Recombinant Attenuated Salmonella Typhi Vaccine Vectors Producing Streptococcus Pneumoniae PspA

Inclusion criteria: Subjects will be healthy adults who fully understand the purpose and details of the study. * Age: 18-40 years inclusive at the time of enrollment * Sex: Male or non-pregnant female Note: For females, negative pregnancy test at the time of entry. Females agree to use effective birth control measures to prevent pregnancy for one month prior to vaccination and for 28 days after vaccination and while on antibiotics. * Willing and able to remain in the inpatient facility for the duration of approximately 13-15 days and longer if needed. * In good health * Willing and able to provide past medical history * History of normal,regular bowel habits defined by at least 3 stools per week and less than three stools per day without frequent (greater than one per month) use of laxatives or antidiarrheal agents * Normal physical examination * Laboratory evaluation: Urine dipstick: negative or trace protein Negative urine glucose Complete blood count: WBC, hemoglobin and neutrophil count within normal limits SGPT (ALT) and alkaline phosphatase within normal limits Blood urea nitrogen (BUN), creatinine within normal limits Nonreactive ELISA for HIV-1 Negative HCV-Ab Negative HBSAg Negative nasopharyngeal (a nose and throat swab) culture for S. pneumoniae * Normal gallbladder ultrasound (ie, no gall stones) * Able to understand and follow enteric precautions, i.e., practice good hygiene, wash hands thoroughly after using the toilet and avoid food preparation for others until shedding has resolved. * Lives and works in situations with access to restrooms or bathrooms with flush toilets. * Willing to avoid eating undercooked poultry and eggs. * Able to read and willing to sign informed consent form. * Willing and able to complete a questionnaire to demonstrate an understanding of various protocol issues including potential adverse effects and precautions to limit the spread of Salmonella as discussed in the informed consent. * Willing and able to undergo rectal swabbing or stool collection. * Willing and able to maintain a daily memory aid of potential vaccine-associated adverse events, record oral temperatures and collect stool specimens * Agrees to not be involved in another study during this trial unless discussed with the investigator and approved. Exclusion criteria: * History of Salmonella infection or vaccination * History of pneumococcal vaccine * Employed as a health care worker with any patient contact, child care provider, long-term care, assisted living or nursing home care taker, or food handler. Has close contact with children less than one year of age, and has close or intimate contact with immunocompromised persons. * Pregnant or lactating women * Placement of any prosthetic device of any kind, including but not limited to, orthopedic implants, CNS shunts, endovascular grafts or shunts, cardiac pacemakers, and cochlear implants * History of splenectomy * History of gall bladder disease * History of gastric achlorhydria or use of B12 * Frequent antacid or H2 blocker usage (i.e., Tagamet) (more than once a week) * History of immunodeficiency, chronic illness, autoimmune disease, or use of immunosuppressive medications. \[Persons with vitiligo or thyroid disease (e.g. taking thyroid hormone replacement) are not excluded.\] * History of medical or psychiatric condition or occupational responsibilities which preclude subject compliance with the protocol * History of diarrheal illness within 30 days prior to enrollment (Diarrhea is defined as loose, watery stools occurring more than three times a day lasting more than a day and/or associated with fever.) * History of anaphylaxis or other serious adverse reactions to vaccines * History of allergy to ciprofloxacin and quinolones, ampicillin, penicillin, amoxicillin and third generation cephalosporins. * History of any antibiotic therapy within 14 days prior to vaccination * Receipt of live attenuated vaccine within 30 days prior to the study * Receipt of any vaccine within 14 days prior to the study * Use of experimental agents within 30 days prior to the study * Receipt of blood products or immune globulin within 6 months prior to the study * Donation of a unit of blood within 56 days prior to vaccination and for the duration of the study * Persons taking inhaled steroids will be excluded. * Persons who required pulsed steroids for conditions other than poison ivy will be excluded. * Persons who required pulsed steroids for poison ivy within 14 days prior to vaccination will be excluded.