Contamination of Peripheral Hematopoeitic Stem Cell Products With aMycobacterium mucogenicum–Related Pathogen

A gram-positive rod with a restriction pattern closely related to the published nucleotide sequence ofMycobacterium mucogenicumwas isolated from 6 of 45 units of peripheral blood stem cell products. The source of the contamination was traced to ice cubes used in processing the peripheral blood stem cell products. Substituting reusable ice trays for ice from an ice machine terminated the outbreak.

Nosocomial Mycobacterial Pseudoinfection in a Georgia Hospital

Nosocomial pseudoepidemics may be detected when clustering of pseudoinfections occur or when artificial clusters of real infection are observed. Nontuberculous mycobacteria were reportedly isolated from specimens obtained from seven patients at one hospital from October 1980 to January 1981. Because the patients' clinical illnesses were not uniformly consistent with mycobacterial disease, we hypothesized that pseudoinfections had occurred and searched for a common source of contamination. The investigation suggested that specimen contamination was associated with one microbiology laboratory technician: 6 of 22 (27%) specimens processed by that person were positive compared with 1 of 103 (1%) specimens processed by the other five technicians. However, a specific mechanism of contamination was not identified. Nosocomial pseudoepidemics associated with false infections should be suspected and investigated when clinical features and laboratory findings do not agree.

Distribution and respiratory activity of mycobacteria in household water system of healthy volunteers in Japan

The primary infectious source of nontuberculous mycobacteria (NTM), which are known as opportunistic pathogens, appears to be environmental exposure, and it is important to reduce the frequency of exposure from environmental sources for preventing NTM infections. In order to achieve this, the distribution and respiratory activity of NTM in the environments must be clarified. In this study, we determined the abundance of mycobacteria and respiratory active mycobacteria in the household water system of healthy volunteers using quantitative PCR and a fluorescent staining method, because household water has been considered as one of the possible infectious sources. We chose healthy volunteer households in order to lessen the effect of possible residential contamination from an infected patient. We evaluated whether each sampling site (bathroom drain, kitchen drain, bath heater pipe and showerhead) have the potential to be the sources of NTM infections. Our results indicated that drains in the bathroom and kitchen sink are the niche for Mycobacterium spp. and M. avium cells were only detected in the bathtub inlet. Both physicochemical and biologic selective pressures may affect the preferred habitat of Mycobacterium spp. Regional differences also appear to exist as demonstrated by the presence (US) or absence (Japan) of Mycobacterium spp. on showerheads. Understanding of the country specific human activities and water usage will help to elucidate the infectious source and route of nontuberculous mycobacterial disease.

The Two Faces of Autophagy: Coxiella and Mycobacterium

In the world of pathogen-host cell interactions, the autophagic pathway has been recently described as a component of the innate immune response against intracellular microorganisms. Indeed, some bacterial survival mechanisms are hampered when this process is activated. Mycobacterium tuberculosis infection of macrophages, for example, is impaired upon autophagy induction and the bacterial phagosomes are redirected to autophagosomes. On the other hand, pathogens like Coxiella burnetii are benefited by this cellular response and subvert the autophagy process resulting in a more efficient replication. We study at the molecular level these two different faces of the autophagy process in pathogen life in order to elucidate the intricate routes modulated by the microorganisms as survival strategies.

Surgical intervention for thoracic infections

Multidisciplinary management of thoracic infection, including experts in thoracic surgery, pulmonology, infectious disease, and radiology, is ideal for optimal outcomes. Initial assessment of parapneumonic effusion and empyema requires computed tomographic evaluation and consideration for fluid sampling or drainage. Goals for the treatment of parapneumonic effusion and empyema include drainage of the pleural space and complete lung reexpansion. Pulmonary abscess is often successfully treated with antibiotics and observation. Surgical intervention for the treatment of fungal or tuberculous lung disease should be undertaken by experienced surgeons following multidisciplinary assessment. Sternoclavicular joint infection often requires joint resection.

[Identification of Mycobacterium spp. isolates using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS)]

STUDY OBJECTIVE

Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has recently been widely used in diagnostic microbiological laboratories. It is a cheap and rapid method for the identification of bacteria and micromycetes. Apart from this purpose, it is also used for the detection of antibiotic resistance mechanisms. It has the potential to be extended for other purposes in microbiology. The aim of this study was to validate MALDI-TOF MS for the identification of mycobacteria.

