Microbiome and Abdominopelvic Radiotherapy Related Chronic Enteritis: A Microbiome-based Mechanistic Role of Probiotics and Antibiotics

Chronic diarrhea and abdominal pain after radiotherapy continue to be a problem in cancer survivors. Gut microbiomes are essential for preventing intestinal inflammation, maintaining intestinal integrity, maintaining enterohepatic circulation, regulating bile acid metabolism, and absorption of nutrients, including fat-soluble vitamins. Gut microbiome dysbiosis is expected to cause inflammation, bile acid malabsorption, malnutrition, and associated symptoms. Postradiotherapy, Firmicutes and Bacteroidetes phylum are significantly decreased while Fusobacteria and other unclassified bacteria are increased. Available evidence suggests harmful bacteria Veillonella, Erysipelotrichaceae, and Ruminococcus are sensitive to Metronidazole or Ciprofloxacin. Beneficial bacteria lactobacillus and Bifidobacterium are relatively resistant to metronidazole. We hypothesize and provide an evidence-based review that short-course targeted antibiotics followed by specific probiotics may lead to alleviation of radiation enteritis.

The Effects of Ionizing Radiation on Gut Microbiota, a Systematic Review

BACKGROUND

The human gut microbiota is defined as the microorganisms that collectively inhabit the intestinal tract. Its composition is relatively stable; however, an imbalance can be precipitated by various factors and is known to be associated with various diseases. Humans are daily exposed to ionizing radiation from ambient and medical procedures, and gastrointestinal side effects are not rare.

METHODS

A systematic search of PubMed, EMBASE, and Cochrane Library databases was conducted. Primary outcomes were changes in composition, richness, and diversity of the gut microbiota after ionizing radiation exposure. Standard methodological procedures expected by Cochrane were used.

RESULTS

A total of 2929 nonduplicated records were identified, and based on the inclusion criteria, 11 studies were considered. Studies were heterogeneous, with differences in population and outcomes. Overall, we found evidence for an association between ionizing radiation exposure and dysbiosis: reduction in microbiota diversity and richness, increase in pathogenic bacteria abundance (Proteobacteria and Fusobacteria), and decrease in beneficial bacteria (Faecalibacterium and Bifidobacterium).

CONCLUSIONS

This review highlights the importance of considering the influence of ionizing radiation exposure on gut microbiota, especially when considering the side effects of abdominal and pelvic radiotherapy. Better knowledge of these effects, with larger population studies, is needed.

Microbial etiology, susceptibility profile of postradiation nasopharyngeal necrosis patients with nasopharyngeal carcinoma

OBJECTIVE

Postradiation nasopharyngeal necrosis (PRNN) is a notorious complication after radiotherapy that affects prognosis in patients with nasopharyngeal carcinoma (NPC). It is important for clinical doctors to realize this problem in order to cope with this severe clinical situation. The aim of our study was to assess the bacteriology of PRNN and to demonstrate the antimicrobial susceptibility pattern that should guide the clinicians towards more appropriate antibiotic use.

METHODS

Sixty-nine NPC patients with PRNN in our department between March 2013 and December 2017 were retrospectively enrolled. Pathogenic culture and drug sensitivity test were performed in these 69 NPC patients with PRNN. The infection rate of Pathogens and the sensitivity of the drugs were analyzed based on these results.

RESULTS

Sixty-nine NPC patients with PRNN were enrolled in our study. Pathogens were identified in 58 (84%) patients. Of the 58 patients, Staphylococcus aureus was isolated in 34 (58.6%) patients. And the second most common group of bacterial isolates was Pseudomonas aeruginosa. Antibiotic sensitivity showed that Levofloxacin was the highest (88.5%), followed by Ciprofloxacin (85.2%) and Gentamicin (80.3%). The only pathologic fungus was Candidaalbicans, about 6.8%. The positive rates of bacterial and fungal culture in PRNN patients were not significantly different from the patients' gender, age, stage, number of radiotherapy courses (P>0.05), but the cure rate was statistically higher in culture-negative patients in comparison with culture-positive patients (63.6% vs 20.7%, P=0.011).

