Human Microbial Flora Research Articles

Staphylococcal scalded skin syndrome in neonate: Another face of CA-MRSA.

Staphylococcal scalded skin syndrome (SSSS), also known as Ritter's disease, in its severe form occurs predominantly in infants and children. It is caused by infection with group II (often phage group 71) Staphylococcus aureus. The foci of infection include nasopharynx, less commonly umbilicus, urinary tract, superficial abrasion, conjunctivae, and blood. Staphylococci are non-motile, non-spore-forming, catalase-positive, gram-positive cocci that appear predominantly as grape-like clusters. Although this organism is frequently a part of normal human microbial flora, it can cause significant opportunistic infections under certain conditions such as when extremes of age groups are involved, the presence of indwelling medical devices, and intravenous (iv) drug abuse. Staphylococcus aureus may cause a variety of infectious manifestations ranging from relatively benign skin infections to life-threatening systemic illnesses. SSSS caused by S. aureus strains produces exfoliative toxins which result in the development of blisters, erythema, and desquamation. Here, we present a case of an 11-day-old neonate who was diagnosed with SSSS. The causative agent responsible for this syndrome was identified as methicillin-resistant Staphylococcus aureus (MRSA). The molecular characterization of the gene Panton-Valentine leukocidin (PVL) was done by polymerase chain reaction (PCR) and was detected positive for PVL which is a distinctive virulence factor seen almost in all of the community-acquired MRSA strains. The patient was discharged after parenteral clindamycin therapy with almost complete resolution of symptoms.

Strain-Level Dynamics Reveal Regulatory Roles in Atopic Eczema by Gut Bacterial Phages.

The vast population of bacterial phages or viruses (virome) plays pivotal roles in the ecology of human microbial flora and health conditions. Obstacles, including poor viral sequence inference, strain-sensitive virus-host relationship, and the high diversity among individuals, hinder the in-depth understanding of the human virome. We conducted longitudinal studies of the virome based on constructing a high-quality personal reference metagenome (PRM). By applying long-read sequencing for representative samples, we could build a PRM of high continuity that allows accurate annotation and abundance estimation of viruses and bacterial species in all samples of the same individual by aligning short sequencing reads to the PRM. We applied this approach to a series of fecal samples collected for 6 months from a 2-year-old boy who had experienced a 2-month flare-up of atopic eczema (dermatitis) in this period. We identified 31 viral strains in the patient's gut microbiota and deciphered their strain-level relationship to their bacterial hosts. Among them, a lytic crAssphage developed into a dozen substrains and coordinated downregulation in the catabolism of aromatic amino acids (AAAs) in their host bacteria which govern the production of immune-active AAA derivates. The metabolic alterations confirmed based on metabolomic assays cooccurred with symptom remission. Our PRM-based analysis provides an easy approach for deciphering the dynamics of the strain-level human gut virome in the context of entire microbiota. Close temporal correlations among virome alteration, microbial metabolism, and disease remission suggest a potential mechanism for how bacterial phages in microbiota are intimately related to human health. IMPORTANCE The vast populations of viruses or bacteriophages in human gut flora remain mysterious. However, poor annotation and abundance estimation remain obstacles to strain-level analysis and clarification of their roles in microbiome ecology and metabolism associated with human health and diseases. We demonstrate that a personal reference metagenome (PRM)-based approach provides strain-level resolution for analyzing the gut microbiota-associated virome. When applying such an approach to longitudinal samples collected from a 2-year-old boy who has experienced a 2-month flare-up of atopic eczema, we observed thriving substrains of a lytic crAssphage, showing temporal correlation with downregulated catabolism of aromatic amino acids, lower production of immune-active metabolites, and remission of the disease. The PRM-based approach is practical and powerful for strain-centric analysis of the human gut virome, and the underlying mechanism of how strain-level virome dynamics affect disease deserves further investigation.

