Scedosporium inflatum osteomyelitis in a dog.

Scedosporium inflatum Malloch et Salkin was found to cause osteomyelitis in a 6-year-old spayed female beagle. The previously healthy dog suddenly developed right-forelimb lameness. Bony changes consisting of proliferation with some lysis were noted on radiographic examinations. Microscopic observations of stained sections of tissue obtained by biopsy of the distal humerus revealed the presence of septate branching hyphae. Cultures inoculated with tissue from a later biopsy yielded a mold subsequently identified as S. inflatum. Tissue sections stained with specific Scedosporium fluorescent-antibody conjugate were positive, further substantiating the diagnosis. Although the dog was treated with oral itraconazole, no improvement in the animal's condition was noted, and it was euthanized. Autopsy revealed dissemination of the etiologic agent to the lungs.     

Candida parapsilosis, an emerging fungal pathogen

SUMMARY: Candida parapsilosis is an emerging major human pathogen that has dramatically increased in significance and prevalence over the past 2 decades, such that C. parapsilosis is now one of the leading causes of invasive candidal disease. Individuals at the highest risk for severe infection include neonates and patients in intensive care units. C. parapsilosis infections are especially associated with hyperalimentation solutions, prosthetic devices, and indwelling catheters, as well as the nosocomial spread of disease through the hands of health care workers. Factors involved in disease pathogenesis include the secretion of hydrolytic enzymes, adhesion to prosthetics, and biofilm formation. New molecular genetic tools are providing additional and much-needed information regarding C. parapsilosis virulence. The emerging information will provide a deeper understanding of C. parapsilosis pathogenesis and facilitate the development of new therapeutic approaches for treating C. parapsilosis infections.     

Mycobacterium avium complex, an emerging pathogen in Massachusetts.

We report a study of 1,953 patients whose laboratory records from 1972 through 1983 at the Massachusetts Mycobacteria Reference Laboratory indicated the isolation of Mycobacterium avium complex (MAC) organisms. At least one clinical specimen from each patient during this period exhibited the organism. The incidence of isolation of MAC has increased fivefold since 1972, with a doubling of the number of patients with positive MAC specimens from normally sterile sites occurring since 1980. A concomitant increase of more than fourfold in other nontuberculous mycobacteria has occurred. Most isolates came from high-density population centers. Communities whose drinking water comes from a distant rather than a local source were more likely to have patients with MAC.     

Trichosporon beigelii, an emerging pathogen resistant to amphotericin B.

Trichosporon beigelii caused fatal disseminated infections that were resistant to amphotericin B in two granulocytopenic patients. In vitro susceptibility studies demonstrated that both index strains of T. beigelii were inhibited but not killed by amphotericin B at achievable concentrations in serum. The minimum lethal concentration for both isolates was greater than or equal to 18 micrograms/ml. Five of seven other isolates were found to have a similar pattern of amphotericin B resistance. The fact that the minimum lethal concentration of T. beigelii was many times greater than its MIC was consistent with a resistance pattern of tolerance. We concluded that T. beigelii may be resistant in vitro to amphotericin B and that this in vitro resistance was correlated with refractory, disseminated trichosporonosis in granulocytopenic patients. T. beigelii should be included in the expanding list of amphotericin B-resistant fungi.     

Exserohilum: an emerging human pathogen

Exserohilum is a dematiaceous fungus that may cause a spectrum of diseases in humans, including skin and corneal infection, invasive disease, and allergic fungal sinusitis. The aim of this work is to describe two new cases of Exserohilum infection and to review the literature. The review yielded 33 cases of Exserohilum infection, of which 23 were reported since 1993. Most occurred in regions with hot climates, such as India, Israel, and the southern USA. Impaired immunity was present in the majority of patients with invasive and skin infections, whereas local trauma and atopy were the predisposing factors in those with corneal infections and allergic fungal sinusitis, respectively. Surgical debridement was the principal mode of therapy for allergic fungal sinusitis. Amphotericin B was the initial single antifungal agent used in all cases of invasive disease; the response rate was low but improved with the addition of triazole agents. Outcome appeared to be better than for other mold infections and depended mainly on the underlying diseases.An erratum to this article can be found at     

Ribosomal DNA internal transcribed spacer analysis supports synonomy of Scedosporium inflatum and Lomentospora prolificans.

