Andrew George Smith, 86, a former microbiologist at the University of Maryland School of Medicine, died of Alzheimer's disease Sept. 2 at the Joseph Richey Hospice in Baltimore. He lived in Ellicott City.

Dr. Smith was born in Williamsport, Pa., and graduated from Penn State University in 1940 with majors in microbiology and chemistry. After working in several laboratories in the Philadelphia area, he joined the Marine Corps in 1942. He served in the Pacific, participating in the invasions of Roi-Namur, Saipan, Tinian and Iwo Jima islands.

He received his discharge in December 1945 as a first lieutenant, and remained a proud veteran of the Star Spangled Banner Chapter No. 25, 4th Marine Division, throughout his life.

Upon returning from the war, Dr. Smith enrolled as a graduate student at the University of Pennsylvania, receiving his master's degree in 1947 and his doctorate in 1950. His graduate research focused on microscopy, a career-long interest, and bacterial morphology. He also was an expert in mycology, the branch of botany dealing with fungi.

He joined the faculty of the University of Maryland School of Medicine and except for brief stints at the University of Vermont School of Medicine and the Baltimore Biological Laboratory in Cockeysville, remained there throughout his career.

Dr. Smith held professorships in the departments of microbiology, pathology, medical technology and medicine. He also served as director of the Division of Microbiology at the University of Maryland's Medical Center laboratories. His library of slides and cultures augmented his lectures and demonstrations, and he received many teaching awards from his students and the university.

He retired in 1983, but returned to work for the medical soon after. He retired again in 1995.

He was a member of the American Society of Microbiology, American Association for the Advancement of Science, the International Society for Human and Animal Mycology and the Medical Mycological Society of the Americas. He was a diplomate of the American Board of Medical Microbiology and a fellow of the Academy of Microbiology.

Survivors include his wife of 59 years, Lucy Smith of Ellicott City; two daughters, Eileen Smith of Albany, Calif., and Diane Smith Kownacki of Herndon; two granddaughters; and a great-grandson.