Mycobacterium neoaurum bloodstream infection: report of 4 cases and review of the literature

Review of methods for detection and characterization of non-tuberculous mycobacteria in aquatic organisms

Mycobacteriosis is an emerging and often lethal disease of aquatic organisms caused by several non-tuberculous mycobacteria (NTM) species. Early diagnosis of mycobacteriosis in aquaculture and aquatic settings is critical; however, clinical diagnoses and laboratory detection are challenging, and the available literature is scarce. In an attempt to fill the gap, here we review the most relevant approaches to detect and characterize mycobacteria in clinical specimens of aquatic organisms. Emphasis is given to recent advances in molecular methods used to differentiate NTM species spanning from targeted gene sequencing to next-generation sequencing. Further, given that there are major gaps in our understanding of the prevalence of the different NTM species, partially because of their distinct requirements for in vitro growth, we also reviewed the most relevant NTM species reported to cause disease in aquatic organisms and their specific in vitro growth conditions. We also highlight that traditional bacterial culture continues to be relevant for NTM identification, particularly in non-automated laboratories. However, for NTM species discrimination, a high level of accuracy can be achieved with MALDI-TOF MS and molecular approaches, especially targeted gene sequencing applied from clinical specimens or from pure NTM isolates.

New RAPMYCOI SensititreTM Antimicrobial Susceptibility Test for Atypical Rapidly Growing Mycobacteria (RGM)

Rapidly growing mycobacteria (RGM) cause an increasing international concern, mainly due to their natural resistance to many antibiotics. The aim of this study was to conduct species identification and determine the antimicrobial susceptibility profiles of RGM isolated in Poland. Antimicrobial susceptibility was tested using broth microdilution and the RAPMYCOI panel. A total of 60 strains were analysed, including the following species: M. fortuitum complex (30), M. abscessus subsp. abscessus (16), M. abscessus subsp. massiliense (7), M. chelonae (5), and M. mucogenicum (2). For 12 M. abscessus subsp. abscessus strains, the presence of the erm 41T28 genotype associated with inducible macrolide resistance and a functional erm gene was confirmed. A MUT2 mutation in the rrl gene (constitutive resistance) was identified for two strains from the subtype M. abscessus subsp. massiliense. Among the 15 tested antibiotics, amikacin and linezolid had the strongest antimycobacterial activity. Most of the tested strains were resistant to doxycycline and trimethoprim/sulfamethoxazole. Tigecycline MICs were low for all tested strains. Findings from our study highlight the importance of correct identification of clinical isolates and antimicrobial susceptibility testing.

3β-Hydroxysteroid dehydrogenase expressed by gut microbes degrades testosterone and is linked to depression in males

Testosterone deficiency can lead to depressive symptoms in humans; however, the causes of this deficiency are incompletely understood. Here, we isolated Mycobacterium neoaurum from the fecal samples of testosterone-deficient patients with depression and showed that this strain could degrade testosterone in vitro. Furthermore, gavaging rats with M. neoaurum reduced their serum and brain testosterone levels and induced depression-like behaviors. We identified the gene encoding 3β-hydroxysteroid dehydrogenase (3β-HSD) as the enzyme causing testosterone degradation. Introducing 3β-HSD into Escherichia coli enhanced its ability to degrade testosterone. Gavaging rats with 3β-HSD-producing E. coli reduced their serum and brain testosterone levels and caused depression-like behaviors. Finally, compared with 16.67% of participants without depression, 42.99% (46/107) of the fecal samples of patients with depression harbored 3β-HSD, and 60.87% (28/46) of these fecal samples expressed 3β-HSD. These results suggest that 3β-HSD expressed by gut microbes may be associated with depressive symptoms due to testosterone degradation.