Scedosporium inflatum is a dematiaceous opportunistic pathogen originally described by D. Malloch and I.F. Salkin (Mycotaxon 21:247-255, 1984). However, E. Gueho and G. S. De Hoog (J. Mycol. Med. 118:3-9, 1991) recently suggested reducing this mold to synonomy with Lomentospora prolificans on the basis of their similar morphological and molecular characteristics. We have investigated the ribosomal DNA internal transcribed spacers (ITS), i.e., ITS I and ITS II, of 18 isolates, including these two fungi and a closely related pathogen, Scedosporium apiospermum, and its telemorph, Pseudallescheria boydii. Identical ITS restriction fragment length polymorphisms were found in eight isolates of S. inflatum and L. prolificans. These results support Gueho and De Hoog's proposal to combine S. inflatum and L. prolificans into the binomial Scedosporium prolificans. However, the ITS I sequence of S. apiospermum and the ITS restriction fragment length polymorphisms of S. apiospermum and P. boydii were found to be significantly different from those of S. inflatum and L. prolificans. The ITS restriction pattern differences may be valuable in clinical settings for distinguishing these fungi.     

Helcococcus ovis, an emerging pathogen in bovine valvular endocarditis

The initial isolation of Helcococcus ovis from a valvular thrombus prompted us to investigate the prevalence of this bacterium in bovine valvular endocarditis. Specimens from 55 affected hearts were examined by culture using Columbia blood agar and cross streaking the inoculated plate with a Staphylococcus aureus strain. As confirmed by 16S rRNA gene sequencing, H. ovis was isolated with an unexpectedly high frequency of 33%, predominantly as heavy growth and pure culture. The majority of H. ovis isolates showed distinct satellitism around S. aureus and pyridoxal dependency, resembling “nutritionally variant streptococci” (now assigned to the genera Abiotrophia and Granulicatella). Using the API rapid ID 32 Strep, API ZYM, and Rosco Diatabs systems, incongruent results were obtained for alkaline phosphatase, β-galactosidase, β-glucuronidase, and leucine aminopeptidase activities. Based on the satellitism/pyridoxal dependency; hemolysis on blood agar; the API rapid ID 32 Strep results for arginine dihydrolase, α-galactosidase, β-galactosidase, β-glucuronidase, and pyroglutamic acid arylamidase activities; hippurate hydrolysis; and acidification of sucrose, a scheme for the identification of H. ovis and its differentiation from other members of the Helcococcus genus and the pyridoxal-dependent species Abiotrophia defectiva, Granulicatella adiacens, and Granulicatella elegans is proposed. By establishing specific fluorescence in situ hybridization, large H. ovis aggregates were specifically detected within the fibrinous exudate of the valvular thrombi. Our results demonstrate for the first time that H. ovis represents an emerging pathogen in bovine valvular endocarditis that is frequently isolated if appropriate culture conditions are used.     

Moraxella catarrhalis: an emerging respiratory pathogen

In the past years Moraxella (Branhamella) catarrhalis has finally gained respect as a pathogen thanks to the many reports of its causal role. The intent of this review is to provide a critical evaluation of the intent of this review is to provide a critical evaluation of the microbiological features (taxonomy, diagnosis, virulence, epidemiology and drug resistance), clinical diseases and therapy of this microorganism     

Mycoplasma pneumoniae—an emerging extra-pulmonary pathogen

Mycoplasma is a well-recognised pathogen that colonises mucosal surfaces of humans and animals. Mycoplasma pneumoniae infects the upper and lower respiratory tracts of children and adults, leading to a wide range of respiratory and non-respiratory clinical conditions. M. pneumoniae infection is frequently considered in the differential diagnosis of patients with respiratory illnesses, and is commonly managed empirically with macrolides and fluoroquinolones. This contrasts with patients who present with non-respiratory symptoms in the context of a recent or current unrecognised M. pneumoniae infection, for whom this pathogen is rarely considered in the initial differential diagnosis. This review considers the microbiological, epidemiological, pathogenic and clinical features of this frequent pathogen that need to be considered in the differential diagnosis of respiratory and non-respiratory infections.     

