiting nocardiosis at a tertiary care institution: Any change in recent years?

OBJECTIVE

To analyse relevant changes in incidence, clinical and microbiological characteristics of nocardiosis over the last 24 years at the current institution.

MATERIALS AND METHODS

The clinical records of patients with nocardiosis (2006-2018) were reviewed and then compared with a previous cohort (1995-2006). Nocardia isolates were identified by 5'-end-16S-rRNA-gene-PCR targeting the first 500 bp of the gene and sequencing. Susceptibility tests were determined by broth microdilution (CLSI guidelines).

RESULTS

Forty-two patients (64.3% male) with nocardiosis were evaluated in the recent cohort: 51.2% had COPD, 43.9% were on corticosteroid therapy and 31.7% had cancer. The incidence of nocardiosis varied from 6.3 to 7.1/100,000 admissions (p = 0.62). There was a decrease in HIV patients (27% vs. 4.9%, p = 0.01) and solid organ transplantation (SOT) recipients (18.9% vs. 2 .4%, p = 0.01). Cases with pulmonary involvement had increased (70.3% vs. 90.5%, p = 0.04). Nocardia species were similar but the most common were N. cyriacigeorgica (32.4% vs. 40.5%, p = 0.49) and N. farcinica (24.3% vs. 14.3%, p = 0.39). Antibiotic resistance remained stable: cotrimoxazole (10.8% vs. 5.7%, p = 0.68), imipenem (5.4% vs. 5.6%, p = 1.0); amikacin and linezolid were 100% active. No differences were found in breakthrough nocardiosis (21.6% vs. 9.8%, p = 0.21) or related mortality (21.6% vs. 21.4%, p = 1.0). The multivariate analysis confirmed that nocardiosis caused by N. farcinica is a risk factor for poor outcome (p = 0.045).

CONCLUSIONS

Nocardiosis incidence has remained stable. It mainly affected elderly patients with chronic respiratory conditions and those on corticosteroid treatment. Infections in HIV and SOT patients have practically disappeared. Pulmonary involvement remains the most common area to be affected. Nocardiosis caused by N. farcinica is apparently a risk factor for poor clinical outcome.

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.

[Sporotrichoid nocardiosis by Nocardia brasiliensis]

Nocardia brasiliensis is a gram-positive, branched, aerobic, acid-resistant, rod-shaped bacillus that inhabits in soil, rotten organic matter and waters. Cutaneous nocardiosis in immunocompetent individuals can manifest in three different forms: actinomycetoma, superficial skin infection or lymphocutaneous infection. A case of an 85-year-old woman with an ulcerated lesion on the back of her left hand with erythematous papules in the lymphatic tract infected by N. brasiliensis is described. The microorganism was presumptively identified by conventional and inexpensive methods for a medium complexity laboratory at the species level. The morphological characteristics of colonies, the mold smell, a positive Kinyoun stain and the presence of aerial mycelium were the key tests to identify the genus. Species level identification was confirmed by mass spectrometry (MALDI-TOF MS). The trimethoprim-sulfamethoxazole treatment was effective as this agent was active in the susceptibility testing.

Clinical manifestations of nocardiosis: Study of risk factors and outcomes in a tertiary care hospital

PURPOSE

The aim of this study is to evaluate the predisposing risk factors, clinical presentations, laboratory parameters, and treatments taken and outcomes in patients of nocardiosis in the span of 5 years in a tertiary care hospital.

MATERIALS AND METHODS

The patients whose specimens showed Nocardia like organism in Gram-staining, Kinyoun staining and characteristic colonies in culture were included in the retrospective analysis study. Retrospective analysis of associated risk factors, clinical presentations, and radiological findings was performed.

RESULTS

Of the thirteen patients, 11 (76.9%) had immunosuppressive pathologies including solid organ transplantation, autoimmune disease, use of steroids, and immunosuppressive drugs as important risk factors. Four types of clinical manifestations were observed, pulmonary (46.1%), cutaneous (23.07%), cerebral (15.3%), and bacteremia (15.3%). The most common presentation was pulmonary with steroid therapy as a significant risk factor. Consolidation and pleural effusion were the common radiological findings in these cases. In eight of the nine patients anti-nocrdial drugs were given. Cotrimoxazole as monotherapy was given in four cases (44.44%), cotrimoxazole in combination with meropenem in two cases (22.22%); minocycline and linezolid were given in one case each. The overall mortality was 36.36% and was seen in patients with pulmonary nocardiosis.

CONCLUSIONS

The study indicates that Nocardial infections are re-emerging on account of an increase in numbers of immunocompromised patients due to increased organ transplants, autoimmune diseases, malignancies, and use of immunosuppressive drugs and steroids. The diagnosis is often missed/not suspected and delayed because of the clinical resemblance to many other infections. Nocardial infection should be suspected and assessed particularly in immunocompromised patients not responding to treatment/improving clinically.