Pin tract infection caused by Mycobacterium neoaurum in a 14-year-old child: A case report

Although rapidly growing non-tuberculosis mycobacterium can occasionally cause postoperative infections, Mycobacterium neoaurum is a rare pathogen of surgical site infection. We report a case of pin tract infection caused by M. neoaurum in a 14-year-old girl who was admitted for lengthening of her right fourth metatarsal bone. Pain, redness, and exudate were observed 18 days after external fixator insertion. Repeated exudate cultures revealed M. neoaurum, and she was diagnosed with a mycobacterial pin tract infection. She was initially administered intravenous ciprofloxacin and minocycline, and then was switched to oral trimethoprim-sulfamethoxazole and minocycline for a total of 6 months. Despite the pin tract infection, bone lengthening was completed under antibiotic treatment without removal of the pin; no other complications were noted. There are no prior reports of external fixator pin tract infection by M. neoaurum. While such cases may be rare, this case demonstrates that bone distraction may still be successfully completed using appropriate antibiotic therapy without pin removal.

Mycobacterium mucogenicum and Mycobacterium neoaurum bacteremia in immunocompromised hosts

BACKGROUND

Mycobacterium mucogenicum and Mycobacterium neoaurum are infrequent causes of bacteremia in humans. When they are isolated from blood, it is not unusual for them to initially be considered contaminants.

METHODS

A retrospective chart review of patients diagnosed with M. mucogenicum and M. neoaurum bacteremia from January 1998 to December 2018 was conducted at the University Health Network, Toronto, Ontario, Canada.

RESULTS

We identified 28 patients who had bacteremia caused by these organisms. These patients were primarily immunocompromised, had chronically indwelling vascular access devices, or used intravenous drugs. For 29% of the patients, the isolation of these mycobacteria was considered colonization, whereas 82% of the patients received antimicrobial therapy and 95% had the central line removed.

CONCLUSIONS

The removal of the vascular access device and treatment with either single or combination antimicrobial therapy produced successful outcomes for people with these infections.

Catheter-related blood stream infection caused by Mycobacterium chelonae in a child with myeloid leukemia associated with Down syndrome

Rapidly growing nontuberculous mycobacteria should be considered if GPRs gram-positive rods are detected in blood cultures 2-3 days after the blood sample collection.

Mycobacterium neoaurum Bloodstream Infection Associated with a Totally Implanted Subclavian Port in an Adult with Diabetes and History of Colon Cancer

Background. Mycobacterium neoaurum is a rapidly growing nontuberculosis mycobacterium (NTM) that was first isolated from soil in 1972 and is ubiquitous in soil, water, and dust. The first reported case of human infection by M. neoaurum was published in 1988, presenting as a Hickman catheter-related bacteremia in a patient with ovarian cancer. M. neoaurum has since been recognized as a source of predominantly opportunistic bloodstream infections in immunocompromised hosts. We report the case of an adult diabetic male with M. neoaurum bloodstream infection secondary to an infected venous-access port that had been implanted nearly six years prior for temporary chemotherapy. Case Presentation. A 66-year-old male with schizophrenia, type 2 diabetes mellitus, and a history of excision and chemotherapy to treat adenocarcinoma of the colon 6 years prior, presented with fever and behavioral changes. He was found to have a M. neoaurum bloodstream infection secondary to his implanted subclavian port. Multiple preoperative blood cultures, as well as the removed catheter tip culture, were positive for M. neoaurum. The patient's condition improved to near premorbid levels after port removal and 6 weeks of targeted antimicrobial therapy. Discussion and Conclusions. Bloodstream infections due to rapidly growing NTM, such as M. neoaurum, have been infrequently reported; however, improved isolation and identification techniques based on genomic testing are resulting in a more in-depth recognition of these widely scattered environmental microbes in human infections. Nonetheless, lengthy identification and susceptibility processes remain a diagnostic and treatment barrier. Patients such as ours who have a history of malignancy and an indwelling foreign body have most often been reported as acquiring M. neoaurum bacteremia. Fortunately, device removal and appropriate antimicrobial therapy guided by susceptibility data is often enough to manage these atypical mycobacterial infections.