MATERIAL AND METHODS

Thirty isolates of Mycobacterium spp. isolated in the Laboratory of Mycobacteriology of the Plzeň University Hospital were included in the study. The isolates were identified to the species level using biochemical tests, gene probes, and sequencing of the gene encoding 16S rRNA. The identification by MALDI-TOF MS was performed with the use of silica beads. Strain identification by sequencing the gene encoding 16S rRNA was considered as the reference method.

RESULTS

MALDI-TOF MS correctly identified all isolates of Mycobacterium spp. (score range 1.461 - 2.168). The species identified were Mycobacterium tuberculosis (n= 5), Mycobacterium kansasii (n=5), Mycobacterium avium (n=6), Mycobacterium intracelullare (n=3), Mycobacterium xenopi (n=3), Mycobacterium gordonae (n=1), Mycobacterium abscessus (n=1), Mycobacterium kumamotonense (n=2), Mycobacterium mantenii (n=1), Mycobacterium lentiflavum (n=1), Mycobacterium fortuitum (n=1), and Mycobacterium scrofulaceum (n=1).

CONCLUSION

MALDI-TOF MS is a suitable tool for the routine identification of Mycobacterium spp. in laboratories using this method for the conventional identification of microbes.

First description of Mycobacterium heckeshornense infection in a feline immunodeficiency virus-positive cat

A 13-year-old cat was presented to the veterinary clinic with poor condition, vomiting and a reduced appetite. A painful abdomen was diagnosed because of tension and defence reactions on palpation. Diagnostic laparotomy showed a thickening of the colon and caecal intestinal wall. Histopathological investigation of intestinal biopsies revealed focal severe granulomatous inflammation with numerous acid-fast bacilli in the tela submucosa. The complete blood count test showed a severe lymphopenia and anaemia, and the cat tested positive for feline immunodeficiency virus (FIV) antibodies by enzyme-linked immunosorbent assay. The cat was euthanased and necropsied. Multifocal granulomatous nodules were present in the intestines, liver and kidneys. The gastric lymph node was markedly enlarged and showed a caseous cut surface. Histopathology revealed a systemic mycobacteriosis affecting intestine, lymph nodes, liver and kidneys. The mycobacterial strain was cultured and determined by its unique 16S rRNA gene sequence as Mycobacterium heckeshornense. This is the first reported case of M heckeshornense in a cat. It was suspected that the disseminated mycobacteriosis was supported by the FIV infection.

Small RNAs in mycobacteria: an unfolding story

Mycobacteria represent a class of powerful pathogens, including those causing tuberculosis and leprosy, which continue to be worldwide health challenges. In the last 20 years, an abundance of non-coding, small RNAs (sRNAs) have been discovered in model bacteria and gained significant attention as regulators of cellular responses, including pathogenesis. Naturally, a search in mycobacteria followed, revealing over 200 sRNAs thus far. Characterization of these sRNAs is only beginning, but differential expression under environmental stresses suggests relevance to mycobacterial pathogenesis. This review provides a comprehensive overview of the current knowledge of sRNAs in mycobacteria, including historical perspective and techniques used for identification and characterization.

Mycobacteria counteract a TLR-mediated nitrosative defense mechanism in a zebrafish infection model

Pulmonary tuberculosis (TB), caused by the intracellular bacterial pathogen Mycobacterium tuberculosis (Mtb), is a major world health problem. The production of reactive nitrogen species (RNS) is a potent cytostatic and cytotoxic defense mechanism against intracellular pathogens. Nevertheless, the protective role of RNS during Mtb infection remains controversial. Here we use an anti-nitrotyrosine antibody as a readout to study nitration output by the zebrafish host during early mycobacterial pathogenesis. We found that recognition of Mycobacterium marinum, a close relative of Mtb, was sufficient to induce a nitrosative defense mechanism in a manner dependent on MyD88, the central adaptor protein in Toll like receptor (TLR) mediated pathogen recognition. However, this host response was attenuated by mycobacteria via a virulence mechanism independent of the well-characterized RD1 virulence locus. Our results indicate a mechanism of pathogenic mycobacteria to circumvent host defense in vivo. Shifting the balance of host-pathogen interactions in favor of the host by targeting this virulence mechanism may help to alleviate the problem of infection with Mtb strains that are resistant to multiple drug treatments.

