Diagnostic Stewardship Programs (DSPs) in microbiology aim to ensure that the right diagnostic test is performed on the right patient at the right time, optimizing resource utilization. To maximize their effectiveness against antimicrobial resistance (AMR), DSPs must be integrated with Infection Prevention and Control (IPC) programs and Antimicrobial Stewardship Programs (ASPs). This article focuses on the pre-analytical phase of DSPs, specifically on test ordering, and additionally, it offers some recommendations for resource-limited settings. It presents a series of algorithms for ordering blood cultures, urine cultures, and respiratory specimens. A crucial concept in this phase is pretest probability, which guides rational test ordering, prevents overutilization and associated costs, and reduces laboratory workload. Regarding blood cultures, it is essential to standardize ordering criteria, prioritizing high-risk populations. Routine use is discouraged in cases of low pretest probability or when results do not alter clinical management. Blood volume and the number of bottles are critical for optimal yield. For urine cultures, it is fundamental to order them only when characteristic urinary symptoms are present, avoiding requests for asymptomatic bacteriuria or nonspecific symptoms. Finally, for respiratory specimens, the choice of diagnostic method should consider the patient's condition and available resources. Molecular techniques enhance pathogen detection, but must be integrated within an ASP for proper interpretation and rational antimicrobial use.

La enfermedad invasiva por Streptococcus pneumoniae constituye una importante causa de morbilidad y mortalidad, y es la primera causa de muerte prevenible mediante vacunación en el mundo, no solo en niños sino en todas las edades. Tanto la vacuna polisacárida como la vacuna conjugada antineumocócicas han demostrado reducción de las tasas de enfermedad invasiva en adultos. En los últimos años, a la luz de nueva evidencia disponible, los esquemas de vacunación antineumocócica para esta población han sufrido modificaciones. Este documento ofrece una actualización sobre las recomendaciones de vacunación a través de los fundamentos que han llevado a dicho cambio

Skin and soft tissue infections (SSTIs) are extremely common, and while the vast majority are mild, they can occasionally lead to serious local and systemic complications. Therefore, early recognition and appropriate medical and surgical management are of primary importance. In 2009, the Argentine Society of Infectious Diseases (SADI), along with other scientific societies, published its latest recommendations. This Guide was developed by specialists from the Argentine Society of Infectious Diseases (SADI) and discussed in a plenary meeting with the participation of representatives from six other Scientific Societies: Argentine Society of Dermatology, Argentine Association of Surgery, Argentine Society of Medicine, Argentine Association of Clinical Microbiology, Buenos Aires Society of Internal Medicine, and Argentine Society of Intensive Care, based on their experience in this subject. Each chapter contains recommendations based on scientific evidence and expert opinion, including useful diagnostic tools, with special emphasis on clinical assessment and differential diagnoses, and antimicrobial therapy, with attention to the responsible use of antibiotics.

Approximately 10% of the population reports being allergic to penicillin, although usually less than 1% really are. In addition, people with proven allergies over the years may no longer be allergic. Unconfirmed penicillin allergy and use of alternative antimicrobials result in more treatment failures; more severe adverse effects. Higher cost; longer hospitalizations; increase in the emergence of multi-resistant germs associated with health care. The risk of cross-allergy between beta-lactam groups is usually <2%, depending on the similarity of the side chains, so prescribing antibiotics from another beta-lactam group is safe as long as we take into account the structural similarity. Incorporating the reassessment of allergies and improving the prescription of antibiotics in this group of patients reduces the generation and spread of multi-resistant germs, and the associated costs. There are simple methods and specific scores that simplify allergy reassessment. The objective of this review is to expose how, through these methods, the delabeling of patients erroneously labeled as allergic and the safe prescription of beta-lactam antibiotics can be achieved.