Nocardiosis: A Neglected Disease

Nocardiosis is a neglected tropical disease. It has varied geographical presence and a spectrum of clinical presentations. This review aims to focus on the epidemiology of nocardial infections with a systematic approach to their diagnosis and treatment. Nocardiacauses chronic infections and ailments, and may remain cryptic but progressive in its course. Unless suspected, diagnosis can be easily missed resulting in increased morbidity and mortality. Thorough knowledge of local epidemiology, demography, clinical course and presentation, diagnostic modalities, and antibiotic susceptibility patterns of the prevalent Nocardia species is essential to curb spread of this infection. This is a systematic review in which internet search has been done for citation indices (Embase, PubMed, Ovid, and other individual journals) till March 2020 utilizing the following key words "Nocardia," "taxonomy," "prevalence," "clinical features," "diagnosis," "treatment," and "susceptibility." We selected a total of 87 review articles, case series, and case reports all in English language.

Nocardiosis: 7-year experience at an Australian tertiary hospital

BACKGROUND

Nocardiosis has historically been reported in immunocompromised patients, but Australian epidemiological and antimicrobial susceptibility data are limited.

AIM

To describe the epidemiology, diagnosis and initial treatment of nocardiosis in an Australian tertiary hospital over 7 years.

METHODS

In this retrospective study, all positive cultures for Nocardia species from any site isolated at the Alfred Hospital, Melbourne, between 1 January 2010 and 31 December 2016 were identified, and corresponding laboratory data and medical records reviewed.

RESULTS

Sixty-eight non-duplicate isolates were identified from 67 patients. Common predisposing factors were chronic lung disease (38/67; 57%), organ, particularly lung, transplantation (13/67; 19%) and solid organ malignancy (6/67; 9%); 12% (8/67) of patients had no identifiable systemic risk factors. Seventy-nine percent (53/67) of patients had pulmonary nocardiosis only. Nocardia nova was the most commonly isolated species (20/68; 29%). In 48% (32/67) of patients, Nocardia species were isolated only on specific mycobacterial media. All tested species were susceptible to sulfamethoxazole-trimethoprim and amikacin, with the majority (58/63; 92%) susceptible to imipenem. All-cause mortality rates at 6 and 12 months where data were available were 15% (10/66 patients) and 22% (14/64 patients) respectively.

CONCLUSION

In the largest Australian series in 25 years, nocardiosis predominantly affected patients with chronic lung disease or impaired cell-mediated immunity. A significant proportion of organisms from pulmonary sites were isolated on mycobacterial culture media only, suggesting that its use may improve yield. Isolates remain highly susceptible to sulfamethoxazole-trimethoprim, amikacin and imipenem, while other agents should be used only after confirmation of in vitro susceptibility.

Antimicrobial susceptibility profiles and species distribution of medically relevant Nocardia species: Results from a large tertiary laboratory in Australia

OBJECTIVES

There are limited surveillance studies on the epidemiology and resistance rates ofNocardia spp. in Australia, particularly in the jurisdiction of New South Wales. This study aimed to investigate the species distribution and antimicrobial susceptibility of a large number of contemporary (2011-2016) clinical Nocardia spp. referred to a large tertiary hospital in Sydney, Australia.

METHODS

A total of 270Nocardia spp. isolates identified to species level by dual-target gene sequencing were investigated. Antimicrobial susceptibility testing was performed using a Sensititre™ RAPMYCOI panel, with the minimum inhibitory concentration (MIC) range and geometric mean MIC obtained for each species and drug combination. Antimicrobial susceptibility profiles and species distribution were analysed.

RESULTS

The respiratory system is the most affected site in nocardiosis. In this study, Nocardia nova complex was the most frequently isolated Nocardia spp. (n = 80; 29.6%), followed by Nocardia cyriacigeorgica (n = 61; 22.6%), Nocardia brasiliensis (n = 52; 19.3%) and Nocardia farcinica (n = 38; 14.1%). Of the tested isolates, 9.3% and 59.3% displayed resistance to trimethoprim/sulfamethoxazole (SXT) and imipenem, respectively. Nocardia farcinica accounted for the highest number of SXT-resistant isolates. High imipenem resistance in N. cyriacigeorgica is atypical to its drug pattern but has been reported elsewhere. All tested isolates remained susceptible to linezolid, with only 0.7% exhibiting resistance to amikacin.

CONCLUSION

Linezolid and amikacin remain good empirical options for treatment of nocardiosis. Routine antimicrobial susceptibility testing ofNocardia is advisable with the detection of sulfonamide resistance and atypical antibiograms in this study.

