The Host Response to Coccidioidomycosis.

Coccidioidomycosis is an important fungal disease that is found in many desert regions of the western hemisphere. The inhaled organisms are highly pathogenic, but only half of infected, immunologically intact people develop symptomatic pneumonia; most symptomatic infections resolve spontaneously, although some resolve very slowly. Furthermore, second infections are very rare and natural immunity after infection is robust. Therefore, the host response to this organism is very effective at resolving the infection in most cases and immunizing to prevent second infections. People who are immunocompromised are much more likely to develop disseminated infection. This is a comprehensive review of the innate and acquired immune responses to Coccidioides spp., the genetics of resistance to severe infection, and the search for an effective vaccine.

Immunogenetics associated with severe coccidioidomycosis.

Disseminated coccidioidomycosis (DCM) is caused by Coccidioides, pathogenic fungi endemic to the southwestern United States and Mexico. Illness occurs in approximately 30% of those infected, less than 1% of whom develop disseminated disease. To address why some individuals allow dissemination, we enrolled patients with DCM and performed whole-exome sequencing. In an exploratory set of 67 patients with DCM, 2 had haploinsufficient STAT3 mutations, and defects in ß-glucan sensing and response were seen in 34 of 67 cases. Damaging CLEC7A and PLCG2 variants were associated with impaired production of ß-glucan-stimulated TNF-α from PBMCs compared with healthy controls. Using ancestry-matched controls, damaging CLEC7A and PLCG2 variants were overrepresented in DCM, including CLEC7A Y238* and PLCG2 R268W. A validation cohort of 111 patients with DCM confirmed the PLCG2 R268W, CLEC7A I223S, and CLEC7A Y238* variants. Stimulation with a DECTIN-1 agonist induced DUOX1/DUOXA1-derived hydrogen peroxide [H2O2] in transfected cells. Heterozygous DUOX1 or DUOXA1 variants that impaired H2O2 production were overrepresented in discovery and validation cohorts. Patients with DCM have impaired ß-glucan sensing or response affecting TNF-α and H2O2 production. Impaired Coccidioides recognition and decreased cellular response are associated with disseminated coccidioidomycosis.

Coccidioides Species: A Review of Basic Research: 2022.

Coccidioides immitis and posadasii are closely related fungal species that cause coccidioidomycosis. These dimorphic organisms cause disease in immunocompetent as well as immunocompromised individuals and as much as 40% of the population is infected in the endemic area. Although most infections resolve spontaneously, the infection can be prolonged and, in some instances, fatal. Coccidioides has been studied for more than 100 years and many aspects of the organism and the disease it causes have been investigated. There are over 500 manuscripts concerning Coccidioides (excluding clinical articles) referenced in PubMed over the past 50 years, so there is a large body of evidence to review. We reviewed the most accurate and informative basic research studies of these fungi including some seminal older studies as well as an extensive review of current research. This is an attempt to gather the most important basic research studies about this fungus into one publication. To focus this review, we will discuss the mycology of the organism exclusively rather than the studies of the host response or clinical studies. We hope that this review will be a useful resource to those interested in Coccidioides and coccidioidomycosis.

Controversies in the Management of Central Nervous System Coccidioidomycosis.

Central nervous system infection with Coccidioides spp. is fatal if untreated and complications occur even when therapy is directed by experienced clinicians. We convened a panel of clinicians experienced in the management of coccidioidal meningitis to summarize current controversies and provide consensus for the management of this difficult infection.

Antimicrobial-Resistant Shigella spp. in San Diego, California, USA, 2017-2020.

Annually, Shigella spp. cause ≈188 million cases of diarrheal disease globally, including 500,000 cases in the United States; rates of antimicrobial resistance are increasing. To determine antimicrobial resistance and risk factors in San Diego, California, USA, we retrospectively reviewed cases of diarrheal disease caused by Shigella flexneri and S. sonnei diagnosed during 2017-2020. Of 128 evaluable cases, S. flexneri was slightly more common than S. sonnei; most cases were in persons who were gay or bisexual cisgender men, were living with HIV, were unhoused, or used methamphetamines. Overall, rates of resistance to azithromycin, fluoroquinolones, ampicillin, and trimethoprim/sulfamethoxazole (TMP/SMX) were comparable to the most recent national data reported from the Centers for Disease Control and Prevention; 55% of isolates were resistant to azithromycin, 23% to fluoroquinolones, 70% to ampicillin, and 83% to TMP/SMX. The rates that we found for TMP/SMX were slightly higher than those in national data.

Invasive Non-typhoidal Salmonella (iNTS) Infections.

