CephalosporinsAnti-Bacterial AgentsMicrobial Sensitivity Testsbeta-LactamasesDrug Resistance, Multiple, BacterialGram-Negative BacteriaContraceptives, Oral, SyntheticDrug Resistance, BacterialDesogestrelNorpregnenesContraceptives, Oral, CombinedUreterolithiasisCephalosporin ResistanceContraceptives, OralThromboembolismCephaloridineCephalosporinaseCefotaximeCephalexinCefiximePenicillinsbeta-LactamsHepatitis C AntibodiesAromatase InhibitorsCeftriaxoneDrug Resistance, MicrobialCephalothinCefmenoximeEnterobacteriaceaebeta-Lactam ResistanceBacteriaCeftazidimeHepatitis CRisk FactorsCefotiamCeftizoximeEnterobacterCephradineTime FactorsKlebsiella pneumoniaeCefazolinPenicillinasePenicillin ResistancePedigreeAztreonamTreatment OutcomeEnterobacteriaceae InfectionsCefoxitinPrevalenceEscherichia coliCefamandoleCephamycinsKlebsiellaCohort StudiesInfant, NewbornCarbapenemsProspective StudiesCase-Control StudiesCefaclorCefoperazoneAmpicillinCefmetazoleCefadroxilBacterial InfectionsPenicillin GMoxalactamIsoelectric FocusingEnterobacter cloacaeRetrospective StudiesKlebsiella InfectionsCross InfectionCefotetanStructure-Activity RelationshipCefuroximeLactamsClavulanic AcidCephaloglycinNeisseria gonorrhoeaeMolecular Sequence DataGram-Positive BacteriaImipenemPenicillanic AcidBacterial ProteinsGonorrheaGram-Negative Bacterial InfectionsCloxacillinCefatrizineKineticsPenicillin-Binding ProteinsEscherichia coli InfectionsHydrolysisPlasmidsDNA, BacterialCefsulodinDrug ResistanceThienamycinsChemistry