Endocarditis due to Kytococcus schroeteri: case report and review of the literature

We report the third case of endocarditis caused by the newly described micrococcal species Kytococcus schroeteri. A 49-year-old woman was admitted to the hospital with suspected prosthetic valve endocarditis. Five blood cultures and prosthetic valve cultures grew the same type of organism, initially identified as Micrococcus sp. Assignment to the genus Kytococcus was suggested by the arginine dihydrolase activity and resistance to oxacillin. After sequencing of the 16S rRNA genes, the isolate was recognized as K. schroeteri. The patient was treated first with vancomycin combined with gentamicin and later with pristinamycin and rifampin. Three cases of K. schroeteri endocarditis described within a short period of time might indicate a specific pathogenicity of this new species. The isolation of kytococci from normally sterile sites should not be overlooked.     

Low Virulence of Escherichia coli Strains Causing Urinary Tract Infection in Renal Disease Patients

 The distribution of urinary bacterial species was determined and the virulence factors of Escherichia coli urinary strains analysed by molecular and phenotyping methods in episodes of urinary tract infection in renal disease patients (n=68) in comparison with other immunocompromised patients (n=59) and non-immunocompromised patients (n=21). Escherichia coli was isolated in 116 (78%) of the 148 patients, being the species most frequently isolated in all groups (75% of renal disease patients, 76% of other immunocompromised patients, 95% of non-immunocompromised patients). All other pathogens showed a similar distribution in the renal disease and other immunocompromised patient groups. All virulence factors of Escherichia coli tested for (genes for G adhesins, expression of MR adhesins, production of haemolysin, presence of certain O and K antigens) were found more often in non-immunocompromised than in immunocompromised patients. The factors allowing the highest degree of discrimination between immunocompromised and non-immunocompromised patients were the prevalence of genes for G adhesins (35% vs. 65%) and expression of MR adhesins (32% vs. 55%). It is concluded that there is a lower prevalence of G adhesins and MR adhesins in Escherichia coli strains from immunocompromised patients than non-immunocompromised patients, suggesting that less virulent Escherichia coli strains may cause urinary tract infections more frequently in renal disease patients and other immunocompromised patients. Moreover, the spectrum of urinary pathogens other than Escherichia coli is similar in both immunocompromised patient groups investigated.     

Community-acquired pneumonia in immunocompromised older patients: incidence,causative organisms and outcome

The number of elderly patients in the community with immunosuppressive conditions has increased progressively over recent decades. We sought to determine the incidence, causative organisms and outcome of community-acquired pneumonia (CAP) occurring in immunocompromised older patients. We prospectively compared cases of CAP in immunocompromised and non-immunocompromised patients admitted to five public hospitals in three Spanish regions. Of 320 cases studied, 115 (36%) occurred in immunocompromised patients, including: solid or hematological malignancy (97), corticosteroids or other immunosuppressive drugs (44), solid organ or stem cell transplant (five), and other conditions (eight). The etiology was established in 44% of immunocompromised patients vs. 32% of non-immunocompromlsed patients (p 0.03). Streptococcus pneumoniae was the most common causative organism in both groups (29% vs. 21%; p 0.08), followed by Legionella pneumophila (3% vs. 6%; p 0.01). Gram-negative bacilli were more frequent among immunocompromised patients (5% vs. 0.5%; p <0.01), particularly Pseudomonas aeruginosa (3% vs. 0%; p 0.04). Nocardiosis was only observed in immunocompromised patients (two cases). Bacteremia occurred similarly in the two groups. No significant differences were found with respect to ICU admission (8%, in both groups) or the length of stay (12.5 vs. 10.4 days). The early (<48 h) (3.5 vs. 0.5%; p 0.04) and overall case-fatality rates (12% vs. 3%; p <0.01) were higher in immunocompromised patients. In conclusion, a substantial number of older patients hospitalized for CAP are immunocompromised. Although relatively uncommon, CAP due to gram-negative bacilli, including P. aeruginosa, is more frequent among these patients. CAP occurring in immunocompromised patients causes significant morbidity and mortality.     