Metagenomic Analysis of the Outdoor Dust Microbiomes: A Case Study from Abu Dhabi, UAE

Outdoor dust covers a shattered range of microbial agents from land over transportation, human microbial flora, which includes pathogen and commensals, and airborne from the environment. Dust aerosols are rich in bacterial communities that have a major impact on human health and living environments. In this study, outdoor samples from roadside barricades, safety walls, and fences (18 samples) were collected from Abu Dhabi, UAE and bacterial diversity was assessed through a 16S rRNA amplicon next generation sequencing approach. Clean data from HiSeq produced 1,099,892 total reads pairs for 18 samples. For all samples, taxonomic classifications were assigned to the OTUs (operational taxonomic units) representative sequence using the Ribosomal Database Project database. Analysis such as alpha diversity, beta diversity, differential species analysis, and species relative abundance were performed in the clustering of samples and a functional profile heat map was obtained from the OTUs by using bioinformatics tools. A total of 2814 OTUs were identified from those samples with a coverage of more than 99%. In the phylum, all 18 samples had most of the bacterial groups such as Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes. Twelve samples had Propionibacteria acnes and were mainly found in RD16 and RD3. Major bacteria species such as Propionibacteria acnes, Bacillus persicus, and Staphylococcus captis were found in all samples. Most of the samples had Streptococcus mitis, Staphylococcus capitis. and Nafulsella turpanensis and Enhydrobacter aerosaccus was part of the normal microbes of the skin. Salinimicrobium sp., Bacillus alkalisediminis, and Bacillus persicus are halophilic bacteria found in sediments. The heat map clustered the samples and species in vertical and horizontal classification, which represents the relationship between the samples and bacterial diversity. The heat map for the functional profile had high properties of amino acids, carbohydrate, and cofactor and vitamin metabolisms of all bacterial species from all samples. Taken together, our analyses are very relevant from the perspective of out-door air quality, airborne diseases, and epidemics, with broader implications for health safety and monitoring.

The spectrum of opportunistic fungal infections in relation with ART in HIV patients

Recent years have witnessed a phenomenal increase in prevalence as well as severity of opportunistic fungal infection (OFIs) despite of availability of different therapeutic options. This could be attributed to various reasons including increased prevalence of immunocomprised patients. Awareness of spectrum of fungal infections in immunocompromised conditions and their epidemiological changes is critical for early diagnosis and proper management. Method: A total of 277 clinical samples were collected from 216 HIV patients suspected of OFI. Sample processing and identification of fungi carried out by standard conventional methods. Result: Out of 216 patients, 30% (65) showed positive fungal etiology with single or multiple system involvement. Oral candidiasis ranked highest (46%) followed by Cryptococcal meningitis (35%), Candidial pneumonia (10%), Oesophageal candidiasis (7%), Dermatophytoses (6%), Pulmonary aspergillosis (4%), Systemic candidiasis (4%), Pneumocystis pneumonia (3%) etc. Discussion: As most of opportunistic fungi (OF) are part of the normal human microbial flora, clinical significance of fungal isolates must be confirmed by standard criteria laid down such as repeated isolation, supportive clinical findings and radiographical evidences. Although Antiretroviral Therapy for minimum 6 months duration provides protection against OFI by maintaining CD4 count, compliance to treatment important.

Estimation Of Adherance Of Candida Albicans To Different Denture Base Materials And Its Relationship With Denture Stomatitis – An In Vivo Study

Background - Candida albicans is the most common human oral fungi frequently recovered from the denture surface causing denture stomatitis. Modern treatment approaches suppress the normal host defense mechanisms, alter the normal human microbial flora& allow non bacterial species to become more prevalent in commensal flora.
 Aims & Objectives - The objective of the present study was to evaluate the prevalence & incidence of Candida albicans in DPI & Lucitone 199 heat cure acrylic denture wearers & its relationship with denture stomatitis.
 Materials & Methods – The study was conducted at our institution wherein 52 edentulous patients enrolled in the study .These patients were randomly assigned to two groups DPI and Lucitone 199 . Dentures were made using the two materials . At three months follow up swab samples were taken from the denture surfaces and sent to lab for culture .
 Result – The prevalence of Candida albicans in denture wearers was found to be 23%. The incidence of denture stomatitis was 27%. Prevalence of Candida albicans & incidence of denture stomatitis was less with Lucitone 199 heat cure acrylic dentures.
 Conclusion - Any treatment that we do should not be cause of other pathology. Denture stomatitis falls into such category. Follow up should be done on a mandatory basis to evaluate the changes & performing necessary modifications.

