Book excerpt: Public Health Microbiology: Methods and Protocols is focused on microorganisms that can present a hazard to human health in the course of everyday life. There are chapters dealing with organisms that are directly pathogenic to humans, including bacteria, viruses, and fungi; on organisms that produce toxins during growth in their natural habitats; on the use of bacteriocins produced by such organisms as lactobacilli and bifidobacteria; as well as several chapters on hazard analysis, the use of disinfectants, microbiological analysis of cosmetics, and microbiological tests for sanitation equipment in food factories. Additional chapters look at the use of animals (mice) in the study of the various characteristics of milk and their relationships with lactic acid bacteria in particular. Other chapters focus on special methods for determining particular components of milk. In particular, in Parts I and II, on bacterial and viral pathogens, special attention is given to methods for PCR detection of genes with resistance to tetracycline, as well as to Salmonella enterica; for identification and typing of Campylobacter coli; for detection of the abundance of enteric viruses, hepatitis A virus, and rotaviruses in sewage, and of bacteriophages infecting the O157:H7 strain of Escherichia coli. Part III offers methods for computerized analysis and typing of fungal isolates, for isolation and enumeration of fungi in foods, and for the determination of aflatoxin and zearalenone.