Mycobacterium barrassiae sp. nov., a Mycobacterium moriokaense group species associated with chronic pneumonia

Potentially pathogenic culturable bacteria in hemodialysis waters

BACKGROUND

Hemodialysis patients are at risk of acquiring healthcare-related infections due to using non-sterile water to prepare hemodialysis fluid. Therefore, microbiological control and monitoring of used water are of crucial importance.

MATERIALS AND METHODS

In this work, we identified bacterial populations occupying a hemodialysis water distribution system for almost a 6-month period in Ahvaz city, southwest of Iran. A total of 18 samples from three points were collected. We found high colony counts of bacteria on R2A agar. 31 bacteria with different morphological and biochemical characteristics were identified by molecular-genetic methods based on 16 S rRNA gene sequencing. Endotoxin concentrations were measured, using Endosafe® Rapid LAL Single-Test Vials.

RESULTS

A diverse bacterial community was identified, containing predominantly Gram-negative bacilli. The most frequently isolated genus was Sphingomonas. Five species including M. fortuitum, M. lentiflavum, M.szulgai, M. barrassiae, and M. gordonae was identified .Despite the presence of Gram-negative bacteria the endotoxin analysis of all samples revealed that their endotoxin values were below the detection limit.

CONCLUSION

The members of Sphingomonas genus along with Bosea and mycobacteria could be regarded as pioneers in surface colonization and biofilm creation. These bacteria with others like Pelomonas, Bradyrhizobium, staphylococcus, and Microbacterium may represent a potential health risk to patients under hemodialysis treatment.

Phylogenetic Profile of Nonulcerans and Nontuberculous Environmental Mycobacteria Isolated in Côte d'Ivoire

BACKGROUND

Environmental mycobacteria are involved in several infections ranging from lung to skin infections. In Côte d'Ivoire, apart from Mycobacterium ulcerans and Mycobacterium tuberculosis, little information exists on other species. The culture of these species, a real challenge, especially in developing countries like Cote d'Ivoire, limits their identification. However, there are reports in literature of infections caused by these mycobacteria, and few species have never been described in human or animal infections. These are difficult cases to treat because of their resistance to most antituberculosis antibiotics. The aim of our work was to study the diversity of potentially pathogenic mycobacterial species in wastewater drainage channels in different townships and in two hospital effluents in the city of Abidjan.

METHODS

Wastewater samples were cultured, followed by conventional polymerase chain reaction (PCR) targeting mycobacterial 16S ribonucleic acid (16S RNA) using PA/MSHA primers. 16 S RNA identified were sequenced by Sanger techniques. Sequences obtained were analyzed, and a phylogenic tree was built.

RESULTS

Fast-growing mycobacteria, including Mycobacterium fortuitum, Mycobacterium phocaicum, Mycobacterium sp., and others presence, were confirmed both by culture and molecular techniques. M. fortuitum strain was the same in effluents of the Treichville University Hospital and in the wastewater of the township of Koumassi. New species never isolated in Côte d'Ivoire, such as M. phocaicum, have been identified in wastewater of the township of Yopougon.

CONCLUSION

This study showed that the sewer network in the city of Abidjan is colonized by both potentially pathogenic mycobacteria and saprophytic environmental mycobacteria.

Phenotypic and molecular characterisation of a novel species, Mycobacterium hubeiense sp., isolated from the sputum of a patient with secondary tuberculosis in Hubei of China

A new fast-growing mycobacterium, designated strain QGD101^T, was isolated from the sputum of an 84-year-old man suspected of tuberculosis in Wuhan Medical Treatment Center, Hubei, China. This strain was a gram-staining-negative, aerobic, non-spore-forming and catalase-positive bacterium, which was further identified as the NTM by PNB and TCH tests. The moxifloxacin and levofloxacin exhibited strong suppressing function against QGD101^T with MIC values of 0.06 and 0.125 µg/ml after drug susceptibility testing of six main antimicrobial agents on mycobacteria. Based on the sequence analysis of 16S rRNA, rpoB, hsp65 and 16S-23S rRNA internal transcribed spacer, the strain QGD101^T could not be identified to a species level. Mycobacterium moriokaense ATCC43059^T that shared the highest 16S rRNA gene sequence similarity (98%) with strain QGD101^T was actually different in genomes average nucleotide identity (78.74%). In addition, the major cellular fatty acids of QGD101^T were determined as C18:1ω9c, C16:0 and C18:2ω6c. The DNA G + C content was 64.9% measured by high performance liquid chromatography. Therefore, the phenotypic and genotypic characterisation of this strain led us to the conclusion that it represents a novel species of mycobacteria, for which the name Mycobacterium hubeiense sp. nov. (type strain QGD101^T = CCTCCAA 2017003^T = KCTC39927^T) was proposed. Thus, the results of this study are very significant for the clinical diagnosis of tuberculosis and future personalised medicine.

