Prevalence of cases of amebic liver abscess in a tertiary care centre in India: A study on risk factors, associated microflora and strain variation of Entamoeba histolytica

BACKGROUND

Amebiasis, caused by Entamoeba histolytica (E. histolytica), is a significant cause of morbidity and mortality in developing countries. Mortality due to amebiasis is mostly by extra intestinal infections, amebic liver abscess being the most common one. This study was conducted to determine the current epidemiological status, risk factors, associated microflora and strain variation of E. histolytica causing liver abscesses.

METHODS/FINDINGS

A total of 115 liver abscess cases comprising of 107 (93%) males and 8 (6.9%) females were included in the study. Microscopic examination of pus samples from the abscesses and species discrimination using nested multiplex PCR showed the presence of E. histolytica in 101 (87.5%) cases. Data collected by face to face interviews using a pre tested questionnaire suggested intake of untreated drinking water (ORs: 6.4, p = 0.002), habit of alcohol consumption (ORs: 4.0, p = 0.019) and lack of urban services (ORs: 0.08, p = 0.017) to be major risk factors associated with E. histolytica infections. The study of associated bacterial flora through aerobic culture of liver aspirates and conventional PCR for detection of anaerobes revealed the presence of Fusobacterium (19, 25.5%), Peptococcus (19, 25.5%), Prevotella (18, 24.3%), Bacteroides (8, 10.8%), Staphylococcus aureus (3, 4%), Escherichia coli (2, 2.7%), Peptostreptococcus (2, 2.7%), Clostridium (2, 2.7%) and Klebsiella pneumoniae (1, 1.3%). Further to study the clonality, genotyping of E. histolytica targeting six tRNA-linked polymorphic STR loci (A-L, D-A, N-K, R-R, STGA -D and S-Q) was carried out which showed the presence of 89 different genotypes in the liver aspirate samples.

CONCLUSION

The findings highlight the high prevalence of genetically diverse E. histolytica from the liver abscess cases in this geographical region. Low socio-economic status and habit of alcohol consumption were important predictors of amebic liver abscess.

Causative agents of liver abscess in HIV-seropositive patients: a 10-year case series in Thai hospitalized patients

Liver abscess is an important tropical gastrointestinal disorder. HIV seropositive patients show relative immunosuppression and are more susceptible to infection, including liver abscess. This retrospective case review was made on 23 patients who were diagnosed as HIV seropositive with liver abscess in Bangkok, Thailand. We demonstrated the high rate of amoebic liver abscess in our series (17.4%) from fresh smear with five cases of tuberculosis and one case of Nocardosis. The rates of positive bacterial culture were 17.4% from blood and 47.8% from pus. Gram-negative aerobes were the major abscess pathogens in our series. Among Gram-negative aerobes, Klebsiella was the most significant microorganism, followed by Escherichia coli and Pseudomonas aeruginosa.

Vagotomy induces deregulation of the inflammatory response during the development of amoebic liver abscess in hamsters

BACKGROUND

The parasympathetic nervous system modulates the immune response in the abdominal-pelvic gut through the vagus nerve, which releases acetylcholine. This endogenous ligand acts on α7 nicotinic receptors expressed on immune cells.

OBJECTIVE

To study the mechanism of the production and regulation of cytokines in parasympathectomized and control hamsters during the development of amoebic liver abscesses (ALA) caused by Entamoeba histolytica.

METHODOLOGY

Six- to 8-week-old male hamsters with and without vagotomy were used in a model of ALA. The animals were infected with trophozoites (350,000; HM1:IMSS strain) via the intrahepatic route and sacrificed at 6, 12, and 24 h and at 2, 4, and 7 days postinfection. Immune parameters were recorded at each time point using morphometric techniques including immunofluorescence and immunohistochemistry assays. These parameters included signal transducer and activator of transcription 3 (STAT3) levels, pro- and anti-inflammatory cytokine levels, and nuclear factor-κB (NFκB) activation in neutrophils and macrophages.

RESULTS

Compared to the control groups, the vagotomized (VAG) hamsters showed a significant increase in NFκB activation in neutrophils and macrophages, and higher levels of interleukin (IL)-1β, IL-6, interferon-γ, and tumor necrosis factor-α. VAG hamsters showed an increase in the expression of IL-8 and phosphorylated STAT3 during the first 24 h postinfection as well as slightly increased levels of transforming growth factor-β on days 2-7 postinfection. No significant differences were demonstrated in the levels of IL-10.

