Modified Ziehl-Neelsen Method Research Articles

Effect of antiretroviral therapy on cryptosporidiosis and microsporidiosis in patients infected with human immunodeficiency virus type 1.

To better understand whether potent antiretroviral therapies can modify the natural history of HIV-1-associated microsporidiosis and cryptosporidiosis, the response to antimicrobial treatment of these opportunistic infections was evaluated in patients with or without antiretroviral treatment. Fifty patients with diarrhoea, all positive for Cryptosporidium parvum or Enterocytozoon bieneusi, were included in the study. Retrospective data were collected concerning demographics, clinical and microbiological characteristics of the parasitic infection, antiretroviral therapy and prophylaxis against opportunistic infections. Faecal samples were prepared using the Richie formalin-ethyl acetate method and stained using the modified Ziehl-Neelsen method for detection of Cryptosporidium parvum and Isospora belli, the modified trichrome and calcofluor white technique for detection of Enterocytozoon spp., and iodine for detection of ova, cysts or vegetative forms. Diarrhoea was defined as an abnormal increase in stool liquidity, an abnormal increase in stool frequency and a daily stool weight of more than 250 g for a period of at least 4 days. Patients treated with double antiretroviral therapy or protease inhibitors demonstrated an excellent response and a sustained therapeutic effect after follow-up (range, 5-36 months). The relapse of cryptosporidiosis in two patients who discontinued antiretroviral therapy suggests that the infection might remain in a latent stage. The resolution of the diarrhoea seems to be related to an increased CD4+ cell count rather than to the viral load. In conclusion, these data strongly support the hypothesis that combination antiretroviral therapy is able to greatly modify the course of cryptosporidiosis and microsporidiosis in patients infected with HIV-1.

Prevalence of Cryptosporidium in children with enteritis in southern Italy.

Cryptosporidium parvum is a protozoan which causes self-limiting diarrhea in immunocompetent subjects, and severe life-threatening disease in immunocompromised patients. Cryptosporidiosis is more common in developing countries and in infants. In this paper we have evaluated the prevalence of C. parvum in 368 hospitalized children with enteritis, of whom 359 were immunocompetent and 9 HIV-infected. Stool specimens were concentrated by sedimentation and stained with a modified Ziehl-Neelsen method. Cryptosporidium parvum oocysts were found in 7 (1.90%) out of 368 subjects. Six of these were immunocompetent (with an infection rate in this population of 1.67%) and 1 HIV-infected, asymptomatic except for diarrhea. In all children symptoms of enteritis and oocyst excretion cleared within 10 days. These results indicate that the prevalence of C. parvum as a causative agent of diarrheal illness in hospitalized immunocompetent children is rather low in our region (Apulia, South Italy).

Evaluation of the optimal number of faecal specimens in the diagnosis of cryptosporidiosis in AIDS and immunocompetent patients

This study determines the optimal number of faecal samples that should be examined in order to minimize the occurrence of false-negative results in the diagnosis of cryptosporidiosis using routine techniques. A total of 23,023 faecal samples from 10,870 patients submitted for parasitological examination were processed by the formalin-ethyl acetate concentration technique and stained using a modified Ziehl-Neelsen method. Cryptosporidiosis was diagnosed in 232 patients (2.13%), 44 of whom were infected by HIV, the prevalence rate in this population group being 15.54%. The increase in the number of diagnoses obtained by the examination of n and (n-1) specimens was evaluated statistically. This study found that three is the optimal number of faecal samples that should be examined when cryptosporidiosis is suspected in immunocompetent patients; whereas, only two samples are required for diagnosing this protozoosis in AIDS patients.

Differential Staining of Schistosome Ova in Biopsies

The significance of identifying the infecting schistosome species has been highlighted recently by the availability of specific chemotherapeutic agents and an awareness that the tissue response – and therefore the prognosis – may be species-dependent. Moreover, human interference with the ecological systems in parts of the developing world has modified the epidemiological map of schistosomiasis resulting in a rising incidence of mixed infections. Differentiation between the ova of Schistosoma mansoni and S. haematobium, the two species commonly seen in immigrants to Kuwait and to other non-endemic areas of the world, usually poses no problems in urinary and faecal specimens. However, in histopathological samples, their distinctive morphological features cannot often be assessed reliably. We obtained satisfactory differentiation by using a modified Ziehl-Neelsen method on 81 routinely fixed and processed biopsy samples. Moreover, on destained sections previously stained with haematoxylin and eosin, the differences were equally evident. Details of the method and its applications both in routine histopathological practice and for research are discussed.

Cryptosporidiosis in southern Sweden.

Two different groups of patients with diarrhoea, altogether 1,478 individuals, were examined for cryptosporidium oocysts. The technique used was feces concentration and staining according to a modified Ziehl-Neelsen method. 20 cases of cryptosporidiosis (3%) were found among 698 consecutive patients with acute gastroenteritis. In feces samples sent for parasitological examination from 780 patients, cryptosporidia were found on 9 occasions (1%). None of 519 healthy persons excreted cryptosporidia. 19/29 patients with cryptosporidiosis had recently been abroad and in 8 of these additional enteric pathogens were found. The median duration of diarrhoea was 14 days. All patients except 1 were cryptosporidia-negative in faeces within 2 months. An immunosuppressed patient excreted cryptosporidia for 14 months.

Negative staining method with nigrosin for the detection of cryptosporidial oocysts: a comparative study

A comparison was made between two methods for the detection of cryptosporidial oocysts in human faecal sediments of formalin-ether concentrates: a cover-slipped, wet method (containing Gram's iodine) and an air-dried, negative staining method using nigrosin solution. A modified Ziehl-Neelsen technique was used as a reference method. The negative staining method with nigrosin gave a positive diagnosis more often than the cover-slipped wet method. A comparison of the nigrosin method with the modified Ziehl-Neelsen method gave almost identical results. Restaining the nigrosin slides with the modified Ziehl-Neelsen technique showed that the round, refractile bodies were cryptosporidial occysts.