Mycobacterium bovis prevalence affects the performance of a commercial serological assay for bovine tuberculosis in African buffaloes

The endemic presence of bovine tuberculosis (BTB) in African buffaloes in South Africa has severe consequences for BTB control in domestic cattle, buffalo ranching and wildlife conservation, and poses a potential risk to public health. This study determined the BTB prevalence in free-ranging buffaloes in two game reserves and assessed the influence of the prevalence of mycobacterial infections on the performance of a commercial cattle-specific serological assay for BTB (TB ELISA). Buffaloes (n = 997) were tested with the tuberculin skin test and TB ELISA; a subset (n = 119) was tested longitudinally. Culture, PCR and sequencing were used to confirm infection with M. bovis and/or non-tuberculous mycobacteria (NTM). Prevalence of BTB, but not NTM, influenced the TB ELISA performance. Multiple testing did not increase test confidence. The findings strongly illustrate the need for development of novel assays that can supplement existing assays for a more comprehensive testing scheme for BTB in African buffaloes.

Mycobacterium komaniense sp. nov., a rapidly growing non-tuberculous Mycobacterium species detected in South Africa

Some species of non-tuberculous mycobacteria (NTM) have been reported to be opportunistic pathogens of animals and humans. Recently there has been an upsurge in the number of cases of NTM infections, such that some NTM species are now recognized as pathogens of humans and animals. From a veterinary point of view, the major significance of NTM is the cross-reactive immune response they elicit against Mycobacterium bovis antigens, leading to misdiagnosis of bovine tuberculosis. Four NTM isolates were detected from a bovine nasal swab, soil and water, during an NTM survey in South Africa. These were all found using 16S rRNA gene sequence analysis to be closely related to Mycobacterium moriokaense. The isolates were further characterised by sequence analysis of the partial fragments of hsp65, rpoB and sodA. The genome of the type strain was also elucidated. Gene (16S rRNA, hsp65, rpoB and sodA) and protein sequence data analysis of 6 kDa early secretory antigenic target (ESAT 6) and 10 kDa culture filtrate protein (CFP-10) revealed that these isolates belong to a unique Mycobacterium species. Differences in phenotypic and biochemical traits between the isolates and closely related species further supported that these isolates belong to novel Mycobacterium species. We proposed the name Mycobacterium komaniense sp. nov. for this new species. The type strain is GPK 1020^T (=CIP 110823T=ATCC BAA-2758).

Mycobacterium malmesburyense sp. nov., a non-tuberculous species of the genus Mycobacterium revealed by multiple gene sequence characterization

Non-tuberculous mycobacteria (NTM) are ubiquitous in the environment, and an increasing number of NTM species have been isolated and characterized from both humans and animals, highlighting the zoonotic potential of these bacteria. Host exposure to NTM may impact on cross-reactive immune responsiveness, which may affect diagnosis of bovine tuberculosis and may also play a role in the variability of the efficacy of Mycobacterium bovis BCG vaccination against tuberculosis. In this study we characterized 10 NTM isolates originating from water, soil, nasal swabs of cattle and African buffalo as well as bovine tissue samples. These isolates were previously identified during an NTM survey and were all found, using 16S rRNA gene sequence analysis to be closely related to Mycobacterium moriokaense. A polyphasic approach that included phenotypic characterization, antibiotic susceptibility profiling, mycolic acid profiling and phylogenetic analysis of four gene loci, 16S rRNA, hsp65, sodA and rpoB, was employed to characterize these isolates. Sequence data analysis of the four gene loci revealed that these isolates belong to a unique species of the genus Mycobacterium. This evidence was further supported by several differences in phenotypic characteristics between the isolates and the closely related species. We propose the name Mycobacterium malmesburyense sp. nov. for this novel species. The type strain is WCM 7299T (=ATCC BAA-2759T=CIP 110822T).

