Pregnancy Outcomes in Women Screened for Tuberculosis Infection in Swedish Antenatal Care

BACKGROUND

Tuberculosis (TB) disease has been associated with pregnancy complications. However, the potential impact of TB infection (TBI) on pregnancy outcome is unknown. To investigate this, we conducted a register-based study in immigrant women screened with QuantiFERON assays for TBI in antenatal care in Sweden.

METHODS

Women with history of immigration from TB-endemic countries were eligible for inclusion if national identification numbers and available QuantiFERON results obtained during pregnancy from 2014 to 2018 were available. QuantiFERON results were linked to data on maternal characteristics and pregnancy outcomes from the national Pregnancy and Patient Registers. TBI was defined as nil-corrected QuantiFERON result ≥0.35 IU/mL, in the absence of TB disease. Pregnancies in women with TB disease or human immunodeficiency virus were excluded, as were multiplex pregnancies, pregnancies resulting in miscarriage, and pregnancies occurring >10 years after immigration. Odds of defined adverse pregnancy outcomes were compared by maternal TBI status using mixed effects logistic regression with adjustment for maternal age and region of origin.

RESULTS

In total, 7408 women with 12 443 pregnancies were included. In multivariable analysis, stillbirth (adjusted odds ratio [AOR], 1.90; 95% confidence interval [CI], 1.13-3.21; P = .016), severe preeclampsia (AOR, 1.62; 95% CI, 1.03-2.56; P = .036), low birthweight (<2500 g; AOR, 1.38; 95% CI, 1.01-1.88; P = .041), and emergency cesarean section (AOR, 1.28; 95% CI, 1.02-1.63; P = .033) were significantly associated with TBI.

CONCLUSIONS

Among immigrant women seeking antenatal care in Sweden, TBI was independently associated with adverse pregnancy outcomes. Further studies are needed to corroborate these findings and to explore mechanisms involved.

Mechanisms of a Mycobacterium tuberculosis Active Peptide

Multidrug-resistant tuberculosis (MDR) continues to pose a threat to public health. Previously, we identified a cationic host defense peptide with activity against Mycobacterium tuberculosis in vivo and with a bactericidal effect against MDR M. tuberculosis at therapeutic concentrations. To understand the mechanisms of this peptide, we investigated its interactions with live M. tuberculosis and liposomes as a model. Peptide interactions with M. tuberculosis inner membranes induced tube-shaped membranous structures and massive vesicle formation, thus leading to bubbling cell death and ghost cell formation. Liposomal studies revealed that peptide insertion into inner membranes induced changes in the peptides' secondary structure and that the membranes were pulled such that they aggregated without permeabilization, suggesting that the peptide has a strong inner membrane affinity. Finally, the peptide targeted essential proteins in M. tuberculosis, such as 60 kDa chaperonins and elongation factor Tu, that are involved in mycolic acid synthesis and protein folding, which had an impact on bacterial proliferation. The observed multifaceted targeting provides additional support for the therapeutic potential of this peptide.

Tuberculosis infection and stillbirth in Ethiopia—A prospective cohort study

Background

Tuberculosis is among the leading causes of death among infectious diseases. Regions with a high incidence of tuberculosis, such as sub-Saharan Africa, are disproportionately burdened by stillbirth and other pregnancy complications. Active tuberculosis increases the risk of pregnancy complications, but the association between latent tuberculosis infection (LTBI) and pregnancy outcomes is unknown. We explored the effect of latent tuberculosis infection on the risk of stillbirth in women attending antenatal care clinics in Ethiopia, a country with >170 000 annual cases of active tuberculosis.

Method

Pregnant women were enrolled from antenatal care at three health facilities in Adama, Ethiopia, during 2015–2018, with assessment for previous and current active tuberculosis and testing for LTBI using QuantiFERON-TB-GOLD-PLUS. Proportions of stillbirth (≥ 20 weeks of gestation) and neonatal death (< 29 days of birth) were compared with respect to categories of maternal tuberculosis infection (tuberculosis-uninfected, LTBI, previous-, and current active tuberculosis). Multivariable logistic regression was performed for stillbirth.

Results

Among 1463 participants enrolled, the median age was 25 years, 10.2% were HIV-positive, 34.6% were primigravidae, and the median gestational age at inclusion was 18 weeks. Four (0.3%) were diagnosed with active tuberculosis during pregnancy, 68 (4.6%) reported previous treatment for active tuberculosis, 470 (32.1%) had LTBI, and 921 (63.0%) were tuberculosis-uninfected. Stillbirth was more frequent in participants with LTBI compared to tuberculosis-uninfected participants, although not reaching statistical significance (19/470, 4.0% vs 25/921, 2.7%, adjusted [for age, gravidity and HIV serostatus] odds ratio 1.38, 95% confidence interval 0.73–2.57, p = 0.30). Rates of neonatal death (5/470, 1.1% vs 10/921, 1.1%) were similar between these categories.

Conclusion

Latent tuberculosis infection was not significantly associated with stillbirth or neonatal death in this cohort. Studies based on larger cohorts and with details on causes of stillbirth, as well as other pregnancy outcomes, are needed to further investigate this issue.

Tuberculosis Infection in Women of Reproductive Age: A Cross-sectional Study at Antenatal Care Clinics in an Ethiopian City

BACKGROUND

Knowledge on tuberculosis (TB) infection epidemiology in women of reproductive age living in TB-endemic areas is limited. We used a composite definition of TB infection in a cohort of pregnant women recruited in an Ethiopian city as a model for TB exposure patterns, and to identify factors associated with TB infection.

METHODS

Women seeking antenatal care at public health facilities underwent structured interviews, physical examination, and QuantiFERON-TB Gold-Plus (QFT) testing. Women with symptoms compatible with TB disease, and all human immunodeficiency virus (HIV)-positive women, were investigated for active TB by sputum bacteriological testing. TB infection (TB+) was defined as either positive QFT (≥ 0.35 IU/mL), self-reported previous active TB, or current active TB. Associations between TB infection and clinical, demographic, and socioeconomic characteristics were tested in multiple logistic regression analysis.

RESULTS

Among 1834 participants, 679 (37.0%) met criteria for TB+ (80 [4.4%] previous active TB, 5 [0.3%] current active TB, and 594 [32.4%] QFT-positive without previous or current active TB). Age (annual adjusted odds ratio [AOR], 1.069 [95% confidence interval {CI}, 1.045-1.093]) and HIV infection (AOR, 1.43 [95% CI, 1.033-1.988]) were independently associated with TB+. The relationship with increasing age was only observed in HIV-negative women, and translated to an estimated annual risk of TB infection of 2.1% in HIV-negative women.