Salmonella enterica invade the host via the intestinal tract. There are ~2 thousand distinct serovars of non-typhoidal Salmonella (NTS) that can cause gastroenteritis in normal hosts, but bacteremia is an uncommon complication of gastroenteritis except at the extremes of age (in Graham et al. Nontyphoidal Salmonella infections of children in tropical Africa. Pediatr Infect Dis J 2000; 19:1189-96). In contrast, enteric fever and invasive NTS infections (iNTS) are each caused by only a few serovars of S. enterica (Table 1), and bacteremia not gastroenteritis is their principal manifestation.

Decoding Transcription Regulatory Mechanisms Associated with Coccidioides immitis Phase Transition Using Total RNA.

New or emerging infectious diseases are commonly caused by pathogens that cannot be readily manipulated or studied under common laboratory conditions. These limitations hinder standard experimental approaches and our abilities to define the fundamental molecular mechanisms underlying pathogenesis. The advance of capped small RNA sequencing (csRNA-seq) now enables genome-wide mapping of actively initiated transcripts from genes and other regulatory transcribed start regions (TSRs) such as enhancers at a precise moment from total RNA. As RNA is nonpathogenic and can be readily isolated from inactivated infectious samples, csRNA-seq can detect acute changes in gene regulation within or in response to a pathogen with remarkable sensitivity under common laboratory conditions. Studying valley fever (coccidioidomycosis), an emerging endemic fungal infection that increasingly impacts livestock, pet, and human health, we show how csRNA-seq can unravel transcriptional programs driving pathogenesis. Performing csRNA-seq on RNA isolated from different stages of the valley fever pathogen Coccidioides immitis revealed alternative promoter usage, connected cis-regulatory domains, and a WOPR family transcription factor, which are known regulators of virulence in other fungi, as being critical for pathogenic growth. We further demonstrate that a C. immitis WOPR homologue, CIMG_02671, activates transcription in a WOPR motif-dependent manner. Collectively, these findings provide novel insights into valley fever pathogenesis and provide a proof of principle for csRNA-seq as a powerful means to determine the genes, regulatory mechanisms, and transcription factors that control the pathogenesis of highly infectious agents. IMPORTANCE Infectious pathogens like airborne viruses or fungal spores are difficult to study; they require high-containment facilities, special equipment, and expertise. As such, establishing approaches such as genome editing or other means to identify the factors and mechanisms underlying caused diseases, and, thus, promising drug targets, is costly and time-intensive. These obstacles particularly hinder the analysis of new, emerging, or rare infectious diseases. We recently developed a method termed capped small RNA sequencing (csRNA-seq) that enables capturing acute changes in active gene expression from total RNA. Prior to csRNA-seq, such an analysis was possible only by using living cells or nuclei, in which pathogens are highly infectious. The process of RNA purification, however, inactivates pathogens and thus enables the analysis of gene expression during disease progression under standard laboratory conditions. As a proof of principle, here, we use csRNA-seq to unravel the gene regulatory programs and factors likely critical for the pathogenesis of valley fever, an emerging endemic fungal infection that increasingly impacts livestock, pet, and human health.

Transcriptional Analysis of Coccidioides immitis Mycelia and Spherules by RNA Sequencing.

Coccidioides immitis and C. posadasii are dimorphic fungi that transform from mycelia with internal arthroconidia in the soil to a tissue form known as a spherule in mammals. This process can be recapitulated in vitro by increasing the temperature, CO2 and changing other culture conditions. In this study, we have analyzed changes in gene expression in mycelia and young and mature spherules. Genes that were highly upregulated in young spherules include a spherule surface protein and iron and copper membrane transporters. Genes that are unique to Coccidioides spp. are also overrepresented in this group, suggesting that they may be important for spherule differentiation. Enriched GO terms in young spherule upregulated genes include oxidation-reduction, response to stress and membrane proteins. Downregulated genes are enriched for transcription factors, especially helix-loop-helix and C2H2 type zinc finger domain-containing proteins, which is consistent with the dramatic change in transcriptional profile. Almost all genes that are upregulated in young spherules remain upregulated in mature spherules, but a small number of genes are differentially expressed in those two stages of spherule development. Mature spherules express more Hsp31 and amylase and less tyrosinase than young spherules. Some expression of transposons was detected and most of the differentially expressed transposons were upregulated in spherules.

Interleukin-8 Receptor 2 (IL-8R2)-Deficient Mice Are More Resistant to Pulmonary Coccidioidomycosis than Control Mice.

