[The dimension of the paradigm of complexity in health systems].

This article presents elements to better understand health systems from the complety paradigm, innovative perspective that offers other ways in the conception of the scientific knowledge prevalent away from linear, characterized by the arise of emerging dissociative and behaviors, based on the intra and trans-disciplinarity concepts such knowledges explain and understand in a different way what happens in the health systems with a view to efficiency and effectiveness. The complexity paradigm means another way of conceptualizing the knowledge, is different from the prevalent epistemology, is still under construction does not separate, not isolated, is not reductionist, or fixed, does not solve the problems, but gives other bases to know them and study them, is a different strategy, a perspective that has basis in the systems theory, informatics and cybernetics beyond traditional knowledge, the positive logics, the newtonian physics and symmetric mathematics, in which everything is centered and balanced, joint the "soft sciences and hard sciences", it has present the Social Determinants of Health and organizational culture. Under the complexity paradigm the health systems are identified with the following concepts: entropy, neguentropy, the thermodynamic second law, attractors, chaos theory, fractals, selfmanagement and self-organization, emerging behaviors, percolation, uncertainty, networks and robusteness; such expressions open new possibilities to improve the management and better understanding of the health systems, giving rise to consider health systems as complex adaptive systems.

[Pneumonia and its social representations].

Objective: To correlate the sociostructural variables with the knowledge about pneumonia and to explore the social representations about the etiology, prevention, development and treatment in poor communities.

Methods: A survey in 848 adults from seven Rural Health Centers affiliated to IMSS-Oportunidades Program in four States, was carried out.

Results: One-third of the sample did not understand the term pneumonia; 35 % of the patients with risk factors did not know its etiology; 43 % did not know about associated complications but 85 % considered that it causes death.

[Social politics against poverty and in favor of health in Mexico].

One of the biggest challenges that Mexico faces is to fight against the poverty. The transition of a characteristic welfare model from the government in a closed economy, to an open economy where the functions of the State are limited, has modified the modalities of the social politics against poverty. Six indispensable conditions are identified for poverty's reduction: 1.

[Antimicrobial sensitivity and characterization of Streptococcus pyogenes strains isoleated from a scarlatina outbreak].

Objective: To evaluate the in vitro activities of 13 antimicrobial agents against 47 group A Streptococcus pyogenes (GAS) strains, and to determine the presence of genes encoding streptococcal pyrogenic exotoxin A (SpeA) and the M-protein serotypes.

Materials And Methods: A cross-sectional study was conducted at Centro de Salud Dr. José Castro Villagrana, during a scarlet fever outbreak occurring between December 1999 and January 2000, among 137 children at Colegio Espíritu de América.