CONCLUSIONS

TB infection in women of reproductive age in Ethiopia was independently associated with HIV infection and increasing age, suggesting exposure to contagious TB and continuous acquisition of TB infection in this population.

Alternative biomarkers for classification of latent tuberculosis infection status in pregnant women with borderline Quantiferon plus results

Borderline interferon-gamma (IFN-γ) results (near the cut-off level 0.35 IU/ml) occur in QuantiFERON (QFT) assays. We investigated the performance of alternative biomarkers for classification of latent tuberculosis infection (LTBI) status in pregnant women with borderline QFT IFN-γ responses. Pregnant women (n = 96) were identified from a cohort study in Ethiopia, based on QFT-Plus IFN-γ results (QFT-low: <0.20 IU/ml, n = 33; QFT-borderline: 0.20-0.70 IU/ml, n = 31; QFT-high: >0.70 IU/ml, n = 32), including 12 HIV-positive individuals in each group and with 20 HIV-negative non-pregnant women from the same cohort with QFT IFN-γ <0.20 IU/ml as controls. Concentrations of 8 markers (IL-1ra, IL-6, IL-8, IP-10, MCP-1, MCP-2, osteopontin and resistin) were measured in whole blood QFT supernatants, stimulated separately with TB1 and TB2 antigens. K-nearest neighbor analysis (KNN) was used to classify participants with regard to likelihood of LTBI. Concentrations of MCP-2, IP-10 and IL-1ra were higher in QFT-borderline compared to QFT-low participants in both antigen stimulations (p < 0.001). KNN classification indicated high likelihood of LTBI in 13/31 (42%) women with QFT-borderline IFN-γ results. MCP-2, IP-10 and IL-1ra expressed in whole blood after TB antigen stimulation may be considered as alternative biomarkers for classification of LTBI status in pregnant women with borderline QFT IFN-γ results.

A novel derivative of the fungal antimicrobial peptide plectasin is active against Mycobacterium tuberculosis

Tuberculosis has been reaffirmed as the infectious disease causing most deaths in the world. Co-infection with HIV and the increase in multi-drug resistant Mycobacterium tuberculosis strains complicate treatment and increases mortality rates, making the development of new drugs an urgent priority. In this study we have identified a promising candidate by screening antimicrobial peptides for their capacity to inhibit mycobacterial growth. This non-toxic peptide, NZX, is capable of inhibiting both clinical strains of M. tuberculosis and an MDR strain at therapeutic concentrations. The therapeutic potential of NZX is further supported in vivo where NZX significantly lowered the bacterial load with only five days of treatment, comparable to rifampicin treatment over the same period. NZX possesses intracellular inhibitory capacity and co-localizes with intracellular bacteria in infected murine lungs. In conclusion, the data presented strongly supports the therapeutic potential of NZX in future anti-TB treatment.

Performance of QuantiFERON-TB Gold Plus for detection of latent tuberculosis infection in pregnant women living in a tuberculosis- and HIV-endemic setting

We evaluated the performance of QuantiFERON-TB Gold Plus (QFT-Plus), which includes two Mycobacterium tuberculosis antigen formulations (TB1 and TB2), for detection of latent tuberculosis infection during pregnancy. Eight-hundred-twenty-nine Ethiopian pregnant women (5.9% HIV-positive) were tested with QFT-Plus, with bacteriological sputum analysis performed for women with clinically suspected tuberculosis and HIV-positive women irrespective of clinical presentation. QFT-Plus read-out was categorized according to the conventional cut-off (0.35 IU/ml) for both antigen formulations. In addition, we analysed the distribution of QFT-Plus results within a borderline zone (0.20–0.70 IU/ml), and interferon-γ response in relation to HIV infection and gestational age. Two-hundred-seventy-seven women (33%) were QFT-Plus-positive (HIV-positive 16/49 [33%]; HIV-negative 261/780 [33%]). There was a strong agreement between the two antigen formulations (κ = 0.92), with discordant results in 29 cases (3.5%). Whereas discordant QFT-Plus results were rare in pregnancy, several results with both TB1 and TB2 within the borderline range were observed (11/49 [22%] vs. 43/780 [5.5%] in HIV-positive and HIV-negative women, respectively; p<0.0001). HIV-positive women had lower absolute interferon-γ levels (TB1: 0.47 vs. 2.16 IU/ml; p<0.001, TB2: 0.49 vs. 2.24 IU/ml, p<0.001, considering results ≥0.20 IU/ml) compared to HIV-negative women. QFT-Plus-positive women who submitted samples at later stages of pregnancy had lower mitogen- (p<0.001) but higher TB-antigen-specific (p = 0.031 for TB1, p = 0.061 for TB2) interferon-γ response. Considering their lower capacity to produce TB-specific interferon-γ, a lower cut-off level for defining QFT-Plus-positivity may be considered in HIV-positive pregnant women.

What Is Resistance? Impact of Phenotypic versus Molecular Drug Resistance Testing on Therapy for Multi- and Extensively Drug-Resistant Tuberculosis

Rapid and accurate drug susceptibility testing (DST) is essential for the treatment of multi- and extensively drug-resistant tuberculosis (M/XDR-TB). We compared the utility of genotypic DST assays with phenotypic DST (pDST) using Bactec 960 MGIT or Löwenstein-Jensen to construct M/XDR-TB treatment regimens for a cohort of 25 consecutive M/XDR-TB patients and 15 possible anti-TB drugs. Genotypic DST results from Cepheid GeneXpert MTB/RIF (Xpert) and line probe assays (LPAs; Hain GenoType MTBDRplus 2.0 and MTBDRsl 2.0) and whole-genome sequencing (WGS) were translated into individual algorithm-derived treatment regimens for each patient. We further analyzed if discrepancies between the various methods were due to flaws in the genotypic or phenotypic test using MIC results. Compared with pDST, the average agreement in the number of drugs prescribed in genotypic regimens ranged from just 49% (95% confidence interval [CI], 39 to 59%) for Xpert and 63% (95% CI, 56 to 70%) for LPAs to 93% (95% CI, 88 to 98%) for WGS. Only the WGS regimens did not contain any drugs to which pDST showed resistance. Importantly, MIC testing revealed that pDST likely underestimated the true rate of resistance for key drugs (rifampin, levofloxacin, moxifloxacin, and kanamycin) because critical concentrations (CCs) were too high. WGS can be used to rule in resistance even in M/XDR strains with complex resistance patterns, but pDST for some drugs is still needed to confirm susceptibility and construct the final regimens. Some CCs for pDST need to be reexamined to avoid systematic false-susceptible results in low-level resistant isolates.