Cost-effective implementation of a custom MALDI-TOF library for the identification of South Australian Nocardia isolates

Mass spectrometry plays a significant role in the routine identification of micro-organisms and provides the ability to incorporate newly found pathogens into the database in a cost-effective fashion. This work aims to highlight the role of mass spectrometry through improved identification of Nocardia species in a diagnostic clinical microbiology laboratory. Prior to this study we constructed a custom in-house matrix-assisted laser desorption ionisation-time of flight (MALDI-TOF) library for Nocardia isolates consisting of isolates identified to the species level. Subsequently over a period of 5 years, we isolated a further 153 Nocardia clinical isolates, of which 91.5% (140/153) were identified correctly with the custom MALDI-TOF library and 8.5% (13/153) needed further molecular sequencing for final identification. We estimate our cost savings to be approximately 9,800 AUD overall with this implementation over the study period. Continued expansion and maintenance of this custom library will eventually result in little or no 16S ribosomal DNA sequencing needed for specific identification of Nocardia isolates.

Pulmonary infection caused by Nocardia cyriacigeorgica in a patient with allergic bronchopulmonary aspergillosis: A case report

RATIONALE

Nocardia species is known as conditional pathogenic bacteria. Among Nocardia species, pulmonary infection caused by Nocardia cyriacigeorgica associated with Aspergillus fumigatus complex lung disease is rarely reported.

PATIENT CONCERNS

A 55-year-old female with a history of productive cough with recurrent expectoration for 20 years presented with increasing cough for 12 months. The patient presented complaining of respiratory symptoms including increasing cough with yellow phlegm, poor appetite, and generalized fatigue for a week prior to admission.

DIAGNOSES

Nocardia cyriacigeorgica pneumonia was identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequencing.

INTERVENTIONS

Combined treatments (trimethoprim-sulfamethoxazole and meropenem) were administered after identification of N cyriacigeorgica.

OUTCOMES

The respiratory symptoms of the patient had improved both clinically and radiologically after 4 weeks of antibacterial therapy.

LESSONS

Early precise diagnosis and prompt combined therapy are of vital importance in severe Nocardia pulmonary infection.

Comment on a Primary Cutaneous Nocardiosis of the Hand

Nocardia spp. are gram-positive, partially acid-fast bacteria which are lives in environmental sources and cause of various infection that called nocardiosis in animals and humans. Identification of this group of bacteria was important due to accurate diagnosis, patient management and prevention of antibiotic resistant among of bacteria. Molecular methods including PCR-RFLP and sequencing using housekeeping genes such as 16S rRNA, hsp65, rpoB and gyrB are recommended to accurate and reliable identification of nocardiosis.

Nocardia arthritidis as a cause of disseminated nocardiosis in a patient with chronic lymphocytic leukemia

A case of disseminated nocardiosis caused by Nocardia arthritidis in an immunocompromised patient with a history of chronic lymphocytic leukemia and rheumatoid arthritis is presented. This report highlights the use for multilocus sequence typing (MLST) in addition to single gene molecular sequencing to identify rare Nocardia species.

Pulmonary nocardiosis in Chronic Obstructive Pulmonary Disease: A new clinical challenge

Pulmonary nocardiosis (PN) is a rare but severe disease caused by Nocardia spp. Despite the traditional description as opportunistic infection, case reports and case series of pulmonary nocardiosis have recently been reported in immunocompetent patients too, in particular among people with chronic pulmonary diseases such as advanced Chronic Obstructive Pulmonary Disease (COPD). PN is characterized by non-specific symptoms and radiological findings; bacteriological culture can be difficult. For the reasons above, diagnosis of PN is challenging, sometimes resulting in a misdiagnosis of tuberculosis. We report an interesting case of PN in a 75-year-old male with COPD. He complained a 3-months history of fatigue, evening rise in body temperature, night sweats, unexplained weight loss of 5 kg, worsening dyspnea, cough and mucopurulent sputum. The chest X-ray showed multiple nodules with cavitations bilaterally in the apical and subclavian regions. Nocardia cyriacigeorgica with 100% identity was identified in three sputum samples. Since the patient has never undergone a systemic and/or inhaled steroid therapy, and has no respiratory failure and comorbidities entailing immunodepression, it is conceivable that, in this immunocompetent patient, the COPD could represent an isolated risk factor for PN. Risk factors, clinical presentations, radiographic findings, differential diagnosis and review of the literature of PN cases in COPD, pointing out the similarities and differences, are also described.