Desarrollada por la Comisión de Uso Adecuado de Recursos de la Sociedad Argentina de Infectología

Introducción: La endocarditis infecciosa de válvula protésica (EIP) presenta diferente epidemiología, agentes etiológicos y pronóstico que la endocarditis infecciosa de válvula nativa. Disponemos de escasa información local que evalúe las características y la evolución en este grupo de pacientes. Método: Estudio unicéntrico, observacional de cohorte retrospectiva. Se incluyeron pacientes mayores de 18 años con diagnóstico clínico-imagenológico de EIP definida en el periodo de marzo de 2012 a abril de 2023. Se analizaron las características clínicas e imagenológicas de presentación, así como la evolución intrahospitalaria y al año de seguimiento. Resultados: Se incluyeron 74 pacientes con EIP. La mediana de edad fue de 71 años (RIC: 65-78) y el 67% eran hombres. La prótesis más afectada fue la aórtica (71.6%). El 65% (n = 48) presentaron disfunción protésica y el 46% (n = 36) compromiso anular. Staphylococcus coagulasa negativo fue el agente etiológico más frecuente, en el 30.5% de los casos. Del total de los pacientes, el 84% (n = 62) presentaron indicación quirúrgica. La principal indicación fue por infección no controlada (62%). La mortalidad intrahospitalaria fue del 25.7% (n = 19). No hubo muertes intrahospitalarias en los pacientes sin indicación quirúrgica (0/12). En aquellos con indicación quirúrgica, la mortalidad intrahospitalaria en los que recibieron cirugía fue del 25% (13/51) y en los que no la recibieron fue del 54% (n = 6/11). Conclusiones: La EIP es una complicación grave en pacientes con prótesis valvulares. Pese a los avances en las técnicas diagnósticas y terapéuticas, continúa presentando una mortalidad elevada.

Objetivo: Evaluar prevalencia y adecuación de ceftriaxona tras una intervención educativa en un servicio de urgencias. Métodos: Estudio cuasi experimental que incluyó un mues- treo consecutivo de consultas no programadas de pacien- tes adultos, durante dos meses preintervención y posin- tervención. Dicha intervención consistió en capacitación a médicos para limitar su indicación sólo a situaciones clínicas específicas (meningitis, enfermedad pélvica infla- matoria y abdomen agudo). Se utilizaron datos retrospecti- vos, con adicional revisión manual de historias, para validar adecuación de inicio antibiótico y apropiabilidad de droga. Se utilizó estadística descriptiva y analítica. Resultados: De un total de 28.570 consultas, 512 recibie- ron ceftriaxona (1,79%; IC95% 1,64-1,95), y sólo 60,54% se hospitalizaron. En cuanto a la comparación antes-después, se observó una reducción en la tasa de uso (de 3,66% a 0,63%; p<0,001), la adecuación en el inicio de un antimicro- biano se mantuvo (de 84,52% a 86,21%; p=0,778), aunque la adecuación de ceftriaxona aumentó en forma significativa (de 41,78% a 84,00% respectivamente; p<0,001). Adicional- mente, se redujo el tiempo de estadía hospitalaria (media- na de 6 a 5 días; p=0,014), sin diferencias en la mortalidad intrahospitalaria (19,44% vs 17,24%; p=0,691), ni en la mor- talidad a los 30 días (23,41% vs 18,96%; p=0,464). Conclusiones: Esta intervención resultó eficaz. Los hallaz- gos representan un paso fundamental en los programas de optimización del uso de antimicrobianos hospitalarios, que apuntan a reducir su sobreutilización y la consecuente resistencia.

INTRODUCTION:Clinical features and outcomes of SARSCoV-2 infections may change between different waves of the pandemic. The objective of this study was to compare clinical characteristics and outcomes between two cohorts of patients hospitalized for COVID-19 during the first and second waves in Argentina.METHODS:Multicenter and prospective registry of patients =18 years old with a confirmed diagnosis of COVID-19 admitted to 18 hospitals in Argentina during the first wave (March to October 2020) and second wave (March to July 2021) of the pandemic. Demographics, clinical characteristics, and outcomes of these patients were compared.RESULTS:A total of 1691 patients were included (first wave n = 809, second wave n = 882). Hospitalized patients during the second wave were older (median 53 years vs. 61 years, p < 0.001), had more comorbidities (71% vs. 77%, p=0.007) and required more supplemental oxygen at admission (21% vs 62%, p < 0.001). During hospitalization, patients of the second wave required more supplemental oxygen (49% vs. 85%, p < 0.001), invasive ventilation (12% vs. 22%, p < 0.001) and had higher 30- day mortality (11% vs. 26%, p < 0.001). Comparing only patients who required supplemental oxygen during hospitalization, 30-day mortality was 20% and 30% p < 0.001 for the first and second wave, respectively.CONCLUSION:Compared to patients admitted during the first wave, patients admitted with SARS-CoV2 during the second wave in Argentina were more seriously ill and had a higher mortality.

