[Prevalence of mycobacteriosis and tuberculosis in a reference hospital, Cordoba province]

Environmental mycobacteria (EM) constitute an important group of bacteria species found in the environment. They can colonize and occasionally produce disease in man. Sixteen thousand three hundred samples from 9300 adult symptomatic patients from the Hospital Regional of Tuberculosis in Cordoba were bacteriolocally investigated. The isolations were performed by culture on Lowenstein Jensen and Stonebrink culture media. The colonies of acid fast bacilli (AFB) were identified by biochemical and molecular tests. Among 716 culture positive cases, 684 (95.5%) were due to Mycobacterium tuberculosis complex and 32 to environmental mycobacteria. Serial samples allowed the confirmation of the etiological agent in culture and correlated with consistent clinical and radiological abnormalities. Seventy-five percent of these patients were affected by M. avium complex, 15.6% by M. fortuitum, 3.1% Mycobacterium kansasii and 6.3% Mycobacterium chelonae. Among tuberculosis cases, 94.5% and 5.5% had pulmonary and extrapulmonary disease respectively.

Decline of high hepatitis C virus prevalence in a hemodialysis unit with no isolation measures during a 6-year follow-up

AIMS

It has been recently suggested that isolation measures may be necessary to avoid hepatitis C virus (HCV) spread in hemodialysis units with a high HCV prevalence. To assess the variation in prevalence and long-term incidence of HCV infection, we studied our hemodialysis patients during a 6-year follow-up period.

MATERIAL AND METHODS

We compared anti-HCV prevalence in 1994, 1996, 1998 and 2000 according to the anti-HCV status, and we analyzed the seroconversion of anti-HCV. Strict adherence to universal precautions has been fulfilled since 1993 and systematic anti-HCV testing in blood donors has been performed since 1994. No isolation measures were adopted.

RESULTS

In 1994,22 of 53 (41.5%) patients tested positive for anti-HCV; in 1996, 18 of 67 (26.9%); in 1998,9 of 75 (12.0%); and in 2000, 7 of 82 (8.5%) (p < 0.001). In 2000, 7 of 14 (50.0%) patients who had been attending the unit since 1994 and 0 of 68 (0%) who had entered after 1994 were anti-HCV-positive (p = 0.000). Eight of 1 71 (4.7%) patients who entered the unit and 24 of 142 (16.9%) who left it were anti-HCV-positive (p < 0.001). Two patients became anti-HCV-negative. Seroconversion of anti-HCV was observed in 3 patients. The yearly seroconversion rate was 0.5% during the period 1994-1996 (1 of 98 patients at risk), 0.5% during the period 1996-1998 (1 of 91 patients at risk), and 0.4% during the period 1998-2000 (1 of 120 patients at risk).

CONCLUSIONS

It was possible to reduce a high HCV prevalence in a hemodialysis unit when a low incidence was achieved without taking isolation measures. All anti-HCV-positive patients in 2000 had been undergoing hemodialysis since 1994.

The role of transfusion-transmitted virus in patients undergoing hemodialysis

GOALS

To study transfusion-transmitted virus (TTV) infection in 75 patients on hemodialysis and examine its relationship with age, sex, duration of dialysis, history of transfusion, and chronic elevation of alanine aminotransferase (ALT) levels.

STUDY

Serum TTV was analyzed by polymerase chain reaction (PCR), TTV genotypes by restriction fragment length polymorphism, and hepatitis C virus (HCV) RNA by PCR.

RESULTS

Transfusion-transmitted virus was detected in 32 patients (42.7%). Transfusion-transmitted virus genotypes were as follows: G1 in 16 patients; G2, 3; G3, 1; G4, 2; G2-G5, 6; and unclassified, 4. Mean duration of dialysis was 37 +/- 32 months for TTV-positive patients and 43 +/- 37 months for TTV-negative patients (not significant). Twenty-seven (84%) TTV-positive patients and 27 (63%) TTV-negative patients had a history of transfusions ( p = 0.04). Chronic ALT elevation was observed in 9 patients; 5 of them were TTV-positive (16%) and 4 were TTV-negative (9%) (not significant). Four (40%) HCV RNA-positive patients and 5 (8%) HCV RNA-negative patients had chronic ALT elevation ( p = 0.003). Three TTV-positive patients with chronic ALT elevation were also infected with HCV. The two patients with isolated TTV infection did not have another clinical feature to explain their ALT elevation.

CONCLUSIONS

Transfusion-transmitted virus had a high prevalence in the patients on hemodialysis; genotype G1 accounts for half of the cases. Transfusion-transmitted virus infection depends on the transfusional antecedent but not on the duration of dialysis. Chronic ALT elevation is significantly associated with HCV infection but not TTV infection. However, TTV could be a causative agent of chronic ALT elevation in some patients.

Evidence of hepatitis C virus passage across dialysis membrane

The passage of hepatitis C virus (HCV) across the dialysis membrane is a controversial issue. We performed a study applying extreme conditions of permeability to the dialysis membrane and avoiding the use of heparin and dialysis bath that might interfere with polymerase chain reaction (PCR) results. We obtained samples from the ultrafiltrate at the beginning of 18 hemodialysis sessions carried out in 6 HCV RNA-positive patients. HCV RNA was detected by PCR in 3 (16.7%) ultrafiltrate samples belonging to 1 of the patients. HCV genotype was the same as that found in positive ultrafiltrate samples and in the serum corresponding to this patient. The viral load of this patient was under the levels detectable by the assay employed. Therefore, contamination of the ultrafiltrate may constitute a potential risk for HCV transmission in hemodialysis units.