Granulomatous lesions in a wild mullet population from the eastern Ligurian Sea (Italy): mycobacteriosis vs. pseudotuberculosis

Mycobacterium spp. and Photobacterium damselae subsp. piscicida are recognized as the most frequent causative agents of granulomatous lesions in fish. Although frequent episodes of mycobacterial infections have been reported in wild fish worldwide, only sporadic cases have been documented to date in Italy. To investigate for the presence of lesions referable to mycobacteriosis and to identify the mycobacterial species involved, a total of 159 wild mullets were fished from the eastern coast of the Ligurian Sea, killed and necropsied. Liver and spleen samples were collected from all fish for histopathological and microbiological analyses. Molecular investigations for identification of Photobacterium damselae subsp. piscicida were performed. Gross examination revealed granulomatous lesions in one animal; microscopically, 42.14% of fish displayed granulomas with various histological features, 19.50% resulted positive at Ziehl-Neelsen staining, and were confirmed as mycobacterial lesions by culture. The identified colonies were characterized as M. fortuitum, M. abscessus, M. flavescens, M. chelonae, M. septicum and M. nonchromogenicum. In all, 35% of animals resulted positive for Photobacterium damselae subsp. piscicida. These data suggest widespread mycobacterial infection also by Photobacterium damselae subsp. piscicida infections in wild fish. Moreover, the pathogenicity of some mycobacterial species, previously considered as saprophytic, was demonstrated.

[Interferon-gamma receptor 1 deficiency in a 19-month-old child: case report and literature review]

OBJECTIVE

To analyze the clinical manifestation of interferon gamma receptor 1 deficiency (IFN-γR1 deficiency) and to improve the recognition of this disease in children, decrease diagnostic errors and missed diagnosis.

METHOD

The information of one case with IFN-γR1 deficiency (past history of illness, clinical manifestation, laboratory examination and treatment) were analyzed.

RESULT

The patient was a 19-month-old girl with IFN-γR1 deficiency, 1-2 weeks after she was vaccinated with BCG at the age of 18 months, she manifested with lymph nodes at the same site as vaccination site, and repeated rash. Examination found a mass in the right armpit, the size was 3 cm × 3 cm, protruded on the skin, tenacious in nature, poorly mobile. B-mode ultrasound showed right armpit chest heterogeneous hypoechoic mass; abdominal B-mode ultrasound showed pancreatic lymph nodes around the abdominal aorta and mild swelling; chest X-ray showed right axillary lymph nodes, increased double markings. Initial diagnosis was (1) bronchitis, (2) BCG vaccination reaction, (3) Sepsis? . After admission, the patient was given rifampicin + isoniazid + latamoxef + amoxicillin and clavulanate potassium, and then changed to meropenem and Fusidic acid, but treatment showed no improvement. After adding the treatment with anti-inflammatory treatment, i.e., gamma globulin and methylprednisolone, the fever subsided. Conventional treatment with rifampicin + isoniazid 3 months after discharge from hospital were effective, and the axillary lymph nodes were not palpable. Six months after BCG vaccination bone tuberculosis occurred. CT of left hip and left knee showed bilateral hip joint effusion, left distal femur and left proximal tibia bone destruction. Gene detection showed the presence of homozygous IFNγ-R1 gene mutation of c.114_135del(p.E38fsX54). Her parents are consanguinity, both were carriers. In the literature, 99 cases with IFN-γR1 deficiency were reported, 95% of the cases had disseminated tuberculosis, and in 60 cases the dissemination occurred after BCG vaccination.

CONCLUSION

IFN-γR1 is an extremely rare disease in children. If disseminated tuberculosis infection occured, especially after BCG vaccination, or if there were focal/multifocal bone tuberculosis, immune function with conventional detection is considered normal, then IFN-γR1 deficiency should be considered, and early genetic testing for confirming the diagnosis and selecting the appropriate treatment are needed.

Characterization of Mycobacterium salmoniphilum as causal agent of mycobacteriosis in Atlantic salmon, Salmo salar L., from a freshwater recirculation system

Thirty Atlantic salmon, Salmo salar L., with low corporal condition relative to other fish present in the culture system, were sampled from a freshwater recirculation pisciculture located in Chile. The most characteristic signs and lesions were cachexia and presence of multiple greyish-white granulomas within internal organs. The external and internal lesions, along with the microscopic, histologic and biochemical findings, were consistent with mycobacteriosis. The identification of Mycobacterium salmoniphilum as the causal agent of the lesions was possible through the use of molecular analyses. This study represents the first report of Mycobacterium salmoniphilum in a freshwater recirculation system and the first case of fish mycobacteriosis described in Chile.