CONCLUSION

Our results provide an overall picture of the microbiology and drug susceptibility patterns for NPC patients with PRNN and could help implement guidelines for more rational treatment and improve therapeutic outcome.

The Microbiome and Radiation Induced-Bowel Injury: Evidence for Potential Mechanistic Role in Disease Pathogenesis

Radiotherapy has played a major role in both the curative and palliative treatment of cancer patients for decades. However, its toxic effect to the surrounding normal healthy tissue remains a major drawback. In cases of intra-abdominal and/or pelvic malignancy, healthy bowel is inevitably included in the radiation field, causing undesirable consequences that subsequently manifest as radiation-induced bowel injury, which is associated with significant morbidity and mortality. The pathophysiology of radiation-induced bowel injury is poorly understood, although we now know that it derives from a complex interplay of epithelial injury and alterations in the enteric immune, nervous, and vascular systems in genetically predisposed individuals. Furthermore, evidence supporting a pivotal role for the gut microbiota in the development of radiation-induced bowel injury has been growing. In this review, we aim to appraise our current understanding of radiation-induced bowel injury and the role of the microbiome in its pathogenesis as well as prevention and treatment. Greater understanding of the relationship between the disease mechanism of radiation-induced bowel injury and gut microbiome might shed light on potential future prevention and treatment strategies through the modification of a patient's gut microbiome.

Radiation induces proinflammatory dysbiosis: transmission of inflammatory susceptibility by host cytokine induction

OBJECTIVE

Radiation proctitis (RP) is a complication of pelvic radiotherapy which affects both the host and microbiota. Herein we assessed the radiation effect on microbiota and its relationship to tissue damage using a rectal radiation mouse model.

DESIGN

We evaluated luminal and mucosa-associated dysbiosis in irradiated and control mice at two postradiation time points and correlated it with clinical and immunological parameters. Epithelial cytokine response was evaluated using bacterial-epithelial co-cultures. Subsequently, germ-free (GF) mice were colonised with postradiation microbiota and controls and exposed to radiation, or dextran sulfate-sodium (DSS). Interleukin (IL)-1β correlated with tissue damage and was induced by dysbiosis. Therefore, we tested its direct role in radiation-induced damage by IL-1 receptor antagonist administration to irradiated mice.

RESULTS

A postradiation shift in microbiota was observed. A unique microbial signature correlated with histopathology. Increased colonic tumor necrosis factor (TNF)α, IL-1β and IL-6 expression was observed at two different time points. Adherent microbiota from RP differed from those in uninvolved segments and was associated with tissue damage. Using bacterial-epithelial co-cultures, postradiation microbiota enhanced IL-1β and TNFα expression compared with naïve microbiota. GF mice colonisation by irradiated microbiota versus controls predisposed mice to both radiation injury and DSS-induced colitis. IL-1 receptor antagonist administration ameliorated intestinal radiation injury.

CONCLUSIONS

The results demonstrate that rectal radiation induces dysbiosis, which transmits radiation and inflammatory susceptibility and provide evidence that microbial-induced radiation tissue damage is at least in part mediated by IL-1β. Environmental factors may affect the host via modifications of the microbiome and potentially allow for novel interventional approaches via its manipulation.

