Infectious diseases (ID) specialists either directly manage infections or they provide consultation service to other hospital departments. Patients with infections, seen by ID consultants, are more likely to receive effective and appropriate empirical antimicrobial therapy, to have decreased treatment costs, to survive the infection and be cured [^1-4]. Referring clinicians expect ID specialists to mainly focus on recommendations for prompt and accurate methods to diagnose infection, design local hospital antibiotic policies to facilitate appropriate antimicrobial therapy and prophylaxis, surveillance of antimicrobial resistance and hospital epidemiology, and the establishment of hospital infection control programs [⁵]. On the other hand, as physicians working in their own departments, ID specialists are required to meet all the clinical needs of ID patients, not only the provision of infection management.

In medical practice much of the work done by both ID physicians and clinical microbiologists requires both laboratory and clinical skills. Supporters of combined ID and clinical microbiology practice are already known in the world. For instance, according to Peter Moss, the vice-president of the British Infection Association, there are proposals to bring the two training curricula together in the United Kingdom in the future. In Turkey, ID physicians come from a laboratory background and have been working as ID and Clinical Microbiology (IDCM) specialists (IDCMSs). According to regulations implemented in 2010 by Turkish Medical Postgraduate Training Council, a total of five-year ID training in Turkey involved 12 months of internal medicine, two months of pulmonology, and one month of pediatrics teaching [⁶]. Before that date internal medicine made up a total of six months in the postgraduate ID training calendar in Turkey. However, this was not applied compulsorily in most of the training hospitals, but rather accepted as an advice before 2010 in Turkey. On the other hand, every ID department has its own laboratory inside the clinic, and the IDCM fellows have been trained in the field of microbiology in due course of all their training at the bench side. Thus, this study aims to provide data to determine which medical disciplines are frequently necessary to fulfil the needs of patients hospitalized in ID clinics, and at which point the IDCMSs need to consult with other discipline specialists. Consequently, our study aims to identify possible ways to strengthen ID training, which is and should be interrelated to microbiology. The idea behind this was that how an IDCM fellow could be trained in other medical fields to offer perfect medical service in the treatment of an ID patient with coexistent disorders or for those the infections caused considerable organ based injuries. That point of view did not target the utopia for IDCMSs to substitute clinicians from other medical disciplines. Rather, we believe that this approach will help the optimization of the processes like referring the patients to other specialists, the decision of optimal timing of consultation, compliance to their recommendations, and the adaptability of the IDCMSs into the changing status of the patient either due to concordant non-ID problems or owing to the ID-based organ injuries. In addition, combining the curricula of other medical branches into the ID training will contribute handling the situation by IDCMSs' own to a degree at the minimum. We believe that this evidence-based training policy will decrease the workload in the hospital and purify the interdisciplinary collaborations. On the other hand, to the best of the authors' knowledge, this is the first study of its kind in the literature on the utilization of specialty consultation services provided to ID departments.

In this study, 1343 consultations belonging to 605 patients were included. IDCMSs requested 815 consultations (60.7%) from medical disciplines and 528 consultations (39.3%) from surgical clinics. Seventy-nine patients were hospitalized for two distinct infections and 526 cases had just one ID diagnosis. When patients were evaluated according to sepsis definitions, 148 (24.5%) were defined as having sepsis, 130 (21.5%) had severe sepsis, and 18 (3.0%) had septic shock. The evaluation on patients' outcomes indicated that, 363 cases (60.0%) were discharged with complete cure, 131 (21.7%) were sent home after clinical improvement or with sequential therapy, 59 cases (9.8%) were transferred to another department in the same hospital, 26 patients (4.3%) died, 16 cases (2.6%) were transferred to another hospital, and ten cases (1.6%) took their own discharge. Among the patients transferred to another department, 20 (3.3%) cases were assigned to medical disciplines and 39 (6.5%) were transferred to surgical departments. General surgery was the most frequent transfer location area with 12 cases, followed by five patients transferred to neurosurgery. When the consultation requests were assessed owing to invasive expectations of the IDCMSs or due to either symptom or syndrome-based grounds, IDCMSs consulted surgical departments for invasive procedures more frequently than medical departments (χ² = 12.340, P = 0.002).

The consultant departments are presented in Table 1 and the distribution of referred clinics according to ID diagnoses for which the patients were hospitalized are presented in Table 2. Analyses for FCR are shown in table 3 and the independent variables affecting FCR are assessed in a logistic regression model, which is presented in table 4.