INTRODUCTION:Mortality of infective endocarditis (IE) in Argentina continues to be high. The aim objective was to describe the clinical characteristics and identify factors associated with in-hospital and long-term mortality in patients with native valve IE.METHODS:Retrospective cohort study including adult patients with diagnosis of native valve IE, hospitalized during 2011-2021.RESULTS:A total of 129 patients with a mean age of 66±17 years were included. The most frequent responsible organism was Staphylococcus aureus (SA) (38.8%). Surgical indication criteria were present in 63.6% of the patients. Mortality during hospitalization was 22.5% .In the multivariate analysis that included Charlson comorbidity index, SA infection and the presence of surgical indication criteria, an adjusted OR of mortality of 1.32 (95%CI 1.10-1.57; p = 0.003), 2.75 (95%CI 1.11-6.8; p = 0.028) and 4.14 (95%CI 1.34-12; p = 0.013), respectively, was observed. In the multivariate analysis for long term mortality, that added surgical indication criteria and the performance of surgery during hospitalization, an adjusted OR of 1.62 (CI95% 1.31-2.00; p<001), 0.77 (95%CI 0.31-1.93; p = 0.58), 7.49 (95%CI 2.07-27.07; p = 0.002) and 0.21 (95%CI 0.06-0.70; p = 0.01), respectively, was observed.CONCLUSIONS:Mortality in IE was associated with the degree of previous comorbidity, with the presence of surgical indication criteria and, inversely, with the timely completion of surgical treatment.

Abstract Background Antimicrobial resistance has worsened in Latin America. There is an urgent need to understand the development of antimicrobial stewardship programs (ASPs) and the barriers to implementing effective ASPs in light of limited national action plans or policies to promote ASPs in the region. Methods We performed a descriptive mixed-methods study of ASPs in 5 Latin American countries in March-July 2022. An electronic questionnaire with an associated scoring system (hospital ASP self-assessment) was used, and ASP development was classified based on the scores (inadequate, 0–25; basic, 26–50; intermediate, 51–75; or advanced, 76–100). Interviews among healthcare workers (HCWs) involved in antimicrobial stewardship (AS) inquired about behavioral and organizational factors that influence AS activities. Interview data were coded into themes. Results from the ASP self-assessment and interviews were integrated to create an explanatory framework. Results Twenty hospitals completed the self-assessment, and 46 AS stakeholders from these hospitals were interviewed. ASP development was inadequate/basic in 35% of hospitals, intermediate in 50%, and advanced in 15%. For-profit hospitals had higher scores than not-for-profit hospitals. Interview data validated the self-assessment findings and provided further insight into ASP implementation challenges, which included limited formal hospital leadership support, inadequate staffing and tools to perform AS work more efficiently, limited awareness of AS principles by HCWs, and limited training opportunities. Conclusions We identified several barriers to ASP development in Latin America, suggesting the need to create accurate business cases for ASPs to obtain the necessary funding for their effective implementation and sustainability.

BACKGROUND:Clinical features and outcomes of SARS-CoV-2 infections diverge in different countries. The aim of this study was to describe clinical characteristics and outcomes in a cohort of patients hospitalized with SARS-CoV-2 in Argentina.METHODS:Multicenter prospective cohort study of ≥18 years-old patients with confirmed SARS-CoV-2 infection consecutively admitted to 19 hospitals in Argentina. Multivariable logistic regression models were used to identify variables associated with 30-day mortality and admission to intensive care unit (ICU).RESULTS:A total of 809 patients were analyzed. Median age was 53 years, 56% were males and 71% had at least one comorbidity. The most common comorbidities were hypertension (32%), obesity (23%) and diabetes (17%). Disease severity at admission was classified as mild 25%, moderate 51%, severe 17%, and critical 7%. Almost half of patients (49%) required supplemental oxygen, 18% ICU, and 12% invasive ventilation. Overall, 30-day mortality was 11%. Factors independently associated with ICU admission were male gender (OR 1.81; 95%CI 1.16-2.81), hypertension (OR 3.21; 95%CI 2.08-4.95), obesity (OR 2.38; 95%CI 1.51-3.7), oxygen saturation ≤93% (OR 6.45; 95%CI 4.20-9.92) and lymphopenia (OR 3.21; 95%CI 2.08-4.95). Factors independently associated with 30-day mortality included age ≥60 years-old (OR 2.68; 95% CI 1.63-4.43), oxygen saturation ≤93% (OR 3.19; 95%CI 1.97-5.16) and lymphopenia (OR 2.65; 95%CI 1.64-4.27).CONCLUSIONS:This cohort validates crucial clinical data on patients hospitalized with SARS-CoV-2 in Argentina.