An Actinomyces Long-Bone Osteomyelitis Case Report and Review

Abstract Historically, anaerobic bacteria as monomicrobial pathogens or components of polymicrobial infections have been found to play a minor role in osteomyelitis. Various Actinomyces species reside as constituents of the normal human microbial flora found in the oropharynx and in the most people may also be present as commensal microorganisms in the gastrointestinal, genitourinary, and, to a lesser degree, the upper respiratory tracts. Bone infections due to Actinomyces species are relatively uncommon and usually associated with concomitant cervicofacial disease. To date, only a sparse amount of cases of long bone osteomyelitis due to Actinomyces bacteria have been published in the medical literature. We report a case of monomicrobial subacute late-onset tibia bone osteomyelitis involving Actinomyces presenting 10 years after an open reduction and internal fixation surgical procedure performed to stabilize a traumatic fracture and review actinomycotic osteomyelitis including the rare association of Actinomyces odontolyticus with long bone infections.

Abstract B02: E-cigarette vape and cigarette smoke potentially increase S. aureus oral colonization and inflammatory epithelial signaling

Abstract E-cigarette (E-cig) vaping has gained popularity among middle and high-school students within the last decade, being advertised as a safer alternative to cigarette smoke. While acute lung illness has been reported, it is too early to have epidemiologic data suggesting a role of E-cig on oral squamous cell carcinoma. However, recent studies point to its potentially adverse effects on the human epithelium and the oral human microbial flora. Staphylococcus aureus is a resident of the oral microbiota and its carriage has been shown to be significantly higher in the periodontal pocket of patients with actively progressing periodontitis, which is a chronic inflammatory disease and known precursor for oral squamous cell carcinoma (OSCC). Additionally, S. aureus has also been isolated from OSCC tissues. In this study, we aim to identify the response of S. aureus and the oral epithelium to E-cig vape exposure and, further, to determine the effect of E-cig vape on the interaction of S. aureus with the oral epithelium. To measure differences in the ability to form biofilm upon E-cig vape exposure with (3mg/mL) and without nicotine, we analyzed two clinical S. aureus strains isolated from healthy individuals following a 30s puff delivery and a 5-minute incubation. We observed that E-cig vape induced significantly higher biofilm formation than control air exposure in a specifically designed vape chamber regardless of nicotine content (p<0.01). Furthermore, S. aureus strain obtained from cigarette smokers had a significantly higher attachment capacity to oral epithelial cells than sequence-type matched strains from healthy controls (p<0.05), suggesting an augmented potential for oral colonization upon E-cig vape and cigarette smoke exposure. Oral epithelial cells, when exposed to E-cig vape alone, showed a proinflammatory response, through an increase in COX2, TNFα, and IL8 gene expression by qRT-PCR. Additionally, we observed that E-cig vape induced an increase in the DNA damage marker, p-H2A.X, seen by immunofluorescence staining. E-cig vape and S. aureus exposure induced inflammatory signaling as demonstrated by qRT-PCR for COX2 and TNFα, and nuclear translocation of NF-KB seen by immunofluorescence staining. Furthermore, we observed an epithelial stress response through p-ERK1/2 signaling activation by Western blot. Our research suggests that E-cig exposure could be supporting increased oral carriage of S. aureus, therefore perpetuating an inflammatory response and causing extended DNA damage, which could eventually initiate OSCC. Citation Format: Alma R. Catala-Valentin, Matthew Caldwell, Alexander M. Cole, Sean Moore, Claudia Andl. E-cigarette vape and cigarette smoke potentially increase S. aureus oral colonization and inflammatory epithelial signaling [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr B02.

Optimise the microbial flora with milk and yoghurt to prevent disease

Pathogenic bacteria, which are temporary or permanent members of our microbial flora, cause or contribute to a wide range of human disease at all ages. Conditions include Alzheimer’s disease, atherosclerosis, diabetes mellitus, obesity, cancer, autoimmunity and psychosis, amongst others. The mechanism of damage is inflammation which can be chronic or acute. An optimal microbial flora includes a wide range of pathogenic bacteria in low dose. This allows specific immunity to be developed and maintained with minimal inflammatory damage. Human milk has evolved to deliver an optimal microbial flora to the infant. Cow’s milk has the potential, following appropriate fortification, to maintain an optimal human microbial flora throughout life. Yoghurt is a fermented milk product in which bacteria normally present in milk convert sugars to lactic acid. The acid suppresses the growth of pathogens in the oral cavity, oropharynx and oesophagus. Thus yoghurt can restore an optimal flora in these regions in the short term. Since bacteria are transported between epithelial surfaces, yoghurt will also optimise the flora elsewhere. The judicious use of milk and yogurt could prevent a high proportion of human disease.

