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PubMed1998

[Promotion of phagocytosis and prevention of phagosome-lysosome (P-L) fusion in human peripheral blood monocytes by serotype specific glycopeptidolipid (GPL) antigen of Mycobacterium avium complex (MAC)].

Mycobacterium avium complex (MAC) is one of the most important opportunistic pathogens co-infected with HIV (AIDS) and a typical intracellular parasitic bacteria similar to M. tuberculosis. It is also noticed that M. avium infection causes immunosuppression especially in the cellular immunity of host animals, and specific serotype-subspecies such as sero-2, -4 or -8 can be isolated frequently in human infection. Furthermore, the prognosis after infection differs by the serotypes and serotype-4 shows heavy infection in general, while serotype-16 shows rapid improvement. Therefore, we have been interested in the immunomodifying activity of surface glycopeptidolipid (GPL) antigen. However, to date, no information has been available on the virulence factor of MAC related directly with intracellular bactericidal activity. Recently, we have tested the effect of various GPLs purified form MAC complex on phagocytic processes of human peripheral blood monocytes (PBMC). We have used GPL-coated heat-killed staphylococcal cells to be phagocytosed by PBMC, and phagosome-lysosome (P-L) fusion was estimated by the acridine orange staining of fused vesicles including bacteria. It was revealed that the serotype-4, -12 and -17 GPLs showed strong phagocytosis promotion and marked inhibition of P-L fusion, while serotype-9, -13, -16 and -19 GPLs showed neither promotion of phagocytosis, nor inhibition of P-L fusion in phagocytic cells. Serotype-5, -7, -8 and -10 GPLs showed stimulation of both phagocytosis and P-L fusion, concomitantly. These effects may be due to unknown interaction between specific carbohydrate chain of MAC and phagocytic cell membranes, and serotype-4, -12 and -17 GPLs may be one of the possible virulence factors in MAC.

Antigens, Bacterial↗
PubMed1992

Comparative antigenic analysis of Mycobacterium avium complex (MAC) isolates from AIDS patients.

Sonicates of several Mycobacterium avium complex (MAC) strains isolated from acquired immunodeficiency syndrome (AIDS) patients were characterized in order to study the prominent antigens of these strains. Sonicates of 6-week-old cultures were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting. A major 12 kDa glycoprotein antigen was observed in all the sonicates along with other proteins ranging up to 100 kDa. Western blotting, using the 12 kDa M. leprae 'specific' murine monoclonal antibody (MAb) MLO6, indicated the presence of a determinant in the 12 kDa antigen (in all the MAC isolates studied) which was immunologically cross-reactive with the 12 kDa antigen of M. leprae. The transparent variant of MAC 101 also demonstrated MLO6 reactivity while the opaque variant did not. Polyclonal antiserum raised against MAC 101 sonicate reacted with all the MAC isolates in immunodiffusion. These observations point to the cross-reactivity between these strains and suggest that they possess a M. leprae 'specific' determinant on a cross-reacting component which could be involved in virulence.

AIDS-Related Opportunistic Infections↗
PubMed1994

Comparison of virulence of Mycobacterium avium complex (MAC) strains isolated from AIDS and non-AIDS patients.

Mycobacterium avium complex (MAC) strains from AIDS and non-AIDS patients and from the environment were studied for their colony morphology and virulence in beige mice. The majority of the MAC isolates from AIDS patients, in contrast to those from non-AIDS patients and the environment, showed increased virulence. Similarly, the majority of the MAC isolates from AIDS patients formed smooth transparent (ST) colonies, whereas most of the non-AIDS isolates formed smooth opaque (SO) or intermediate (IM) type of colonies. MAC isolates from the same AIDS patient obtained at different times were found to be heterogenic with respect to serotype, RFLP and glycolipid patterns, suggesting that these patients might be infected with more than one strain of MAC.

AIDS-Related Opportunistic Infections↗
PubMed1993

Superoxide dismutase activity of Mycobacterium avium complex (MAC) strains isolated from AIDS patients.