Response of high-, mid- and low-abundant taxa and potential pathogens to eight disinfection methods and their interactions in domestic hot water system

Eight disinfection methods were applied to control biofilm contamination in domestic hot water system. The inactivation efficiency, responses of high- (≥1%), mid- (0.1% ~ 1%) and low-abundant taxa (≤0.1%) to disinfection, and interactions within and across three sub-communities were investigated. Ultraviolet was the most effective disinfection method for total bacteria and Escherichia coli, and chlorine dioxide had the highest inactivation efficiency on heterotrophic bacteria, while silver ions exhibited poor performance on all of them. At the phylum level, the responses of microorganisms to eight disinfection methods were different, but Proteobacteria and Firmicutes dominated in most samples. Eight disinfection methods had a greater impact on the proportion of high- and mid-abundant taxa than that of low-abundant taxa, and led to dissimilar transformations of genera among high-, mid- and low-abundant taxa in each sample. High-, mid- and low-abundant taxa of different samples showed similar structures and were roughly clustered into three Groups. Moreover, high-abundant taxa had more complex internal interactions than mid- and low-abundant taxa, and mainly presented co-occurrence patterns. The associations between high- and low-abundant taxa were close, and some low-abundant genera were identified as hub bacteria, such as Paracoccus, Thioalkalispira and Flavitalea. Furthermore, a total of 23 potential pathogens were detected in this study, and they mainly showed positive interactions, with Mycobacteria and Streptococcus as keystone genera. These results highlight the dissimilar responses of high-, mid- and low-abundant taxa to disinfection, and the critical role of some low-abundant genera in the microbial network, as well as the co-occurrence patterns among potential pathogens.

Response of bacterial regrowth, abundant and rare bacteria and potential pathogens to secondary chlorination in secondary water supply system

This study investigated the effects of secondary chlorination on bacterial regrowth, microbial communities (abundant and rare taxa) and bacterial functions of pipe wall biofilm and bulk water in simulated secondary water supply system (SWSS). Continuous secondary chlorination was more effective than short-term secondary chlorination to control the bacterial regrowth in both biofilm and water samples. Bacterial diversity slightly reduced after continuous secondary chlorination, and 19.27% of the total operational taxonomic units (OTUs) were shared by biofilm and water samples, with Bacillus as the dominant genus. Abundant and rare taxa exhibited different community structures. Proteobacteria and candidate division WPS-1 predominated in abundant and rare phyla were sensitive to chlorine, while Firmicutes, Acidobacteria and Bacteroidetes, exhibited relative strong chlorine resistance. The abundant genera in control sample (e.g., Bosea, Sphingobium and Gemmata) exhibited poor tolerance to chlorine, while Bacillus in biofilm and Defluviimonas in water were the main chlorine-resistant genera. Moreover, the composition of rare genera in each sample was obviously different. Furthermore, a total of 18 potential pathogens were detected with Pseudomonas as the dominant genus, most of which were significantly reduced after disinfection. There were mainly positive interactions among potential pathogenic bacteria, with Enterococcus, Legionella and Vibrio as the hub genera as revealed by network analysis. Similar bacterial functions in both biofilm and water were observed with metabolism as the predominant bacterial function, while, human disease function only accounted for 1.07% of bacterial functions. These results highlighted the importance of continuous secondary chlorination for controlling biosafety of SWSS and identified the dissimilar responses of abundant and rare bacteria to the disinfection, as well as the co-occurrence patterns among potential pathogens, improving our understanding of bacterial communities in SWSS.

Biodiversity of organisms inhabiting the water supply network of Wroclaw. Detection of pathogenic organisms constituting a threat for drinking water recipients

The objective of the article was to present the diversity of organisms inhabiting the water supply network with particular consideration of pathogenic organisms that can cause an epidemiological threat, with the application of high throughput sequencing (HTS). The study material was water sampled from 15 points in the water supply system. High species diversity of bacteria was evidenced, as well as the presence of microorganisms from genus Clostridium and family Enterobacteriaceae. No presence of bacteria Clostridium perfringens was recorded, which suggests proper performance of water treatment processes. Owing to advanced techniques of molecular biology, the article also presents species very similar to pathogenic bacteria the detection of which is not possible by means of standard water analysis (plate culture). Based on literature data and very high similarity of the genome of the bacteria to that of pathogenic bacteria, the species are considered to potentially show the same negative character towards the recipient, and cause a serious epidemiological threat. Therefore, the performed analyses show that classic methods of assessment of sanitary quality of water are not fully sufficient, and HTS analysis should be performed as an auxiliary tool to provide the complete image of the community in the existing network.