The pathology of human coccidioidomycosis is granulomatous inflammation with many neutrophils surrounding ruptured spherules, but the chemotactic pathways that draw neutrophils into the infected tissues are not known. We previously showed that formalin-killed spherules (FKS) stimulate mouse macrophages to secret macrophage inflammatory protein 2 (MIP-2), which suggested that CXC ELR+ chemokines might be involved in neutrophil recruitment in vivo To test that hypothesis, we intranasally infected interleukin-8R2 (IL-8R2) (Cxcr2)-deficient mice on a BALB/c background with Coccidioides immitis RS. IL-8R2-deficient mice had fewer neutrophils in infected lungs than controls, but unexpectedly the IL-8R2-deficient mice had fewer organisms in their lungs than the control mice. Infected IL-8R2-deficient mouse lungs had higher expression of genes associated with lymphocyte activation, including the Th1 and Th17-related cytokines Ifnγ and Il17a and the transcription factors Stat1 and Rorc Additionally, bronchial alveolar lavage fluid from infected IL-8R2-deficient mice contained more IL-17A and interferon-γ (IFN-γ). We postulate that neutrophils in the lung directly or indirectly interfere with the development of a protective Th1/Th17 immune response to C. immitis at the site of infection.

Innate Immune Receptors and Defense Against Primary Pathogenic Fungi.

The innate immune system is critical for natural resistance to all pathogenic microorganisms, including fungi. The innate response plays a vital role in resistance to infections before the antigen-specific immune response and also influences antigen-specific adaptive immunity. There are many different receptors for the innate immune response to fungi, and some receptors have been found to play a significant role in the response to human infections with opportunistic fungi. Most human infections are caused by opportunistic fungi, but a small number of organisms are capable of causing infections in normal hosts. The primary pathogenic fungi that cause invasive infections include Blastomyces spp., Cryptococcus gattii, Coccidioides spp., Histoplasma spp., and Paracoccidioides spp. In this review of innate immune receptors that play a role in infections caused by these organisms, we find that innate immunity differs between organisms.

Ethambutol-resistant Mycobacterium kansasii cervical lymphadenitis in an immunocompetent adult patient: A case report and literature review.

Mycobacterium kansasii extrapulmonary infections are infrequent in immunocompetent adults. Rifampin (RIF), clarithromycin (CLR), isoniazid (INH) and ethambutol (EMB) are included in all the standard regimens against M.kansasii. We report a case of a healthy 65-year-old male farmer who presented with isolated right supraclavicular lymphadenopathy. The lymph node FNA showed acid-fast-bacilli and granulomatous inflammation. Quantiferon TB Gold test, HIV serology, and functional immunological studies were all negative or normal. He was put on a standard 4 drugs anti-tuberculous regimen that was switched to RIF + CLR+ INH after the Microbiology lab demonstrated an EMB-resistant Mycobacterium kansasii isotype I strain. The patient was cured after 12 months of therapy. This is the 6th reported case of M. kansasii extrapulmonary lymphadenitis in an immunocompetent adult and the 2nd showing EMB resistance in the world literature. Antimycobacterial regimens against M. kansasii, classically resistant to pyrazinamide (PZA) might also exclude EMB due to its increasing resistance in Europe. A 612 months therapy with at least 2 effective antimycobacterial drugs including RIF + CLR might be enough to treat extrapulmonary M. kansasii infections in immunocompetents.

The N125S polymorphism in the cathepsin G gene (rs45567233) is associated with susceptibility to osteomyelitis in a Spanish population.

BACKGROUND: Osteomyelitis is a bone infection, most often caused by Staphylococcus aureus, in which neutrophils play a key role. Cathepsin G (CTSG) is a bactericidal serine protease stored in the neutrophil azurophilic granules. CTSG regulates inflammation, activating matrix metalloproteinases (MMPs), and coagulation. Lactoferrin (LF), a neutrophil glycoprotein, increases CTSG catalytic activity and induces inflammation. The aim of this study was to analyze a potential association between a CTSG gene polymorphism (Asn125Ser or N125S, rs45567233), that modifies CTSG activity, and could affect susceptibility to, or outcome of, bacterial osteomyelitis. METHODS: CTSG N125S polymorphism was genotyped in 329 osteomyelitis patients and 415 controls), Blood coagulation parameters, serum CTSG activity, LF, MMP-1, MMP-13, and soluble receptor activator for nuclear factor κ B ligand (sRANKL) levels were assessed in carriers of the different CTSG genotypes. RESULTS: CTSG N125S (AG) genotype was significantly more frequent among osteomyelitis patients than controls (15.5% vs. 9.4%, p = 0.014). CTSG N125S variant G allele (AG +GG) was also more frequent among osteomyelitis patients (8.1% vs. 4.7%, p = 0.01). Serum CTSG activity and LF levels were significantly higher in osteomyelitis patients carrying the G allele compared to those with the AA genotype, (p<0.04). Serum MMP-1 was lower in the G allele carriers (p = 0.01). There was no association between these genotypes and clinical characteristics of osteomyelitis, or coagulation parameters, MMP-13, and sRANKL serum levels. CONCLUSIONS: Differences in the CTSG gene might enhance osteomyelitis susceptibility by increasing CTSG activity and LF levels.