An Integrated Multi-Omic Approach to Assess Radiation Injury on the Host-Microbiome Axis

Medical responders to radiological and nuclear disasters currently lack sufficient high-throughput and minimally invasive biodosimetry tools to assess exposure and injury in the affected populations. For this reason, we have focused on developing robust radiation exposure biomarkers in easily accessible biofluids such as urine, serum and feces. While we have previously reported on urine and serum biomarkers, here we assessed perturbations in the fecal metabolome resulting from exposure to external X radiation in vivo. The gastrointestinal (GI) system is of particular importance in radiation biodosimetry due to its constant cell renewal and sensitivity to radiation-induced injury. While the clinical GI symptoms such as pain, bloating, nausea, vomiting and diarrhea are manifested after radiation exposure, no reliable bioindicator has been identified for radiation-induced gastrointestinal injuries. To this end, we focused on determining a fecal metabolomic signature in X-ray irradiated mice. There is overwhelming evidence that the gut microbiota play an essential role in gut homeostasis and overall health. Because the fecal metabolome is tightly correlated with the composition and diversity of the microorganism in the gut, we also performed fecal 16S rRNA sequencing analysis to determine the changes in the microbial composition postirradiation. We used in-house bioinformatics tools to integrate the 16S rRNA sequencing and metabolomic data, and to elucidate the gut integrated ecosystem and its deviations from a stable host-microbiome state that result from irradiation. The 16S rRNA sequencing results indicated that radiation caused remarkable alterations of the microbiome in feces at the family level. Increased abundance of common members of Lactobacillaceae and Staphylococcaceae families, and decreased abundances of Lachnospiraceae, Ruminococcaceae and Clostridiaceae families were found after 5 and 12 Gy irradiation. The metabolomic data revealed statistically significant changes in the microbial-derived products such as pipecolic acid, glutaconic acid, urobilinogen and homogentisic acid. In addition, significant changes were detected in bile acids such as taurocholic acid and 12-ketodeoxycholic acid. These changes may be associated with the observed shifts in the abundance of intestinal microbes, such as R. gnavus , which can transform bile acids.

Fermentation of sugars and sugar alcohols by plaque Lactobacillus strains

OBJECTIVE

The objective was to analyse the ability of Lactobacillus strains isolated from supragingival plaque of subjects with hyposalivation and from healthy controls to ferment sugars and sugar alcohols.

MATERIAL AND METHODS

Fifty strains isolated from interproximal plaque from subjects with radiation-induced hyposalivation (25 strains), subjects with primary Sjögren's syndrome (16 strains) and from subjects with normal salivary secretion rate (9 strains) were tested. Growth and pH were determined after 24 and 48 h of anaerobic incubation in vials containing basal media with 1 % of glucose, fructose, sucrose, mannitol, sorbitol or xylitol.

RESULTS

No differences between strains isolated from hyposalivated subjects and controls were detected. All strains lowered the pH to <5.0 from fructose and the majority of the strains from glucose and sucrose. A pH of <5.5 was seen for 52 % of the strains using mannitol, 50 % using sorbitol and 36 % using xylitol. The ability to produce acids from sugars and sugar alcohols was highest among strains of Lactobacillus rhamnosus, Lactobacillus casei and Lactobacillus paracasei and lowest among Lactobacillus fermentum strains.

CONCLUSION

A large number of Lactobacillus strains are able to ferment not only sugars but also the sugar substitutes mannitol, sorbitol and xylitol to pH levels critical for enamel demineralisation.

CLINICAL RELEVANCE

Our findings suggest that products containing mannitol, sorbitol and/or xylitol may contribute to the acidogenic potential of the dental plaque and especially in hyposalivated subjects with high numbers of lactobacilli.

Intramedullary cervical spinal cord abscess by viridans group Streptococcus secondary to infective endocarditis and facilitated by previous local radiotherapy

The risk factors, microbial patterns, and prognosis of intramedullary abscess have varied with time. The development of an intramedullary abscess of the spinal cord (IASC) constitutes an exceptional complication of infective endocarditis (IE) in the post-antibiotic era. We present a case of cervical IASC by viridans group Streptococcus in a patient with mitral valve IE. We hypothesize that previous cervical radiotherapy for non-Hodgkin's lymphoma favoured the occurrence of this uncommon entity. This physiopathologic mechanism has not been previously reported.

Exploratory Analysis of the Bacteriological Status of Post-irradiation Wounds and Its Relationship to Healing

AIMS

To investigate the bacteriological status of post-irradiation wounds and its relationship to wound healing in patients with nasopharyngeal cancer.