The most frequently contacted medical disciplines were pulmonology, neurology, general internal medicine, cardiology, gastroenterology, nephrology, dermatology, haematology, and endocrinology while ear-nose-throat (ENT), general surgery, urology, orthopaedics, ophthalmology, and neurosurgery were the most commonly needed surgical clinics.

When D1 and D2 groups were compared for patients with IRFD, IDCMSs have significantly higher unchanged initial diagnoses in urology consultations (% 59.6) (χ² = 4.226, P = 0.040). Therapeutic approaches after the establishment of definite diagnosis such as starting treatment, changing the regimen, addition of drugs to the initial regimen or continuing the initial treatment without modification were not related to higher consultation demands (χ² = 7.17, P = 0.06). There was a significant difference for T1 and T2 groups between the departments (Mantel Haenszel χ² = 29.16, P = 0.000). IDCMSs have significantly higher unchanged therapeutic approaches for patients with IRFD in the consultations of general internal medicine (66.0%) and urology (66.7%) (χ² = 10.106, P = 0.001; χ² = 4.707, P = 0.030 respectively).

Infectious Diseases training is commonly accepted to be a combination of clinical microbiology, internal medicine and epidemiology [^9-12]. ID clinicians possess an array of valuable skills. Experienced ID physicians often reduce the use of unnecessary expensive diagnostic tests; use the outpatient field for continued intravenous therapy; switch to sequential oral therapy when appropriate; and enhance patient satisfaction by optimizing the overall quality [⁹]. The question is how to provide the relevant training to achieve these skills. The optimum training design should be based on the needs of, and fit well within the overall health structure of the country. For this reason, the specialty of ID has developed differently in different countries over the years [¹¹]. The purpose of this paper was not either to advocate any particular design or to evaluate the lacking skills in a qualitative way. But, rather to focus on the clinical requisites or the dependency of the ID specialist training based on clinical microbiology.

Patient flow in the ID department is mainly thorough the ID polyclinic, where the patients first applied in the hospital. This is followed by the other patients transferred from the other departments including the emergency room. According to Guven Celebi, who worked on a survey on the remuneration of IDCMSs in Turkey, these doctors are generally paid in 2000 to 3000 Euros range depending on the workload in Turkish Public and University Hospitals.

According to our data pulmonology support was the most frequent requisite of hospitalized ID cases followed by neurology. The cooperation requirements were also clear for other internal medicine disciplines such as cardiology, gastroenterology, nephrology, hematology, and endocrinology. Dermatology support was frequently sought and IRFD comprised more than half of the cases for that discipline. IDCMSs were found to have better therapeutic approaches for the patients with IRFD who were consulted to general internal medicine. That department is the primary application site of all internal medicine disciplines and the patients are distributed to other internal medicine clinics via general internal medicine. Hence, IDCMSs had better patient management for ID patients when they were to consult general internal medicine, probably due to the relatively basic nature of this branch. Another standpoint was that ID patients needed 1.8 fold more frequent external help when the coexisting noninfectious disorders increased from one to two. In our patients the most frequent comorbid noninfectious conditions were related to cardiology, nephrology, and endocrinology. Some concordant disorders have the particular potential ID impacts, as in diabetes mellitus [¹³] or chronic renal insufficiency [¹⁴]. According to our data, IDCMSs seldom needed oncology, rheumatology and immunology for their patients. Consequently, it appears that these clinics and general internal medicine are not the principal skills for IDCMSs in patient management.

In this study, ENT department, general surgery, and urology were the most frequent surgical contacts in supervising ID patients. Therapeutic and diagnostic approaches were significantly better in patients with IRFD in urology consultations probably due to the fact that urinary infections are common in hospitals [¹⁵] and that increasing awareness of IDCMSs had already been established on this issue and related subjects. In more than half of the consultations provided by all surgical departments, the final diagnoses of the patients were related to ID and the IDCMSs referral was largely for invasive procedures. This occurred less commonly in referrals to other medical disciplines. This is consistent with the historical need for surgeons in ID patient management where surgical intervention is required to control or eliminate infection. Moreover, two-thirds of the hospitalized ID patients who were transferred to another department were passed on to surgical clinics, general surgery being the most frequent one. That is, 6.5% of our ID patients were transferred to surgeons. Obviously, these frequent interrelations with surgeons cannot be inferred as combining the curricula of surgical clinics into ID training. But rather, strengthening ID training in aforementioned medical areas may contribute optimal viewpoints for their surgical counterparts as in neurology and neurosurgery, pulmonology and thoracic surgery, cardiology and cardiovascular surgery, nephrology and urology, and finally, gastroenterology and general surgery.