Chiasmitis caused by Mycobacterium haemophilum in an immunocompromised adult

We report a case of chiasmitis caused by a rare nontuberculous mycobacterium in an immunocompromised patient. A 44-year-old man with a history of AIDS presented with recurrent vision loss and headache. Magnetic resonance imaging (MRI) demonstrated an enhancing mass involving the optic chiasm. Histopathologic and microbiological evaluation revealed infection with Mycobacterium haemophilum. While combination antimicrobial and steroid therapy contributed to improvement in his vision, the patient's symptoms recurred. Follow-up MRI showed extension of infection to the hypothalamus and leptomeninges, indicative of basilar meningitis. MRI is a valuable tool for early diagnosis of chiasmitis as well as for monitoring infection progression and treatment response.

Evaluation and management of patients with pulmonary nontuberculous mycobacterial infections

Nontuberculous mycobacteria (NTM) are emerging pathogens increasingly associated with chronic pulmonary disease. NTM are environmental saprophytes found in soil, dust and water and, unlike Mycobacterium tuberculosis, NTM are not transmitted from person to person. Pulmonary disease caused by NTM is a particular problem in older people without underlying immune compromise. The diagnosis of NTM pulmonary disease usually requires either multiple respiratory cultures that grow NTM or heavy growth of NTM from a single bronchoscopy or lung-biopsy specimen. High resolution computed tomography is the most useful radiographic study for diagnosis and to determine the extent of disease. Treatment includes multiple medications with activity against the particular NTM species, as single-drug therapy is likely to select for resistant organisms. Data demonstrating the effectiveness of specific drug regimens for NTM pulmonary disease are limited. Clarithromycin and azithromycin form the backbone of most treatment regimens because these drugs are active against many NTM species. Drug tolerability and cost are the major barriers to successful treatment of NTM pulmonary disease. Adjunctive therapies, including mucus clearance techniques and appetite stimulants, are unproven but may be of value in management of NTM pulmonary disease. Multicenter, randomized trials of macrolide-based therapies are sorely needed to determine the safest and most effective treatments for NTM pulmonary disease.

Molecular methods for detection of invasive fungal infections and mycobacteria and their clinical significance in hematopoietic stem cell transplantation

Infection remains an important source of morbidity and mortality in patients who undergo hematopoietic stem cell transplantation (HSCT). In the immune reconstitution period after transplantation, HSCT recipients are most likely to have bacterial or fungal infections. Invasive fungal infections (IFIs) and mycobacterial infections (MBIs) are among the complications of HSCT, with high morbidity and mortality rates. Early diagnosis of both is crucial in order to manipulate the disease and to avoid fulminant outcomes. This chapter reviews the current knowledge on the molecular diagnosis of IFIs and MBIs in HSCT recipients, describing two different polymerase chain reaction (PCR)-based methods, one commercial (qPCR, Roche) and one in-house IS6110-based protocol.

Paramecium caudatum enhances transmission and infectivity of Mycobacterium marinum and M. chelonae in zebrafish Danio rerio

Mycobacterial infections in laboratory zebrafish Danio rerio are common and widespread in research colonies. Mycobacteria within free-living amoebae have been shown to be transmission vectors for mycobacteriosis. Paramecium caudatum are commonly used as a first food for zebrafish, and we investigated this ciliate's potential to serve as a vector of Mycobacterium marinum and M. chelonae. The ability of live P. caudatum to transmit these mycobacteria to larval, juvenile and adult zebrafish was evaluated. Infections were defined by histologic observation of granulomas containing acid-fast bacteria in extraintestinal locations. In both experiments, fish fed paramecia containing mycobacteria became infected at a higher incidence than controls. Larvae (exposed at 4 d post hatch) fed paramecia with M. marinum exhibited an incidence of 30% (24/80) and juveniles (exposed at 21 d post hatch) showed 31% incidence (14/45). Adult fish fed a gelatin food matrix containing mycobacteria within paramecia or mycobacteria alone for 2 wk resulted in infections when examined 8 wk after exposure as follows: M. marinum OSU 214 47% (21/45), M. marinum CH 47% (9/19), and M. chelonae 38% (5/13). In contrast, fish feed mycobacteria alone in this diet did not become infected, except for 2 fish (5%) in the M. marinum OSU 214 low-dose group. These results demonstrate that P. caudatum can act as a vector for mycobacteria. This provides a useful animal model for evaluation of natural mycobacterial infections and demonstrates the possibility of mycobacterial transmission in zebrafish facilities via contaminated paramecia cultures.