MATERIALS AND METHODS

One hundred and forty-six nasopharyngeal cancer patients with post-irradiation wounds on one or both sides of the neck were studied prospectively. Swabs were taken from the wounds at the initial study visit for bacteriological examination. A further swab for culture was taken when possible signs of infection developed. Wound healing was assessed on alternate days with respect to wound condition, the presence of clinical infection and healing time.

RESULTS

The results showed that most of the post-irradiation wounds were colonised with bacteria. This was not associated with clinical signs of infection in any instance. There was no association between wound healing time and the presence of organisms, the identity of organisms, the number of species of organisms, or the use of antibiotics.

CONCLUSIONS

The presence of bacteria in post-irradiation wounds, in the absence of clinical signs of wound infection, is not a barrier to wound healing. Oncology practitioners should recognise the unique features of radiation-induced wounds and skin reactions with confidence and provide appropriate treatment as needed.

The use of a novel biodegradable preparation capable of the sustained release of bacteriophages and ciprofloxacin, in the complex treatment of multidrug-resistant Staphylococcus aureus-infected local radiation injuries caused by exposure to Sr90

In December 2001, three Georgian lumberjacks from the village of Lia were exposed to a strontium-90 source from two Soviet-era radiothermal generators they found near their village. In addition to systemic effects, two of them developed severe local radiation injuries which subsequently became infected with Staphylococcus aureus. After hospitalization in Tbilisi, Georgia, the patients were treated with various medications, including antibiotics and topical ointments; however, wound healing was only moderately successful, and their S. aureus infection could not be eliminated. Approximately 1 month after hospitalization, treatment with PhagoBioDerm (a wound-healing preparation consisting of a biodegradable polymer impregnated with ciprofloxacin and bacteriophages) was initiated. Purulent drainage stopped within 2-7 days. Clinical improvement was associated with rapid (7 days) elimination of the aetiologic agent, a strain of S. aureus resistant to many antibiotics (including ciprofloxacin), but susceptible to the bacteriophages contained in the PhagoBioDerm preparation.

[Methods for estimation of organism's nonspecific characteristics of infection resistance under biomonitoring in the territories polluted as a consequence of the Chernobyl AFS accident]

It was shown that the methods of organism infection resistance valuation employment allows to detect easily and quickly the presence or absence of skin and saliva disbiosis and is considered as an important integral indicator of the state of the organism immunological activity. The methods under consideration are effective for swift studying the state of health of different age groups of population with increased sick rate and for revealing risk groups. They also make it possible to estimate the effectiveness of sanitary measures.

Mucositis reduction by selective elimination of oral flora in irradiated cancers of the head and neck: a placebo-controlled double-blind randomized study

PURPOSE

The aim of the study was to test the hypothesis that aerobic Gram-negative bacteria (AGNB) play a crucial role in the pathogenesis of radiation-induced mucositis; consequently, selective elimination of these bacteria from the oral flora should result in a reduction of the mucositis.

METHODS AND MATERIALS

Head-and-neck cancer patients, when scheduled for treatment by external beam radiation therapy (EBRT), were randomized for prophylactic treatment with an oral paste containing either a placebo or a combination of the antibiotics polymyxin E, tobramycin, and amphotericin B (PTA group). Weekly, the objective and subjective mucositis scores and microbiologic counts of the oral flora were noted. The primary study endpoint was the mucositis grade after 3 weeks of EBRT.

RESULTS

Seventy-seven patients were evaluable. No statistically significant difference for the objective and subjective mucositis scores was observed between the two study arms (p = 0.33). The percentage of patients with positive cultures of AGNB was significantly reduced in the PTA group (p = 0.01). However, complete eradication of AGNB was not achieved.

CONCLUSIONS

Selective elimination of AGNB of the oral flora did not result in a reduction of radiation-induced mucositis and therefore does not support the hypothesis that these bacteria play a crucial role in the pathogenesis of mucositis.