Value of detection of antibodies toCandida albicans germ tube in the diagnosis of systemic candidosis

To test the value of detection of anti-Candida albicans germ tube antibodies by indirect immunofluorescence assay in the diagnosis of systemic candidosis, a retrospective study was done using 126 sera from 27 patients with presumptive systemic candidosis (13 immunocompromised), 165 sera from 45 patients with aspergillosis (29 immunocompromised), 35 sera from eight patients with cryptococcosis (6 immunocompromised), and 101 sera from 101 blood donors. While 21 of 27 patients with systemic candidosis (77.8%) had anti-germ tube antibodies, these antibodies were absent in all patients with cryptococcosis and in all blood donors. They were however detected in 5 of 45 patients with aspergillosis (11.1%). Ten of 13 (76.9%) immunocompromised patients with candidosis had anti-germ tube antibodies; similar results were obtained in immunocompetent patients with candidosis (78.6%). The specificity was 96.8%, indicating a high degree of discrimination was possible between systemic candidosis and other invasive mycoses in the patients studied. Anti-germ tube responses did not appear to be significantly reduced in immunocompromised patients.     

Immunization of immunocompromised persons

Advances in medicine, science, and technology have led to increasing numbers of people in the general population with altered host defenses. The risk for clinical infection in an immunocompromised host, such as a person who has received a solid organ transplant, is determined largely by the interaction between two factors: the epidemiologic exposures the person encounters and the person's net state of immunosuppresson. Vaccination represents a crucial approach for preventing infection in the general public and immunocompromised persons. This article reviews the benefits of and risks for immunization in immunocompromised persons and provides recommendations for the use of specific vaccines.     

Pathogenicity test for Listeria monocytogenes using immunocompromised mice.

The lethality of Listeria isolates was determined with normal adult mice and mice that were immunocompromised by treatment with 20 mg of carrageenan per kg. The mean 50% lethal doses (LD50s) of the pathogenic isolates were significantly lower (alpha = 0.05) in the immunocompromised mice than in the untreated mice, with an average reduction of 5.8 log10 units. In contrast, the mean LD50s of the nonpathogenic isolates were lower in the immunocompromised mice by an average of only 0.4 log10 unit, a difference that was not significant (alpha = 0.05). When immunocompromised mice were used, the LD50s of pathogenic Listeria monocytogenes isolates were lower than those of nonpathogenic L. innocua and L. seeligeri isolates by greater than or equal to 6 log10 units and lower than those of nonpathogenic L. ivanovii isolates by greater than or equal to 4 log10 units. Pathogenic L. monocytogenes isolates could be distinguished from nonpathogenic isolates by their ability to cause deaths in immunocompromised mice in 3 days at a dose of approximately 10(4) CFU per mouse. An alternative procedure using iron-overloaded mice failed to effectively differentiate pathogenic Listeria isolates.     

Meningoencephalitis with Subdural Empyema Caused by Toxigenic Clostridium perfringens Type A

We report a clinical case of meningoencephalitis with subdural empyema in an immunocompromised farmer caused by toxigenic Clostridium perfringens type A, which was identified by 16S RNA gene analysis of cerebrospinal fluid and subdural empyema. In immunocompromised patients, C. perfringens should be considered a potential pathogen of sepsis.     

Enterocolitis in immunocompromised patients

Diarrhea is a very common complaint among immunocompromised patients, and the most common causes of this and other gastrointestinal complaints in this population differ from those commonly seen in immunocompetent patients. Underlying immunodeficiencies may be associated with particular patterns of gastrointestinal tract injury, and particular immunodeficiencies may lead to increased susceptibility to infection by specific organisms depending upon the etiology of the immune compromise. It is important to become familiar with the causes of gastrointestinal disease in the immunocompromised patient population because prompt and proper treatment is of the essence in this patient group. This review focuses on common causes of enterocolitis in the immunocompromised with attention to primary immunodeficiency disorders, the post-transplant setting, chemotherapy-related injury, and a select group of common or emerging infections.     