A borderline range for Quantiferon Gold In-Tube results

Objective

Interferon gamma release assays like Quantiferon Gold In-Tube (QFT) are used to identify individuals infected with Mycobacterium tuberculosis. A dichotomous cut-off (0.35 IU/ml) defines a positive QFT without considering test variability. Our objective was to evaluate the introduction of a borderline range under routine conditions.

Methods

Results of routine QFT samples from Sweden (2009–2014) were collected. A borderline range (0.20–0.99 IU/ml) was introduced in 2010 recommending a follow-up sample. The association between borderline results and incident active TB within 3 to 24 months was investigated through linkage with the national TB-register.

Results

Using the recommended QFT cut-off, 75.1% tests were negative, 21.4% positive and 3.5% indeterminate. In total, 9% (3656/40773) were within the borderline range. In follow-up samples, individuals with initial results between 0.20–0.34 IU/ml and 0.35–0.99 IU/ml displayed negative results below the borderline range (<0.20 IU/ml) in 66.1% (230/348) and 42.5% (285/671) respectively, and none developed incident TB. Among 6712 individuals with a positive initial test >0.99 IU/ml, 65 (0.97%) developed incident TB within 3–24 months.

Conclusions

We recommend retesting of subjects with QFT results in the range 0.20–0.99 IU/ml to enhance reliability and validity of the test. Half of the subjects in the borderline range will be negative at a level <0.20 IU/ml when retested and have a very low risk of developing incident active TB.

Long-term Outcome of Antiretroviral Treatment in Patients With and Without Concomitant Tuberculosis Receiving Health Center-Based Care-Results From a Prospective Cohort Study

Background

In order to increase treatment coverage, antiretroviral treatment (ART) is provided through primary health care in low-income high-burden countries, where tuberculosis (TB) co-infection is common. We investigated the long-term outcome of health center-based ART, with regard to concomitant TB.

Methods

ART-naïve adults were included in a prospective cohort at Ethiopian health centers and followed for up to 4 years after starting ART. All participants were investigated for active TB at inclusion. The primary study outcomes were the impact of concomitant TB on all-cause mortality, loss to follow-up (LTFU), and lack of virological suppression (VS). Kaplan-Meier survival estimates and Cox proportional hazards models with multivariate adjustments were used.

Results

In total, 141/729 (19%) subjects had concomitant TB, 85% with bacteriological confirmation (median CD4 count TB, 169 cells/mm³; IQR, 99-265; non-TB, 194 cells/mm³; IQR, 122-275). During follow-up (median, 2.5 years), 60 (8%) died and 58 (8%) were LTFU. After ≥6 months of ART, 131/630 (21%) had lack of VS. Concomitant TB did not influence the rates of death, LTFU, or VS. Male gender and malnutrition were associated with higher risk of adverse outcomes. Regardless of TB co-infection status, even after 3 years of ART, two-thirds of participants had CD4 counts below 500 cells/mm³.

Conclusions

Concomitant TB did not impact treatment outcomes in adults investigated for active TB before starting ART at Ethiopian health centers. However, one-third of patients had unsatisfactory long-term treatment outcomes and immunologic recovery was slow, illustrating the need for new interventions to optimize ART programs.

Factors Associated with Early Mortality in HIV-Positive Men and Women Investigated for Tuberculosis at Ethiopian Health Centers

Introduction

Despite increasing access to antiretroviral treatment (ART) in low-income countries, HIV-related mortality is high, especially in the first months following ART initiation. We aimed to evaluate the impact of TB coinfection on early mortality and to assess gender-specific predictors of mortality in a cohort of Ethiopian adults subjected to intensified casefinding for active TB before starting ART.

Material and Methods

Prospectively recruited ART-eligible adults (n = 812, 58.6% female) at five Ethiopian health centers were followed for 6 months. At inclusion sputum culture, Xpert MTB/RIF, and smear microscopy were performed (158/812 [19.5%] had TB). Primary outcome was all-cause mortality. We used multivariate Cox models to identify predictors of mortality.

Results

In total, 37/812 (4.6%) participants died, 12 (32.4%) of whom had TB. Karnofsky performance score (KPS) and mid-upper arm circumference (MUAC) were associated with mortality in the whole population. However, the associations were different in men and women. In men, only MUAC remained associated with mortality (adjusted hazard ratio [aHR] 0.71 [95% CI 0.57–0.88]). In women, KPS <80% was associated with mortality (aHR 10.95 [95% CI 2.33–51.49]), as well as presence of cough (aHR 3.98 [95% CI 1.10–14.36]). Cough was also associated with mortality for TB cases (aHR 8.30 [95% CI 1.06–65.14]), but not for non-TB cases.

Conclusions

In HIV-positive Ethiopian adults managed at health centers, mortality was associated with reduced performance score and malnutrition, with different distribution with regard to gender and TB coinfection. These robust variables could be used at clinic registration to identify persons at increased risk of early mortality.

ESX-1 exploits type I IFN-signalling to promote a regulatory macrophage phenotype refractory to IFNγ-mediated autophagy and growth restriction of intracellular mycobacteria

The ability of macrophages to eradicate intracellular pathogens is normally greatly enhanced by IFNγ, a cytokine produced mainly after onset of adaptive immunity. However, adaptive immunity is unable to provide sterilizing immunity against mycobacteria, suggesting that mycobacteria have evolved virulence strategies to inhibit the bactericidal effect of IFNγ-signalling in macrophages. Still, the host-pathogen interactions and cellular mechanisms responsible for this feature have remained elusive. We demonstrate that the ESX-1 type VII secretion systems of Mycobacterium tuberculosis and Mycobacterium  marinum exploit type I IFN-signalling to promote an IL-12(low) /IL-10(high) regulatory macrophage phenotype characterized by secretion of IL-10, IL-27 and IL-6. This mechanism had no impact on intracellular growth in the absence of IFNγ but suppressed IFNγ-mediated autophagy and growth restriction, indicating that the regulatory phenotype extends to function. The IFNγ-refractory phenotype was partly mediated by IL-27-signalling, establishing functional relevance for this downstream cytokine. These findings identify a novel macrophage-modulating function for the ESX-1 secretion system that may contribute to suppress the efficacy of adaptive immunity and provide mechanistic insight into the antagonistic cross talk between type I IFNs and IFNγ in mycobacterial infection.