Candida dubliniensis in radiation-induced oropharyngeal candidiasis

Candida dubliniensis is a recently described species that has been shown to cause oropharyngeal candidiasis in patients with HIV. We present a detailed evaluation of a patient undergoing head and neck radiation for oral cancer who developed oropharyngeal candidiasis from a mixed infection of C dubliniensis and Candida albicans. To our knowledge, this is the first described case of C dubliniensis contributing to oropharyngeal candidiasis in this patient population.

[Bacterial endotoxins and their effects]

The lipopolysaccharide endotoxin macromolecules are cell wall's components of the Gram negative bacteria. The endotoxins are produced by Gram negative bacteria of intestinal flora. If the endotoxins are translocated from the intestinal tract to the circulation or injected into bloodstream, they elicit (depending from the quantity of endotoxin), slight or serious effects (e.g. endotoxin shock). In the effects of endotoxin certain cell populations (e.g. thrombocytes, macrophages, leukocytes, etc.), certain organs and organ-systems (e.g. liver, spleen, bone marrow, endocrine and lymphoreticular systems etc.) are involved. Effects of endotoxin are produced by mediators (e.g. endotoxin binding proteins, cytokines, prostaglandins, prostacyclins, NO etc.). The endotoxin sensitivity of vertebrate organisms is dependent from the phylogenetical status of the species. Most sensitive species is the human. Generally accepted that endotoxin has an important role in the pathogenesis of septic shock. In other pathological processes (e.g. intestinal syndrome of radiation disease, Gram negative infections, various shock forms etc.) are supposed or proved the role of endotoxins. Lead acetate induced endotoxin hypersensitivity or LAL methods are good tools for demonstration of the role of endotoxin in the pathogenesis of various processes. For this reason, the experimental endotoxin shock is used a model of septic and other shocks.

[The pathomorphological characteristics of duodenal peptic ulcer in the victims of the accident at the Chernobyl Atomic Electric Power Station: changes in the gastric mucosa]

Gastrobiopsies were studied from patients with duodenal ulcer, 62 of whom took part in the elimination of the effects of the Chernobyl Nuclear Power Plant breakdown, 33 were permanent residents in the territories affected by radioactive contamination, and 36 formed the control group. Several distinguishing features were noted in chronic Helicobacter gastritis in victims of Chernobyl accident versus control, such as higher degree and activity of the inflammatory process spreading over large tissue areas, with Helicobacter pylori being recordable in the gastric mucosa in highly increased numbers, and more frequent occurrence of atrophic changes. Incorporation of radionuclides and external irradiation at dose levels exceeding 25 cause most significant disturbances in regeneration of epithelium, with its enterolyzation and dysplasia going on, which fact makes the risk of neoplastic transformations higher.

[The antagonistic properties of microaerophilic bacteria isolated from the human and mink digestive tracts]

Study of antagonistic properties of microaerophilic bacteria isolated from human and mink gastroenteric tract have helped to establish differences in species composition, quantity and level of antagonistic activity of the studied microorganisms in respect to pathogenic microflora. It is shown that lactic acid bacteria identified as Lactobacillus fermentum and L. reuteri prevail among the strains isolated from the stomach and thin intestine of minks kept in the 30-km zone of Chernobyl NPP. Species composition of microaerophilic bacteria isolated from the digestive tract of the control minks is more variable. Antagonistically active bifidobacteria prevail in large intestine of experimental and control animals. Strains of lactic acid bacteria with the expressed antagonistic activity belonging to L. bavaricus, L. reuteri, L. coryniformis and L. maltaromicus have been found parallel with such known producers of antibiotic-like substances as L. fermentum. L. acidophilum. Streptococcus faecalis and bifidobacteria. L. maltaromicus most frequently occurred among antagonistically active strains revealed in feces of people which stayed in the zone of liquidation of the Chernobyl accident. Microaerophilic strains of bacteria (lactic acid, bifidobacteria and enterococci) manifest the expressed antagonistic activity connected with the capacity to not only acid formation but also to accumulation of antibiotic products of unknown nature. A strain of lactic acid bacteria L. fermentum 91 has been isolated from the contents of human gastroenteric tract. These bacteria are distinguished by most expressed and stable antagonism and characterized by the lack of pathogenicity in respect of albino mice that may be used to raise the microorganism resistance to gastric diseases.