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.

Molecular Identification of Nontuberculous Mycobacteria in Humans in Zimbabwe Using 16S Ribosequencing

Background:

Several nontuberculous mycobacteria (NTM) were previously isolated from diverse environments such as water, soil, sewage, food and animals. Some of these NTM are now known to be opportunistic pathogens of humans.

Objective:

The main purpose of the study was to identify NTM isolates stored at the National Microbiology Reference Laboratory (NMRL) and were previously isolated from humans during a national tuberculosis (TB) survey.

Methods:

Pure NTM cultures already isolated from human sputum samples during the national TB survey were retrieved from the NMRL and used for this study. DNA was extracted from the samples and 16S ribosomal RNA gene amplified by polymerase chain reaction. The amplicons were sequenced and bioinformatics tools were used to identify the NTM species.

Results:

Out of total of 963 NTM isolates stored at the NMRL, 81 were retrieved for speciation. Forty isolates (49.4%) were found to belong to Mycobacterium avium-intracellulare complex (MAC) species. The other 41 isolates (50.6%) were identified as M. lentiflavum (6.2%), M. terrae complex (4.9%), M. paraense (4.9%), M. kansasii (3.7%), M. moriokaense (3.7%), M. asiaticum (2.5%), M. novocastrense (2.5%), M. brasiliensis (2.5%), M. elephantis (2.5%), M. paraffinicum (1.2%), M. bohemicum (1.2%), M. manitobense (1.2%), M. intermedium (1.2%), M. tuberculosis complex (1.2%), M. parakoreense (1.2%), M. florentinum (1.2%), M. litorale (1.2%), M. fluoranthenivorans (1.2%), M. sherrisii (1.2%), M. fortuitum (1.2%) and M septicum (1.2%). Two isolates (2.5%) could not be identified, but were closely related to M. montefiorense and M. phlei respectively. Interestingly, the MAC species were the commonest NTM during the survey.

Conclusion:

The study emphasizes the importance of identifying species of NTM in Zimbabwe. Future studies need to ascertain their true diversity and clinical relevance.

Microbiological features and clinical relevance of new species of the genus Mycobacterium

Nontuberculous mycobacteria (NTM) are present in the environment, mainly in water, and are occasionally responsible for opportunistic infections in humans. Despite the fact that NTM are characterized by a moderate pathogenicity, the diseases caused by NTM at various body sites are increasing on a worldwide level. Among over 150 officially recognized NTM species, only two or three dozen are familiar to clinicians, and even to most microbiologists. In this paper, approximately 50 new species described in the last 8 years are reviewed, and their role in human infections is assessed on the basis of reported clinical cases. The small number of reports concerning most of the "new" mycobacterial species is responsible for the widespread conviction that they are very rare. Their role is actually largely underestimated, mainly because they often remain unrecognized and misidentified. Aiming to minimize such bias, emphasis has been placed on more common identification pitfalls. Together with new NTM, new members of the Mycobacterium tuberculosis complex described in the last few years are also an object of the present review.

Current and past strategies for bacterial culture in clinical microbiology

A pure bacterial culture remains essential for the study of its virulence, its antibiotic susceptibility, and its genome sequence in order to facilitate the understanding and treatment of caused diseases. The first culture conditions empirically varied incubation time, nutrients, atmosphere, and temperature; culture was then gradually abandoned in favor of molecular methods. The rebirth of culture in clinical microbiology was prompted by microbiologists specializing in intracellular bacteria. The shell vial procedure allowed the culture of new species of Rickettsia. The design of axenic media for growing fastidious bacteria such as Tropheryma whipplei and Coxiella burnetii and the ability of amoebal coculture to discover new bacteria constituted major advances. Strong efforts associating optimized culture media, detection methods, and a microaerophilic atmosphere allowed a dramatic decrease of the time of Mycobacterium tuberculosis culture. The use of a new versatile medium allowed an extension of the repertoire of archaea. Finally, to optimize the culture of anaerobes in routine bacteriology laboratories, the addition of antioxidants in culture media under an aerobic atmosphere allowed the growth of strictly anaerobic species. Nevertheless, among usual bacterial pathogens, the development of axenic media for the culture of Treponema pallidum or Mycobacterium leprae remains an important challenge that the patience and innovations of cultivators will enable them to overcome.