Plasma Levels of Neopterin and C-Reactive Protein (CRP) in Tuberculosis (TB) with and without HIV Coinfection in Relation to CD4 Cell Count

Background

While the risk of TB is elevated in HIV-positive subjects with low CD4 cell counts, TB may in itself be associated with CD4 lymphocytopenia. We investigated markers of immune activation (neopterin) and inflammation (CRP) in TB patients with and without HIV coinfection and their association with CD4 cell levels, and determined their predictive capacity as alternative markers of advanced immunosuppression.

Methods

Participants selected from a cohort of adults with TB at Ethiopian health centers (195 HIV+/TB+, 170 HIV-/TB+) and 31 controls were tested for plasma levels of neopterin and CRP. Baseline levels of neopterin and CRP were correlated to CD4 cell count before and after anti-TB treatment (ATT). The performance to predict CD4 cell strata for both markers were investigated using receiver operating curves.

Results

Levels of both biomarkers were elevated in TB patients (neopterin: HIV+/TB+ 54 nmol/l, HIV-/TB+ 23 nmol/l, controls 3.8 nmol/l; CRP: HIV+/TB+ 36 μg/ml, HIV-/TB+ 33 μg/ml, controls 0.5 μg/ml). Neopterin levels were inversely correlated (-0.53, p<0.001) to CD4 cell count, whereas this correlation was weaker for CRP (-0.25, p<0.001). Neither of the markers had adequate predictive value for identification of subjects with CD4 cell count <100 cells/mm³ (area under the curve [AUC] 0.64 for neopterin, AUC 0.59 for CRP).

Conclusion

Neopterin levels were high in adults with TB, both with and without HIV coinfection, with inverse correlation to CD4 cell count. This suggests that immune activation may be involved in TB-related CD4 lymphocytopenia. However, neither neopterin nor CRP showed promise as alternative tests for immunosuppression in patients coinfected with HIV and TB.

Screening for cryptococcal antigenemia using the lateral flow assay in antiretroviral therapy-naïve HIV-positive adults at an Ethiopian hospital clinic

Background

Since treatment for latent cryptococcal infection (CI) before starting antiretroviral therapy (ART) reduces mortality in HIV-infected subjects, screening for cryptococcal antigen (CrAg) in blood is recommended for individuals with CD4 cell counts < 100 cells/µL in regions with high CI prevalence. We assessed CrAg screening using the lateral flow assay in HIV-infected adults eligible for ART in central Ethiopia.

Results

HIV-positive patients (age ≥ 18 years, CD4 cell count < 350 cells/μL and/or WHO stage IV, no current or previous ART) were recruited at Adama Regional Hospital, Ethiopia (February 2013 until March 2014). CrAg was determined in plasma by lateral flow assay. Among 129 included participants (median age 35 years, 64 % female) the median CD4 cell count was 210 cells/μL (interquartile range 110–309); 29 (23 %) had CD4 cell count < 100 cells/μL. Two (1.6 %) participants were CrAg-positive (CD4 cell counts 171 vs. 250 cells/µL), one of whom had clinically manifest cryptococcal meningitis at the time of testing.

Conclusions

In contrast to two recent reports from Ethiopia, we found few cases of CI among ART-naïve adults. Our study, which is the first using lateral flow assay for CrAg screening in this country, illustrates the need of larger surveys of CI prevalence among ART-naïve patients before defining recommendations on CI screening.

Outcome of tuberculosis treatment in HIV-positive adults diagnosed through active versus passive case-finding

Background

The World Health Organization strongly recommends regular screening for tuberculosis (TB) in HIV-positive individuals.

Objective

To compare the outcome of anti-tuberculosis treatment (ATT) in HIV-positive adults diagnosed with TB through active case-finding (ACF) or passive case-finding (PCF).

Design

Antiretroviral therapy (ART)-naïve adults diagnosed with TB were included from two prospective cohort studies conducted in Ethiopia between September 2010 and March 2013. The PCF cohort was based at out-patient TB clinics, whereas participants in the ACF cohort were actively screened for TB by bacteriological sputum testing (smear microscopy, Xpert MTB/RIF assay, and liquid culture) without pre-selection on the basis of symptoms and signs. Outcomes of ATT were compared between participants in the two cohorts; characteristics at diagnosis and predictors of adverse outcomes were analysed.

Results

Among 439 TB/HIV co-infected participants, 307 and 132 belonged to PCF and ACF cohorts, respectively. Compared with the ACF participants, hemoptysis, conjunctival pallor, bedridden status, and low mid upper-arm circumference (MUAC) were significantly more common in participants identified through PCF. Sputum smear-positivity rates among pulmonary TB cases were 44.2% and 21.1% in the PCF and ACF cohorts, respectively (p<0.001). Treatment success was ascertained in 247 (80.5%) of the participants in the PCF cohort and 102 (77.2%) of the participants in the ACF cohorts (p=0.223). Low MUAC (p=0.001) independently predicted mortality in the participants in both cohorts.

Conclusion

Although patients identified through ACF had less advanced TB disease, ATT outcome was similar to the patients identified through PCF. To achieve a better outcome, case management in ACF strategy should be strengthened through enhanced patient-centred counselling and adherence support.

A Clinical Scoring Algorithm for Determination of the Risk of Tuberculosis in HIV-Infected Adults: A Cohort Study Performed at Ethiopian Health Centers

BACKGROUND

The World Health Organization (WHO) tuberculosis (TB) symptom screening instrument (WHO-TB) can identify human immunodeficiency virus (HIV)-infected individuals at low risk of tuberculosis (TB); however, many patients report WHO-TB symptoms and require further TB investigations. We hypothesized that further clinical scoring could classify subjects with a positive WHO-TB screening result (WHO-TB(+)) for the likelihood of TB.

METHODS

HIV-infected adults eligible to initiate antiretroviral therapy (ART) were recruited and prospectively followed at 5 Ethiopian health centers. Irrespective of symptoms, all participants underwent sputum bacteriological testing for TB. Symptoms, physical findings, hemoglobin, and CD4 cell count results were compared between subjects with and those without bacteriologically confirmed TB. Variables associated with TB in WHO-TB(+) individuals were used to construct a scoring algorithm with multiple logistic regression analysis.

