Characterization and comparison of strains of Pasteurella multocida associated with cases of progressive atrophic rhinitis and porcine pneumonia in Argentina

Background:

Pasteurella multocida (Pm) is the causative agent of progressive atrophic rhinitis (PAR) and pneumonic pasteurellosis (PN) in pigs. Pm is a member of the porcine respiratory complex responsible for important economic loss in the pig industry.

Aim:

This study aimed to characterize the Pm strains recovered from clinical cases of PN and PAR and to elucidate the antibiotic susceptibility profiles of the strains.

Materials and Methods:

Sixty strains were characterized molecularly by polymerase chain reaction to determine species-specific gene, capsular type (A or D), and toxin A production. The agar diffusion method was employed to evaluate antibiotic resistance profiles.

Results:

We found that 65% of strains belonged to capsular type A or D, and 15% of those were positive to toxA gene. The antibiotic susceptibility profiles found were sensitive in decreasing order to: Enrofloxacin, ceftiofur (CTF), ampicillin, tilmicosin (TIL), florfenicol (FFN), spectinomycin (SPC), gentamicin, oxytetracycline (OTC), and trimethoprim-sulfamethoxazole (TMS). Strains were resistant in decreasing order to: Lincomycin (LIN), tylosin (TYL), erythromycin (ERY), TMS, SPC, OTC, FFN, TIL, and CTF.

Conclusion:

The toxA gene was detected in many Pm isolates from pneumonic lungs. Capsule type A or D was the most frequently found among the collected isolates. LIN, TYL, and ERY are the drugs which showed higher percentages of resistant isolates.

Tuberculosis incidence among contacts of active pulmonary tuberculosis

BACKGROUND

Treatment of latent tuberculosis (TB) infection (LTBI) in Brazil is recommended only in the case of contacts of pulmonary smear-positive TB patients aged<or=15 years with a tuberculin skin test (TST)>or=10 mm and no previous bacille Calmette-Guérin (BCG) vaccination or with a TST>or=15 mm regardless of previous BCG vaccination.

OBJECTIVE

To evaluate the 2-year incidence and predictors of TB among contacts who did not meet the Brazilian criteria for LTBI treatment.

DESIGN

Retrospective cohort study. Contacts aged between 12 and 15 years and those aged>or=15 years who did not meet the Brazilian criteria for LTBI treatment were enrolled in the study.

RESULTS

TB incidence was 3.2% (22/667), with an estimated TB rate of 1649 per 100000 population. Risk of TB was greater among the 349 contacts with TST>or=5 mm (5.4%) compared to the 318 contacts with TST<5 mm (0.9%; RR 6.04, 95%CI 1.7-20.6).

CONCLUSION

The high incidence of TB among contacts who did not meet the Brazilian criteria for LTBI treatment strongly suggests that these criteria should be reviewed. Furthermore, even among BCG-vaccinated contacts, TST induration>or=5 mm was the only variable that predicted the development of TB disease within 2years.

Alternative anti-tuberculosis regimen including ofloxacin for the treatment of patients with hepatic injury

SETTING

Tuberculosis (TB) clinic of a university-based public hospital in Rio de Janeiro city, Brazil.

OBJECTIVE

To describe treatment outcomes for TB patients with liver injury who received a 12-month regimen of ethambutol (E, EMB) and ofloxacin (O, OFL), including streptomycin (S, SM) for the first 3 months (3SEO/9EO) under routine clinical care conditions.

DESIGN

A retrospective study of a cohort of TB patients prescribed 3SEO/9EO was conducted over a 66-month period. Data were obtained by review of existing medical records. Primary outcomes assessed were cure, treatment failure, treatment default, TB relapse and death.

RESULTS

Outcomes were assessed for 40 patients with hepatic injury who met study criteria. Twenty-three (58%) were male and 13 (33%) were human immunodeficiency virus seropositive. Thirty-four (85%) patients were cured. Three patients (7.5%) defaulted from treatment, and three other patients died (7.5%). There were no treatment failures or relapses during 2 years of follow-up. Clinically recognized drug toxicity occurred in five patients (12.5%), and in each case was attributed to SM.

CONCLUSION

In this series of TB patients with serious liver injury, 3SEO/9EO was well-tolerated, and it was effective in 85% of patients when used under routine clinical care conditions.

Prevalence of pulmonary tuberculosis among respiratory symptomatic subjects in an out-patient primary health unit

SETTING

Out-patient primary health unit (OPHU) in Rio de Janeiro City, Brazil.

