Spectrum of activity<unk> s have a broad spectrum of antibiotic action. Originally, they possessed some level of bacteriostatic activity against almost all medically relevant aerobic and anaerobic bacterial genera, both Gram-positive and Gram-negative, with a few exceptions, such as Pseudomonas aeruginosa and Proteus spp., which display intrinsic resistance. However, acquired (as opposed to inherent) resistance has proliferated in many pathogenic organisms and greatly eroded the formerly vast versatility of this group of antibiotics. Resistance amongst Staphylococcus spp., Streptococcus spp., Neisseria gonorrhoeae, anaerobes, members of the Enterobacteriaceae, and several other previously sensitive organisms is now quite common.<unk> s remain especially useful in the management of infections by certain obligately intracellular bacterial pathogens such as Chlamydia, Mycoplasma, and Rickettsia. They are also of value in spirochaetal infections, such as syphilis, leptospirosis, and Lyme disease. Certain rare or exotic infections, including anthrax, plague, and brucellosis, are also susceptible to<unk> s.<unk>  tablets were used in the plague outbreak in India in 1994.<unk>  is first-line therapy for Rocky Mountain spotted fever (Rickettsia), Lyme disease (B. burgdorferi), Q fever (Coxiella), psittacosis, Mycoplasma pneumoniae, and nasal carriage of meningococci. It is also one of a group of antibiotics which together may be used to treat peptic ulcers caused by bacterial infections. The mechanism of action for the antibacterial effect of<unk> s relies on disrupting protein translation in bacteria, thereby damaging the ability of microbes to grow and repair; however, protein translation is also disrupted in eukaryotic mitochondria leading to effects that may confound experimental results. The following list presents MIC susceptibility data for some medically significant microorganisms: * Escherichia coli: 1 / to >128 μg/mL * Shigella : 1 μg/mL to 128 μg/mL Anti-eukaryote use The<unk> s also have activity against certain eukaryotic parasites, including those responsible for diseases such as dysentery caused by an amoeba, malaria (a plasmodium), and balantidiasis (a ciliate). Use as a biomarker<unk>  hydrochloride is available as yellow crystalline powder. Since<unk>  is absorbed into bone, it is used as a marker of bone growth for biopsies in humans.<unk>  labeling is used to determine the amount of bone growth within a certain period of time, usually a period around 21 days.<unk>  is incorporated into mineralizing bone and can be detected by its fluorescence. In "double<unk>  labeling", a second dose is given 11–14 days after the first dose, and the amount of bone formed during that interval can be calculated by measuring the distance between the two fluorescent labels.<unk>  is also used as a biomarker in wildlife to detect consumption of medicine- or vaccine-containing baits.
Tetracycline
Minocycline
Chloramphenicol
Oxytetracycline
Cephalosporin
Anisomycin
Methicillin
Thiamphenicol