RESULTS

Among 812 participants, 137 (16.9%) had TB. One hundred fifty-nine persons (20%) had a negative WHO-TB screen, 10 of whom had TB (negative predictive value [NPV], 94% [95% confidence interval {CI}, 90%-97.5%]). For WHO-TB(+) subjects, the following variables were independently associated with TB, and were assigned 1 point each in the clinical scoring algorithm: cough, Karnofsky score ≤80, mid-upper arm circumference <20 cm, lymphadenopathy, and hemoglobin <10 g/dL. Among subjects with 0-1 points, 20 of 255 had TB (NPV, 92% [95% CI, 89%-95%]), vs 19 of 34 participants with ≥4 points (positive predictive value, 56% [95% CI, 39%-73%]). The use of WHO-TB alone identified 159 of 784 (20%) with a low risk of TB, vs 414 of 784 (53%) using WHO-TB followed by clinical scoring (P< .001). The difference in proportions of confirmed TB in these subsets was nonsignificant (6.3% vs 7.2%; P= .69).

CONCLUSIONS

Clinical scoring can further classify HIV-infected adults with positive WHO-TB screen to assess the risk of TB, and would reduce the number of patients in need of further TB investigations before starting ART.

CLINICAL TRIALS REGISTRATION

NCT01433796.

High rates of virological suppression in a cohort of human immunodeficiency virus-positive adults receiving antiretroviral therapy in ethiopian health centers irrespective of concomitant tuberculosis

Rates of virological suppression after 6 months of ART were high in a cohort of 678 HIV-positive adults managed in Ethiopian health centers, with no significant difference with regard to concomitant tuberculosis at baseline (TB 135; non-TB 543).

Background.

 Antiretroviral therapy (ART) initiation during treatment for tuberculosis (TB) improves survival in human immunodeficiency virus (HIV)/TB-coinfected patients. We compared virological suppression (VS) rates, mortality, and retention in care in HIV-positive adults receiving care in 5 Ethiopian health centers with regard to TB coinfection.

Methods.

 Human immunodeficiency virus-positive ART-naive adults eligible for ART initiation were prospectively recruited. At inclusion, all patients underwent microbiological investigations for TB (sputum smear, liquid culture, and polymerase chain reaction). Virological suppression rates after 6 months of ART (VS; viral load <40 and <400 copies/mL) with regard to TB status was the primary outcome. The impact of HIV/TB coinfection on VS rates was determined by multivariate regression analysis. Mortality and retention in care were analyzed by proportional hazard models.

Results.

 Among 812 participants (TB, 158; non-TB, 654), 678 started ART during the follow-up period (TB, 135; non-TB, 543). No difference in retention in care between TB and non-TB patients was observed during follow-up; 25 (3.7%) patients died, and 17 (2.5%) were lost to follow-up (P = .30 and P = .83, respectively). Overall rates of VS at 6 months were 72.1% (<40 copies/mL) and 88.7% (<400 copies/mL), with similar results for subjects with and without TB coinfection (<40 copies/mL: 65 of 92 [70.7%] vs 304 of 420 [72.4%], P = .74; <400 copies/mL: 77 of 92 [83.7%] vs 377 of 420 [89.8%], P = .10, respectively).

Conclusions.

 High rates of VS can be achieved in adults receiving ART at health centers, with no significant difference with regard to TB coinfection. These findings demonstrate the feasibility of combined ART and anti-TB treatment in primary healthcare in low-income countries.

Clinical Trials Registration.

 NCT01433796.

Proficiency of drug susceptibility testing of Mycobacterium tuberculosis against pyrazinamide: the Swedish experience

BACKGROUND

Pyrazinamide (PZA) is a key drug in the treatment of tuberculosis (TB), including multidrug-resistant TB. Drug susceptibility testing (DST) of Mycobacterium tuberculosis against PZA is not included in the World Health Organization's yearly proficiency testing. There is an increasing need to establish quality control of PZA DST.

OBJECTIVE

To evaluate the performance of PZA DST and to introduce a quality assurance system for the test in Sweden.

METHOD

Panels with PZA-susceptible and -resistant isolates were used in three rounds of proficiency testing in all five Swedish clinical TB laboratories and our reference laboratory. All laboratories used the MGIT 960 system. Minimum inhibitory concentrations (MICs) were determined and the pncA gene was sequenced to further characterise the 52 panel strains.

RESULTS

Good agreement was seen between the phenotypic PZA DST and pncA sequence data, and MIC determination confirmed high levels of resistance. However, in contrast to other drugs, for which correct proficiency test results were observed, specificity problems occurred for PZA DST in some laboratories.

CONCLUSIONS

In Sweden, using panel testing, differences were seen in the proficiency of TB laboratories in correctly identifying PZA susceptibility. Improved results were noted in the third round; PZA has therefore been included in yearly proficiency testing.

Intensified tuberculosis case-finding in HIV-positive adults managed at Ethiopian health centers: diagnostic yield of Xpert MTB/RIF compared with smear microscopy and liquid culture

Background

Detection of active tuberculosis (TB) before antiretroviral therapy (ART) initiation is important, but optimal diagnostic methods for use in resource-limited settings are lacking. We assessed the prevalence of TB, evaluated the diagnostic yield of Xpert MTB/RIF in comparison with smear microscopy and culture, and the impact of Xpert results on clinical management in HIV-positive adults eligible for ART at health centers in a region of Ethiopia.

Methods

Participants were prospectively recruited and followed up at 5 health centers. Trained nurses collected data on socio-demographic characteristics, medical history and symptoms, and performed physical examination. Two paired morning sputum samples were obtained, and lymph node aspirates in case of lymphadenopathy. Diagnostic yield of Xpert MTB/RIF in sputum was compared with smear microscopy and liquid culture.

Results

TB was diagnosed in 145/812 participants (17.9%), with bacteriological confirmation in 137 (16.9%). Among bacteriologically confirmed cases, 31 were smear-positive (22.6%), 96 were Xpert-positive (70.1%), and 123 were culture-positive (89.8%). Xpert MTB/RIF increased the TB detection rate by 64 cases (47.4%) compared with smear microscopy. The overall sensitivity of Xpert MTB/RIF was 66.4%, and was not significantly lower when testing one compared with two samples. While Xpert MTB/RIF was 46.7% sensitive among patients with CD4 cell counts >200 cells/mm³, this increased to 82.9% in those with CD4 cell counts ≤100 cells/mm³. Compared with Xpert-positive TB patients, Xpert-negative cases had less advanced HIV and TB disease characteristics.