Mycoplasma pneumoniae-an emerging extra-pulmonary pathogen.

Mycoplasma is a well-recognised pathogen that colonises mucosal surfaces of humans and animals. Mycoplasma pneumoniae infects the upper and lower respiratory tracts of children and adults, leading to a wide range of respiratory and non-respiratory clinical conditions. M. pneumoniae infection is frequently considered in the differential diagnosis of patients with respiratory illnesses, and is commonly managed empirically with macrolides and fluoroquinolones. This contrasts with patients who present with non-respiratory symptoms in the context of a recent or current unrecognised M. pneumoniae infection, for whom this pathogen is rarely considered in the initial differential diagnosis. This review considers the microbiological, epidemiological, pathogenic and clinical features of this frequent pathogen that need to be considered in the differential diagnosis of respiratory and non-respiratory infections.     

Nosocomial outbreak caused by Scedosporium prolificans (inflatum): four fatal cases in leukemic patients.

Four cases of fatal disseminated Scedosporium prolificans (inflatum) infection occurring in neutropenic patients are reported. Because of hospital renovation, the patients were cared for in a temporary hematologic facility. S. prolificans (inflatum) was isolated from blood cultures of these four patients, two of whom underwent full necropsy, and revealed abundant vegetative hyphae and ovoid conida with truncate bases in many organs. In vitro susceptibility testing of fungal strains showed all isolates to be resistant to amphotericin B, flucytosine, miconazole, ketoconazole, fluconazole, and itraconazole, with MICs greater than 16 micrograms/ml. The reported infections, two in each of two rooms, occurred over a period of 1 month, with very similar clinical outcomes. Circumstancial evidence suggested a nosocomial outbreak, but the environmental samples collected from the rooms, corridors, and adjacent areas did not yield S. prolificans (inflatum). Nevertheless, circumstantial evidence suggested a nosocomial outbreak of S. prolificans (inflatum) infection.     

Leptotrichia amnionii, an emerging pathogen of the female urogenital tract

Leptotrichia amnionii, a recently described, very fastidious, gram-negative anaerobic bacterium, is an opportunistic pathogen of the female urogenital tract. We report a case of second-trimester abortion in a patient with chorioamnionitis and L. amnionii bacteremia and a case of renal abscess in a female 5 weeks postpartum.     

Innate immunity against Granulibacter bethesdensis, an emerging gram-negative bacterial pathogen

Acetic acid bacteria were previously considered nonpathogenic in humans. However, over the past decade, five genera of Acetobacteraceae have been isolated from patients with inborn or iatrogenic immunodeficiencies. Here, we describe the first studies of the interactions of the human innate immune system with a member of this bacterial family, Granulibacter bethesdensis, an emerging pathogen in patients with chronic granulomatous disease (CGD). Efficient phagocytosis of G. bethesdensis by normal and CGD polymorphonuclear leukocytes (CGD PMN) required heat-labile serum components (e.g., C3), and binding of C3 and C9 to G. bethesdensis was detected by immunoblotting. However, this organism survived in human serum concentrations of ≥90%, indicating a high degree of serum resistance. Consistent with the clinical host tropism of G. bethesdensis, CGD PMN were unable to kill this organism, while normal PMN, in the presence of serum, reduced the number of CFU by about 50% after a 24-h coculture. This finding, together with the observations that G. bethesdensis was sensitive to H(2)O(2) but resistant to LL-37, a human cationic antimicrobial peptide, suggests an inherent resistance to O(2)-independent killing. Interestingly, 10 to 100 times greater numbers of G. bethesdensis were required to achieve the same level of reactive oxygen species (ROS) production induced by Escherichia coli in normal PMN. In addition to the relative inability of the organism to elicit production of PMN ROS, G. bethesdensis inhibited both constitutive and FAS-induced PMN apoptosis. These properties of reduced PMN activation and resistance to nonoxidative killing mechanisms likely play an important role in G. bethesdensis pathogenesis.     