Nocardia infections among immunomodulated inflammatory bowel disease patients: A review

Human nocardiosis, caused by Nocardia spp., an ubiquitous soil-borne bacteria, is a rare granulomatous disease close related to immune dysfunctions. Clinically can occur as an acute life-threatening disease, with lung, brain and skin being commonly affected. The infection was classically diagnosed in HIV infected persons, organ transplanted recipients and long term corticosteroid treated patients. Currently the widespread use of immunomodulators and immunossupressors in the treatment of inflammatory diseases changed this scenario. Our purpose is to review all published cases of nocardiosis in immunomodulated patients due to inflammatory diseases and describe clinical and laboratory findings. We reviewed the literature concerning human cases of nocardiosis published between 1980 and 2014 in peer reviewed journals. Eleven cases of nocardiosis associated with anti-tumor necrosis factor (TNF) prescription (9 related with infliximab and 2 with adalimumab) were identified; 7 patients had inflammatory bowel disease (IBD), 4 had rheumatological conditions; nocardia infection presented as cutaneous involvement in 3 patients, lung disease in 4 patients, hepatic in one and disseminated disease in 3 patients. From the 10 cases described in IBD patients 7 were associated with anti-TNF and 3 with steroids and azathioprine. In conclusion, nocardiosis requires high levels of clinical suspicion and experience of laboratory staff, in order to establish a timely diagnosis and by doing so avoid worst outcomes. Treatment for long periods tailored by the susceptibility of the isolated species whenever possible is essential. The safety of restarting immunomodulators or anti-TNF after the disease or the value of prophylaxis with cotrimoxazole is still debated.

Differentiation between Nocardia spp. and Mycobacterium spp.: Critical aspects for bacteriological diagnosis

New methodologies were developed for the identification of Nocardia but the initial diagnosis still requires a fast and accurate method, mainly due to the similarity to Mycobacterium, both clinical and bacteriologically. Growth on Löwenstein-Jensen (LJ) medium, presence of acid-fast bacilli through Ziehl-Neelsen staining, and colony morphology can be confusing aspects between Nocardia and Mycobacterium. This study describes the occurrence of Nocardia spp. in a mycobacterial-reference laboratory, observing the main difficulties in differentiating Nocardia spp. from Mycobacterium spp., and correlating isolates with nocardiosis cases. Laboratory records for the period between 2008 and 2012 were analyzed, and the isolates identified as Nocardia sp. or as non-acid-fast filamentous bacilli were selected. Epidemiological and bacteriological data were analyzed as well. Thirty-three isolates identified as Nocardia sp. and 22 as non-acid-fast bacilli were selected for this study, and represented 0.12% of isolates during the study period. The presumptive identification was based on macroscopic and microscopic morphology, resistance to lysozyme and restriction profiles using the PRA-hsp65 method. Nocardia spp. can grow on media for mycobacteria isolation (LJ and BBL MGIT™) and microscopy and colony morphology are very similar to some mycobacteria species. Seventeen patients (54.8%) were reported and treated for tuberculosis, but presented signs and symptoms of nocardiosis. It was concluded that the occurrence of Nocardia sp. during the study period was 0.12%. Isolates with characteristics of filamentous bacilli, forming aerial hyphae, with colonies that may be pigmented, rough and without the BstEII digestion pattern in PRA-hsp65 method are suggestive of Nocardia spp. For a mycobacterial routine laboratory, a flow for the presumptive identification of Nocardia is essential, allowing the use of more accurate techniques for the correct identification, proper treatment and better quality of life for patients.

Identification of Nocardia species using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry

BACKGROUND

The MALDI (matrix-assisted laser desorption/ionization) Biotyper system for bacterial identification has already been utilized in clinical microbiology laboratories as a successful clinical application of protoemics. However, in cases of Nocardia, mass spectra suitable for MALDI Biotyper identification are often not obtained if such specimens are processed like general bacteria. This problem is related to the insufficiencies in bacterial spectrum databases that preclude accurate specimen identification. Here, we developed a bacterial processing method to improve mass spectra from specimens of the genus Nocardia. In addition, with the new processing method, we constructed a novel in-house bacterial database that combines a commercial database and mass spectra of Nocardia strains from the Department of Clinical Laboratory at Chiba University Hospital (DCLC) and the Medical Mycology Research Center at Chiba University (MMRC).

RESULTS

The newly developed method (Nocardia Extraction Method at DCLC [NECLC]) based on ethanol-formic acid extraction (EFAE) improved mass spectra obtained from Nocardia specimens. The Nocardia in-house database at Chiba University Hospital (NDCUH) was then successfully validated. In brief, prior to introduction of the NECLC and NDCUH, 10 of 64 (15.6%) clinical isolates were identified at the species level and 16 isolates (25.0%) could only be identified at the genus level. In contrast, after the introduction, 58 isolates (90.6%) were identified at the species level and 6 isolates (9.4%) were identified at the genus level.