The second part of the Inter-Society Argentine Consensus on Urinary Tract Infection (UTI) includes the analysis of special situations. In patients with urinary catheter, urine culture should be requested only in the presence of UTI symptomatology, before instrumentation of the urinary tract, or as a post-transplant control. The antibiotics recommended for empirical treatment in patients without risk factors are third-generation cephalosporins or aminoglycosides. UTIs associated with stones are always considered complicated. In case of obstruction with urosepsis, an emergency drainage should be performed via a percutaneous nefrostomy or ureteral stenting. In patients with stents or ureteral prostheses, such as double J catheters, empirical treatment should be based on epidemiology, prior antibiotics, and clinical status. Before the extracorporeal lithotripsy procedure, bacteriuria should be investigated and antibiotic prophylaxis should be administered in case of positive result, according to the antibiogram. First generation cephalosporins or aminoglycosides are valid alternatives. The use of antibiotic prophylaxis with first-generation cephalosporins or aminoglycosides before percutaneous nephrolithotomy is recommended. Transrectal prostatic biopsy can be associated with infectious complications, such as UTI or acute prostatitis, mainly due to Escherichia coli or other enterobacteria. In patients without risk factors for multiresistant bacteria and negative urine culture, prophylaxis with intravenous amikacin or ceftriaxone is recommended. In patients with positive urine culture, prophylaxis will be performed according to the antibiogram, from 24 hours before to 24 hours post-procedure. For the targeted treatment of post-transrectal biopsy prostatitis, carbapenems for 3-4 weeks are the treatment of choice.

In recent years, new antimicrobials have been developed to combat infections caused by multidrug-resistant microorganism (MDR), including combinations between β-lactam agents (BL) and β-lactamase inhibitors (IBL). Two new combinations of BL / IBL are available in our country: ceftolozano / tazobactam (C / T) and ceftazidime / avibactam (CAZ / AVI). The addition of tazobactam to ceftolozano increases in vitro activity against microorganisms producing extended spectrum BL (ESBL), so the combination has a potent intrinsic activity against P. aeruginosa. For its part, CAZ / AVI retains the characteristics that define the activity profile of ceftazidime, to which with the addition of avibactam it presents a potent inhibitory activity against ESBL and carbapenemases (KPC, β-lactamases of class C and some of class D). A review of the published evidence is presented below. Based on this, and considering the current situation of increasing rates of antimicrobial resistance, particularly in Gram-negative bacilli, we consider that the use of C/T or CAZ/AVI is an excellent alternative for the management of serious infections caused by multi-resistant microorganisms. However, its use empirically is not recommended, except in specific and strictly selected situations, and in the context of a program for the rational use of antibiotics, under the control of the responsible infectious disease team.