Mycobacterium abscessus: an emerging rapid-growing potential pathogen

Mycobacterium abscessus is the most pathogenic and chemotherapy-resistant rapid-growing mycobacterium. It is commonly associated with contaminated traumatic skin wounds and with post-surgical soft tissue infections. It is also one of the mycobacteria that are most often isolated from cystic fibrosis patients. It is essential to differentiate this species from the formerly indistinct "M. chelonae-complex", as chemotherapy is especially difficult in M. abscessussenso strictu. Clarithromycin or azithromycin are the only regular oral antimycobacterial agents with an effect on M. abscessus, and should preferably be supplemented with other drugs since long-term monotherapy may cause resistance. Amikacin is a major parenteral drug against M. abscessus that should also be given in combination with another drug. The recently introduced drug tigecycline may prove to be an important addition to chemotherapy, but has yet to be fully clinically evaluated as an antimycobacterial agent. Surgery can be curative, or at least helpful, in the healing of M. abscessus infection, and if conducted, it should include the removal of all foreign or necrotic material. There is increasing awareness of M. abscessus as an emerging pathogen.     

Quorum sensing in Acinetobacter: an emerging pathogen

Acinetobacter is emerging as one of the major nosocomial infectious pathogens, facilitated by tolerance to desiccation and multidrug resistance. Quorum sensing (autoinducer-receptor mechanism) plays role in biofilm formation in Acinetobacter, though its role in regulation of other virulence factors is yet to be established. Phylogenetic studies indicate that Acinetobacter baumannii is closely related to Burkholderia ambifaria but its quorum sensing genes (abaI and abaR) were acquired horizontally from Halothiobacillus neapolitanus. The prospects of quorum quenching to control the infections caused by Acinetobacter have also been discussed.     

Non-diphtheriae Corynebacterium species: an emerging respiratory pathogen

The purpose of the study was to describe the microbiological and clinical features of ten cases of lower respiratory tract infection due to Corynebacterium striatum, Corynebacterium propinquum and Corynebacterium pseudodiphtheriticum. Respiratory samples were recovered from hospitalised patients who were diagnosed of pneumonia and exacerbations of chronic respiratory infections. The samples were Gram-stained and seeded on conventional bacterial growing media. Bacteria were identified by matrix-assisted linear desorption/ionisation–time-of-flight mass spectrometry (MALDI-TOF MS). Antibiotic susceptibility was tested by the disk diffusion method. All patients presented an acute respiratory onset, most of them in the context of an underlying disease and/or immunosuppression. In all patients, the microscopical examination of Gram-stained respiratory samples showed numerous polymorphonuclear cells and Gram-positive bacilli, suggestive of the Corynebacterium morphotype. A pure culture growth of Corynebacterium was obtained in the majority (72 %) of samples. The conclusions are that non-diphtheriae Corynebacterium species are an emerging cause of respiratory infection among patients with chronic respiratory disease and/or immunosuppression, and cannot always be considered as mere colonisers. The microorganism’s predominance in Gram-stained purulent respiratory samples together with abundant growth in the culture is the key for the microbiological diagnosis.     

Stenotrophomonas maltophilia: an emerging global opportunistic pathogen

Stenotrophomonas maltophilia is an emerging multidrug-resistant global opportunistic pathogen. The increasing incidence of nosocomial and community-acquired S. maltophilia infections is of particular concern for immunocompromised individuals, as this bacterial pathogen is associated with a significant fatality/case ratio. S. maltophilia is an environmental bacterium found in aqueous habitats, including plant rhizospheres, animals, foods, and water sources. Infections of S. maltophilia can occur in a range of organs and tissues; the organism is commonly found in respiratory tract infections. This review summarizes the current literature and presents S. maltophilia as an organism with various molecular mechanisms used for colonization and infection. S. maltophilia can be recovered from polymicrobial infections, most notably from the respiratory tract of cystic fibrosis patients, as a cocolonizer with Pseudomonas aeruginosa. Recent evidence of cell-cell communication between these pathogens has implications for the development of novel pharmacological therapies. Animal models of S. maltophilia infection have provided useful information about the type of host immune response induced by this opportunistic pathogen. Current and emerging treatments for patients infected with S. maltophilia are discussed.