SARS-CoV-2 mRNA Vaccine Response in People Living with HIV According to CD4 Count and CD4/CD8 Ratio.

BACKGROUND: Our aim was to estimate the rates of not achieving a robust/above-average humoral response to the COVID-19 mRNA vaccine in people living with HIV (PLWH) who received ≥2 doses and to investigate the role of the CD4 and CD4/CD8 ratio in predicting the humoral response. METHODS: We evaluated the humoral anti-SARS-CoV-2 response 1-month after the second and third doses of COVID-19 mRNA vaccine as a proportion of not achieving a robust/above-average response using two criteria: (i) a humoral threshold identified as a correlate of protection against SARS-CoV-2 (<90% vaccine efficacy): anti-RBD < 775 BAU/mL or anti-S < 298 BAU/mL, (ii) threshold of binding antibodies equivalent to average neutralization activity from the levels of binding (nAb titer < 1:40): anti-RBD < 870 BAU/mL or anti-S < 1591 BAU/mL. PLWH were stratified according to the CD4 count and CD4/CD8 ratio at first dose. Logistic regression was used to compare the probability of not achieving robust/above-average responses. A mixed linear model was used to estimate the mean anti-RBD titer at various time points across the exposure groups. RESULTS: a total of 1176 PLWH were included. The proportions of participants failing to achieve a robust/above-average response were significantly higher in participants with a lower CD4 and CD4/CD8 ratio, specifically, a clearer gradient was observed for the CD4 count. The CD4 count was a better predictor of the humoral response of the primary cycle than ratio. The third dose was pivotal in achieving a robust/above-average humoral response, at least for PLWH with CD4 > 200 cells/mm3 and a ratio > 0.6. CONCLUSIONS: A robust humoral response after a booster dose has not been reached by 50% of PLWH with CD4 < 200 cells mm3. In the absence of a validated correlate of protections in the Omicron era, the CD4 count remains the most solid marker to guide vaccination campaigns in PLWH.

The battle against fungi: lessons in antifungal stewardship from COVID 19 times

The COVID-19 pandemic has highlighted the detrimental effect of secondary pathogens in patients with a primary viral insult. In addition to superinfections with bacterial pathogens, invasive fungal infections were increasingly reported. The diagnosis of pulmonary fungal infections has always been challenging; however, it became even more problematic in the setting of COVID-19, particularly regarding the interpretation of radiological findings and mycology test results in patients with these infections. Moreover, prolonged hospitalization in ICU, coupled with underlying host factors. such as preexisting immunosuppression, use of immunomodulatory agents, and pulmonary compromise, caused additional vulnerability to fungal infections in this patient population. In addition, the heavy workload, redeployment of untrained staff, and inconsistent supply of gloves, gowns, and masks during the COVID-19 outbreak made it harder for healthcare workers to strictly adhere to preventive measures for infection control. Taken together, these factors favored patient-to-patient spread of fungal infections, such as those caused by Candida auris, or environment-to-patient transmission, including nosocomial aspergillosis. As fungal infections were associated with increased morbidity and mortality, empirical treatment was overly used and abused in COVID-19-infected patients, potentially contributing to increased resistance in fungal pathogens. The aim of this paper was to focus on essential elements of antifungal stewardship in COVID-19 for three fungal infections, COVID-19-associated candidemia (CAC), -pulmonary aspergillosis (CAPA), and -mucormycosis (CAM).

Clinical management of severe infections caused by carbapenem-resistant gram-negative bacteria: a worldwide cross-sectional survey addressing the use of antibiotic combinations.

OBJECTIVES: Optimal treatment of carbapenem-resistant Gram-negative bacteria (CR-GNB) infections is uncertain because of the lack of good-quality evidence and the limited effectiveness of available antibiotics. The aim of this survey was to investigate clinicians' prescribing strategies for treating CR-GNB infections worldwide. METHODS: A 36-item questionnaire was developed addressing the following aspects of antibiotic prescribing: respondent's background, diagnostic and therapeutic availability, preferred antibiotic strategies and rationale for selecting combination therapy. Prescribers were recruited following the snowball sampling approach, and a post-stratification correction with inverse proportional weights was used to adjust the sample's representativeness. RESULTS: A total of 1012 respondents from 95 countries participated in the survey. Overall, 298 (30%) of the respondents had local guidelines for treating CR-GNB at their facility and 702 (71%) had access to Infectious Diseases consultation, with significant discrepancies according to country economic status: 85% (390/502) in high-income countries versus 59% (194/283) in upper-medium-income countries and 30% (118/196) in lower-middle-income countries/lower-income-countries). Targeted regimens varied widely, ranging from 40 regimens for CR-Acinetobacter spp. to more than 100 regimens for CR-Enterobacteriaceae. Although the majority of respondents acknowledged the lack of evidence behind this choice, dual combination was the preferred treatment scheme and carbapenem-polymyxin was the most prescribed regimen, irrespective of pathogen and infection source. Respondents noticeably disagreed around the meaning of 'combination therapy' with 20% (150/783) indicating the simple addition of multiple compounds, 42% (321/783) requiring the presence of in vitro activity and 38% (290/783) requiring in vitro synergism. CONCLUSIONS: Management of CR-GNB infections is far from being standardized. Strategic public health focused randomized controlled trials are urgently required to inform evidence-based treatment guidelines.