Mycobacterium neoaurum line-related bacteremia with pulmonary involvement: Case report and review of literature

Mycobacterium neoaurum is a rapidly growing non-tuberculous mycobacterium which is ubiquitous in nature. While it can cause line related infections in immunocompromised host, case reports of urinary tract infections, cutaneous infections, pulmonary infections, and meningoencephalitis have also been reported. We report the first case of Mycobacterium neoaurum line related bacteremia with concomitant pulmonary involvement. Our patient responded well to a nine week course of antimicrobials after removal of infected central line.

Molecular Identification of Mycobacterium Species of Public Health and Veterinary Importance from Cattle in the South State of México

Mycobacterium genus causes a variety of zoonotic diseases. The best known example is the zoonotic tuberculosis due to M. bovis. Much less is known about "nontuberculous mycobacteria (NTM)," which are also associated with infections in humans. The Mexican standard NOM-ZOO-031-1995 regulates the presence of M. bovis in cattle; however, no regulation exists for the NTM species. The objective of this study was to isolate and identify nontuberculous mycobacteria species from cattle of local herds in the south region of the State of Mexico through the identification and detection of the 100 bp molecular marker in the 23S rRNA gene with subsequent sequencing of the 16S rRNA gene. Milk samples (35) and nasal exudate samples (68) were collected. From the 108 strains isolated, 39 were selected for identification. Thirteen strains isolated from nasal exudates amplified the 100 bp molecular marker and were identified as M. neoaurum (six strains), M. parafortuitum (four strains), M. moriokaense (two strains), and M. confluentis (one strain). Except M. parafortuitum, the other species identified are of public health and veterinary concern because they are pathogenic to humans, especially those with underlying medical conditions.

Rapidly Growing Mycobacteria

Rapidly growing mycobacteria (RGM) compose approximately one-half of the currently validated mycobacterial species and are divided into six major groups, including the Mycobacterium fortuitum group, M. chelonae/M. abscessus complex, M. smegmatis group, M. mucogenicum group, M. mageritense / M. wolinskyi , and the pigmented RGM. This review discusses each group and highlights the major types of infections associated with each group. Additionally, phenotypic and molecular laboratory identification methods, including gene sequencing, mass spectrometry, and the newly emerging whole-genome sequencing, are detailed, along with a discussion of the current antimicrobial susceptibility methods and patterns of the most common pathogenic species.

Prevalence and diversity of Chlamydiales and other amoeba-resisting bacteria in domestic drinking water systems

A growing number of human infections incriminate environmental bacteria that have evolved virulent mechanisms to resist amoebae and use them as a replicative niche. These bacteria are designated amoeba-resisting bacteria (ARB). Despite the isolation of these ARB in various human clinical samples, the possible source of infection remains undetermined in most cases. However, it is known that the ARB Legionella pneumophila, for instance, causes a respiratory infection in susceptible hosts after inhalation of contaminated water aerosols from various sources. The Chlamydiales order contains many ARB, such as Parachlamydia acanthamoebae or Simkania negevensis, previously implicated in human respiratory infections with no identified contamination sources. We thus investigated whether domestic water systems are a potential source of transmission of these Chlamydiales to humans by using amoebal culture and molecular methods. Other important ARB such as mycobacteria and Legionella were also investigated, as were their possible amoebal hosts. This work reports for the first time a very high prevalence and diversity of Chlamydiales in drinking water, being detected in 35 (72.9%) of 48 investigated domestic water systems, with members of the Parachlamydiaceae family being dominantly detected. Furthermore, various Legionella and mycobacteria species were also recovered, some species of which are known to be causal agents of human infections.

