A Rare Case of Simultaneous Histoplasmosis and Coccidioidomycosis.

Histoplasma and Coccidioides are fungi that can cause serious infections in immunocompromised patients. Histoplasma is primarily endemic to the central and eastern United States, while Coccidioides is primarily endemic to the southwestern United States. Here, we present a case of simultaneous histoplasmosis and coccidioidomycosis. A 69-year-old female with a past medical history of rheumatoid arthritis and polymyalgia rheumatica on immunosuppression presented to the emergency department (ED) with fevers, malaise, and confusion. She initially developed these symptoms a month prior while visiting her son in Tennessee. During this time, she lived in his basement where mold exposure was confirmed. Her symptoms gradually improved but recurred, prompting her to come to the ED. In the ED, her vital signs were as follows: temperature of 36.5˚C, heart rate of 88, respiratory rate of 16, blood pressure of 158/88, and oxygen saturation of 94% on room air. She was alert and oriented without focal neurologic deficits. Heart sounds were regular rate and rhythm, lungs were clear to auscultation bilaterally and abdomen was soft, non-tender, and non-distended. No skin rashes were observed either. Laboratory work revealed an elevated C-reactive protein (CRP), thrombocytopenia, and transaminitis. Chest X-ray showed patchy airspace disease in the left lower lobe, and she underwent a lumbar puncture which was negative for meningitis. Due to her travel to Tennessee, a urine Histoplasma antigen test was ordered which resulted positive, along with a beta-1,3-D-glucan level >500 picograms per milliliter (pg/mL), indicating disseminated histoplasmosis. Coccidioides antibodies also resulted positive, pointing to concurrent coccidioidomycosis. The patient was subsequently started on intravenous amphotericin B. Over the following days, the patient's transaminitis and thrombocytopenia improved, and she was ultimately discharged on oral itraconazole with outpatient infectious disease follow-up. Although the patient's exposure to mold was likely the source of her histoplasmosis, the source of her coccidioidomycosis is less clear given its endemicity. Even rarer is the coinciding infections, and to the best of our knowledge, this is one of the very few known cases. Immunocompromised patients who present with infectious symptoms should have a low threshold for a fungal infection workup, as prompt treatment is crucial to limiting the morbidity and mortality of these infections. Furthermore, geographic location should not narrow one's workup to endemic fungi only, as evidenced by this patient's simultaneous infections.

Mtb-Selective 5-Aminomethyl Oxazolidinone Prodrugs: Robust Potency and Potential Liabilities.

Linezolid is a drug with proven human antitubercular activity whose use is limited to highly drug-resistant patients because of its toxicity. This toxicity is related to its mechanism of action─linezolid inhibits protein synthesis in both bacteria and eukaryotic mitochondria. A highly selective and potent series of oxazolidinones, bearing a 5-aminomethyl moiety (in place of the typical 5-acetamidomethyl moiety of linezolid), was identified. Linezolid-resistant mutants were cross-resistant to these molecules but not vice versa. Resistance to the 5-aminomethyl molecules mapped to an N-acetyl transferase (Rv0133) and these mutants remained fully linezolid susceptible. Purified Rv0133 was shown to catalyze the transformation of the 5-aminomethyl oxazolidinones to their corresponding N-acetylated metabolites, and this transformation was also observed in live cells of Mycobacterium tuberculosis. Mammalian mitochondria, which lack an appropriate N-acetyltransferase to activate these prodrugs, were not susceptible to inhibition with the 5-aminomethyl analogues. Several compounds that were more potent than linezolid were taken into C3HeB/FeJ mice and were shown to be highly efficacious, and one of these (9) was additionally taken into marmosets and found to be highly active. Penetration of these 5-aminomethyl oxazolidinone prodrugs into caseum was excellent. Unfortunately, these compounds were rapidly converted into the corresponding 5-alcohols by mammalian metabolism which retained antimycobacterial activity but resulted in substantial mitotoxicity.

Discovery and Structure-Activity-Relationship Study of N-Alkyl-5-hydroxypyrimidinone Carboxamides as Novel Antitubercular Agents Targeting Decaprenylphosphoryl-ß-d-ribose 2'-Oxidase.

Magnesium plays an important role in infection with Mycobacterium tuberculosis ( Mtb) as a signal of the extracellular environment, as a cofactor for many enzymes, and as a structural element in important macromolecules. Raltegravir, an antiretroviral drug that inhibits HIV-1 integrase is known to derive its potency from selective sequestration of active-site magnesium ions in addition to binding to a hydrophobic pocket. In order to determine if essential Mtb-related phosphoryl transfers could be disrupted in a similar manner, a directed screen of known molecules with integrase inhibitor-like pharmacophores ( N-alkyl-5-hydroxypyrimidinone carboxamides) was performed. Initial hits afforded compounds with low-micromolar potency against Mtb, acceptable cytotoxicity and PK characteristics, and robust SAR. Elucidation of the target of these compounds revealed that they lacked magnesium dependence and instead disappointingly inhibited a known promiscuous target in Mtb, decaprenylphosphoryl-ß-d-ribose 2'-oxidase (DprE1, Rv3790).

MEPicides: α,ß-Unsaturated Fosmidomycin Analogues as DXR Inhibitors against Malaria.

Severe malaria due to Plasmodium falciparum remains a significant global health threat. DXR, the second enzyme in the MEP pathway, plays an important role to synthesize building blocks for isoprenoids. This enzyme is a promising drug target for malaria due to its essentiality as well as its absence in humans. In this study, we designed and synthesized a series of α,ß-unsaturated analogues of fosmidomycin, a natural product that inhibits DXR in P. falciparum. All compounds were evaluated as inhibitors of P. falciparum. The most promising compound, 18a, displays on-target, potent inhibition against the growth of P. falciparum (IC50 = 13 nM) without significant inhibition of HepG2 cells (IC50 > 50 µM). 18a was also tested in a luciferase-based Plasmodium berghei mouse model of malaria and showed exceptional in vivo efficacy. Together, the data support MEPicide 18a as a novel, potent, and promising drug candidate for the treatment of malaria.