Strongyloides stercoralis hyperinfection associated with cimetidine in an immunosuppressed patient: diagnosis by endoscopic biopsy

The Phylogeny and Biological Function of Gastric Juice-Microbiological Consequences of Removing Gastric Acid

Gastric juice is a unique combination of hydrochloric acid (HCl), lipase, and pepsin. Acidic gastric juice is found in all vertebrates, and its main function is to inactivate microorganisms. The phylogenetic preservation of this energy-consuming and, at times, hazardous function (acid-related diseases) reflects its biological importance. Proton pump inhibitors (PPIs) are one of the most widely used drugs in the world. Due to the reduced prevalence of Helicobacter pylori infection as well as the increased use of inhibitors of gastric acid secretion, the latter has become the most important cause of gastric hypoacidity. In the present manuscript, we review the microbiological consequences of removing gastric acidity. The resulting susceptibility to infections has not been studied extensively, and focus has mainly been restricted to bacterial and parasitic agents only. The strongest evidence concerning the relationship between hypochlorhydria and predisposition to infections relates to bacterial infections affecting the gastrointestinal tract. However, several other clinical settings with increased susceptibility to infections due to inhibited gastric acidity are discussed. We also discuss the impact of hypochlorhydria on the gut microbiome.

Acid-Suppressive Therapy and Risk of Infections: Pros and Cons

This narrative review summarises the benefits, risks and appropriate use of acid-suppressing drugs (ASDs), proton pump inhibitors and histamine-2 receptor antagonists, advocating a rationale balanced and individualised approach aimed to minimise any serious adverse consequences. It focuses on current controversies on the potential of ASDs to contribute to infections-bacterial, parasitic, fungal, protozoan and viral, particularly in the elderly, comprehensively and critically discusses the growing body of observational literature linking ASD use to a variety of enteric, respiratory, skin and systemic infectious diseases and complications (Clostridium difficile diarrhoea, pneumonia, spontaneous bacterial peritonitis, septicaemia and other). The proposed pathogenic mechanisms of ASD-associated infections (related and unrelated to the inhibition of gastric acid secretion, alterations of the gut microbiome and immunity), and drug-drug interactions are also described. Both probiotics use and correcting vitamin D status may have a significant protective effect decreasing the incidence of ASD-associated infections, especially in the elderly. Despite the limitations of the existing data, the importance of individualised therapy and caution in long-term ASD use considering the balance of benefits and potential harms, factors that may predispose to and actions that may prevent/attenuate adverse effects is evident. A six-step practical algorithm for ASD therapy based on the best available evidence is presented.

Indications and safety of proton pump inhibitor drug use in patients with cancer

INTRODUCTION

Although the exact prevalence of proton pump inhibitor (PPI) use in cancer patients is not known, it is generally perceived to be widespread. PPIs are generally well tolerated and carry an excellent safety profile. However, increasing and longer term PPI use has raised concerns about the risk of pneumonia, bone fractures and enteric infections, and a possible interaction with clopidogrel that could increase the risk of cardiovascular events.

AREAS COVERED

We conducted a PubMed search of English language articles addressing the safety and adverse events associated with PPI use with particular emphasis in cancer patients.

EXPERT OPINION

PPIs, frequently used in cancer patients, are generally well tolerated and carry an excellent safety profile. PPI-induced acid suppression may increase the risk of Clostridium difficile or other enteric infections, nutritional deficiencies and community acquired pneumonia, all particularly important in cancer patients. The indications for PPI use in cancer patients should be carefully reviewed prior to use.

Adverse effects of long-term proton pump inhibitor therapy

Proton pump inhibitors have an excellent safety profile and have become one of the most commonly prescribed class of drugs in primary and specialty care. Long-term, sometimes lifetime, use is becoming increasingly common, often without appropriate indications. This paper is a detailed review of the current evidence on this important topic, focusing on the potential adverse effects of long-term proton pump inhibitor use that have generated the greatest concern: B12 deficiency; iron deficiency; hypomagnesemia; increased susceptibility to pneumonia, enteric infections, and fractures; hypergastrinemia and cancer; drug interactions; and birth defects. We explain the pathophysiological mechanisms that may underlie each of these relationships, review the existing evidence, and discuss implications for clinical management. The benefits of proton pump inhibitor use outweigh its risks in most patients. Elderly, malnourished, immune-compromised, chronically ill, and osteoporotic patients theoretically could be at increased risk from long-term therapy.

Prevention of strongyloides hyperinfection syndrome: a rheumatological point of view

BACKGROUND

Strongyloides stercoralis (S.stercoralis) is a parasite that infects humans and in conditions of immunodeficiency may disseminate, causing the potentially fatal strongyloides hyperinfection syndrome (SHS). The aim of this review was to investigate the literature evidence on the prophylaxis of SHS in immunosuppressed patients with rheumatological disorders.