Conclusions

Previously undiagnosed TB is common among HIV-positive individuals managed in Ethiopian health centers. Xpert MTB/RIF increased TB case detection, especially in patients with advanced immunosuppression. An algorithm based on the use of a single morning sputum sample for individuals with negative sputum smear microscopy could be considered for intensified case finding in patients eligible for ART. However, technical and cost-effectiveness issues relevant for low-income countries warrant further study.

A case of Mycobacterium goodii prosthetic valve endocarditis in a non-immunocompromised patient: use of 16S rDNA analysis for rapid diagnosis

BACKGROUND

Mycobacterium goodii is a rare cause of significant infection. M. goodii has mainly been associated with lymphadenitis, cellulitis, osteomyelitis, and wound infection.

CASE PRESENTATION

A case of a 76-year-old Caucasian female is presented. The patient developed a prosthetic valve endocarditis caused by M. goodii. She had also suffered from severe neurological symptoms related to a septic emboli that could be demonstrated as an ischemic lesion found on CT of the brain. Transesophageal echocardiography verified a large vegetation attached to the prosthetic valve. Commonly used blood culture bottles showed growth of the bacteria after 3 days.

CONCLUSIONS

Although M. goodii is rarely involved in these kinds of severe infections, rapidly growing mycobacteria should be recognized during conventional bacterial investigations and identified by molecular tools such as analysis of 16S rDNA. Species identification of nontuberculous mycobacteria is demanding and is preferably done in collaboration with a mycobacterial laboratory. An early diagnosis provides the opportunity for adequate treatment. In the present case, prolonged antimicrobial treatment and surgery with replacement of the prosthetic valve was successful.

Wild-type MIC distributions of four fluoroquinolones active against Mycobacterium tuberculosis in relation to current critical concentrations and available pharmacokinetic and pharmacodynamic data

OBJECTIVES

To describe wild-type distributions of the MIC of fluoroquinolones for Mycobacterium tuberculosis in relation to current critical concentrations used for drug susceptibility testing and pharmacokinetic/pharmacodynamic (PK/PD) data.

METHODS

A 96-stick replicator on Middlebrook 7H10 medium was used to define the MICs of ciprofloxacin, ofloxacin, moxifloxacin and levofloxacin for 90 consecutive clinical strains and 24 drug-resistant strains. The MICs were compared with routine BACTEC 460 susceptibility results and with MIC determinations in the BACTEC MGIT 960 system in a subset of strains using ofloxacin as a class representative. PK/PD data for each drug were reviewed in relation to the wild-type MIC distribution.

RESULTS

The wild-type MICs of ciprofloxacin, ofloxacin, moxifloxacin and levofloxacin were distributed from 0.125 to 1, 0.25 to 1, 0.032 to 0.5 and 0.125 to 0.5 mg/L, respectively. The MIC data correlated well with the BACTEC 960 MGIT and BACTEC 460 results. PD indices were the most favourable for levofloxacin, followed by moxifloxacin, ofloxacin and ciprofloxacin.

CONCLUSIONS

We propose S (susceptible) <or= 1.0 mg/L as the tentative epidemiological cut-off (ECOFF) for ofloxacin and ciprofloxacin, and S <or= 0.5 mg/L for levofloxacin and moxifloxacin, although it is possible that adding more MIC data could shift the ECOFFs for ofloxacin and levofloxacin one dilution upwards. The proposed ECOFFs may be more appropriate if used as clinical breakpoints on Middlebrook 7H10 agar than the current critical concentrations of S <or= 2.0 mg/L for ciprofloxacin, ofloxacin and levofloxacin, and S <or= 0.5 mg/L could be considered as a clinical breakpoint for moxifloxacin, provided other investigators can confirm our findings.

Evaluation of wild-type MIC distributions as a tool for determination of clinical breakpoints for Mycobacterium tuberculosis

OBJECTIVES

The aim of this study was to establish wild-type MIC distributions of first-line drugs for Mycobacterium tuberculosis, as well as to explore the usefulness of such distributions when setting clinical breakpoints.

METHODS

We determined the MICs of rifampicin, isoniazid and ethambutol for M. tuberculosis using a Middlebrook 7H10 dilution method for 90 consecutive clinical isolates, 8 resistant strains and 16 isolates from the WHO proficiency test panel. M. tuberculosis H37Rv was used for quality control and susceptibility results using 7H10 were compared with the results obtained with BACTEC460.

RESULTS

The agreement with BACTEC460 was very high for isoniazid (99.1%) and rifampicin (99.1%) but lower for ethambutol (94.7%). Intra- and inter-assay variation was below one MIC dilution. The MIC distributions for isoniazid and rifampicin provided a clear separation between susceptible and resistant strains. Regarding ethambutol, the current breakpoint for 7H10 (5 mg/L) is close to the wild-type and all strains (n = 6) showing a disagreement between BACTEC460 and 7H10 were distributed very close to the breakpoint (MIC 4-8 mg/L). This problematic relation was confirmed by investigating isolates from the WHO panel with an agreement <95% (64%-88% among 26 laboratories, n = 4) for which the MICs were 4-8 mg/L.

CONCLUSIONS

Utilizing the wild-type MIC distribution was found to be as useful in M. tuberculosis as in other bacteria when setting clinical breakpoints. We suggest that the present clinical breakpoints should be re-evaluated, taking into account wild-type MIC distributions and available pharmacokinetic data.

Swedish moist snuff accelerates gastric cancer development in Helicobacter pylori-infected wild-type and gastrin transgenic mice

The Swedish variant of moist oral smokeless tobacco (snus) is popular in Sweden and Norway, banned from sale within the European Union and is currently being introduced in USA. The aim of the present study was to determine if snus is carcinogenic to the stomach, particularly in Helicobacter pylori (H.P.)-infected hosts at increased risk for gastric cancer development. Snus (Generaltrade mark; Swedish Match, Sweden) was mixed with powdered standard mouse chow at a concentration of 5-9% (wt/wt) and given to wild-type (WT, FVB) and gastrin transgenic (INS-GAS, FVB) mice for 6 months with or without H.P. (strain 67:21, CagA+, VacA+) infection. At necropsy, pathological evaluation of stomachs from uninfected snus-treated WT mice showed mild morphological changes, whereas 50% snus-treated INS-GAS mice developed carcinoma in situ (CIS), compared with 25% not exposed to snus. When snus was given to H.P.-infected mice, 9 of 17 WT mice developed CIS with intramucosal invasion, and the remaining 8 of 17 WT mice developed high-grade dysplasia (score >1.5) that was associated with increased gastritis, epithelial defects, oxyntic atrophy, hyperplasia and intestinal metaplasia. Twelve of 12 H.P.-infected INS-GAS mice developed CIS with intramucosal invasion and submucosal herniation. We suggest that snus is a potential gastric carcinogen in mice. The development of CIS was associated with increased rates of the epithelial cell proliferation and apoptosis, common features of gastric carcinogenesis.