Bacteremia with an Unusual Pathogen: Mycobacterium neoaurum

Mycobacterium neoaurum (M. neoaurum) is an infrequently encountered cause of infection in humans. It is a member of the rapidly growing mycobacteria family. It predominately afflicts those with a compromised immune status and a chronically indwelling vascular access. Isolation of this organism is challenging yet the advent of 16s ribosomal sequencing paved the way for more sensitive detection. No treatment guidelines are available and treatment largely depends on the experience of the treating physician and nature of the isolate. We report a case of M. neoaurum bacteremia in an immune competent host, with a chronically placed peripherally inserted central catheter (PICC line).

Infections Caused by Rapidly Growing Mycobacteria spp in Children and Adolescents With Cancer

BACKGROUND

Rapidly growing mycobacteria (RGM) infections in pediatric oncology patients have not been completely characterized.

METHODS

We reviewed medical records of oncology patients at St. Jude Children's Research Hospital (St. Jude) from 1990 to 2010 with RGM infections and summarized the results of previously published cases.

RESULTS

Twenty-five St. Jude patients had 27 episodes of infection. Approximately half of the cases occurred in patients with hematological malignancies and in males; infections were more common in white patients. Most patients were not neutropenic or lymphopenic. The most common causative species were Mycobacterium chelonae, Mycobacterium abscessus, and Mycobacterium fortuitum. Most isolates were susceptible to amikacin and clarithromycin; all were susceptible to at least 1 of these. Treatment regimens varied considerably, particularly with respect to the duration of antimicrobial chemotherapy. Two St. Jude patients died; both had pulmonary infections. The literature search identified an additional 58 cases of infection. Localized catheter-associated infections were more common than bloodstream infections in the current series than in previous reports, and outbreaks were not recognized. Otherwise, the demographic and clinical characteristics of patients were similar.

CONCLUSIONS

Localized catheter-associated infections were most common in this largest reported single center experience reported to date. Pulmonary infection is uncommon in children but, as in adults, has a high mortality rate. Relatively short-term antimicrobial treatment and surgical debridement of infected tissue, if present, may be as effective for catheter-associated infections as prolonged antimicrobial use and may reduce adverse drug effects in these patients, who are vulnerable to drug-drug interactions and toxicity.

[Non-tuberculous mycobacterial infection of a totally implanted perfusion device]

INTRODUCTION

Catheter-related infection by non-tuberculous mycobacteria is rare but difficult to diagnose and the treatment is not standardized.

CASE REPORT

A 64-year-old woman treated for lung cancer with intravenous chemotherapy developed an infection of her totally implanted perfusion device with Mycobacterium chelonae. The infection was cured after surgical removal of the device and treatment with oral clarithromycin.

CONCLUSION

Mycobacteria may infect vascular access devices. Rapid diagnosis of such infections allows early treatment.

Infections caused by non-tuberculous mycobacteria in recipients of hematopoietic stem cell transplantation