According to our data, when hospitalized ID patients had additional infectious diagnoses, consultation demands of IDCMSs were not enhanced. Moreover, the consultation patterns were similar for both HCAIs and community-acquired infections and they did not significantly vary between the major ID clinical syndromes. In routine ID practice, infections pose a formidable challenge particularly due to resistance issues or highly virulent microorganisms [^16-18]. But the results of this study indicated that an infection of any origin in an ID department required similar external help. Accordingly, the hospital admission source of the patients or discharge types including death did not increase consultation demands in due course of hospitalization. As expected, increased length of hospital stay and advancing age slightly increased the consultation needs. Interestingly, being a female increased consultation demands according to our data. The reason for this finding is unclear and needs further clarification. Consequently, when the patient was once accepted in an ID clinic, the IDCMSs had uniform approaches in consulting to other departments. However, a major difference was seen in the institutions where the patients were hospitalized. Training hospitals are generally more well-equipped institutions and enriched with many medical sub-disciplines not possible in ordinary public hospitals in Turkey. It appears that the IDCMSs found it easier to consult with other disciplines in training hospitals, and according to our study they requested consultation services 2.7 times more frequently than in public hospitals.

In this study, we evaluated the critical status of the patients to disclose whether consultation demands were affected in this particular subgroup of cases or not. According to the results of our logistic regression model, presences of sepsis, severe sepsis, septic shock, administration of the oxygen by nasal cannula or by a mask, noninvasive mechanical ventilation, invasive mechanical ventilation, and ICU admission in an ID patient did not enforce the patient's doctor to seek additional help and the behaviour of IDCMSs were homogeneous in either critical or non-critical ID patients.

Historically, the practice of ID and clinical microbiology come from a common origin in Turkey. In 1929 this ancestral branch was referred to as "Bacteriology" in the National Medical Specialization Act followed by "Bacteriology and Infectious Diseases" according within the 1947 regulations. Finally in 1983, the discipline was defined as "Infectious Diseases and Clinical Microbiology" [¹⁹]. According to our data, some of the internal medicine disciplines, plus pulmonology, neurology and dermatology are principal clinical requisites in the training of laboratory based ID specialists, rather than internal medicine as a whole. Moreover, the results of our study showed that consultation habits of IDCMSs are quite homogenous and not affected by either the nature of infections or the status of ID patients. It appears that IDCMSs have uniform consulting behaviours in the management of critical ID patients, and the routine training programs of aforementioned disciplines seemingly may contribute to this issue. As a result, in providing better patient care, optimal follow-up, and for more professional collaboration with frequently contacted clinics, combining the curricula of these disciplines with the ID training appears to be a rational strategy.

The authors declare that they have no competing interests.

FG conceived of the study, and participated in its design and coordination. HE designed and coordinated the study. ST-K helped designing and coordinating the study. IK participated in the design of the study and performed the statistical analysis. DT-K produced data for the study from her local centre. AU-K produced data for the study from her local centre. OO produced data for the study from his local centre. RG produced data for the study from her local centre. SB produced data for the study from his local centre. GM produced data for the study from his local centre. SN-A produced data for the study from her local centre. NE-T produced data for the study from her local centre. TD produced data for the study from his local centre. NE produced data for the study from his local centre. CA-H produced data for the study from her local centre. EY produced data for the study from her local centre. BM produced data for the study from her local centre. BK produced data for the study from her local centre. NC produced data for the study from her local centre. OK produced data for the study from his local centre. DI produced data for the study from her local centre. MC produced data for the study from her local centre. SS produced data for the study from her local centre. BY-D produced data for the study from her local centre. SY produced data for the study from her local centre. CA produced data for the study from her local centre. YB produced data for the study from his local centre. YA produced data for the study from her local centre. ST produced data for the study from his local centre. HY produced data for the study from his local centre. HB produced data for the study from his local centre. HAE produced data for the study from his local centre. ND produced data for the study from her local centre. MD produced data for the study from his local centre. SO produced data for the study from his local centre. NS produced data for the study from her local centre. TS produced data for the study from her local centre. ORS produced data for the study from his local centre. SU produced data for the study from his local centre. EsY produced data for the study from her local centre. SK produced data for the study from his local centre. AU participated the design and the coordination of the study. HK participated the design and the coordination of the study. BB participated the design and the coordination of the study. HV participated the design and the coordination of the study. YT participated the design and the coordination of the study. GU participated the design and the coordination of the study. DA participated the design and the coordination of the study. HD participated the design and the coordination of the study. SU participated the design and the coordination of the study. HL participated the design and the coordination of the study. All authors read and approved the final manuscript.

We would like to express our gratitude to Jane Stockley for her contributions in presenting this material.