OBJECTIVE: To explore whether Mycobacterium avium complex (MAC) strains isolated from AIDS patients produce and secrete superoxide dismutase (SOD). DESIGN: SOD was assayed in the crude extracts and in cell-free medium of 18 MAC strains (MAC 101, LR and SK strains) isolated from AIDS patients to determine intracellular and extracellular activity. The SODs were characterized by PAGE and by their sensitivity to azide, cyanide and hydrogen peroxide. RESULTS: SOD activity was detected in cell extracts as well as in extracellular medium of all AIDS-MAC strains. PAGE demonstrated a single activity band for each strain, though there were differences in mobility. All LR strains demonstrated an activity band with Rf = 0.30, while SOD band for MAC 101 and for SK strains migrated further (Rf = 0.87). The differences in mobility correlated with differences in sensitivity to NaN3 and H2O2. The SOD activity of LR strains was irreversibly inhibited 100% by 5 mM H2O2, and exhibited greater sensitivity to NaN3, suggesting the presence of iron in the enzyme. The SOD activity of SK strains and MAC 101, however, was not inhibited by 5 mM H2O2 but was inhibited to a lesser extent by NaN3, which is characteristic of a manganese-containing SOD. CONCLUSION: Our data indicate that MAC strains are rich in manganese- or iron-containing SOD, which could contribute to the organism's resistance to the oxidative burst of activated macrophages. The secretion of SOD may play an important role in the pathogenesis of MAC strains.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Mycobacterium avium complex (MAC): an unusual potential pathogen in cerebrospinal fluid of AIDS patients.

Mycobacterium avium complex (MAC) is frequently isolated from patients with late complications of Acquired Immunodeficiency Syndrome (AIDS), especially in North America and Europe. However, its isolation from the central nervous system (CNS) has been seldom reported in these countries. MAC infections in AIDS patients in African and Latin American countries are believed to be uncommon. We report the isolation of MAC from cerebrospinal fluid (CSF) of 11 AIDS patients out of 1723 (0.63%) seen at "Centro de Referência e Treinamento-AIDS", São Paulo and discuss the significance of its isolation.

Acquired Immunodeficiency Syndrome↗
PubMed2000

[Effect of serotype specific glycopeptidolipid (GPL) isolated from Mycobacterium avium complex (MAC) on phagocytosis and phagosome-lysosome fusion of human peripheral blood monocytes].

Mycobacterium avium complex (MAC) is a typical intracellular parasite similar to M. tuberculosis and is one of the most important pathogens that coinfects AIDS patients. Attention has been focused on M. avium infection causing immunosuppression of hosts. Specific serotype-subspecies such as 1, -4 or -8 serotypes can be isolated frequently in humans infected with HIV. Furthermore, the prognosis after infection differs depending on the serotype. Serotype-4 in general shows unfavourable prognosis, while serotype-16 yields rapid recovery. Therefore, we have been interested in the immunomodifying activity of the surface glycopeptidolipid (GPL) antigen. However, no information has been available to date dealing on the virulent factor of MAC that is directly related with intracellular bactericidal activity. Recently, we have tried to test the effect of various GPLs purified from MAC on phagocytic processes of human peripheral blood monocytes (PBMC). We have used GPL-coated heat-killed staphylococcal cells to be phagocytosed by PBMC, and phagosome-lysosome fusion (P-L fusion) was estimated by the acridine orange staining of fused vesicles and bacteria. Results showed strong promotion of phagocytosis and marked inhibition of P-L fusion by serotype-4 GPL, while neither promotion of phagocytosis nor inhibition of P-L fusion in phagocytic cells were shown by serotype-16 GPL. Serotype-8 GPL showed concomitant stimulation of both phagocytosis and P-L fusion. These effects may be due to some unknown interaction between specific carbohydrate chain and organella membranes and serotype-4 GPL may be one of the possible virulent factors in MAC. Comparison with known possible virulent factors such as trehalose 6,6'-dimycolate (TDM), trehalose 6-monomycolate (TMM), glucose 6-monomycolate (GM) or sulfatide was also reported.

Cells, Cultured↗
PubMed2001

The significance of bronchoscopy for the diagnosis of Mycobacterium avium complex (MAC) pulmonary disease.

