Vectorial role of Acanthamoeba in Legionella propagation in water for human use.

Legionella spp. is the causative agent of Legionnaires' disease and is transmitted through aerosols emanating from man-made water systems. Legionella resistance to water treatments has been related to its association with environmental amoebae such as Acanthamoeba. Due to the high presence of this protozoon in Spain and the high rate of notification of Legionnaires' disease of this country, the aims of this work were to study the coexistence of these bacteria and protozoa in water as well as their interaction. The usefulness of Acanthamoeba co-culture for the isolation of environmental Legionella was also studied. For this purpose, 70 water samples were collected in 2011 from three Drinking Water Treatment Plants, three Wastewater Treatment Plants and five Natural Pools in Spain. Acanthamoeba was found by PCR in 87.1% (61/70) samples and, by culture in 85.7% (60/70) samples. Legionella was detected by PCR in 58.6% (41/70) of water samples, in 5.7% (4/70) by agar culture and 75.7% (53/70) by Acanthamoeba co-culture. From the 54 Acanthamoeba water isolates, Legionella was detected in 43 of them independently of Acanthamoeba's genotype (T3, T4 and T11). Legionella feeleii, Legionella birminghamiensis, Legionella gresilensis/berliardensis, Legionella fairfieldensis, Legionella drozanski and Legionella falloni were identified. In conclusion, our results showed that environmental Acanthamoeba is infected by Legionella to a high percentage, and due to its ubiquity, high resistance and its pathogenic potential per se, new methods for its elimination should be studied. Also, the high effectivity of Acanthamoeba co-culture for Legionella detection has been shown.

[Detection of serum IgG (ELISA) against Helicobacter pylori: relationship with age and gastroduodenal disease]. / Detección de IgG sérica (ELISA) frente a Helicobacter pylori: relación con la edad y patología gastroduodenal.

OBJECTIVE: An attempt was made to investigate the serological response against Helicobacter pylori by using a IgG serum detection technique (ELISA Biometra) to establish a relationship with age and gastroduodenal pathology. The serological response was compared with the microbiologic and histologic studies of biopsy samples from 4 locations in each patient: duodenal bulb, gastric antrum, corpus and fundus. PATIENTS: A total of 309 patients with gastrointestinal symptoms who underwent an upper digestive endoscopy were included. RESULTS: The overall sensitivity of the serological technique (cut-off value 15 U/ml) was 89.3%, the specificity 75.7%, the positive predictive value 96.9% and the negative predictive value 45.4%. The mean titer in patients with a negative microbiology increased with age: 13.5 U/ml, 14-30 years; 10.0 U/ml, 31-50 years; 18.5 U/nl, 51-65 years and 29.2 U/ml, > 65 years. By increasing the cut-off value to 20 and 30 U/ml in the last two age groups, the specificity increased without a significant decrease in the sensitivity. Patients without abnormal findings at endoscopy had mean titers considerably lower (64.7 U/ml) than those with the stomach resected -Billroth I or II- (99.6 U/ml) and those with gastritis, duodenitis and ulcus (86.7-83.1 U/ml), Patients with gastritis but without acute inflammatory activity had mean titers (62.5 U/ml) lower than those observed in patients with active gastritis (p < 0.01) and increased in parallel with the increasing activity of gastritis. In contrast, patients with atrophic gastritis had the lowest mean titers (54 U/ml). CONCLUSIONS: Our results suggest that the cut-off value in the serological technique should be increased according to the patient's age. Moreover, there is a clear relationship between the serum levels of IgG and the activity of gastritis.

[Evaluation of a selective medium for the isolation of Moraxella catarrhalis]. / Evaluación de un medio selectivo para aislamiento de Moraxella catarrhalis.

The recovery rate of Moraxella catarrhalis in a selective culture medium with acetazolamide and in a conventional blood-agar medium was compared from 1291 samples from the respiratory tract and conjunctivae of children and adults with respiratory and ocular symptomatology. M. catarrhalis was recovered in 215 samples on the acetazolamide medium, and only. 18 cases in the blood agar medium (p < 0.001). The highest recovery of M. catarrhalis was in samples with an accompanying flora, either pathogenic or commensal, such as pharyngeal and nasal exudates. The prevalence of M. catarrhalis in adults and children was 2% and 28%, respectively. We therefore, recommend the use of the acetazolamide medium for the recovery of M. catarrhalis in samples where M. catarrhalis is expected to be present with an accompanying flora.