CONCLUSIONS

The results of this study suggest that MALDI-TOF (time-of-flight) Biotyper system can identify Nocardia accurately in a short time in combination with a simple processing method and an in-house database.

Brain Abscesses Caused by Nocardia paucivorans in a Multiple Myeloma Patient Treated with Lenalidomide and Dexamethasone: a Case Report and Review of Literature

We report the first case of multiple brain abscesses caused by Nocardia paucivorans in a patient suffering from multiple myeloma on treatment with lenalidomide and dexamethasone. N. paucivorans is a recently described species of the genus Nocardia, which is supposed to have a heightened neurotropism in cases of disseminated infection. Although nocardiosis itself is an uncommon infectious complication in multiple myeloma so far, nocardial brain abscess should be added to the spectrum of adverse effects due to this novel chemotherapy regimen.

Nocardiosis in 132 patients with cancer: microbiological and clinical analyses

OBJECTIVES

To correlate the microbiological and clinical features of infections caused by Nocardia species.

METHODS

We determined the species and drug susceptibility of 138 Nocardia strains isolated from 132 patients at the University of Texas M. D. Anderson Cancer Center (Houston, TX) from 2002 through 2012 and analyzed the clinical features.

RESULTS

The 132 patients included 82 men and 50 women with a mean age of 59.1 years. All except two had underlying cancer, and 47 (35.6%) also received a stem cell transplant. These patients experienced 136 episodes of Nocardia infection, including pulmonary infection, abscess of deep skin and soft tissue, bacteremia and dissemination, and brain abscess. The 138 Nocardia strains involved 27 species, of which 20 species have been described since 2000. Common species included Nocardia nova, Nocardia cyriacigeorgica, Nocardia farcinica, and Nocardia abscessus, together accounting for 59.4%. N nova caused most bacteremia cases, whereas N farcinica caused most of the skin and brain infections. Infections with a few recent species likely represented first confirmation or report of human infections. Antimicrobial susceptibility tests of 117 strains showed that they were all susceptible to trimethoprim-sulfamethoxazole and linezolid but variably susceptible to other drugs depending on species. Most patients who were treated for the infection showed improvement or resolution.

CONCLUSIONS

Diverse Nocardia species can cause secondary infections in patients with cancer. Timely species identification and antimicrobial susceptibility tests may guide treatment.

Dual disseminated infection with Nocardia farcinica and Mucor in a patient with systemic lupus erythematosus: a case report

INTRODUCTION

Infections remain a major cause of morbidity and mortality in immunocompromised patients and require early diagnosis and treatment. However, correct diagnosis and treatment are often delayed by a multitude of factors. We report what we believe to be the first case of a combined disseminated infection with Nocardia and Mucor in a patient with systemic lupus erythematosus.

CASE PRESENTATION

A 74-year-old Caucasian woman with systemic lupus erythematosus presented with recurrent pneumonia. Despite empirical treatment with antibiotics, her condition gradually deteriorated. Microbiological sampling by thoracoscopy revealed the presence of Nocardia. Despite the institution of therapy for disseminated nocardiosis, she died of multi-organ failure. A post-mortem investigation confirmed nocardiosis, but showed concomitant disseminated mucormycosis infection as well.

CONCLUSION

Members of the bacterial genus Nocardia and the fungal genus Mucor are ubiquitous in the environment, have the ability to spread to virtually any organ, and are remarkably resistant to appropriate therapy. Both pathogens can mimic other pathologies both on clinical and radiological investigations. Invasive sampling procedures are often needed to prove their presence. Establishing a timely, correct diagnosis and a specific treatment is essential for patient survival.

Nocardia mikamiia Novel Species Causing Disseminated Nocardiosis: A Literature Review of Disseminated Nocardiosis

Nocardiais an uncommon Gram-positive organism. It typically appears as delicate filamentous Gram-positive branching rods. In the United States it was estimated to be approximately 500 to 1000 new cases per year. The organism causes disease in immunocompromised individuals with pulmonary infection representing the most common site of infection.Nocardia mikamiihas been a recently isolated pathogen and not many cases of disseminated infection with this organism has been reported in the literature; we present a case of disseminated nocardiosis (mikamii sp.) in an immunocompromised patient. We also present a literature review on nocardiosis.