The reduction of radiation mucositis by selective decontamination antibiotic pastilles: a placebo-controlled double-blind trial

The aim of this study was to see if antibiotic pastilles could reduce radiation mucositis, pain, dysphagia and weight loss in patients undergoing radical radiotherapy for head and neck cancer. A total of 275 patients with T1-T4 tumours entered the study; 136 were allocated to suck four times daily a pastille containing amphotericin, polymyxin and tobramycin. The remaining 139 patients received an identical placebo. In all, 54 patients were unevaluable (24 active, 30 placebo). Bacteriological monitoring was carried out before and twice weekly during treatment. Both arms of the study were well balanced for T and N stage, age, sex and radiation dose (60 Gy). There was a slight imbalance in the site of disease which had no substantive effect on the results. The primary study end point was the percentage of patients who developed intermediate or thick pseudomembranes. No statistically significant difference was found in this end point, with 36% of patients in the active arm developing this type of membrane compared with 48% in the placebo arm (P = 0.118). The estimated odds ratio (placebo/active) of developing an intermediate or thick pseudomembrane was 1.59 (95% CI 0.89-2.82). However a more sensitive test comparing the worst recorded mucositis grade between the two arms was statistically significant (P = 0.009). This indicated that the active pastilles had a beneficial effect, but the magnitude was probably smaller than the trial was designed to detect. There was a reduction in mucositis distribution (P = 0.002), mucositis area (P = 0.028), dysphagia (P = 0.006) and weight loss (P = 0.009) in the active arm. There was a clear tendency for patients with positive cultures for aerobic Gram-negative bacteria (AGNB) (P = 0.003) and yeasts (P = 0.026) during treatment to have more severe mucositis. The active pastilles reduced the percentage of patients with yeast cultures (P = 0.003) but had less effect on AGNB. The benefit derived from the pastilles should materially increase patient tolerance to radical radiotherapy for head and neck cancer.

Therapeutic use of an antibiotic-resistant Bifidobacterium preparation in men exposed to high-dose gamma-irradiation

Five men received high-dose, uneven, whole-body gamma-irradiation by accidental exposure to an unshielded 137Cs source. Analysis of the faeces 9-12 days post-irradiation showed low numbers of anaerobes and high counts of enterobacteria and staphylococci in four of the patients and total viable counts of < 10(3)/g in one. All five were treated with systemic ampicillin and gentamicin and oral nystatin commencing 4-7 days after irradiation. Three of the patients were also treated orally with a suspension of an antibiotic-resistant strain of Bifidobacterium longum for 30 days commencing 10-12 days post-irradiation. At 3 weeks post-irradiation, B. longum had appeared in their faecal flora and total anaerobe counts exceeded those of facultative and obligate aerobes. At 4 weeks and 5-7 weeks post-irradiation, this normalisation of the faecal flora continued. In contrast, in the two patients who received a placebo the faecal flora was dominated by enterobacteria (Klebsiella, Enterobacter and Serratia spp.) showing multiple antibiotic resistance 3 weeks post-irradiation. These potential opportunist pathogens were not isolated from the B. longum-treated group. Only one patient in the control group survived beyond 3 weeks; he continued to show high faecal counts of enterobacteria and staphylococci and low counts of obligate anaerobes. 'Probiotic' treatment with this antibiotic-resistant strain of B. longum may be of benefit in the treatment of radiation sickness, aiding normalisation of the faecal flora and inhibiting colonisation and overgrowth with opportunist pathogens.