OBJECTIVE

To evaluate the impact on the detection of tuberculosis (TB) cases of reducing the time of respiratory symptoms from 'cough > or = 3 weeks' to 'cough > or = 1 week' as a criteria for TB case finding among individuals visiting an OPHU for any other reason.

DESIGN

Cross-sectional study.

RESULTS

During the period of the study, 10.7% (765/ 7174) of subjects reported cough > or = 1 week. Among 542 subjects enrolled in the study with cough > or = 1 week, 15 (2.7%) cases were diagnosed with pulmonary tuberculosis (PTB, 2767/100000). The probability of detecting TB in the OPHU setting among subjects seeking care for respiratory symptoms was significantly higher than among those presenting to the OPHU for other reasons (OR 31.5, 95% CI 4.1-241.9; P < 0.0001). The probability of identifying TB among patients seeking care due to respiratory symptoms was not influenced by the duration of cough (P = 0.7).

CONCLUSION

These findings suggest that the screening criteria for TB case finding of cough for less than the usual 3 weeks among patients who attend a health facility due to respiratory symptoms in settings with a high prevalence of TB may significantly improve the proportion of TB cases diagnosed.

Evaluation of a proposed diagnostic scoring system for pulmonary tuberculosis in Brazilian children

In a case-control study to evaluate a systematic scoring system for diagnosing pulmonary tuberculosis (PTB) in children, cases had gastric lavage cultures positive for Mycobacterium tuberculosis and recovered after anti-tuberculosis treatment, while controls had negative cultures and recovered with non-anti-tuberculosis treatment. Radiological aspect (OR = 25.39), contact with a tuberculous adult (OR = 10.67) and tuberculin skin test > or = 10 mm (OR = 8.23) were associated with PTB diagnosis. The sensitivity of the score ranged from 58% to 89% and the specificity from 98% to 86%, with cut-offs of respectively > or = 40 or > or = 30. The scoring system may be a useful diagnostic method in areas with a high prevalence of TB.

Defaulting from anti-tuberculosis treatment in a teaching hospital in Rio de Janeiro, Brazil

SETTING

Few studies have investigated factors associated with defaulting from anti-tuberculosis (TB) therapy in hospital settings.

OBJECTIVE

To identify the factors associated with defaulting from treatment among TB in-patients in Rio de Janeiro city, Brazil.

DESIGN

Case-control study.

METHODS

All study participants initiated anti-tuberculosis treatment in a teaching hospital. A defaulting case was defined as a person who did not return for anti-tuberculosis medications after 60 days. Cases and controls were interviewed by a trained health care worker using a standardized form.

RESULTS

From 1 January to 31 December 1997, 228 TB cases were registered. After a review of the medical records, 39 were excluded. Household visits were performed in 189 patients; 46 subjects were identified as cases and 117 as controls. Defaulting from anti-tuberculosis treatment was observed in 66 cases (28.9%) before and in 46 (20.2%) after a home visit. After multivariate analysis, the strongest predictors of defaulting from treatment were: 1) returning card not provided (OR 0.099; 95%CI 0.008-1.2; P = 0.07), 2) not feeling comfortable with a doctor (OR 0.16; 95%CI 0.33-0.015; P = 0.001), and 3) blood pressure not measured (OR 0.072; 95%CI 0.036-0.79; P = 0.024).

CONCLUSIONS

In this hospital, the factors associated with defaulting from anti-tuberculosis treatment highlight the necessity for a structured TB Control Program. It is expected that the implementation of such a program, pursuing specific approaches, should enhance completion of anti-tuberculosis treatment and cure.

The usefulness of serum adenosine deaminase 2 (ADA2) activity in adults for the diagnosis of pulmonary tuberculosis

Rapid diagnosis of Mycobacterium tuberculosis remains an obstacle for therapy of tuberculosis (TB). Adenosine deaminase isoform 2 (ADA2) is produced by activated macrophages and has been used for diagnosis of TB from extra-pulmonary sites. However, few studies adequately address whether serum ADA2 activity is useful for diagnosis of active pulmonary tuberculosis (PTB). We prospectively measured serum ADA2 activity in 110 patients with pulmonary disease (65 cases with active PTB and 45 cases with other respiratory diseases) and 78 healthy volunteers (eight with tuberculin skin test positive). The serum ADA2 for the diagnosis of PTB had the sensitivity of 36.9%, the specificity of 84.5%, the positive predictive value of 10.9% and the negative predictive value of 96.2%. We concluded that serum ADA2 activity is neither useful to diagnosis of active PTB nor to differentiate from other respiratory diseases.