Lectin histochemistry of the gastric mucosa in normal and Helicobacter pylori infected guinea-pigs

Helicobacter pylori attaches via lectins, carbohydrate binding proteins, to the carbohydrate residues of gastric mucins. Guinea-pigs are a suitable model for a H. pylori infection and thus the carbohydrate composition of normal and H. pylori infected gastric mucosa was investigated by lectin histochemistry. The stomach of all infected animals showed signs of an active chronic gastritis in their mucosa, whereas no inflammation was present in the control animals. The corpus-fundus regions of the controls showed heterogeneous WGA, SNA-I, UEA-I and HPA binding in almost all parts of the gastric glands. While these lectins labelled the superficial mucous cells and chief cells heterogeneously, the staining of the parietal cells was limited to WGA and PHA-L. Mucous neck cells reacted heterogeneously with UEA-I, HPA, WGA and PHA-L. In the antrum, the superficial mucous cells and glands were stained by WGA, UEA-I, HPA, SNA-I or PHA-L. WGA, UEA-I, SNA-I and HPA labelled the surface lining cells strongly. The mucoid glands reacted heterogeneously with WGA, UEA-I, HPA, SNA-I and PHA-L. In both regions, the H. pylori infected animals showed similar lectin binding pattern as the controls. No significant differences in the lectin binding pattern and thus in the carbohydrate composition between normal and H. pylori infected mucosa could be detected, hence H. pylori does not induce any changes in the glycosylation of the mucosa of the guinea-pig. This unaltered glycosylation is of particular relevance for the sialic acid binding lectin SNA-I as H. pylori uses sialic acid binding adhesin for its attachment to the mucosa. As sialic acid binding sites are already expressed in the normal mucosa H. pylori can immediately attach via its sialic acid binding adhesin to the mucosa making the guinea-pig particularly useful as a model organism.

Gastric bypass surgery does not increase susceptibility to Helicobacter pylori infection in the stomach of rat or mouse

Gastric bypass is a clinical option for obesity surgery. An increased susceptibility to Helicobacter pylori infection in the bypassed stomach has been speculated. The aim of the present study was to examine the susceptibility of the bypassed stomach to H. pylori infection in rats and mice. Adult Sprague-Dawley and Wistar rats and NMRI mice were subjected to either gastric bypass or laparotomy only as control. The animals were inoculated with the CagA- and VacA- positive H. pylori strain 67/21 (not mouse-adapted) in the first experiment and with 9 additional isolates in the second, by injection into the bypassed stomach or the control stomach during surgery. The stomach of each animal was collected for H. pylori culture 2-3 weeks later. While all the rats were H. pylori negative, 54% of gastric bypassed mice and 75% of controls were positive (P = 0.4). We conclude that susceptibility to H. pylori infection in the stomach is not increased by gastric bypass surgery.

PCR-denaturing gradient gel electrophoresis and two feces antigen tests for detection of Helicobacter pylori in mice

PCR-denaturing Gradient Gel Electrophoresis (PCR-DGGE), a method suitable for the detection of microbial species in complex ecosystems, was evaluated for the detection and identification of Helicobacter spp. in feces and stomach tissue of mice. Two commercially available stool antigen tests for clinical diagnostics in humans were also evaluated in the C57Bl/6 mouse model of H. pylori infection. PCR-DGGE detected only Helicobacter ganmani in feces from H. pylori-infected as well as control animals, whereas in stomach specimens it demonstrated the presence of H. pylori in challenged and H. ganmani in control animals. Hence, the method detected DNA only of the predominant Helicobacter spp., which was also shown in cell dilution experiments. The Amplified IDEIA Hp StAR feces antigen test detected H. pylori in feces from all infected animals and generated no false-positive results, whereas the Premier Platinum HpSA-test also detected H. pylori in all infected animals but generated false-positive or equivocal results in 50% of the control animals. Premier Platinum HpSA, as opposed to Hp StAR, cross-reacted with non-pylori Helicobacter spp. in vitro.

High intake of selenium, beta-carotene, and vitamins A, C, and E reduces growth of Helicobacter pylori in the guinea pig

PURPOSE

Helicobacter pylori is a human gastroduodenal pathogen associated with type-B gastritis and gastric cancer. Low gastric tissue antioxidant levels are believed to increase the risk of developing gastric cancer. We investigated whether dietary antioxidant levels protect against infection and type-B gastritis in H. pylori-infected guinea pigs.

METHODS

Dunkin-Hartley guinea pigs infected for 6 weeks with H. pylori were fed diets with various antioxidant levels. Stomach specimens were cultured, and gastritis was graded from 0 to 3.

RESULTS

Supplementation with vitamins A, C, and E and with selenium yielded H. pylori recovery from 17% of challenged animals, compared with 43% of those fed a control diet. Gastritis was scored at 0.33 and 0.93, respectively. Supplementation with only vitamin C or astaxanthin had less effect on gastritis and recovery rate. In a second experiment, gastritis score in a group given vitamins A, C, E, and selenium and beta-carotene was 2.25 and in a control group, it was 2.57. The H. pylori recovery rate was 75 and 100%, respectively, with fewer colonies from animals given antioxidant supplementation (P < 0.05).

CONCLUSIONS

A combination of antioxidants can protect against H. pylori infection in guinea pigs. In animal studies, antioxidant intake should be low to optimize development of H. pylori-associated disease. Furthermore we established that H. pylori causes severe gastritis in guinea pigs.

Comparative study of Helicobacter pylori infection in guinea pigs and mice - elevation of acute-phase protein C3 in infected guinea pigs

Eighteen Dunkin-Hartley guinea pigs and 50 NMRI mice were inoculated with Helicobacter pylori and the infection followed by culture, histopathology, antibody response, and plasma levels of the acute-phase proteins albumin, C3, and transferrin for up to 7 weeks. The immune response to H. pylori surface proteins was studied by an enzyme immunoassay (EIA) and Western immunoblot and the plasma levels of albumin, C3, and transferrin were analyzed by single radial immunodiffusion. Guinea pigs had a more severe gastritis and a higher EIA immune response than NMRI mice. Serum C3 levels were elevated in infected guinea pigs after 3 and 7 weeks indicating a systemic inflammatory response and a possible link between H. pylori infection and extragastric manifestations such as vasculitis associated with atherosclerosis. Serum cholesterol levels were analyzed in guinea pigs at 7 weeks and indicated a higher level in H. pylori-infected than in control animals, but this difference was not statistically significant.

