Humans; Male; Female; Adult; Arginase/metabolism; Arthritis, Reactive/microbiology; Arthritis, Reactive/virology; Leukocytes, Mononuclear/microbiology; Leukocytes, Mononuclear/virology; Nitric Oxide Synthase Type III/metabolism; Nitric Oxide/metabolism; Arthritis, Reactive/complications; Arthritis, Reactive/immunology; Bacterial Infections/complications; Bacterial Infections/immunology; Bacterial Infections/microbiology; Case-Control Studies; Chlamydia trachomatis/classification; Chlamydia trachomatis/isolation & purification; Female Urogenital Diseases/complications; Female Urogenital Diseases/immunology; Female Urogenital Diseases/microbiology; Female Urogenital Diseases/virology; Gastrointestinal Diseases/complications; Gastrointestinal Diseases/immunology; Gastrointestinal Diseases/microbiology; Gastrointestinal Diseases/virology; Hepacivirus/classification; Hepacivirus/isolation & purification; Hepatitis B virus/classification; Hepatitis B virus/isolation & purification; Hepatitis/complications; Hepatitis/immunology; Hepatitis/virology; Leukocytes, Mononuclear/immunology; Male Urogenital Diseases/complications; Male Urogenital Diseases/immunology; Male Urogenital Diseases/microbiology; Male Urogenital Diseases/virology; Nasopharyngeal Diseases/complications; Nasopharyngeal Diseases/immunology; Nasopharyngeal Diseases/microbiology; Nasopharyngeal Diseases/virology; Primary Cell Culture; Streptococcus pyogenes/classification; Streptococcus pyogenes/isolation & purification