A 37-Year-Old Man With Pleuritic Chest Pain.

CASE PRESENTATION: A 37-year-old man with poorly controlled type 2 diabetes presented with severe right-sided pleuritic chest pain, respiratory splinting, and cough. Two weeks earlier, he had been evaluated at an urgent care for cough and was prescribed a 5-day course of azithromycin for bronchitis. He then presented to our ED reporting mild, right-sided pleuritic chest pain. Vital signs were normal, and his chest radiograph showed a trace right pleural effusion (Fig 1A). He was discharged with naproxen for pleurisy. Three days later, he returned, reporting a dramatic increase in the severity of his pleuritic chest pain and a cough that had become productive of yellow-brown sputum. He denied fever, but endorsed chills and night sweats. His medications included atorvastatin, lisinopril, metformin, and saxagliptin. His parents were from Guam, although he was born and raised in San Diego, CA. He was employed as a social worker and denied any history of cigarette smoking, alcohol, or drug use.

A case of inguinal lymphogranuloma venereum imitating malignancy on CT imaging.

Lymphogranuloma venereum is a sexually transmitted infection caused by serovars L1, L2, and L3 of Chlamydia trachomatis. We here report a case of Lymphogranuloma venereum, confirmed by PCR testing, which mimicked malignancy on CT imaging.

A review of innate and adaptive immunity to coccidioidomycosis.

Coccidioidomycosis is a human fungal disease cause by inhalation of aerosol spores produced by Coccidioides posadasii or Coccidioides immitis. This disease is a common cause of community-acquired pneumonia in the endemic areas of the Southwestern United States. It also can present as a life-threatening disease as the fungal cells disseminate to skin, bone, and central nervous system. The outcome of coccidioidomycosis is largely determined by the nature of host immune response to the infection. Escalation of symptomatic infections and increased cost of long-term antifungal treatment warrant a concerted effort to better understand the innate and adaptive immune responses and the genetics associated with coccidioidomycosis susceptibility. This knowledge can be harnessed for development of a human vaccine against Coccidioides and advance clinic management of this disease. This review discusses recently reported studies on innate and adaptive immunity to Coccidioides infection, Mendelian susceptibility to disseminated disease and progress toward a human vaccine against this formidable disease.

APX001 and Other Gwt1 Inhibitor Prodrugs Are Effective in Experimental Coccidioides immitis Pneumonia.

Coccidioidomycosis is a systemic fungal infection caused by the inhalation of the arthroconidia of either of two closely related dimorphic fungi, Coccidioides immitis and C. posadasii, that are endemic in the southwestern United States and other areas in the Western Hemisphere. Chronic cavitary pulmonary infections and extrapulmonary sites of infection are very difficult to treat and often require lifelong azole therapy. APX001A is the first in a new class of broad-spectrum antifungal agents that inhibit Gwt1, an enzyme which is required for cell wall localization of glycosylphosphatidylinositol (GPI)-anchored mannoproteins in fungi. APX001A and several analogs were highly active against clinical isolates of Coccidioides, inhibiting hyphal growth at low nanogram/ml concentrations. APX001 is the N-phosphonooxymethyl prodrug of APX001A, currently in clinical trials for the treatment of invasive fungal infections. Mice were treated orally once daily with 26 mg/kg/day of APX001 and the prodrug analog APX2097, 2 h after administration of the pan-cytochrome P450 inhibitor 1-aminobenzotriazole, which was used to enhance drug half-life and exposures to more closely mimic human pharmacokinetics of APX001A. Five days of treatment reduced lung colony counts by nearly 3 logs and prevented dissemination, similar to the efficacy of fluconazole dosed orally at 25 mg/kg twice daily. In a survival experiment, both APX001- and APX2097-treated mice survived significantly longer than control and fluconazole-treated mice. APX001 and other members of this new class of antifungal agents may offer great promise as effective therapies for coccidioidomycosis.

Coccidioides immitis and posadasii; A review of their biology, genomics, pathogenesis, and host immunity.

Coccidioides immitis and C. posadasii are two highly pathogenic dimorphic fungal species that are endemic in the arid areas of the new world, including the region from west Texas to southern and central California in the USA that cause coccidioidomycosis (also known as Valley Fever). In highly endemic regions such as southern Arizona, up to 50% of long term residents have been infected. New information about fungal population genetics, ecology, epidemiology, and host-pathogen interactions is becoming available. However, our understanding of some aspects of coccidioidomycosis is still incomplete, including the extent of genetic variability of the fungus, the genes involved in virulence, and how the changes in gene expression during the organism's dimorphic life cycle are related to the transformation from a free-living mold to a parasitic spherule. Unfortunately, efforts to develop an effective subunit vaccine have not yet been productive, although two potential live fungus vaccines have been developed.