Infection with cagA- and vacA-positive and -negative strains of Helicobacter pylori in a mouse model

To study the role of cytotoxin-associated protein (cagA) and vacuolating cytotoxin (vacA) in Helicobacter pylori infection in an experimental murine model, mice were infected with seven strains with different cagA and vacA status. Groups of 10 NMRI mice were challenged and were killed 5 weeks later. In a second study, 20 mice were challenged with a mixture of the same seven strains and killed 1, 3, 15 and 17 weeks post-inoculation. All seven strains were found to colonize the mice for the 5-week experimental period. Animals infected with vacA-positive strains, regardless of cagA status, showed an elevation of antibody titers. Two cagA-negative and vacA-positive strains and one cagA- and vacA-positive strain were found to 'take over' in the mixed infection as analyzed by the randomly amplified polymorphic DNA-polymerase chain reaction technique and in one mouse stomach we found coexistence of two of the strains. We found no evidence of the different strains colonizing different parts of the stomach.

The relationship between O-chain expression and colonisation ability of Helicobacter pylori in a mouse model

The influence of lipopolysaccharide (LPS) O-polysaccharide chain production on the colonisation ability of Helicobacter pylori in four mouse models (NMRI, C57BL/6, CBA/Ca, and BALB/cA mice) was studied. H. pylori strains that produced smooth-form LPS (S-LPS) detectable in silver-stained electrophoretic gels colonised mice. In contrast, a laboratory-passaged strain G50 and the culture collection strain CCUG 17874 did not colonise mice; the former strain produced low amounts of O-chains only detectable in immunoblotting but not in silver-stained gels, whereas the latter produced rough-form LPS (R-LPS) without O-chains. Furthermore, a galE isogenic mutant, which produced R-LPS, did not colonise mice. However, after repeated broth culture, strains G50 and CCUG 17874 produced S-LPS detectable in silver-stained gels and were capable of colonising mice. Consistent with the production of O-chains, all colonising strains produced Lewis (Le) antigens, Le(x) and/or Le(y). Except for low expression of Le(y) by non-colonising G50, reflecting low production of O-chains, all other non-colonising strains and the galE mutant lacked expression of Le antigens consistent with their production of R-LPS. Lectin typing of strains supported these findings, and also showed that lectin types did not differ before and after colonisation. The low level of O-chain production and Le antigen expression by the non-colonising G50 may not be sufficient to aid colonisation. Examination of protein profiles of H. pylori strains before inoculation showed that protein expression was not significantly different between colonising and non-colonising strains. These results show that S-LPS production with O-chain expression is required by H. pylori for colonisation in a number of mouse models and that care should be taken with inoculating H. pylori strains that loss of O-chains does not occur during subculturing.

Severe gastritis in guinea-pigs infected with Helicobacter pylori

An appropriate animal model is essential to study Helicobacter pylori infection. The aim of this study was to investigate if H. pylori can colonise the guinea-pig stomach and whether the infection causes gastritis and a serological response similar to that observed in man. Guinea-pigs were infected either with fresh H. pylori isolates from human gastric biopsies or with a guinea-pig passaged strain. When the animals were killed, 3 and 7 weeks after inoculation, samples were taken for culture, histopathology and serology. H. pylori was cultured from 22 of 29 challenged animals. All culture-positive animals exhibited a specific immune response against H. pylori antigens in Western blotting and gastritis in histopathological examination. Antibody titres in enzyme immunoassay were elevated among animals challenged with H. pylori. The inflammatory response was graded as severe in most animals and consisted of both polymorphonuclear leucocytes and lymphocytes. Erosion of the gastric epithelium was found in infected animals. These results suggest that the guinea-pig is suitable for studying H. pylori-associated diseases. Moreover, guinea-pigs are probably more similar to man than any other small laboratory animal as regards gastric anatomy and physiology.

Dietary factors influence the recovery rates of Helicobacter pylori in a BALB/cA mouse model

The aim of this study was to assess the ability of different mouse diets to sustain an H. pylori infection in BALB/cA mice. Four commercially available mouse diets were compared. Experiment 1: Mice were fed the four diets for seven days before infection, infected three times at two-day intervals with 0.1 ml of 10(9) colony-forming units/ml H. pylori cells. H. pylori strains (n = 4) were cultured on GAB-Camp agar for 2 days, harvested and suspended in PBS. All animals were sacrificed at 2 and 4 weeks post inoculation. Experiment 2: Mice infected for 8 weeks were fed RM2, changed to the different diets for 10 days and sacrificed. Stomachs were collected, cultured on GAB-Camp agar to estimate H. pylori growth and stomach biopsies were analyzed by PCR. There were significant differences between diets in their ability to sustain growth of H. pylori. The range was from a few hundred colonies to no growth at all on the GAB-Camp agar. PCR signals showed good correlation with the culture results. All H. pylori-infected mice gave a significantly higher inflammation score compared to non-infected mice. The diet RM2, having the highest number of culturable H. pylori in the mouse stomach, also showed the highest inflammation. These results suggest that the dietary factors affect the amounts of H. pylori in an infection of BALB/cA mice.

Infection of BALB/c A mice by spiral and coccoid forms of Helicobacter pylori

Helicobacter pylori exists in two different morphological forms, spiral and coccoid. This study demonstrated that both forms can infect BALB/c A mice. The animals were inoculated orally three times at 2-day intervals with 10(8) cfu of both spiral and coccoid forms of strain CCUG 17874 (NCTC 11637), strain 25 and strain 553/93. Infection was followed over a 30-week period by histological scoring of the grade of inflammation in gastric biopsies. At each time point sera were collected for analysis in ELISA and immunoblot analysis. Both spiral and coccoid forms of all H. pylori strains gave significantly higher inflammation scores than a control group of animals 1 week after inoculation. The histological evidence persisted throughout the entire 30 weeks. The inflammation was most severe in the pylorus and duodenum. Infection with strain 553/93 displayed the most severe gastritis. The spiral form of strain CCUG 17874 gave an immune response after only 4 weeks, whereas its coccoid form as well as strains 25 and 553/93 (spiral and coccoid forms) gave a significant increase in antibody response in ELISA and immunoblot after 16 weeks. It is concluded that both spiral and coccoid forms of H. pylori can cause acute gastritis in BALB/c A mice.