The Argentine Society of Infectious Diseases and other scientific societies have updated these recommendations based on data on urinary tract infections in adults obtained from a prospective multicenter study conducted in Argentina during 2016-2017. Asymptomatic bacteriuria should be treated only in pregnant women, who should also be systematically investigated; the antibiotics of choice are nitrofurantoin, amoxicillin, clavulanic/amoxicillin, cephalexin and trimethoprim-sulfamethoxazole. In procedures involving injury to the urinary tract with bleeding, it is recommended to request urine culture and, in the presence of bacteriuria, antimicrobial treatment according to sensitivity should be prescribed from immediately before up to 24 hours after the intervention. In women, cystitis can be treated with nitrofurantoin, cephalexin or fosfomycin, while trimethoprim-sulfamethoxazole and fluoroquinolones are not recommended; pyelonephritis can be treated with ciprofloxacin, cefixime or cephalexin in ambulatory women or ceftriaxone, cefazolin or amikacin in those who are hospitalized. In men, urinary tract infections are always considered complicated; nitrofurantoin or cephalexin are recommended for 7 days, alternatively fosfomycin should be given in a single dose. In men, ciprofloxacin, ceftriaxone or cefixime are suggested for pyelonephritis on ambulatory treatment whereas ceftriaxone or amikacin are recommended for hospitalized patients. Acute bacterial prostatitis can be treated with ceftriaxone or gentamicin. Fluoroquinolones were the choice treatment for chronic bacterial prostatitis until recently; they are no longer recommended due to the increasing resistance and recent concerns regarding the safety of these drugs; alternative antibiotics such as fosfomycin are to be considered.

Antibiotic treatment for acute appendicitis is empirically chosen, based on epidemiological information. Resistance rates are different between regions and there are limited data on the situation in Argentina. As a part of a multicenter, observational study of abdominal infections, we performed the analysis of adult patients diagnosed with appendicitis, enrolled in 16 centers of 5 provinces, between Jan/01/2014 and Jun/30/2015. The aim was to analyze the prevalent aerobic pathogens, their resistance rates and the antimicrobial prescription pattern. On a total of 131 appendicitis cases analyzed, we found 184 aerobic pathogens (1.4 bacteria/episode): Escherichia coli 106 (57.6%), Klebsiella spp 16 (8.7%), Pseudomonas aeruginosa 19 (10.3%), Enterobacter spp. 2 (1%), other Gram negative bacilli 5 (2.7%); Enterococcus spp. 16 (8.7%) and other Gram positive cocci 20 (10.9%). The resistance rate of E. coli and enterobacteria to ampicillin/sulbactam was greater than 34% and greater than 31% to ciprofloxacin. However, the resistance of enterobacteria to piperacillin/tazobactam was 4.8%, to ceftriaxone 9.5%, to amikacin 3.6% and 8.2% to gentamicin. No resistance to carbapenems was found. The choice of quinolones or ampicillin/sulbactam for the treatment of appendicitis should be discouraged in our context, due to the high rates of resistance found in this prevalent etiology. Aminoglycoside-based treatments should be considered, given the findings of high antibiotic susceptibility and their low impact on the induction of resistance.

Community-acquired pneumonia in adults is a common cause of morbidity and mortality particularly in the elderly and in patients with comorbidities. Most episodes are of bacterial origin, Streptococcus pneumoniae is the most frequently isolated pathogen. Epidemiological surveillance provides information about changes in microorganisms and their susceptibility. In recent years there has been an increase in cases caused by community-acquired meticillin resistant Staphylococcus aureus and Legionella sp. The chest radiograph is essential as a diagnostic tool. CURB-65 score and pulse oximetry allow stratifying patients into those who require outpatient care, general hospital room or admission to intensive care unit. Diagnostic studies and empirical antimicrobial therapy are also based on this stratification. The use of biomarkers such as procalcitonin or C-reactive protein is not part of the initial evaluation because its use has not been shown to modify the initial approach. We recommend treatment with amoxicillin for outpatients under 65 year old and without comorbidities, for patients 65 years or more or with comorbidities amoxicillin-clavulanic/sulbactam, for patients hospitalized in general ward ampicillin-sulbactam with or without the addition of clarithromycin, and for patients admitted to intensive care unit ampicillin-sulbactam plus clarithromycin. Suggested treatment duration is 5 to 7 days for outpatients and 7 to 10 for those who are hospitalized. During the influenza season addition of oseltamivir for hospitalized patients and for those with comorbidities is suggested.

Isolated pleural effusion due to actinomycosis is rare and poses a diagnostic challenge to clinicians not only because it is uncommon and often forgotten, but also because culture of the causative microorganism is technically difficult. The classic al microscopic appearance of this Gram-positive bacillus on cultures often forms the basis of diagnosis. This is the report of a case of massive left sided pleural effusion due to Actinomyces israelii that improved clinically and radiologically after surgery and prolonged antibiotic treatment.