A Case of Magnusiomyces capitatus Peritonitis Without Underlying Malignancies.

Magnusiomyces capitatus is a rare cause of fungal infection in immunocompromised patients, mainly seen in hematological malignancies. M capitatus infections are extremely rare in immunocompetent patients, as it is part of normal human microbial flora. We are presenting an extremely rare case of M capitatus peritonitis in an otherwise immunocompetent patient who suffered from gastrointestinal leakage due to pancreatitis. Fungal identification was performed at reference laboratory by phenotypic characteristics and DNA sequencing of target internal transcribed spacer region of the rRNA gene and the D1-D2 domain of the large-subunit rRNA gene and susceptibility testing by Clinical and Laboratory Standards Institute guidelines (document M27-S4) broth dilution method. He was successfully treated with a combination of surgical repair and voriconazole single therapy.

Phenotypic diversity and correlation between white-opaque switching and the CAI microsatellite locus in Candida albicans.

Candida albicans is a commensal fungal pathogen that is often found as part of the human microbial flora. The aim of the present study was to establish a relationship between diverse genotypes and phenotypes of clinical isolates of C. albicans. Totally 231 clinical isolates were collected and used for genotyping and phenotypic switching analysis. Based on the microsatellite locus (CAI) genotyping assay, 65 different genotypes were identified, and some dominant types were found in certain human niches. For example, the genotypes of 30-44 and 30-45 were enriched in vaginal infection samples. C. albicans has a number of morphological forms including the single-celled yeasts, multicellular filaments, white, and opaque cell types. The relationship between the CAI genotype and the ability to undergo phenotypic switching was examined in the clinical isolates. We found that the strains with longer CAA/G repeats in both alleles of the CAI locus were more opaque competent. We also discovered that some MTL heterozygous (a/alpha) isolates could undergo white-opaque switching when grown on regular culture medium (containing glucose as the sole carbon source). Our study establishes a link between phenotypic switching and genotypes of the CAI microsatellite locus in clinical isolates of C. albicans.

Oral health care by utilizing food function

We examined the effects of spices and herbs on Candida albicans to develop therapeutic tools against oral diseases such as oral candidiasis. C. albicans, a dimorphic fungus, is a component of the healthy human microbial flora. However, the excessive overgrowth of C. albicans causes oral candidiasis, and the symptoms, accompanied by severe inflammation, reduce the quality of life of elderly people. We found that spices such as clove (Syzygium aromaticum) and cassia (Cinnamomum aromaticum) exhibit inhibitory activity against Candida mycelial growth and show therapeutic efficacy in a murine oral candidiasis model. Our studies also demonstrated that the inhibitory activity of cinnamaldehyde was strengthened in parallel with a prolonged treatment time. Furthermore, when cinnamaldehyde in combination with methylcellulose was administered to the model mice, the therapeutic effect was potentiated. Here, we summarize up-to-date findings on how to use spices and herbs on a daily basis to improve or prevent oral problems such as oral candidiasis with the presentation of our recent data.

Conversion of Phenolic Constituents in Aqueous Hamamelis virginiana Leaf Extracts During Fermentation

Hamamelis virginiana, known for its high level of tannins and other phenolics is widely used for treatment of dermatological disorders. Although reports on hydroalcoholic and aqueous extracts from Hamamelis leaf and bark exist, knowledge on fermented leaf preparations and the underlying conversion processes are still scant. Aqueous Hamamelis leaf extracts were monitored during fermentation and maturation in order to obtain an insight into the bioconversion of tannins and other phenolics. Aliquots taken during the production period were investigated by HPLC-DAD-MS/MS as well as GC-MS after derivatisation into the corresponding trimethylsilyl compounds. In Hamamelis leaf extracts, the main constituents exhibited changes during the observational period of 6 months. By successive depside bond cleavage, the gallotannins were completely transformed into gallic acid after 1 month. Although not completely, kaempferol and quercetin glycosides were also converted during 6 months to yield their corresponding aglycones. Following C-ring fission, phloroglucinol was formed from the A-ring of both flavonols. The B-ring afforded 3-hydroxybenzoic acid from quercetin and 3,4-dihydroxybenzoic acid as well as 2-(4-hydroxyphenyl)-ethanol from kaempferol. Interestingly, hydroxycinnamic acids remained almost stable in the same time range. The present study broadens the knowledge on conversion processes in aqueous fermented extracts containing tannins, flavonol glycosides and hydroxycinnamic acids. In particular, the analogy between the microbial metabolism of phenolics from fermented Hamamelis extracts, fermented sourdough by heterofermentative lactic acid bacteria or conversion of phenolics by the human microbial flora is indicated.