CONCLUSIONS

These results suggest that the vagus nerve plays an important role in the regulation of inflammation during ALA formation.

Common presentation of amebic liver abscess - a study in a tertiary care hospital in Bangladesh

Amebic liver abscess is a tropical disease. It is not uncommon in Bangladesh. Given the often nonspecific nature of complains related to amebic liver abscess, this study was carried out to identify the most common presentation. This hospital based cross sectional study was carried out in 30 cases of amebic liver abscess in the Department of Medicine, Gastroenterology and Hepatology, Comilla Medical College Hospital, Bangladesh. Clinical and laboratory informations were recorded including symptoms, signs, location and number of abscess. Among 30 patients, 27 were male (90%) and 3 female (10%), mean age of male and female were 42±11 and 52±8 respectively. Common clinical symptoms were fever (93%) and abdominal pain (93%). Common signs were right upper quadrant tenderness (60%), hepatomegaly (67%). Most of the patient had single abscess (80%) and location of abscess was predominantly in the right lobe (77%). Radiological abnormality on x-ray chest was present in 30% cases. Common clinical presentation of amebic liver abscess patients were fever and right upper abdominal pain. Duration of symptoms was more than two weeks in most cases.

Endoscopic biliary drainage in patients with amebic liver abscess and biliary communication

BACKGROUND

Percutaneous drainage or surgery is required when amebic liver abscess (ALA) fails to respond to medical management. In some of these patients, non-response may be due to communication of ALA with the biliary tree. This report describes our experience with the use of endoscopic biliary draining in such patients.

METHODS

Medical records of patients with ALA undergoing either needle aspiration or percutaneous pigtail drainage were retrieved; the indications for drainage were: abscess volume exceeding 250 mL, a thin rim of tissue (< 1 cm thick) around the abscess, systemic toxic features and failure to improve on medical treatment. Patients with abscess drain output >25 mL/day persisting for 2 weeks or presence of bile in the drain fluid underwent endoscopic biliary drainage.

RESULTS

A total of 115 patients with ALA underwent percutaneous treatment. None of the 25 patients with needle aspiration needed any further treatment. Of the 90 who underwent catheter drainage, the catheter could be removed within one week in 77 patients; the remaining 13 patients (median age 42 years, range 24-65; all men) had an abscess-biliary communication. In them, the median catheter output was 88 mL/day (range 45-347) and 54 mL/day (28-177) at 2 days and 2 weeks after catheter placement. The drain fluid contained bile in all 13 patients and in addition contained pus in 10 patients. Eleven patients had a solitary abscess and two had multiple abscesses. Cholangiogram showed biliary communication in all 13 patients. All patients were treated with placement of 10F biliary endoprosthesis or 10F nasobiliary drain. Pigtail catheter was removed within 1 week in 11 of 13 patients.

CONCLUSION

In patients with amebic liver abscess communicating with the biliary tree, biliary stenting may hasten clinical recovery and allow early removal of liver abscess catheter drain.

Changes in bacterial profile during amebiasis: demonstration of anaerobic bacteria in ALA pus samples

Little is known about the changes in gut resident flora during amebic colitis and amebic liver abscess (ALA) caused by Entamoeba histolytica infection. Fecal samples from ALA patients, from healthy E. histolytica negative and positive (asymptomatic) individuals, and from pre- and post-metronidazole-treated healthy volunteers and pus samples from ALA patients were tested for the presence of various bacterial genera using 16S rRNA-based primers. Statistically significant reduction in Lactobacillus due to E. histolytica infection was observed in asymptomatic individuals and ALA patients. On the other hand, reduction in Bacteroides, Bifidobacterium, and Clostridium in the same samples was due to metronidazole treatment. Two anaerobic genera, viz. Bacteroides and Peptostreptococcus, were detected in ALA pus samples, and this observation is unprecedented. In addition, PCR revealed metronidazole resistance genes in fecal and pus samples of metronidazole-treated individuals. Re-examination of the ameba-bacterium relationship in amebiasis is suggested.