Molecular identification of nocardia isolates from clinical samples and an overview of human nocardiosis in Brazil

BACKGROUND

Nocardia sp. causes a variety of clinical presentations. The incidence of nocardiosis varies geographically according to several factors, such as the prevalence of HIV infections, transplants, neoplastic and rheumatic diseases, as well as climate, socio-economic conditions and laboratory procedures for Nocardia detection and identification. In Brazil the paucity of clinical reports of Nocardia infections suggests that this genus may be underestimated as a cause of human diseases and/or either neglected or misidentified in laboratory specimens. Accurate identification of Nocardia species has become increasingly important for clinical and epidemiological investigations. In this study, seven clinical Nocardia isolates were identified by multilocus sequence analysis (MLSA) and their antimicrobial susceptibility was also determined. Most Nocardia isolates were associated to pulmonary disease.

METHODOLOGY/PRINCIPAL FINDINGS

The majority of Brazilian human isolates in cases reported in literature were identified as Nocardia sp. Molecular characterization was used for species identification of Nocardia nova, Nocardia cyriacigeorgica, Nocardia asiatica and Nocardia exalbida/gamkensis. Data indicated that molecular analysis provided a different Nocardia speciation than the initial biochemical identification for most Brazilian isolates. All Nocardia isolates showed susceptibility to trimethoprim-sulfamethoxazole, the antimicrobial of choice in the treatment nocardiosis. N. nova isolated from different clinical specimens from one patient showed identical antimicrobial susceptibility patterns and two distinct clones.

CONCLUSIONS/SIGNIFICANCE

Although Brazil is the world's fifth-largest country in terms of land mass and population, pulmonary, extrapulmonary and systemic forms of nocardiosis were reported in only 6 of the 26 Brazilian states from 1970 to 2013. A least 33.8% of these 46 cases of nocardiosis proved fatal. Interestingly, coinfection by two clones may occur in patients presenting nocardiosis. Nocardia infection may be more common throughout the Brazilian territory and in other developing tropical countries than is currently recognized and MLSA should be used more extensively as an effective method for Nocardia identification.

Nocardiosis in transplant recipients

Nocardiosis is a rare opportunistic infection caused by Nocardia spp., an aerobic actinomycete, that mainly affects patients with cell-mediated immunity defects, such as transplant recipients. Despite recent progress regarding Nocardia identification and changes in taxonomic assignment, many challenges remain for the diagnosis or management of nocardiosis. This opportunistic infection affects 0.04 to 3.5 % of patients with solid organ or hematopoietic stem cell transplantation, depending on the organ transplanted, cytomegalovirus (CMV) infection, corticosteroids dose and calcineurin inhibitors level. Nocardiosis diagnosis relies on appropriate clinical, radiological and microbiological workup that includes the sampling of an accessible involved site and molecular microbiology tools. In parallel, extensive clinical and radiological evaluations are mandatory, including brain imaging, even in the absence of neurological signs. In transplanted patients, differential diagnosis is challenging, with co-infections reported in 20 to 64 % of cases. As the antibiotic susceptibility pattern varies among species, the antimicrobial regimen before species identification should rely on the association of antibiotics active on all species of Nocardia. Bactericidal antibiotics are required in cases of severe or disseminated disease. Furthermore, in transplant recipients, combination therapy is difficult to manage because of cumulative toxicity and interactions with immunosuppressive agents. Because of a high recurrence rate, antibiotic therapy should be prescribed for 6 to 12 months.

Co-infection with Nocardia asteroides complex and Strongyloides stercoralis in a patient with autoimmune hemolytic anemia

We describe an unusual case of pulmonary nocardiosis co-existing with Strongyloides stercoralis hyperinfection syndrome in a patient with autoimmune hemolytic anemia who was being treated with corticosteroids. This case highlights the importance of being aware of the possibility that infections can co-exist in immunosuppressed patients. To the best of our knowledge, this is the first report of co-infection with Nocardia asteroides and S. stercoralis.

Clinical spectrum and outcome of Nocardia infection: experience of 15-year period from a single tertiary medical center

INTRODUCTION

Nocardiosis, although very rare, is considered as an important opportunistic infection; however, recent literature is limited. This study describes all cases of nocardial infection treated in the authors' hospital to provide more information about clinical manifestations, species isolated, treatment and outcome of patients with nocardiosis.

METHODS

A retrospective review of the clinical features and outcome of nocardial infections was conducted during a 15-year period (1996-2010) at Rambam Health Care Campus.

RESULTS

The study included 53 patients with nocardial infection, 43 of them had underlying immunodeficiency. The most common clinical form was pulmonary nocardiosis with and without dissemination (60%), followed by skin and soft tissue infection (21%), bacteremia (11%) and pertonitis (5%). Resistance to trimethoprim/sulfamethoxazile was detected in 15% of isolates; to imipenem in 5% and to ciprofloxacin in 65%. Overall mortality was 25% (13/53), mainly observed in patients with pulmonary involvement (37.5%).

CONCLUSIONS

Nocardiosis is a rare infection and mainly affects immunocompromised patients. Higher index of suspicion is needed for earlier diagnosis and treatment to improve prognosis.