MATERIAL AND METHODS

The MEDLINE database (from 1966 to 2008) was searched using the following terms: "strongyloidiasis", "disseminated strongyloidiasis", "Strongyloides stercoralis", "Strongyloides stercoralis dissemination", "strongyloides hyperinfection syndrome", "treatment", "prophylaxis", "prevention", "immunocompromised", "immunodepression", "immunosuppressed", "immunosuppression", "corticosteroids", "glucocorticoids", "lupus erythematosus", "rheumatoid arthritis", "rheumatic diseases". A search of the therapeutic studies using the same set of terms was carried out.

RESULTS

No study on the prophylaxis of SHS restricted to rheumatic immunosuppressed patients was identified. However, two articles have been published on the prophylaxis of strongyloidiasis in other immunosuppressed patients. Additionally, 13 studies dealing with different therapeutical options for strongyloidiasis were identified and presented.

CONCLUSIONS

Since there is no evidence on the prophylaxis of SHS in immunosuppressed rheumatic patients, the suggested regimen for that prophylaxis may rely on the results obtained from therapeutical studies. Ivermectin has the best safety profile, lower cost and best efficacy and should be the drug of choice for the prophylaxis of SHS in such patients. Although a definitive prophylactic regimen has not been defined, the option for 200 microg/kg/day for 2 days, repeated within 2 weeks, seems to be a reasonable approach. Such regimen should be repeated every 6 months in case of persisting immunosuppression in permanent residents of endemic areas.

Histopathology of gastric and duodenal Strongyloides stercoralis locations in fifteen immunocompromised subjects

CONTEXT

Strongyloidiasis is a worldwide parasitic infection affecting approximately 75 million people. In Italy, it was more prevalent in the past among rural populations of irrigated areas.

OBJECTIVE

To determine the histopathologic alterations of the gastric and duodenal mucosa associated with the presence of Strongyloides stercoralis parasites.

DESIGN

Fifteen cases of strongyloidiasis were observed in immunocompromised patients during a recent 6-year period in Italy. S. stercoralis was found histologically in gastric biopsies (10 cases), in a gastrectomy (1 case), and in duodenal biopsies (9 cases). In 5 cases the parasite was present both in gastric and duodenal biopsies. Four patients were affected by lymphoma, 2 by multiple myeloma, 2 by gastric carcinoma, 1 by chronic myeloid leukemia, 1 by sideroblastic anemia, 1 by colorectal adenocarcinoma, 1 by chronic idiopathic myelofibrosis, 1 by chronic gastritis, 1 by gastric ulcers, and 1 by rheumatoid arthritis in corticosteroid therapy. No patient was affected by human immunodeficiency virus infection. Strongyloidiasis was not clinically diagnosed.

RESULTS

Histologic examination revealed several sections of S. stercoralis larvae, many eggs, and some adult forms. All the parasites were located in the gastric and/or the duodenal crypts. Eosinophils infiltrating into the lamina propria were found in all cases; their intensity was correlated with the intensity of the infection.

CONCLUSIONS

Histologic diagnosis of strongyloidiasis must be taken into consideration when examining both gastric and duodenal biopsies in immunocompromised patients, to avoid the development of an overwhelming infection of the parasite, which is dangerous for the life of the patient.

Severe strongyloidiasis in corticosteroid-treated patients: case series and literature review

OBJECTIVE

To describe the main features of severe strongyloidiasis in corticosteroid-treated patients

METHODS

We report on 3 cases of corticosteroid-treated patients with severe strongyloidiasis and review cases of severe strongyloidiasis in corticosteroid-treated patients reported in the literature.

RESULTS

One hundred and fifty-one cases of severe strongyloidiasis complicated a therapy with corticosteroids were evaluated. The mean age of the patients was 48+/-17 years and 71% were men. Corticosteroids were given for hematological malignancies in 34 (23%), systemic lupus erythematosus or vasculitis in 27 (18%), and nephropathy or renal transplantation in 32 (21%). At time of infection, the mean daily dosage of prednisone-equivalent was 52+/-42 mg (median: 40 mg) and 84% of patients had received a cumulative dosage of prednisone-equivalent higher than 1000 mg. The total duration of treatment ranged from 4 days to 20 years (6 months or less: 69%). Non-specific gastro-intestinal symptoms were reported in 91% of these patients associated or not with pulmonary complaints. Low-grade fever was present in 54% of patients. Fifty-nine patients (39%) experienced severe bacterial or yeast infection during the course of severe strongyloidiasis. Peripheral eosinophilia was detected at presentation in 32% of patients. Strongyloidiasis was usually confirmed by repeated stool examinations. Thiabendazole was the treatment the more widely used. Eighty-nine patients (59%) deceased during the course of the disease.