Human Gut Enterotypes

The advent of high-throughput genomic sequencing has extended our understanding of not only the human genome, but also the genomes of normal commensal human microbial flora. A multinational team of investigators has now undertaken a comprehensive analysis of human fecal flora, based on broad genomic sequencing of samples from individuals in Europe (22), Japan …

Mapping the Pathways to StaphylococcalPathogenesis by Comparative Secretomics

The gram-positive bacterium Staphylococcus aureus is a frequent component of the human microbial flora that can turn into a dangerous pathogen. As such, this organism is capable of infecting almost every tissue and organ system in the human body. It does so by actively exporting a variety of virulence factors to the cell surface and extracellular milieu. Upon reaching their respective destinations, these virulence factors have pivotal roles in the colonization and subversion of the human host. It is therefore of major importance to obtain a clear understanding of the protein transport pathways that are active in S. aureus. The present review aims to provide a state-of-the-art roadmap of staphylococcal secretomes, which include both protein transport pathways and the extracytoplasmic proteins of these organisms. Specifically, an overview is presented of the exported virulence factors, pathways for protein transport, signals for cellular protein retention or secretion, and the exoproteomes of different S. aureus isolates. The focus is on S. aureus, but comparisons with Staphylococcus epidermidis and other gram-positive bacteria, such as Bacillus subtilis, are included where appropriate. Importantly, the results of genomic and proteomic studies on S. aureus secretomes are integrated through a comparative "secretomics" approach, resulting in the first definition of the core and variant secretomes of this bacterium. While the core secretome seems to be largely employed for general housekeeping functions which are necessary to thrive in particular niches provided by the human host, the variant secretome seems to contain the "gadgets" that S. aureus needs to conquer these well-protected niches.

Comparative analysis of cell wall surface glycan expression in Candida albicans and Saccharomyces cerevisiae yeasts by flow cytometry

The yeast Candida albicans is an opportunistic pathogen, part of the normal human microbial flora that causes infections in immunocompromised individuals with a high morbidity and mortality levels. Recognition of yeasts by host cells is based on components of the yeast cell wall, which are considered part of its virulence attributes. Cell wall glycans play an important role in the continuous interchange that regulates the balance between saprophytism and parasitism, and also between resistance and infection. Some of these molecular entities are expressed both by the pathogenic yeast C. albicans and by Saccharomyces cerevisiae, a related non-pathogenic yeast, involving similar molecular mechanisms and receptors for recognition. In this work we have exploited flow cytometry methods for probing surface glycans of the yeasts. We compared glycan expression by C. albicans and by S. cerevisiae, and studied the effect of culture conditions. Our results show that the expression levels of α- and β-linked mannosides as well as β-glucans can be successfully evaluated by flow cytometry methods using different antibodies independent of agglutination reactions. We also found that the surface expression pattern of β-mannosides detected by monoclonal or polyclonal antibodies are differently modulated during the growth course. These data indicate that the yeast β-mannosides exposed on mannoproteins and/or phospholipomannan are increased in stationary phase, whereas those linked to mannan are not affected by the yeast growth phase. The cytometric method described here represents a useful tool to investigate to what extent C. albicans is able to regulate its glycan surface expression and therefore modify its virulence properties.

Are infections protecting from atopy?

The 'Hygiene Hypothesis' proposes that overcrowding and unhygienic contacts early in life may protect from atopic diseases by facilitating exposure to microbes. Longitudinal studies have recently shown that among subjects exposed early in life to other children at home, or at day care, the risk of wheezing steadily declined with age to levels significantly lower than controls. Evidences supporting a protective role of respiratory infections or BCG immunization on the development of allergic asthma are still insufficient. By contrast, the observation of a lower prevalence of atopic sensitization among children raised on a farm has been consistently reproduced. Several new studies have recently investigated the role of changes of human microbial flora, declining exposure to foodborne and orofecal infections, to helminths and to environmental sources of endotoxin as putative contributors to the rise of allergy and asthma cases among populations living with a western lifestyle.

Are infections protecting from atopy?