To investigate the usefulness of bronchoscopy for the diagnosis of Mycobacterium avium complex (MAC) pulmonary disease, we retrospectively reviewed the clinical charts, and radiographic and bacteriologic findings of all patients who were admitted to our hospital between 1994 and 2000, and who fulfilled the 1997 American Thoracic Society (ATS) criteria for MAC pulmonary infection. A total of 132 patients were diagnosed as affected by MAC pulmonary disease during that period. Of these, bronchoscopic examination was performed in those patients who showed negative sputum smear for mycobacteria on three consecutive days (n = 43) or who could not expectorate sputum (n = 2). Of 42 patients, sputum culture was positive for MAC in 34 patients (81.0%). Bronchial washing sample was smear-positive for MAC in 17 of 39 patients (43.6%), and culture-positive for MAC in 33 of the 39 patients (84.6%). Transbronchial lung biopsy (TBLB) specimens revealed specific findings (epithelioid cell granuloma and/or acid-fast bacilli) in 14 of 38 patients (36.9%). Bronchial washing of all patients who showed specific histology in TBLB grew MAC in culture. Based on the bronchoscopic examination, we could diagnose MAC pulmonary disease in 36 patients. In addition, smear and polymerase chain reaction (PCR) results of bronchial washing made possible an early diagnosis of MAC pulmonary disease in 15 patients. We examined the relation of CT findings to bronchial washing results. Isolation of MAC in bronchial washing is significantly related to small nodular opacity around the ectatic bronchi on the CT scan (p = 0.016). In our retrospective study, in sputum smear-negative patients with MAC pulmonary disease, MAC isolation by culture of bronchial washing was no more frequent than that with sputum culture. However, bronchial washing is useful to differentiate infection from casual isolation of MAC. In addition, we could make early diagnosis of MAC pulmonary disease based on smear and PCR results of bronchial washing. To make a diagnosis of MAC, bronchial washing is superior to TBLB, and should be done in the bronchus which drains the area revealing small nodular opacity around ectatic bronchi.

Adult↗
PubMed1995

Mycobacterium avium complex (MAC) osteomyelitis and septic arthritis in an immunocompetent host.

We describe a case of Mycobacterium avium complex (MAC) osteomyelitis and septic arthritis in an immunocompetent man. Infection was derived from a chainsaw injury sustained on the lateral aspect of the ankle 13 years earlier, and had spread through the bone, joint and soft tissue emerging at the medial aspect. This was successfully treated with surgical debridement, drainage, arthrodesis and 18 months of chemotherapy consisting of clarithromycin, rifampicin, ethambutol, and ciprofloxacin with an initial 2 weeks of amikacin. Infections with this organisms are generally associated with immunocompromised states, particularly advanced AIDS. However, our patient illustrates that atypical mycobacterial infections must also be considered in immunocompetent patients who have a prolonged clinical course and an appropriate potential source of infection.

Adult↗
PubMed1997

The role of advanced generation macrolides in the prophylaxis and treatment of Mycobacterium avium complex (MAC) infections.

Since the start of the acquired immunodeficiency syndrome (AIDS) epidemic, the role of Mycobacterium avium complex (MAC) as an opportunistic pathogen in advanced AIDS patients has become more and more clear. Once identified in an advanced AIDS patient it is possible to find evidence that the MAC organism and infection is not only present in the pulmonary tree, but has also disseminated to a wide variety of body organs. Treatment of MAC or disseminated MAC (DMAC) infections has historically been very difficult due to the inherent resistance of the MAC pathogen to most standard antimycobacterial agents. This has resulted in the development of new agents for the prevention of DMAC infection as well as combinations of both new and standard agents for its treatment. Three drugs are currently approved for single-agent DMAC prophylaxis, including rifabutin, azithromycin and clarithromycin. Combinations of agents for DMAC treatment are highly variable in content but most experts agree that all combinations should contain one of the advanced generation macrolides (azithromycin or clarithromycin). Both of these agents have favourable intracellular pharmacokinetics and pharmacodynamics which maximise their effects against this mostly intracellular pathogen. Due to the paucity of comparative data, no one macrolide can be recommended over the other. However, the expected increase in compliance, lower weekly and annual costs, and lack of any drug interactions may make azithromycin a preferable choice, but this should be decided on a case-by-case basis.

Anti-Bacterial Agents↗
PubMed1998

Cellular reaction to Mycobacterium avium complex (MAC) clinical isolates differing in hemolytic activity and virulence for C57BL/6 mice.