Mucosal immunity to asymptomatic Entamoeba histolytica and Entamoeba dispar infection is associated with a peak intestinal anti-lectin immunoglobulin A antibody response

We monitored 93 subjects cured of amebic liver abscess (ALA) and 963 close associate controls in Durban, South Africa, and determined by enzyme-linked immunosorbent assay that the intestinal immunoglobulin A (IgA) antibody response to the Entamoeba histolytica galactose-inhibitable adherence lectin is most accurately represented by a complex pattern of transitory peaks. One or more intestinal anti-lectin IgA antibody peaks occurred in 85.9% of ALA subjects over 36 months compared to 41.6% of controls (P < 0.0001). ALA subjects exhibited a greater number of anti-lectin IgA antibody peaks (P < 0.0001) than controls. In addition, their peak optical density values were higher (peak numbers 1 to 3, P < 0.003), peaks were of longer duration (for peaks 1 and 2, P </= 0.0054), and there was a shorter time interval between peaks (between 1 and 2 or 2 and 3, P </= 0.0106) than observed for control subjects. A prior E. histolytica infection was associated with the occurrence of an anti-lectin IgA antibody peak (79.1%, P < 0.0001) more so than for Entamoeba dispar infection (57.2%, P < 0.001). The annual number of anti-lectin IgA antibody peaks in ALA subjects was 0.71 per year, compared to just 0.22 in controls (P<0.0001), indicating a higher rate of exposure to the parasite than previously appreciated. Anti-lectin IgA antibody peaks were of higher amplitude following a E. histolytica infection compared to E. dispar (P = 0.01) and, for either, were of greater height in ALA subjects than controls (P < 0.01). ALA subjects demonstrated greater clearance of amebic infection after an anti-lectin IgA antibody peak compared to controls, and only 14.3% remained with a positive culture after the peak, compared to 38.9% in controls (P = 0.035). In summary, this prospective controlled longitudinal study elucidated the dynamic nature of the human intestinal IgA antibody response to E. histolytica and E. dispar infection and revealed that ALA subjects exhibit heightened intestinal anti-lectin IgA antibody peaks that are associated with clearance of E. histolytica and E. dispar infection.

Detection of Entamoeba histolytica using polymerase chain reaction in pus samples from amebic liver abscess

BACKGROUND AND OBJECTIVE

Direct demonstration of Entamoeba histolytica by conventional microscopy and in vitro culture in pus obtained from amebic liver abscess (ALA) is often unsuccessful. We evaluated polymerase chain reaction (PCR) for detection of E. histolytica DNA in such pus.

METHODS

Species-specific primers were used for the amplification of E. histolytica DNA from liver pus obtained from 30 patients with ALA. Patients with pyogenic liver abscess and sterile (autoclaved) pus spiked with Entamoeba dispar and bacteria (Escherichia coli, Klebsiella spp. and Bacteroides spp.) were used as negative controls.

RESULTS

PCR was positive in 83% of pus specimens from patients with ALA, and was negative in all 25 pus specimens obtained from pyogenic abscess and autoclaved pus spiked with known bacteria. Sensitivity and specificity of PCR were 83% and 100%, respectively. The overall positivity of PCR was higher compared to serological tests.

CONCLUSION

PCR may be a more reliable and better alternative diagnostic modality for ALA.

[Diagnosis and treatment of acute amebian liver abscess with laparoscopic method]

Laparoscopic surgical treatment was performed at 55 patients with acute amebian liver abscess. The diagnosis of acute amebian liver abscess was verified with clinical, serological, echoscopic, x-ray and CT methods. The laparoscopic method permits to sanify the abscess cavity of any localization. All the 55 patients have been discharged in good health. Laparoscopic method is maximally rational, associated with minimal surgical trauma, permits to decrease hospital stay and period of postoperative rehabilitation.