Non-tuberculous mycobacteria (NTM) are acid-fast bacteria that are ubiquitous in the environment and can colonize soil, dust particles, water sources, and food supplies. They are divided into rapidly growing mycobacteria such as Mycobacterium fortuitum, Mycobacterium chelonae, and Mycobacterium abscessus as well as slowly growing species such as Mycobacterium avium, Mycobacterium kansasii, and Mycobacterium marinum. About 160 different species, which can cause community acquired and health care-associated infections, have been identified. NTM are becoming increasingly recognized in recipients of hematopoietic stem cell transplantation (HSCT) with incidence rates ranging between 0.4 and 10%. These infections are 50–600 times commoner in transplant recipients than in the general population and the time of onset ranges from day 31 to day 1055 post-transplant. They have been reported following various forms of HSCT. Several risk factors predispose to NTM infections in recipients of stem cell transplantation and these are related to the underlying medical condition and its treatment, the pre-transplant conditioning therapies as well as the transplant procedure and its complications. Clinically, NTM may present with: unexplained fever, lymphadenopathy, osteomyelitis, soft tissue and skin infections, central venous catheter infections, bacteremia, lung, and gastrointestinal tract involvement. However, disseminated infections are commonly encountered in severely immunocompromised individuals and bloodstream infections are almost always associated with catheter-related infections. It is usually difficult to differentiate colonization from true infection, thus, the threshold for starting therapy remains undetermined. Respiratory specimens such as sputum, pleural fluid, and bronchoalveolar lavage in addition to cultures of blood, bone, skin, and soft tissues are essential diagnostically. Susceptibility testing of mycobacterial isolates is a basic component of optimal care. Currently, there are no guidelines for the treatment of NTM infections in recipients of stem cell transplantation, but such infections have been successfully treated with surgical debridement, removal of infected or colonized indwelling intravascular devices, and administration of various combinations of antimicrobials. Monotherapy can be associated with development of drug resistance due to new genetic mutation. The accepted duration of treatment is 9 months in allogeneic stem cell transplantation and 6 months in autologous setting. Unfortunately, eradication of NTM infections may be impossible and their treatment is often complicated by adverse effects and interactions with other transplant-related medication.

Mycobacterium neoaurum causing prosthetic valve endocarditis: a case report and review of the literature

Mycobacterium neoaurum is a rare cause of bacteremia, and infection usually occurs in an immunocompromised host in the setting of an indwelling catheter. Prosthetic valve endocarditis due to non-tuberculous mycobacteria typically carries a dismal prognosis; we report a case of M. neoaurum prosthetic valve endocarditis with favorable response to antimicrobial therapy without surgical intervention.

Bacterial community of biofilms developed under different water supply conditions in a distribution system

In order to understand the bacterial community characteristics of biofilms developed under different finished water supply histories in drinking water distribution systems (DWDS), biofilm samples on different type of iron corrosion scales in a real DWDS were collected and systematically investigated using 454 pyrosequencing of 16S rRNA gene. The richness and diversity estimators showed that biofilms formed in DWDS transporting finished groundwater (GW) had the lowest level of bacterial diversity. From phylum to genus level, the dominant bacterial groups found in the biofilms under finished surface water (SW) and GW conditions were distinct. Proteobacteria was the dominant group in all biofilm samples (in the range of 40%-97%), but was relatively higher in biofilms with GW. The relative abundance of Firmicutes in biofilms with SW (28%-35%) was significantly higher (p<0.01) than that in biofilms with GW (0.5%-2.88%). Statistical analysis (Spearman's rank) revealed that alkalinity and chemical oxygen demand (CODMn) positively correlated with the relative abundance of Proteobacteria and Firmicutes, respectively. The abundance of sequences affiliated to iron-reducing bacteria (mainly Bacillus) and iron-oxidizing bacteria (mainly Acidovorax) were relatively higher in biofilms with SW, which might contribute to the formation of much thicker or tubercle-formed corrosion scales under SW supply condition. Several potential opportunistic pathogens, such as Burkholderia fungorum, Mycobacterium neoaurum, Mycobacterium frederiksbergense were detected in the biofilms.

Mycobacterium neoaurum and Mycobacterium bacteremicum sp. nov. as causes of mycobacteremia

