Ludwig Halberstädter (9 December 1876, in Beuthen, Oberschlesien – 20 August 1949) was a German-Jewish radiologist.
In 1901 he obtained his medical doctorate from the University of Breslau, and following graduation became an assistant to surgeon Carl Garré (1857–1928) at the University of Königsberg. Afterwards he returned to Breslau as an assistant to dermatologist Albert Neisser (1855–1916), under whose direction he participated on a medical research mission to Java (1907).
Chlamydia trachomatis (/kləˈmɪdiə trəˈkoʊmətɪs/) is a Gram-negative, anaerobic bacterium responsible for chlamydia and trachoma. C. trachomatis exists in two forms, an extracellular infectious elementary body (EB) and an intracellular non-infectious reticulate body (RB). The EB attaches to host cells and enter the cell using effector proteins, where it transforms into the metabolically active RB. Inside the cell, RBs rapidly replicate before transitioning back to EBs, which are then released to infect new host cells.
The earliest description of C. trachomatis was in 1907 by Stanislaus von Prowazek and Ludwig Halberstädter as a protozoan. It was later thought to be a virus due to its small size and inability to grow in laboratories. It was not until 1966 when it was discovered as a bacterium by electron microscopy after its internal structures were visually observed.