A fatal case of pulmonary nocardiosis

Pulmonary nocardiosis is a serious, most often considered an opportunistic infection affecting the respiratory tract. Even though it is more common in immunocompromised hosts, it is not infrequently seen in immunocompetent patients as well. The aerosol route is the main portal of entry in to the body. Molecular techniques have revolutionised the identification of Nocardia species. However such tests are limited to referral laboratories. The radiographic appearances of Nocardia infection vary from a small nodule to bilateral infiltrates with cavitation. Traditionally sulphonamides have been considered the treatment of choice. However, resistance to sulphonamides is increasingly recognised. Carbapenems and linezolid have been found to be uniformly active against all the pathogenic species of Nocardia that affect human beings. The authors report a case of pulmonary nocardiosis in an immunocompetent patient, in whom the infection relentlessly progressed to florid sepsis despite prompt institution of right antibiotics. Florid sepsis relating to pulmonary nocardiosis is rare.

A novel multiplex real-time PCR for the identification of mycobacteria associated with zoonotic tuberculosis

BACKGROUND

Tuberculosis (TB) is the leading cause of death worldwide from a single infectious agent. An ability to detect the Mycobacterium tuberculosis complex (MTC) in clinical material while simultaneously differentiating its members is considered important. This allows for the gathering of epidemiological information pertaining to the prevalence, transmission and geographical distribution of the MTC, including those MTC members associated with zoonotic TB infection in humans. Also differentiating between members of the MTC provides the clinician with inherent MTC specific drug susceptibility profiles to guide appropriate chemotherapy.

METHODOLOGY/PRINCIPAL FINDINGS

The aim of this study was to develop a multiplex real-time PCR assay using novel molecular targets to identify and differentiate between the phylogenetically closely related M. bovis, M. bovis BCG and M. caprae. The lpqT gene was explored for the collective identification of M. bovis, M. bovis BCG and M. caprae, the lepA gene was targeted for the specific identification of M. caprae and a Region of Difference 1 (RD1) assay was incorporated in the test to differentiate M. bovis BCG. The multiplex real-time PCR assay was evaluated on 133 bacterial strains and was determined to be 100% specific for the members of the MTC targeted.

CONCLUSIONS/SIGNIFICANCE

The multiplex real-time PCR assay developed in this study is the first assay described for the identification and simultaneous differentiation of M. bovis, M. bovis BCG and M. caprae in one internally controlled reaction. Future validation of this multiplex assay should demonstrate its potential in the rapid and accurate diagnosis of TB caused by these three mycobacteria. Furthermore, the developed assay may be used in conjunction with a recently described multiplex real-time PCR assay for identification of the MTC and simultaneous differentiation of M. tuberculosis, M. canettii resulting in an ability to differentiate five of the eight members of the MTC.

Nocardia cyriacigeorgica bacteraemia presenting with cytomegalovirus disease and rapidly fatal pneumonia in a renal transplant patient: a case report

INTRODUCTION

Nocardia cyriacigeorgica bacteraemia has been described in the setting of profound immunodeficiency in only two previous case reports. In both instances, diagnosis was rapidly facilitated by 16S rRNA gene sequencing of blood culture isolates. To the best of our knowledge, we believe that our case is the first presentation of N. cyriacigeorgica bacteraemia associated with acute cytomegalovirus disease in a kidney transplant recipient, which was then followed by severe and fatal pneumonia only seven days later.

CASE PRESENTATION

We present the case of a 73-year-old Caucasian woman, a renal transplant recipient, with peripheral vascular disease, hypertension, osteoporosis and vascular dementia who was diagnosed with septicemia and pneumonia. In spite of appropriate anti-microbial therapy for nocardial sepsis, she developed severe pneumonia and acute renal failure.

CONCLUSION

This case illustrates a potential for disseminated nocardial infection to produce clinical syndromes that may be indistinguishable from acute cytomegalovirus disease. An atypical presentation (pneumonia and renal failure) of a rare disease (nocardial septicemia) in the setting of renal transplantation is discussed. This case illustrates that the possibility of severe cytomegalovirus disease should be considered in renal transplanted patients diagnosed with nocardial septicemia who subsequently develop severe sepsis, pneumonia, and renal failure. Molecular diagnosis should readily be available to assist with the prompt diagnosis and treatment of these infections in renal transplant patients.

Nocardia carnea infection in a kidney transplant recipient

We report an unusual case of Nocardia carnea brain and lung abscesses in a 54-year-old kidney transplant recipient. Our case was confirmed by molecular detection despite negative cultures. The patient recovered using prolonged cotrimoxazole treatment.