Comparison of sputum induction with fiberoptic bronchoscopy in the diagnosis of tuberculosis: experience at an acquired immune deficiency syndrome reference center in Rio de Janeiro, Brazil

Many patients with suspected pulmonary tuberculosis (PTB) do not produce sputum spontaneously or are smear-negative for acid-fast bacilli (AFB). We prospectively compared the yield of sputum induction (SI) and fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) for the diagnosis of PTB in a region with a high prevalence of tuberculosis and human immunodeficiency virus (HIV) infection. Fifty seven percent (143 of 251) of patients had diagnoses of PTB, of whom 17% (25 of 143) were HIV seropositive. There were no significant differences in the yields of AFB smears or cultures whether obtained via SI or BAL. Among 207 HIV-seronegative patients, the AFB smear and mycobacterial culture results from specimens obtained by SI and BAL were in agreement in 97% (202 of 207) (kappa test = 0.92) and 90% (186 of 207) (kappa test = 0.78), respectively. Among HIV-seropositive patients the agreements between AFB smear and culture results for SI and BAL specimens were 98% (43 of 44) (kappa test = 0.93) and 86% (38 of 44) (kappa test = 0.69), respectively. We conclude that SI is a safe procedure with a high diagnostic yield and high agreement with the results of fiberoptic bronchoscopy for the diagnosis of PTB in both HIV-seronegative and HIV-seropositive patients.

Mycobacterium tuberculosis lipid antigens: use of multi-antigen based enzyme immunoassay for free and complex dissociated antibodies

OBJECTIVE

To test the sensitivity and specificity of four lipid antigens of Mycobacterium tuberculosis: BDA-TDA, DAT, SL-I, and PIMs, adsorbed in the same microplate well, to detect reactive IgG by enzyme-immunoassay (EIA) from plain serum (MA-EIA) and dissociated immune complexes (ICMA-EIA).

DESIGN

IgG antibodies against four antigens, placed in the same microplate well, were evaluated in serum from 155 tuberculous (TB) cases non-infected with the human immunodeficiency virus (HIV): 78 patients with positive bacilloscopy and culture, 33 patients with positive culture and 44 patients diagnosed by clinical and radiological criteria; and from 211 HIV negative control subjects: 32 patients with other pulmonary diseases, 100 healthy people and 79 close contacts.

RESULTS

MA-EIA had an overall sensitivity and specificity of 61% (94/155) and 95% (200/211), respectively. We further examined whether the dissociation of immune complexes increases the number of positive reactions in those initially found to be seronegative (SN). The subset of 112 (76 controls and 36 TB) MA-EIA SN samples tested using ICMA-EIA yielded an overall sensitivity and specificity of 83% and 100%. The ICMA-EIA results improved the overall sensitivity from 61 to 80% without changing specificity.

CONCLUSION

These preliminary results suggest that MA-EIA followed by ICMA-EIA, for SN samples, might serve as a fast, cheap, and easy method for the diagnosis of TB in less than 48 hours.

Predictive value of the acid fast smear for detection of Mycobacterium tuberculosis in respiratory specimens in a reference center of HIV/AIDS in Rio de Janeiro, Brazil

In order to evaluate the predictive value of acid fast bacilii (AFB) smear for the diagnosis of Mycobacterium tuberculosis in respiratory specimens in a setting with a high prevalence of AIDS and an unknown prevalence of nontuberculous mycobacteria (NTM), we retrospectively examined specimens cultured for mycobacteria between 1 September 1993 and 30 September 1994 and medical records of patients with positive culture in a General Hospital, AIDS reference in Rio de Janeiro, Brazil. Seventy three per cent (1517/2077) of samples were respiratory specimens and mycobacteria were recovered from 20.6% (313/1517) of these. M. tuberculosis was identified in 94.2% (295/313) and NTM in 5.8% (18/313). The yield of positive AFB smear and of positive culture was 6.1% (93/1517) and 20.6% (313/1517), respectively. The positive predictive value (PPV) of AFB for M. tuberculosis was 98.4% in expectorated sputum and 96.4% in bronchoalveolar lavage. Forty four percent (130/295) of specimens with positive culture for M. tuberculosis and 66.7% (12/18) for NTM were from patients HIV positive. The conclusion was that in our study population, the PPV of AFB for M. tuberculosis in respiratory specimens was high and the prevalence of NTM was low despite the high prevalence of HIV positive.