Pseudomonas bronchopulmonary infections in a palliative care setting

Blood stream infections and pneumonia caused by Pseudomonas aeruginosa is associated with high mortality, especially in an immunocompromised host. A large section of the palliative care patient population has varied forms of compromised immunity due to advanced cancer or cancer treatment, organ failures, chronic autoimmune disorders, degenerative conditions, and acquired immunodeficiency syndrome. The lung is one of the most frequently involved organs in a variety of complications in an immunocompromised host and infection is the most common complication. P. aeruginosa is one of the most common pathogens associated with bronchopulmonary infections in an immunocompromised host. Routine radiological tests like chest X-ray may often be unyielding and an early and a prompt initiation of treatment reduces mortality and morbidity risk.     

Online-Only Abstract

Hepatitis E virus (HEV) can cause chronic infections in immunocompromised hosts. Viral kinetics in plasma and stools are poorly understood, particularly during antiviral treatment. Prolonged faecal shedding may be a concern for transmission. We describe HEV kinetics in an immunocompromised patient with prolonged faecal shedding despite undetectable viraemia on ribavirin treatment.     

Long-term hepatitis E viral load kinetics in an immunocompromised patient treated with ribavirin

Hepatitis E virus (HEV) can cause chronic infections in immunocompromised hosts. Viral kinetics in plasma and stools are poorly understood, particularly during antiviral treatment. Prolonged faecal shedding may be a concern for transmission. We describe HEV kinetics in an immunocompromised patient with prolonged faecal shedding despite undetectable viraemia on ribavirin treatment.     

Unusual case of necrotizing fasciitis caused by Vibrio cholerae O137

We report a case of necrotizing fasciitis caused by Vibrio cholerae O137 in an immunocompromised 49-year-old man. The infection was acquired following a minor traumatic injury and exposure to seawater during the summer of 2009 in Italy. Although highly immunocompromised, the patient survived. The strain was cytotoxic, invasive, and adhesive and contained a fragment of the El Tor-like hemolysin (El Tor hlyA) gene.     

Cytodiagnosis of histoplasmosis: Case reports from two patients with variable clinical presentation

Histoplasmosis has emerged as an important opportunistic fungal infection in immunocompromised patients. Histoplasma is a dimorphic fungus that primarily involves lung and the environmental reservoir is soil. Although several cases of histoplasmosis have been reported in India but cytological diagnosis was made in a few cases. We are presenting two cases of histoplasmosis diagnosed on fine‐needle aspiration cytology. In the first case, pulmonary histoplasmosis was diagnosed on transbronchial needle aspiration of lung in a 41‐year‐old immunocompetent male, while second case was of disseminated histoplasmosis in 40‐year‐old immunocompromised female diagnosed on cytology of cervical lymph node. FNAC is a simple, safe, and rapid technique to establish the initial diagnosis, thus promoting early treatment and favorable outcome especially in the immunocompromised patients. Diagn. Cytopathol. 2011; © 2011 Wiley Periodicals, Inc.     

Profuse diarrhoea in a young man

Cryptosporidium parvum is a protozoan parasite with worldwide distribution that commonly causes watery and profuse diarrhoea in both immunocompetent and immunocompromised individuals. Infection in the immunocompetent individual is self-limited, however infection in the immunocompromised individual has a more aggressive course that can become life threatening. We describe a case of a 21-year-old male with symptoms of acute and profuse diarrhoea, and significant weight loss. He reported no past medical history and specifically no history of immunodeficiency. The histopathological examination of the surgical specimens revealed extensive Cryptosporidium parvum infection of the small and large bowel. A severe and protracted presentation of acute diarrhoea and weight loss should alert the physician to consider differentials for infections, inflammatory bowel disease, and metabolic aetiologies. Should histopathological assessment reveal severe cryptosporidiosis causing architectural distortion, and widespread and extensive gastrointestinal infection, an immunocompromised state should be considered.     