Novel multiplex real-time PCR diagnostic assay for identification and differentiation of Mycobacterium tuberculosis, Mycobacterium canettii, and Mycobacterium tuberculosis complex strains

Tuberculosis (TB) in humans is caused by members of the Mycobacterium tuberculosis complex (MTC). Rapid detection of the MTC is necessary for the timely initiation of antibiotic treatment, while differentiation between members of the complex may be important to guide the appropriate antibiotic treatment and provide epidemiological information. In this study, a multiplex real-time PCR diagnostics assay using novel molecular targets was designed to identify the MTC while simultaneously differentiating between M. tuberculosis and M. canettii. The lepA gene was targeted for the detection of members of the MTC, the wbbl1 gene was used for the differentiation of M. tuberculosis and M. canettii from the remainder of the complex, and a unique region of the M. canettii genome, a possible novel region of difference (RD), was targeted for the specific identification of M. canettii. The multiplex real-time PCR assay was tested using 125 bacterial strains (64 MTC isolates, 44 nontuberculosis mycobacteria [NTM], and 17 other bacteria). The assay was determined to be 100% specific for the mycobacteria tested. Limits of detection of 2.2, 2.17, and 0.73 cell equivalents were determined for M. tuberculosis/M. canettii, the MTC, and M. canettii, respectively, using probit regression analysis. Further validation of this diagnostics assay, using clinical samples, should demonstrate its potential for the rapid, accurate, and sensitive diagnosis of TB caused by M. tuberculosis, M. canettii, and the other members of the MTC.

In vitro activity of multiple antibiotic combinations against Nocardia: relationship with a short-term treatment strategy in heart transplant recipients with pulmonary nocardiosis

BACKGROUND/OBJECTIVES

Pulmonary nocardiosis (PN) chiefly affects immunocompromised patients, particularly transplant recipients. Cotrimoxazole is still the mainstay of treatment, but it is associated with nephro- and myelo-toxicity, and can show unpredictable activity against Nocardia isolates.

METHODS

Over a 20-year period, Nocardia isolates were identified from 12 heart transplant (HTx) recipients with PN. The in vitro activity of various antibacterials, alone or in combination, was assessed using disk-diffusion, minimal inhibitory concentration (MIC), and time-kill methodology. The in vitro results were compared with the clinical outcome of the patients.

RESULTS

Seven different Nocardia strains were identified. Disk diffusion and MIC determinations showed that all isolates were susceptible to amikacin, netilmicin, and linezolid, and that moxifloxacin was the most active of the fluoroquinolones. All but 1 of the isolates were susceptible to imipenem. Time-kill studies showed that imipenem/amikacin and imipenem/moxifloxacin combinations were bactericidal for most isolates. Of 12 patients who received 3-4 weeks' intravenous (IV) treatment with amikacin or ciprofloxacin in combination with a beta-lactam, followed by 1-3 months' oral cotrimoxazole, moxifloxacin, or linezolid, 11 were cured; 1 patient died, but not related to Nocardia.

CONCLUSION

Initial PN treatment in HTx recipients can be successfully carried out with bactericidal combinations such as imipenem plus amikacin or moxifloxacin, administered IV for 3-4 weeks. Within 1 month, a significant clinical and radiological improvement may be observed. In our experience, a <3 month oral regimen with cotrimoxazole, moxifloxacin, or doxycycline may then be used. This may allow a reduction of side effects and treatment-related burden, without any recurrence.

Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of nocardia species

The identification of Nocardia species, usually based on biochemical tests together with phenotypic in vitro susceptibility and resistance patterns, is a difficult and lengthy process owing to the slow growth and limited reactivity of these bacteria. In this study, a panel of 153 clinical and reference strains of Nocardia spp., altogether representing 19 different species, were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). As reference methods for species identification, full-length 16S rRNA gene sequencing and phenotypical biochemical and enzymatic tests were used. In a first step, a complementary homemade reference database was established by the analysis of 110 Nocardia isolates (pretreated with 30 min of boiling and extraction) in the MALDI BioTyper software according to the manufacturer's recommendations for microflex measurement (Bruker Daltonik GmbH, Leipzig, Germany), generating a dendrogram with species-specific cluster patterns. In a second step, the MALDI BioTyper database and the generated database were challenged with 43 blind-coded clinical isolates of Nocardia spp. Following addition of the homemade database in the BioTyper software, MALDI-TOF MS provided reliable identification to the species level for five species of which more than a single isolate was analyzed. Correct identification was achieved for 38 of the 43 isolates (88%), including 34 strains identified to the species level and 4 strains identified to the genus level according to the manufacturer's log score specifications. These data suggest that MALDI-TOF MS has potential for use as a rapid (<1 h) and reliable method for the identification of Nocardia species without any substantial costs for consumables.