Biological aspects of a Brazilian strain of Entamoeba dispar

A strain of Entamoeba dispar was characterized by clinical diagnosis, serological and electrophoretical isoenzyme analysis and by the polymorphism of a 482 bp genomic fragment analysis. The pathogenesis and virulence of this strain was investigated considering the experimental infection in hamster livers in association with the original intestinal microbiota. Liver lesions were observed in hamsters experimentally infected with trophozoites from xenic cultures, but not from the monoxenic cultures. Moreover, clones obtained from re-isolated strain Wil1R1 showed a distinct biological behavior. In fact, animals inoculated with Wil1R1ClB3 showed an intense acute inflammatory reaction with destructive focal hepatic lesions. These lesions were characterized as amebic abscesses. The association between bacteria and ameba has been fairly well studied because it affects the pathogenicity of the amebas and has important therapeutic implications. In this study, we demonstrated that E. dispar in association with the original microbiota is able to produce lesions in hamster liver in spite of its having been considered to be non-pathogenic in the hamster model. Based on these results we suggest that diagnosis of amebiasis needs to be made with more care and that clinical and therapeutical procedures need to be revised.

Tuberculous liver abscess: a case report and review of literature

Tuberculous liver abscess is rare worldwide. We report a 45-year-old man who presented with abdominal pain, fever and weight loss. Ultrasound and computed tomography of the abdomen showed multiple cystic lesions in the liver. Ultrasound guided needle aspiration revealed yellowish brownish aspirate, which was flooded with acid-fast bacilli. The abscess was drained under ultrasound guidance. Subsequent abdominal ultrasound a few days later showed resolution of the abscess cavity. He was concomitantly started on systemic antituberculous therapy. A tuberculous liver abscess has to be thought of in the differential diagnosis of liver abscesses and to consider the role of percutaneous drainage along with systemic antituberculous chemotherapy as an alternative to surgery in the management. A greater awareness of this clinical entity is required for successful treatment.

Solitary and multiple pyogenic liver abscesses: characteristics of the patients and efficacy of percutaneous drainage

OBJECTIVES

Although percutaneous drainage has emerged as one of the first line of therapies for pyogenic liver abscesses, the presence of multiple abscesses may warrant surgical drainage, which remains controversial in the literature. We studied whether the multiplicity of the lesions influences the outcome of the treatment.

METHODS

Ultrasonography-guided percutaneous drainage was carried out in 48 patients with pyogenic liver abscesses. The abscesses were solitary in 38 patients and multiple (two to seven lesions) in 10 patients. Clinical characteristics and the efficacy of the treatment were compared between these two groups.

RESULTS

Biliary diseases and malignancies were more frequently observed in the solitary cases than multiple cases. A past history of surgery for cholelithiasis was seen exclusively in the multiple cases. E. coli was more frequently cultured from the abscesses in the multiple cases. Three of the multiple cases required more than a single catheter. All of the multiple cases and 36 of the 38 solitary cases were successfully treated. Two patients died of biliary peritonitis as a complication of the procedure, and three died of other underlining diseases.

CONCLUSION

Ultrasonography-guided percutaneous drainage is effective even in patients with multiple pyogenic liver abscesses by adding catheters to obtain sufficient drainage.

Amebic liver abscess. Report of a case presenting with nonreactive serologic tests for Entamoeba histolytica

We present a patient with an acute amebic liver abscess with nonreactive serologic tests. Motile hematophagous trophozoites of Entamoeba histolytica were seen microscopically in scrapings from the wall of the abscess. Postoperative serologies revealed rapidly rising then falling titers by SAFA and IHA antibody assays. Serologic tests for amebiasis may be reative in greater than 95% of patients with invasive amebiasis. Nevertheless, a reactive serologic test should not be relied upon exclusively to establish the diagnosis. Sequential serologic testing and surgical intervention to obtain material for microscopic examination, gram stain and bacteriologic culture are warranted in patients with hepatic abscess and nonreactive serologic tests for antibodies to E. histolytica.

Tinidazole for the treatment of amoebic liver abscess

Ten patients suffering from amoebic liver abscess were treated with tinidazole (Fasigyn) 800 mg t.d.s. for 5 days. Nine were cured, and 1 patient required further treatment with other drugs. Following this, a double-blind trial was carried out to compare a group of patients treated with tinidazole with a similar group treated with metronidazole. Each series consisted of 14 patients. In the tinidazole series 13 patients were cured and for 1 patient the result of treatment was dubious. All patients in the metronidazole series were cured, but 1 patient admitted to the trial had previously not been cured by metronidazole. It appears that tinidazole and metronidazole are equally efficaceous in the treatment of amoebic liver abscess.