Comparative Evaluation of theIn VitroAntimycobacterial Activities of Six Aminoglycoside Antibiotics Using an Agar Dilution Method

Given the increasing prevalence of mycobacterial resistance to aminoglycoside antibiotics, we examined the susceptibility of 76 clinical isolates of mycobacteria to arbekacin, amikacin, gentamicin, kanamycin, tobramycin and streptomycin using an agar dilution method. Only arbekacin and amikacin showed excellent therapeutic potential (minimum inhibitory concentrationis (MICs) < or =0.25-4 microg/ml) against 30 isolates of rapidly growing mycobacteria, including Mycobacterium fortuitum, M. chelonae and a related organism, Nocardia asteroides. The MIC(90)of tobramycin against 23 isolates of M. avium complex was 8 microg/ml, while that of the other 5 aminoglycosides ranged from 64-256 microg/ml. Of the 23 M. tuberculosis isolates tested, 5 showed aminoglycoside resistance (MICs 128 to > or =1,024 microg/ml), while the others were variably susceptible (MICs < or =0.25-32 microg/ml) to all 6 aminoglycosides. The chemotherapeutic potential of arbekacin, amikacin and streptomycin as treatment of tuberculosis was apparent; however, proper patient management would be required to control against the emergence of the drug-resistant strains during prolonged treatment.

Comparison of fixatives and fixation time for PCR detection of Mycobacterium in zebrafish Danio rerio

Mycobacteriosis is a common disease of laboratory zebrafish Danio rerio. Different infection patterns occur in zebrafish depending on mycobacterial species. Mycobacterium marinum and M. haemophilum produce virulent infections associated with high mortality, whereas M. chelonae is more widespread and is not associated with high mortality. Identification of mycobacterial infections to the species level provides important information for making management decisions. Observation of acid-fast bacilli in histological sections or tissue imprints is the most common diagnostic method for mycobacteriosis in fish, but only allows for diagnosis to the genus level. Mycobacterial culture followed by molecular or biochemical identification is the traditional approach, but DNA of diagnostic value can also be retrieved from paraffin blocks. Here we investigated the type of fixative, time in fixative before processing, species of mycobacteria, and severity of infection as parameters to determine whether the hsp gene PCR assay (primer set HS5F/hsp667R) could detect and amplify mycobacterial DNA from paraffin-embedded zebrafish. Whole zebrafish were experimentally infected with either M. chelonae or M. marinum, and then preserved in 10% neutral buffered formalin or Dietrich's fixative for 3, 7, 21, and 45 d. Subsequently, fish were evaluated by hematoxylin and eosin and Fite's acid-fast stains to detect mycobacteria within granulomatous lesions. The PCR assay was quite effective and obtained PCR product from 75 and 88% of the M. chelonae- and M. marinum-infected fish, respectively. Fixative type, time in fixative, and mycobacterial species showed no statistical relationship with the efficacy of the PCR test.

Rapid diagnosis of Mycobacterium abscessus endophthalmitis

Nontuberculous mycobacteria are widely distributed in the environment and have the potential to cause a wide spectrum of infections including pulmonary, bone, soft tissue or ocular infections. They are a rare cause of endophthalmitis, a potentially devastating condition, which may be acquired through contamination of water or antiseptic solutions. Diagnosis is often delayed due to low clinical suspicion, resulting in poor clinical outcomes. Newer laboratory techniques such as real-time PCR can be used for rapid detection, identification and speciation of mycobacteria and allow for initiation of focused antibiotic therapy. We describe a case of Mycobacterium abscessus endophthalmitis that developed 30 years after traumatic loss of cornea in a patient with diabetes mellitus.

Stress-induced L-forms of Mycobacterium bovis: a challenge to survivability

This study addressed the ability of Mycobacterium bovis to produce unusual extreme morphologic forms (cell wall-deficient or L-forms) under stress conditions. Models using nutrient starvation and cryogenic stress treatments of Mycobacterium bovis, as well as the filtration technique followed by cultivation in semisolid medium, were used for isolation of L-form variants. Morphological transformations and developmental stages, typical for the bacterial L-cycle were observed by electron microscopy. Of special interest was the formation of giant filaments and common extremely thick membranous structures enveloping the entire L-form population. Following collapse of giant filamentous structures small viable cell elements, mainly granules and coccobacilli, were released and proved able to grow into large bodies or multiply by fission or budding. Derivation of viable filterable forms from L-form cultures and parental strain and their identification as Mycobacterium bovis based on specific IS6110 PCR was noteworthy. We suggest that formation of giant filaments and thick common membranous envelopes, observed under stress conditions, may serve a twofold purpose - protection against an unfavourable environment, and a role in reproduction of Mycobacterium bovis L-forms. The observed L-form conversion phenomenon in Mycobacterium bovis seems to be associated with an adaptive strategy of this pathogen for survival and reproduction in an unfavorable environment.