In this study we showed that Mycobacterium avium complex (MAC) clinical isolates differed by the expression of hemolytic activity. Two hemolytic MAC strains were less susceptible to the mycobactericidal effect of murine macrophages than two unhemolytic MAC isolates. In vivo, hemolytic MAC bacilli survived in the spleens of infected mice for a longer time than unhemolytic MAC strains. This suggested a role of hemolysins in the virulence of MAC strains. There was no difference in the cytotoxicity of T cells from mice immunized with M. bovis BCG towards macrophages infected in vitro with MAC strains expressing or not expressing hemolytic activity.

Animals↗
PubMed1997

[The distribution and the characteristics in computed tomography (CT) of the lungs in primary Mycobacterium avium complex (MAC) infection].

We investigated the distribution and the characteristics of the lung lesions of patients with primary Mycobacterium avium complex (MAC) infections mainly by computed tomography (CT). They admitted to our hospital during the period from 1984 to 1995 and none of them had a medical history of tuberculosis or other lung diseases. The subjects consisted of fifty patients: fourteen male (average age +/- SD was 66.4 +/- 14.0 year old) and thirty six female (69.0 +/- 11.9 year old). Of 50 patients 24 were M. intracellulare infection, 10 were M. avium infection and others were not identified. First, by using the ratio of slices with lesions on CT to all CT slices from the apex to the base of the lungs, all the patients were divided into two groups; a slight group with less than 15.0% (n = 19) and a severe group with 15.0% or more (n = 31). Next, the density of abnormal shadows in each segment as divided into 5 grades; none (-), minimal (+/-), slight (+), moderate (+2) and severe (+3). The grading was done by taking into account the grade of distribution, density of lesions and destruction of lung parenchym found mainly on CT, and in addition by a standard roentogenographic and tomographic features supplemental. The characteristics frequently observed findings on CT in primary MAC infection patients were nodular (94%), cavitary (74%), bronchiectatic (62%), infiltrative (74%), atelectatic (56%), and pleural-thickened (36%) shadows. Comparing the incidence of segmental lesions in MAC infection patients by segment, it was higher in right and in left lung, but the difference was statistically not significant. As to the number of segments with lesions graded from (+/-) to (+3), many segments were infected unexpectedly: the mean value was 7.7 +/- 1.5 even in the slight group. The proportion of segments with relatively severe lesions graded from (+2) to (+3) in each segment was observed, and the rate in the slight group was 52.6% in S5, 28.9% in S4, 16.7% in S1 (S1 + 2a, b), and 16.7% in S2 (S1 + 2c). In severe group, it was 54.8% in S5, 45.2% in S4, 46.8% in S1 (S1 + 2a, b) 54% in S2 (S1 + 2c), 27.4% in S3 and 26.2% in S6, respectively. The rate of segments with lesions in the lower lobes were less frequent especially in the slight group while it was slightly higher in the severe group. Speculating the initial lesions in the slight group, it was assumed that there might be two types of foci; the one is relatively localized in the beginning and the other is a diffuse type with lesions in many segments even from its early stage. As to the location of initial lesions, the middle lobe and lingula were the most important sites, and the right upper lobe and the left upper division were the next.

Aged↗
PubMedDate not supplied

Mycobacterium avium complex (MAC) isolated from AIDS patients and the criteria required for its implication in disease.

Before the AIDS pandemia, the Mycobacterium avium complex (MAC) was responsible in most cases for the pneumopathies that attack patients with basic chronic pulmonary diseases such as emphysema and chronic bronchitis. In 1981, with the advent of the acquired immunodeficiency syndrome (AIDS), MAC started to represent one of the most frequent bacterial diseases among AIDS patients, with the disseminated form of the disease being the major clinical manifestation of the infection. Between January 1989 and February 1991, the Section of Mycobacteria of the Adolfo Lutz Institute, São Paulo, isolated MAC from 103 patients by culturing different sterile and no-sterile processed specimens collected from 2304 patients seen at the AIDS Reference and Training Center and/or Emilio Ribas Infectology Institute. Disseminated disease was diagnosed in 29 of those patients on the basis of MAC isolation from blood and/or bone marrow aspirate. The other 74 patients were divided into categories highly (5), moderately (26) and little suggestive of disease (43) according to the criteria of DAVIDSON (1989). The various criteria for MAC isolation from sterile and non-sterile specimens are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1994

In vitro and in vivo synergistic effect of isoniazid with streptomycin and clofazimine against Mycobacterium avium complex (MAC).