Abnormal intestinal motor patterns explain enteric colonization with gram-negative bacilli in late radiation enteropathy

BACKGROUND & AIMS

Bacterial overgrowth and intestinal pseudo-obstruction may succeed abdominal radiotherapy, and absence of intestinal migrating motor complex (MMC) has been reported in bacterial overgrowth. The aims of this study were to address the relationship between intestinal patterns of motility and gastrointestinal microflora and to elucidate the pathogenesis of late radiation enteropathy.

METHODS

Forty-one consecutive female patients with symptoms of late radiation enteropathy were examined by prolonged ambulatory manometry, culture of gastric and duodenal samples with quantification of gram-negative bacilli (GNB) by the glucose gas test, the [14C]D-xylose breath test, and determination of pH and short-chain fatty acids in gastric juice.

RESULTS

The intensity of MMC explained 61% (P < 0.001) and 71% (P < 0.001) of the variability of GNB in the stomach and duodenum, respectively, corresponding to the severity of disease. Abnormal MMC index and presence of irregular bursts were the best predictors of GNB (86%; P < 0.001, multiple regression). Fasting gastric pH explained gastric bacterial counts (63%; P < 0.001) but did not predict GNB.

CONCLUSIONS

Impaired motility emerges as a causal factor for gastrointestinal colonization with GNB, whereas hypochlorhydria facilitates unspecific gastric colonization. Abnormal motility and GNB in the proximal small intestine are essential factors in the pathogenesis of severe late radiation enteropathy.

Correlation between detection of herpes simplex virus in oral secretions by PCR and susceptibility to experimental UV radiation-induced herpes labialis

We examined the oral secretions of 25 patients for herpes simplex virus (HSV) at the time of and following experimental UV radiation (UVR). HSV was detected in one or more oral secretion specimens in 5 of 12 (42%) cases by cell culture and in 8 of 12 (67%) cases by PCR. On the day of UVR, HSV was detected in 1 of 12 (8%) patients who developed a lip lesion and 2 of 16 (13%) patients who did not (the difference is not significant). We conclude that PCR is more sensitive than culture in the detection of HSV and that HSV is not shed with increased frequency from the oral cavity before the development of UVR-induced herpes labialis.

Use of selective decontamination in the prevention of infection after accidental irradiation. A review

Exposure to radiation induces a reduction in the number of gastrointestinal, anaerobic bacterial flora, and an increase in the number of Enterobacteriaceae that are associated with sepsis and mortality. Antimicrobials that suppress anaerobic flora have a deleterious effect on survival by promoting earlier enterobacterial sepsis. In contrast, in studies of animals and immunosuppressed patients, antimicrobials that inhibit gram-negative enteric bacteria and preserve the anaerobic flora have shown a beneficial effect by preventing bacterial translocation and fatal sepsis. The quinolone antimicrobials hold potential for therapy of endogenous and exogenous infection after irradiation.

Tinea corporis confined to irradiated skin. Radiation port dermatophytosis

BACKGROUND

Radiation port dermatophytosis (RPD) is an uncommon condition in which patients receiving radiation therapy concurrently have tinea corporis that is confined primarily to the irradiated skin.

METHODS

The case of a 33-year-old man is reported who was receiving cobalt-60 radiation therapy for a nasopharyngeal carcinoma. During therapy, a dermatophyte infection developed in the treated field.

RESULTS

Including this patient, there have been only three cases of RPD reported in the world literature. The clinical characteristics of patients with RPD are reviewed. The diagnosis, management, and pathogenesis of this condition are discussed.

CONCLUSIONS

Because the cutaneous manifestations of RPD may be misinterpreted clinically as acute radiation-induced dermatitis, this condition may be more prevalent than the paucity of published reports suggests.