Bacterial hazards of sludge brought ashore by the tsunami after the great East Japan earthquake of 2011

OBJECTIVES

The aim of this study was to identify bacteria in sludge brought by the 2011 tsunami in Japan to determine the necessary precautions for workers who handle the sludge.

METHODS

Two sludge samples and one water sample were collected from each of two sites in Miyagi Prefecture in June 2011. We also obtained control samples from a paddy field and a dry beach in Fukuoka, Japan. The samples were subjected to physicochemical analyses, conventional cultivation methods, and molecular methods for bacterial flora analysis. The bacterial floras were analyzed using a clone library method employing fragments of the 16S ribosomal RNA gene (rDNA) amplified with universal primers.

RESULTS

We detected 51-61 genera in sludge samples and 14 and 17 genera in water samples collected in the tsunami-affected areas. In sludge samples collected in the tsunami-affected areas, more genera belonged to Proteobacteria than to Bacteroidetes, but in water samples collected in these areas, more genera belonged to Bacteroidetes than to Proteobacteria. Non-O1, non-O139 V. cholerae (non-agglutinable vibrio) was found at approximately 10(4) cells/m/ near the coast of the tsunami affected area. Sulfate-reducing bacteria were detected in sludge collected from the paddy field, and a relatively high concentration of sulfate ions was found in the water sample (258 mg/l).

CONCLUSIONS

Sludge brought by the tsunami contained some pathogens; therefore, frequent hand washing is recommended for workers who have direct contact with the sludge to minimize their risk of infection. Under the anaerobic conditions of paddy fields, hydrogen sulfide could be produced by sulfate-reducing bacteria metabolizing sulfate ions.

Failure to recognize nontuberculous mycobacteria leads to misdiagnosis of chronic pulmonary tuberculosis

Background

Nontuberculous mycobacterial (NTM) infections cause morbidity worldwide. They are difficult to diagnose in resource-limited regions, and most patients receive empiric treatment for tuberculosis (TB). Our objective here is to evaluate the potential impact of NTM diseases among patients treated presumptively for tuberculosis in Mali.

Methods

We re-evaluated sputum specimens among patients newly diagnosed with TB (naïve) and those previously treated for TB disease (chronic cases). Sputum microscopy, culture and Mycobacterium tuberculosis drug susceptibility testing were performed. Identification of strains was performed using molecular probes or sequencing of secA1 and/or 16S rRNA genes.

Results

Of 142 patients enrolled, 61 (43%) were clinically classified as chronic cases and 17 (12%) were infected with NTM. Eleven of the 142 (8%) patients had NTM disease alone (8 M. avium, 2 M. simiae and 1 M. palustre). All these 11 were from the chronic TB group, comprising 11/61 (18%) of that group and all were identified as candidates for second line treatment. The remaining 6/17 (35.30%) NTM infected patients had coinfection with M. tuberculosis and all 6 were from the TB treatment naïve group. These 6 were candidates for the standard first line treatment regimen of TB. M. avium was identified in 11 of the 142 (8%) patients, only 3/11 (27.27%) of whom were HIV positive.

Conclusions

NTM infections should be considered a cause of morbidity in TB endemic environments especially when managing chronic TB cases to limit morbidity and provide appropriate treatment.

[Infections due to rapidly growing mycobacteria]

Rapidly growing mycobacteria (RGM) are ubiquitous in nature and widely distributed in water, soil and animals. During the past three decades we have observed a notable increment of infections caused by RGM, both localized and disseminated, as well as nosocomial outbreaks of contaminated medical equipment. The microbiological diagnosis of RGM infections includes direct microscopic observation and culture. The taxonomic identification is performed by phenotypic, biochemical, chromatographic and molecular biology techniques. The treatment differs from that of other mycobacteriosis like tuberculosis, owing to the variable in vitro susceptibility of the species of this group. The RGM are resistant to conventional antituberculous drugs, but can be susceptible to broad spectrum antimicrobial agents. In this study we comment on the significant aspects of human infections by RGM, including their biology, epidemiology, pathology, microbiological diagnosis, taxonomic identification, antimicrobial susceptibility and treatment.