SETTING: Isoniazid (INH), the powerful antituberculosis drug, has also been used in regimens for treating disease caused by Mycobacterium avium complex (MAC), an important opportunistic pathogen encountered in AIDS patients. Its use for treatment of MAC disease has also been endorsed by the American Thoracic Society. However some controversy has emerged recently in medical literature, discounting its role and even implying that its use is contraindicated in chemotherapy of MAC disease. OBJECTIVE: In view of the controversy, we investigated its in vitro and in vivo activity in combination with streptomycin (SM) and clofazimine (CFM) against MAC. DESIGN: In the in vitro studies, the minimal inhibitory concentrations (MIC) of individual drugs or combinations of INH and SM as well as INH and CFM were determined in a checker-board type study by both conventional and radiometric (BACTEC) methods. In vivo studies assessed the efficacy of chemotherapy with INH alone or in combination with either SM or CFM against MAC infection in beige mice. RESULTS AND CONCLUSIONS: While MICs of INH and SM were 12.5 micrograms/ml and 6.25 micrograms/ml respectively, complete inhibition of growth was seen at 1.56 micrograms/ml with the combination of both drugs. The synergistic effect was observed both in conventional and BACTEC methods. In vivo studies demonstrated elevated activity when INH was given along with SM or CFM. Based on these observations we stress that isoniazid has still a place in chemotherapy of MAC disease, at least until other potent drugs are discovered.

AIDS-Related Opportunistic Infections↗
PubMed2004

[Outcome of pulmonary Mycobacterium avium complex (MAC) disease treated with clarithromycin (CAM)-containing regimens].

We retrospectively investigated the efficacy of regimens including clarithromycin (CAM) in 129 patients with Mycobacterium avium complex (MAC) pulmonary disease and their outcomes. None of the patients suffered from acquired immunodeficiency syndrome. All were observed for over 12 months. We studied the factors that may affect sputum conversion and fatal outcomes by logistic regression analysis. The results indicated that the presence of either cavitation or bronchiectasis was significantly correlated with persistent MAC-positive culture results in sputum (Odds ratio, 4.71, 95%; CL, 1.21-18.5; P<0.05). Regimens including antituberculous drugs and CAM were administered to 118 patients, 11 of whom received CAM alone because of the adverse events of antituberculous agents. There was no difference in sputum conversion or mortality between the two groups, suggesting that the pattern of drug combination should be further investigated.

Aged↗
PubMed1997

Prophylaxis for disseminated Mycobacterium avium complex (MAC) infection in patients with AIDS: a cost-effectiveness analysis.

OBJECTIVE: To determine the effectiveness and costs of prophylaxis for disseminated Mycobacterium avium complex (MAC) infection in patients with AIDS. DESIGN: A decision analysis model was constructed to compare rifabutin (300 mg/day), azithromycin (1200 mg/week), and clarithromycin (500 mg twice per day) with no prophylaxis. Sensitivity analysis was done on all model parameters, including initial CD4 count for beginning prophylaxis. SETTING: The setting was hypothetical for the cost-effectiveness model. Clinical data were taken from published prospective randomized controlled trials. MAIN OUTCOME MEASURES: Outcomes were measured in terms of projected life expectancy, quality-adjusted life expectancy, direct medical costs, and cost-effectiveness in U.S. dollars per quality-adjusted life-year saved ($/QALY). RESULTS: For patients with AIDS and those having CD4 counts <75 cells/mm3, azithromycin, clarithromycin, and rifabutin prophylaxis increased lifetime per person MAC-related costs by $994, $2,117, and $2,185 U.S., respectively. Quality-adjusted life expectancy increased from 1.6068 QALYs to between 1.6186 and 1.6255 QALYs. The cost-effectiveness ratios were $58,200, $116,000, and $179,100/QALY saved for azithromycin, clarithromycin, and rifabutin prophylaxis, respectively, each compared with no prophylaxis. Results were most dependent on the annual cost of prophylaxis, the initial CD4 count when starting prophylaxis, and any survival benefit with prophylaxis. For each type of prophylaxis, strategies beginning with CD4 counts <25 or 50 cells/mm3 were substantially more cost-effective than those beginning in patients with higher CD4 counts. CONCLUSIONS: MAC prophylaxis is likely to cost society an additional $99 to $219 million U.S. per 100,000 patients treated. In the context of Centers for Disease Control and Prevention (CDC) recommendations to use prophylaxis in patients with CD4 counts <75 cells/mm3, azithromycin represents the best value and is most cost-effective when used in patients with CD4 counts <25 cells/mm3.