CONCLUSIONS

Severe strongyloidiasis is a risk in every corticosteroid-treated patient who has traveled to a soil-infested country, even if the contact was 30 years prior. This diagnosis should be suspected in patients who either experience unusual gastro-intestinal or pulmonary symptoms or suffer from unexplained Gram-negative bacilli sepsis.

Gastric juice: a barrier against infectious diseases

All vertebrates produce gastric acid. Its main function is inactivation of ingested microorganisms. The majority of microbiological pathogens ingested never reaches the intestine because of the gastric barrier. Although gastric hypochlorhydria is fairly common due to atrophic gastritis, gastric surgery or use of inhibitors of gastric acid secretion, the resulting susceptibility to infection has not been studied extensively. Drug-induced blockade of acid secretion leads to gastrointestinal bacterial overgrowth; the clinical significance of this is still controversial. Gastric acidity is known to protect against non-typhoid salmonellosis and cholera and it is suspected that it protects against several parasitic diseases as giardiasis and strongyloides. There is a lack of studies focusing on the impact of the gastric acidic barrier on viral infections. Concerning prion infections only a single study has been performed, demonstrating a possible role of gastric acidity in the protection against foodborne prion disease in mice. The combination of malnutrition and hypochlorhydria may contribute to the high prevalence of gastrointestinal infections in developing countries. Further studies are needed to evaluate the clinical consequences of impaired gastric acidity with respect to susceptibility to infections.

Two cases of fatal strongyloidiasis in Hong Kong

Two cases of fatal strongyloidiasis associated with diabetes mellitus and malnutrition are reported. The patients presented with repeated vomiting and upper gastrointestinal bleeding respectively. Unusual findings in these two patients included: unexplained peripheral leukocytosis, pulmonary infiltrates, gastric aspirate leukocytosis, progression of gastrointestinal symptoms and concurrent presence of adult worms, eggs, filariform and rhabditiform larvae of Strongyloides stercoralis in alimentary canal specimens. Both patients succumbed while receiving treatment with mebendazole. The present report illustrates that unexplained gastrointestinal symptoms with extensive scratch marks below the umbilicus can be important clues to early diagnosis of the disease. In addition, the various presentations of S. stercoralis infestation are discussed with reference to predisposing factors. Current trends in laboratory diagnosis and therapeutic considerations are also delineated.

Review article: infective complications of therapeutic gastric acid inhibition

Gastric acid secretion has a non-specific bactericidal action which contributes to gastrointestinal defence mechanisms against micro-organisms. Therapeutic inhibition of acid secretion with histamine H2 receptor antagonists and proton pump inhibitors might therefore be expected to predispose to infection. This article reviews clinical reports of infection occurring during therapeutic gastric acid inhibition, and assesses the risk of infection incurred by such treatment. Non-typhoid salmonelloses, Campylobacter infections, local candidiasis, and possibly Strongyloides hyperinfections may be more prevalent after acid inhibitory treatment, but concurrent impairment of other gastrointestinal defence mechanisms may be necessary to permit infection.

Strongyloides hyperinfection in two patients with lymphoma, purulent meningitis, and sepsis

Strongyloides stercoralis hyperinfection syndrome is a rare complication of strongyloidiasis that occurs in immunosuppressed patients. It is caused by increasing autoinfection of the host by the nematode, leading to serious superimposed enterobacterial sepsis. Once established, it has a high fatality rate. Two cases are reported of Strongyloides hyperinfection in patients with lymphoma who presented with purulent meningitis. Both were receiving combination chemotherapy that included high-dose corticosteroids, and neither was granulocytopenic at infectious onset. The patients had respiratory insufficiency that required mechanical ventilation and serious septic episodes. Both were treated with thiabendazole, and one survived with clearance of the larvae. These cases illustrate the possibility of strongyloidiasis hyperinfection as an underlying diagnosis of purulent meningitis and serious septic episodes in lymphomatous patients. It may occur even without granulocytopenia.

Opportunistic Strongyloides stercoralis infection in lymphoma patients. Report of a case and review of the literature

Strongyloides stercoralis is an intestinal parasite that may cause fatal opportunistic infections in immunocompromised patients. Herein is reported a patient who developed fatal disseminated strongyloidiasis 6 weeks after the initiation of chemotherapy for a large cell lymphoma of the small intestine. After reviewing the clinical and epidemiologic features of 16 other cases of disseminated strongyloidiasis in patients with malignant lymphomas, the currently available laboratory methods for the diagnosis of this parasite are outlined. Because uncomplicated infections are treatable, candidates for chemotherapy or immunosuppression with a relevant geographic history should be screened for S. stercoralis prior to the initiation of the treatment.

Hyperinfection with strongyloides after treatment for adult T cell leukaemia-lymphoma in an African immigrant

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