In vivo tropisms and kinetics of rat theilovirus infection in immunocompetent and immunodeficient rats

Rat theilovirus (RTV) is a cardiovirus related to Theiler's murine encephalomyelitis virus. While RTV is a prevalent viral pathogen of rats used in biomedical research, the pathogenesis and characterization of RTV infections is not well understood. In the studies reported herein, we used immunohistochemistry to identify viral antigens in enterocytes of the small intestines of Sprague-Dawley (SD) rats. Fecal viral shedding in immunocompromised and immunocompetent rats following oral gavage with RTV1 was high for the first 2 weeks of infection with persistent shedding of high viral loads being observed in immunocompromised nude rats but not in immunocompetent rats. RTV was also detected in mesenteric lymph nodes and spleen of immunocompromised rats but not immunocompetent rats. In addition, the magnitude of serum antibody responses differed between immunocompetent rat strains with Brown Norway and SD rats having a significantly higher antibody response than CD or Fischer 344 rats. These data suggest that RTV1 has a tropism for the epithelial cells of the small intestine, immunocompetent rats have differing serum antibody responses to RTV infection, and sustained fecal shedding and extraintestinal dissemination of RTV1 occurs in rats deficient in T cell-dependent adaptive immunity. RTV infection in immunocompromised and immunocompetent rats has merit as a model for further studies of theilovirus pathogenesis following oral viral exposure.     

Fatal disseminated adenovirus infections in immunocompromised patients

Adenovirus has emerged as an important pathogen in immunocompromised patients, in whom disseminated disease occurs frequently and is associated with a high mortality rate. In a retrospective review of 1,847 consecutive autopsies, we identified 84 cases where adenovirus infection was suspected clinically. Adenovirus infection was confirmed at autopsy in 8 (10%) of 84 cases; all were immunocompromised patients. Six (75%) of these cases had disseminated adenovirus infection that contributed to death. Pathologic findings attributed to adenovirus infection included pneumonia with or without intra-alveolar hemorrhage, hepatic necrosis, enterocolitis with or without mucosal hemorrhage, epicardial hemorrhage, and ulcerations of the larynx, trachea, and ileum. This work shows that severe and fatal adenovirus infections are not infrequent, particularly in the immunocompromised population. Both clinicians and pathologists must become aware of the pathogenicity of adenovirus in this patient population, including its potential for causing life-threatening hemorrhage.     

Mycobacterium haemophilum epididymal abscess in a renal transplant patient

Mycobacterium haemophilum is an established cause of cutaneous lesions in immunocompromised hosts. We report the first known case of epididymal abscess, which highlights the need to work up all specimens that are acid-fast bacillus-positive for M. haemophilum from immunocompromised hosts, regardless of body site.     

Recurrent bacteremia due toBrevibacterium casei in an immunocompromised patient

A case of an immunocompromised patient who experienced two episodes of septicemia caused by a coryneform bacterium is reported. Biochemical characteristics and analysis of cellular fatty acids and of cell wall components showed two identical strains ofBrevibacterium casei to be responsible for these infections. The lack of easy-to-perform methods for identification may have led, in the past, to an underestimation of the role of this bacterium, especially in immunocompromised patients.     

Fungal infections in immunocompromised patients]

The number of immunocompromised patients is increasing due to the intensive therapy being administered those with cancer, organ transplant, and HIV infection. Fungal infections are one of the important opportunistic infections in immunocompromised patients. Early diagnosis is difficult, and the prognosis of these patinas is usually poor. Several methods of diagnosis for fungal infections have been developed: detection of antigens of the infected fungi from the sera is useful for early diagnosis; polymerase chain reaction (PCR) technology may be the most valuable method for the diagnosis of fungal infection in immunocompromised patients, and antifungal agents are the drugs used to the fungal infections in those patients. However, there are only five drugs available to fungal infections in Japan. Although amphotericin B is the recommended first choice for treatment of invasive aspergillosis, its use for immunocompromised patients is limited because of its adverse effects. Novel antifungal agents (azoles, amphotericin B drug deliver system, and 1,3-beta-D-glucan synthetase inhibitors) have been developed and some of these compounds undergoing clinical trials.