AIDS-Related Opportunistic Infections↗
PubMed2004

Comparison of clinical features in patients with pulmonary Mycobacterium-avium complex (MAC) disease treated before and after proposal for guidelines.

We aimed to investigate the transitional pattern of the clinical features of pulmonary Mycobacterium-avium complex (MAC) disease, especially with regard to the clinical effect of treatment, in patients treated before and after the implementation of the 1998 guidelines of the Japanese Society for Tuberculosis for combined chemotherapy for pulmonary MAC disease. The clinical findings and treatments of 220 patients with pulmonary MAC disease during the past 10 years were compared by dividing the patients into two groups, each encompassing a 5-year period. During the past 5 years, we have carried out combined chemotherapy with rifampicin, ethambutol, an aminoglycoside (streptomycin or kanamycin), and clarithromycin (CAM) following the guidelines for the treatment of pulmonary MAC disease proposed in 1998, and we have achieved positive results; both the sputum conversion rate and clinical improvement of the outcome in patients with primary infectious type rose significantly. Although there were no significant differences in the background or in microbiological and radiological findings in the two groups, significant improvement was seen in the sputum conversion rate and in improvement of the clinical effect of treatment. The results of this combined chemotherapy were unsatisfactory, however, when compared with its clinical effect on pulmonary tuberculosis. Therefore, we anticipate the development of new companion drugs for pulmonary MAC disease that are as active as CAM.

Adult↗
PubMed2002

[Pulmonary Mycobacterium avium complex (MAC) disease showing middle lobe syndrome--pathological findings of 2 cases suggesting different mode of development].

Two different processes have been proposed for pathogenesis of Mycobacterium avium complex (MAC) disease which show the middle lobe syndrome: 1) middle lobe bronchiectasis followed by MAC infection and 2) MAC disease resulted in secondary bronchiectasis. Two surgical specimen from MAC cases showing middle lobe syndrome were studied histo-pathologically. The first case was a 60 year-old female with frequent bloody sputum, who had been diagnosed as bronchiectasis in her childhood. Pathological examination of the resected middle lobe showed prominent cylindric bronchiectasis in the indurated middle lobe, and epithelioid cell granulomas were scattered limited to the fibrous bronchial walls, without any granulomas in the lung parenchyma. These findings suggested a secondary infection of MAC to the non-specific pre-existed bronchiectasis. The second case of a 55 year-old female having repeated bloody sputum, who was diagnosed to be tuberculosis but no improvement with anti-tuberculosis drugs. Pathological examination of the middle lobe showed scattered epithelioid cell granulomas with lymphocytic infiltration in the lung parenchyma. A few epithelioid cell granulomas were also found in the mucosa of middle lobe bronchi. In this case, pulmonary MAC lesions seemed to precede the central bronchial lesion with later development of bronchiectasis. Summarizing above findings two different mode of pathogenesis ways may be considered; one is non-specific bronchiectasis followed by middle lobe MAC disease and the other is pulmonary MAC lesion in the middle lobe as a primary change.

Bronchiectasis↗
PubMed1989

The beige mouse model for Mycobacterium avium complex (MAC) disease: optimal conditions for the host and parasite.

We extended our earlier studies to establish the beige (C57B1/6/bgJ/bgJ) mouse model for experimental acute infections with Mycobacterium avium complex (MAC). Optimal conditions of the host and the parasites have been determined. Mice bred at our center showed similar responses to those obtained from Jackson Laboratories, the original supplier. Both male and female mice showed similar responses, but older mice in both sexes showed less susceptibility than younger mice. Strain 101 of MAC showed remarkable consistency in its pathogenicity to beige mice, as evidenced by the distribution of colony forming unit (CFU) counts at various time points after intravenous challenge, in several experiments. CFU counts showed an association with the dose of challenge, and histopathological observations.

Animals↗