[The intestinal microflora of persons subjected to a radiation lesion]

The content of large intestine has been studied in persons exposed to radiation injury in consequence of the accident at the Chernobyl Atomic Power Plant. It is stated that bifidobacteria (10(7)-10(10) cells in 1 g of feces) prevailed (as in healthy people), Bifidobacterium indicum being a dominating species. Amount of lactic-acid bacteria in 1 g of defecations of examined patients was within the range of 10(6)-10(9) cells and in certain persons it reached 10(10) cells (primarily fecal Enterococci). A considerable amount of patients with acute radiation sickness of the 3d degree had in their intestine 10(9)/g of lactic-acid bacteria, Lactobacillus casei and L. plantarum prevailing there. The frequency of yeast isolation from defecations of patients constituted 83%, while the number of cells in 1 g of feces--from 10 to 10(4). Yeast of the Candida genus, mainly Candida parapsilosis, prevailed. The species composition of isolated microorganisms has no substantial differences from microcenosis of healthy people. The content of intestine of persons suffered from radiation is characterized only by greater amount of lactic-acid bacteria and enterococci as compared with healthy adults.

Herpes simplex virus in postradiation cervical smears. A morphologic and immunocytochemical study

From January 1987 to August 1988, cytomorphologic criteria of both herpes simplex virus (HSV) and radiation effects were observed in Papanicolaou smears from 3 of 1,340 patients who had received radiotherapy for squamous cell carcinoma of the cervix. Avidin-biotin immunoperoxidase staining, using a rabbit IgG polyclonal HSV antibody, confirmed the presence of HSV antigen in those three postradiation smears. Both multinucleated molded cells and epithelial cells that lacked cytopathic effects were positive for HSV. Three other postradiation smears from these cases were similarly positive for HSV antigen; the one preradiation smear was negative. In situ hybridization and immunoperoxidase studies on sections from the preradiation biopsies were negative: severely altered neoplastic cells showed no reactivity. The absence of HSV markers in the preradiation specimens suggests that the HSV infections were secondary to the radiotherapy; further studies are needed to prove this association and to assess the possible mechanisms. These cases clearly indicate that the overlapping features of radiation and viral effects (such as multinucleation) may be present simultaneously.

Resistogram typing of Candida albicans isolates from oral and cutaneous sites in irradiated patients

Thirteen resistogram strains of Candida albicans were found among isolates obtained from the mouth and cutaneous sites of irradiation of 27 patients receiving treatment for oral and laryngeal cancer. In all cases the yeast was recovered from the mouth before treatment, but not from the skin site until after treatment had begun. Of the 27 patients, 25 harboured one or more strains with identical resistograms in both sites.

[Yeast fungus flora in tumor irradiation of the upper aerodigestive tract]

The microflora of the oral cavity and pharynx were examined in 28 patients undergoing radiotherapy for cancer of the upper aerodigestive tract. We found no correlation between yeast flora and mucositis: early mucositis occurred between 10 and 20 gy. independent of the concentration of yeast. During radiotherapy the number of patients with detectable yeasts rose from 12 to 22 of the 28. There was a tenfold increase of mean values for yeasts during irradiation, whereas the normal flora (eg. streptococci) remained unchanged. The value of an antifungal local therapy for the prevention of yeast-induced complications is discussed.

Actinomyces israelii in osteoradionecrosis of the jaws. Histopathologic and immunocytochemical study of five cases

Five surgically treated patients with osteoradionecrosis of the jaws are presented. The clinical history of the disease varied from 3 to 17 years. In three cases the progression of the disease was enhanced by surgical procedures performed in the irradiated area causing exfoliation of the premaxillary area in one case and spontaneous mandibular fracture in two cases. Actinomyces israelii was demonstrated in tissue sections of all five cases by using FITC-labeled specific antiserum and additionally with peroxidase-antiperoxidase method in one case. Candida was found in histologic sections of three cases. Radiation damage in the oral soft tissues and jawbones makes the atmosphere favorable for anaerobic microorganisms. The present results indicate that the role of A. israelii in the pathogenesis of osteoradionecrosis of the jaws has not been fully appreciated.