Application of a broad-range resequencing array for detection of pathogens in desert dust samples from Kuwait and Iraq

A significant percentage of the human population is exposed to high levels of naturally occurring airborne dusts. Although the link between airborne particulate inhalation and a variety of respiratory diseases has long been established, little is known about the pathogenic role of the microbial component of the dust. In this study, we applied highly multiplexed PCR and a high-density resequencing microarray (RPM-TEI version 1.0) to screen samples of fine topsoil particles and airborne dust collected in 19 locations in Iraq and Kuwait for the presence of a broad range of human pathogens. The results indicated the presence of potential human pathogens, including Mycobacterium, Brucella, Coxiella burnetii, Clostridium perfringens, and Bacillus. The presence of Coxiella burnetii, a highly infectious potential biowarfare agent, was confirmed and detected in additional samples by use of a more sensitive technique (real-time PCR), indicating a high prevalence of this organism in the analyzed samples. The detection of potentially viable pathogens in breathable dusts from arid regions of Iraq and Kuwait underscores the importance of further study of these environments.

Core gene set as the basis of multilocus sequence analysis of the subclass Actinobacteridae

Comparative genomic sequencing is shedding new light on bacterial identification, taxonomy and phylogeny. An in silico assessment of a core gene set necessary for cellular functioning was made to determine a consensus set of genes that would be useful for the identification, taxonomy and phylogeny of the species belonging to the subclass Actinobacteridae which contained two orders Actinomycetales and Bifidobacteriales. The subclass Actinobacteridae comprised about 85% of the actinobacteria families. The following recommended criteria were used to establish a comprehensive gene set; the gene should (i) be long enough to contain phylogenetically useful information, (ii) not be subject to horizontal gene transfer, (iii) be a single copy (iv) have at least two regions sufficiently conserved that allow the design of amplification and sequencing primers and (v) predict whole-genome relationships. We applied these constraints to 50 different Actinobacteridae genomes and made 1,224 pairwise comparisons of the genome conserved regions and gene fragments obtained by using Sequence VARiability Analysis Program (SVARAP), which allow designing the primers. Following a comparative statistical modeling phase, 3 gene fragments were selected, ychF, rpoB, and secY with R²>0.85. Selected sets of broad range primers were tested from the 3 gene fragments and were demonstrated to be useful for amplification and sequencing of 25 species belonging to 9 genera of Actinobacteridae. The intraspecies similarities were 96.3–100% for ychF, 97.8–100% for rpoB and 96.9–100% for secY among 73 strains belonging to 15 species of the subclass Actinobacteridae compare to 99.4–100% for 16S rRNA. The phylogenetic topology obtained from the combined datasets ychF+rpoB+secY was globally similar to that inferred from the 16S rRNA but with higher confidence. It was concluded that multi-locus sequence analysis using core gene set might represent the first consensus and valid approach for investigating the bacterial identification, phylogeny and taxonomy.

A polyphasic study on the species diversity of the sediment microbiota of Lake Hévíz

Lake Hévíz is the largest natural thermal lake of Europe, harboring special bacterial communities. The aim of the present study was to gain information about the distribution and species diversity of the sediment microbiota, with special focus on Actinobacteria, by using cultivation-based and -independent molecular methods. Samples from two depths were taken in two different locations in October 2007. 245 strains were isolated, grouped to 85 OTUs by ARDRA, and identified by 16S rDNA sequencing. Most of the strains showed highest sequence similarity with Bacillus and related genera. Strains belonging to the phylum Actinobacteria were identified as members of Arthrobacter, Brachybacterium, Brevibacterium, Curtobacterium, Friedmanniella, Gordonia, Kocuria, Microbacterium, Micrococcus, Micromonospora, Mycobacterium, Rhodococcus, Streptomyces and Williamsia . Two clone libraries were constructed from H3M and H4M samples, providing 288 and 192 clones which were grouped to 150 and 125 OTUs, respectively, by ARDRA. The two most abundant group of the H4M library were OP8-related. The phylum Proteobacteria was represented mostly by delta-Proteobacteria, other relevant groups were Cyanobacteria, Bacteroidetes, Acidobacteria and beta-Proteobacteria. The H3M library was dominated by Cyanobacteria, Verrucomicrobia, beta-Proteobacteria, gamma-Proteobacteria and delta-Proteobacteria. Chloroflexi, Bacteroidetes, Spirochetes and Firmicutes were scarce. Results from the clone libraries were compared to the length-heterogeneity-PCR fingerprints of the communities.

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.