The ‘Hygiene Hypothesis’ proposes that overcrowding and unhygienic contacts early in life may protect from atopic diseases by facilitating exposure to microbes. Longitudinal studies have recently shown that among subjects exposed early in life to other children at home, or at day care, the risk of wheezing steadily declined with age to levels significantly lower than controls. Evidences supporting a protective role of respiratory infections or BCG immunization on the development of allergic asthma are still insufficient. By contrast, the observation of a lower prevalence of atopic sensitization among children raised on a farm has been consistently reproduced. Several new studies have recently investigated the role of changes of human microbial flora, declining exposure to foodborne and orofecal infections, to helminths and to environmental sources of endotoxin as putative contributors to the rise of allergy and asthma cases among populations living with a western lifestyle.

Pathogenesis of tuberculosis in mice exposed to low and high doses of an environmental mycobacterial saprophyte before infection.

Mycobacteria are ubiquitous in the environment, but they are not part of the normal human microbial flora. It has been suggested that variable contact with mycobacteria can influence susceptibility to mycobacterial pathogens and the efficacy of subsequent Mycobacterium bovis BCG vaccination. To test this, mice were immunized with high or low doses of an environmental saprophyte, M. vaccae, that is intensely immunogenic as an autoclaved preparation. Two months later, they received an intratracheal challenge with M. tuberculosis H37Rv. Recipients of a low Th1-inducing dose (10(7) organisms) were partially protected and maintained a high ratio of interleukin 2 (IL-2)-positive to IL-4-positive cells in the perivascular, peribronchial, and granulomatous areas of the lung, whereas in unimmunized controls the IL-4-positive cells increased markedly between days 21 and 28. In contrast, recipients of the high dose (10(9) organisms), which primes Th2 as well as Th1 cytokine production, died more rapidly than unimmunized controls and showed massive pneumonia from day 7. The ratio of IL-2-positive to IL-4-positive cells in all compartments of the lung rapidly fell to 1 by day 14 for these animals. These events correlated with cytokine mRNA profiles and with increases in the local toxicity of tumor necrosis factor alpha (TNF-alpha), demonstrable only when a major Th2 component was present. These data indicate that cross-reactive epitopes present in an environmental saprophyte can evoke either protective responses or responses that increase susceptibility to M. tuberculosis. The latter are associated with the presence of a Th2 component and increased sensitivity to TNF-alpha.

Rat intestinal mucosal responses to a microbial flora and different diets.

The effects of diet on the histochemical composition of intestinal mucosubstances and the morphology of the villi and crypts were investigated by comparing the data of germ free and conventionally maintained rats fed either a purified diet or a commercial diet. The influence of intestinal microflora was evaluated by comparing the germ free rats and those harbouring either a conventional rat flora or a human microbial flora. In both germ free rats and those maintained conventionally, feeding a purified diet resulted in shallower crypts in the small intestine but deeper crypts in the large intestine compared with their counterparts fed on the commercial diet. The preliminary data obtained with association of human flora showed a reduction of the villus height and crypt depth in the small intestine and, to some extent, the amount of neutral mucins in the goblet cells of both small and large intestine and an increase in the amount of sulphated mucins in the large intestine. In rats given the commercial diet the periodic acid Schiff staining for neutral mucins was more intense in the upper crypts of the small intestine than in the lower crypts, and to a lesser extent in the upper crypts of the large intestine. These results provide evidence that the dietary composition, microbial flora, as well as the interactions between the dietary constituents and microbial flora change the mucosal architecture and the mucus composition and therefore alter the functional characteristics of the intestinal tract.

Hodgkin's Disease and Non-Hodgkin's Lymphomas

Two areas of study have made the understanding of infections in Hodgkin's disease and non-Hodgkin's lymphoma both clearer and more complicated. First, the overly simple concepts that certain underlying diseases predispose patients to specific infections can no longer be uniformly applied. Second, while Hodgkin's patients were once thought to have cell-mediated immune defects, we now know that mixed T- and B-cell abnormalities as well as alterations in complement and phagocytic processes are seen. Therefore, we can expect to find infecting organisms against which several immune functions appear to be important. The more common organisms found in these patients include the encapsulated bacteria and fungi, intracellular microbes such as the mycobacteria and certain viruses, and, finally, some protozoa. Many are prevalent in the environment and some are considered to be normal human microbial flora. These opportunistic pathogens will continue to cause serious, often fatal infections in this group of compromised patients until more is known about the causes of lymphoproliferative disease and significant advances in immunotherapy are made.