There is growing evidence that pathogens can affect the outcomes of interspecific competition, which may arise indirectly because infection alters the resource utilization of the host. The direct effects of infection on host fitness (generally negative) and the consequences of indirect effects on other species (positive or negative) mediated by host species ultimately dictate species coexistence. Pathogens can adjust interspecific competition by affecting consumer-resource interactions. These indirect effects may transmit through food webs and ripple throughout the ecological communities, and thus possibly affect ecosystem functioning and resilience. Therefore, it is necessary to consider the role of indirect effects of pathogens in species coexistence and community construction. The existing theoretical studies of pathogen-mediated competition, however, are based on phenomenological models (e.g., the Lotka-Volterra competition model). As these models do not specify the mechanism of competition between species, they neither specify what the species compete for nor how they compete. These models use some parameters (e.g., the competition coefficient) to describe the effects of one species on the per capita growth rates of the other species in a community, ignoring the interaction between consumers and resources, and resource dynamics. Thus, using such phenomenological models, it is impossible to capture how pathogens mediate exploitative competition by influencing the resource utilization of their host. To better understand this process, based on resource competition theory (explicitly incorporating resource consumption), we constructed a specialist pathogen-mediated resource competition model in which two species compete for two abiotic essential resources, and one of the competitors can be infected by a directly transmitted specialist pathogen. Our motivation is to understand how the combination of two different interspecific interactions (parasitism and interspecific resource competition) determines species coexistence and community structure. Then, we conducted the analysis and computer simulations of the model. The results showed that:(1) pathogens reduced the host's consumption rate of resources (shorter consumption vector) and raised the host's resource requirement (upward shift of the zero isoclines), which implied a weakening of the host's competitiveness. (2) Although specialist pathogen infection affects the density of the host, it does not change the coexistence status of co-existing species. (3) Specialist pathogens can make it easier for the non-host competitor to invade, resulting in a coexistence situation, which greatly increases the likelihood of the coexistence of competing species and essentially contributes to the maintenance of species diversity. (4) The transmission rate and virulence of specialist pathogens have complicated effects on the coexistence of competing species, with high transmission and moderate virulence promoting species coexistence the most. Our results clarify pathogens' potential alteration of species resource utilization patterns and highlight the importance of pathogens in species coexistence, biological invasions, and maintenance of species diversity.