Reference isolates of Mycobacterium neoaurum, Mycobacterium aurum, and the nonvalidated species "Mycobacterium lacticola" were the focus of two recent molecular taxonomic studies. On the basis of this grouping, we identified 46 clinical pigmented, rapidly growing mycobacterial isolates. By 16S rRNA gene sequencing, only two major taxa were identified: M. neoaurum and a previously uncharacterized "M. neoaurum-like" group. The M. neoaurum-like group exhibited only 99.7% identity to M. neoaurum by 16S rRNA gene sequencing and 96.5% identity to M. neoaurum by rpoB sequencing and was named M. bacteremicum. No clinical isolates of M. aurum or M. lacticola were identified. Of isolates with known sources, 4/8 (50%) of M. bacteremicum isolates and 22/34 (65%) of M. neoaurum isolates were recovered from blood, and 35% of these were known to be from patients with catheter-related sepsis. MIC and clinical data on these 46 isolates of M. neoaurum and M. bacteremicum along with a review of 16 previously reported cases of infection with the M. neoaurum-M. lacticola group demonstrated that the isolates were highly susceptible to all drugs tested except clarithromycin, and most clinical cases were successfully treated. The clarithromycin resistance suggested the presence of an inducible erm gene reported in other species of rapidly growing mycobacteria. Sequencing studies are currently required to identify these two species. Strain ATCC 25791 (originally submitted as an example of Mycobacterium aurum) is proposed to be the type strain of M. bacteremicum.

Nontuberculous mycobacteria infections in immunocompromised patients: single institution experience

Disseminated infection due to nontuberculous Mycobacterium (NTM) species is rare in pediatrics. Here we report 6 infections affecting 5 patients at a single institution in an immunocompromised population of pediatric oncology and stem cell transplant recipients. The patients presented within a 1-year period with catheter-associated bacteremia. New pulmonary nodules were noted in 4 of the 5 patients. All of the infections were due to rapidly growing NTM. Patients were successfully treated with removal of the infected catheter and combination antibiotic therapy. There are currently no consensus guidelines for treatment of NTM infections in this population, and a therapeutic approach is presented here.

Phylogenetic analysis of Mycobacterium aurum and Mycobacterium neoaurum with redescription of M. aurum culture collection strains

We examined American Type Culture Collection (ATCC) strains of Mycobacterium aurum and Mycobacterium neoaurum by using multilocus DNA target sequencing. Apart from the type strain, all 10 ATCC M. aurum strains examined were classified incorrectly, with most being reclassified as belonging to the M. neoaurum-'Mycobacterium lacticola' relatedness group. All four M. neoaurum strains were tightly clustered, but heterogeneity was observed within the cluster. As a result of the incorrect annotation of the M. aurum strains, two commonly used methods of identification are compromised and two case reports implicating M. aurum as a human pathogen are probably incorrect, with the isolates probably belonging to the M. neoaurum-'M. lacticola' relatedness group. These findings together with a review of isolates identified at two large reference laboratories suggest that M. aurum is not a clinically significant isolate.

Mycobacterium neoaurum infection in a patient with renal failure

Mycobacterium neoaurum, a member of the Mycobacterium parafortuitum complex, has only rarely been reported as a pathogen of human infections. We report a case of catheter-related bloodstream infection (CRBSI) due to M. neoaurum in a patient on hemodialysis. The isolate was identified by conventional methods as well as by 16S rRNA gene analysis. The patient was successfully treated with intravenous antibiotics (meropenem and amikacin) for three weeks and the catheter was removed. M. neoaurum should be considered as a possible cause of CRBSI in patients with renal failure. Combination antimicrobial therapy and catheter removal can lead to a favorable clinical outcome.

Bloodstream infections in haematology: risks and new challenges for prevention

Bloodstream infections are an important cause of morbidity and mortality in the haematology population, and may contribute to delayed administration of chemotherapy, increased length of hospitalisation, and increased healthcare expenditure. For gram-positive, gram-negative, anaerobic and fungal infections, specific risk factors are recognised. Unique host and environmental factors contributing to pathogenesis are acknowledged in this population. Trends in spectrum and antimicrobial susceptibility of pathogens are examined, and potential contributing factors are discussed. These include the widespread use of empiric antimicrobial therapy, increasingly intensive chemotherapeutic regimens, frequent use of central venous catheters, and local infection control practices. In addition, the risks and benefits of prophylaxis, and spectrum of endemic flora are identified as relevant factors within individual centres. Finally, challenges are presented regarding prevention, early detection, surveillance and prophylaxis. To reduce the rate and impact of bloodstream infections multifaceted and customised strategies are required within individual haematology units.