Point prevalence survey of antibiotic use in hospitals in Latin American countries.

BACKGROUND: Point prevalence surveys (PPSs) on antibiotic use are useful for understanding different aspects related to prescription patterns in hospitals. METHODS: An adaptation of the WHO methodology for a PPS on antibiotic use was applied. Hospital wards were divided into medical (MED), surgical (SUR), ICUs, gynaecology and obstetrics (GO), high-risk (HR) and mixed wards (MIX). A web application (RedCap©) through a mobile device was used for data collection. RESULTS: Between December 2018 and August 2019, 5444 patients in 33 hospitals in five countries were included (10 hospitals in Cuba, 7 in Paraguay, 6 in El Salvador, 5 in Mexico and 5 in Peru). Of these patients, 54.6% received at least one antibiotic, with variations between and within hospitals and countries. Antibiotics were more frequently used in ICUs (67.2%), SUR (64.5%) and MED wards (54.2%), with 51.2% of antibiotics prescribed for community-acquired infections (CAIs), 22.9% for healthcare-associated infections (HAIs), 11.1% for surgical prophylaxis and 6.1% for unknown reasons. Adherence to guidelines was observed in 68.6% of cases (72.8% for CAIs, 72.4% for HAIs and 44.3% for prophylaxis). Third-generation cephalosporins were the class of antibiotics most frequently used (26.8%), followed by carbapenems (10.3%) and fluoroquinolones (8%). Targeted treatments were achieved in 17.3% of cases. CONCLUSIONS: Antibiotic use was generally higher than that published in other studies. There is an urgent need to promote and strengthen the antimicrobial stewardship programmes in Latin America.

Budget impact analysis of using procalcitonin to optimize antimicrobial treatment for patients with suspected sepsis in the intensive care unit and hospitalized lower respiratory tract infections in Argentina.

BACKGROUND: Inappropriate antibiotic use represents a major global threat. Sepsis and bacterial lower respiratory tract infections (LRTIs) have been linked to antimicrobial resistance, carrying important consequences for patients and health systems. Procalcitonin-guided algorithms may represent helpful tools to reduce antibiotic overuse but the financial burden is unclear. The aim of this study was to estimate the healthcare and budget impact in Argentina of using procalcitonin-guided algorithms to guide antibiotic prescription. METHODS: A decision tree was used to model health and cost outcomes for the Argentinean health system, over a one-year duration. Patients with suspected sepsis in the intensive care unit and hospitalized patients with LRTI were included. Model parameters were obtained from a focused, non-systematic, local and international bibliographic search, and validated by a panel of local experts. Deterministic and probabilistic sensitivity analyses were performed to analyze the uncertainty of parameters. RESULTS: The model predicted that using procalcitonin-guided algorithms would result in 734.5 [95% confidence interval (CI): 1,105.2;438.8] thousand fewer antibiotic treatment days, 7.9 [95% CI: 18.5;8.5] thousand antibiotic-resistant cases avoided, and 5.1 [95% CI: 6.7;4.2] thousand fewer Clostridioides difficile cases. In total, this would save $422.4 US dollars (USD) [95% CI: $935;$267] per patient per year, meaning cost savings of $83.0 [95% CI: $183.6;$57.7] million USD for the entire health system and $0.4 [95% CI: $0.9;$0.3] million USD for a healthcare provider with 1,000 cases per year of sepsis and LRTI patients. The sensitivity analysis showed that the probability of cost-saving for the sepsis patient group was lower than for the LRTI patient group (85% vs. 100%). CONCLUSIONS: Healthcare and financial benefits can be obtained by implementing procalcitonin-guided algorithms in Argentina. Although we found results to be robust on an aggregate level, some caution must be used when focusing only on sepsis patients in the intensive care unit.

An international inventory of antimicrobial stewardship (AMS) training programmes for AMS teams.

BACKGROUND: Healthcare professionals are increasingly expected to lead antimicrobial stewardship (AMS) initiatives. This role in complex healthcare environments requires specialized training. OBJECTIVES: Little is known about the types of AMS training programmes available to clinicians seeking to play a lead role in AMS. We aimed to identify clinicians' awareness of AMS training programmes, characteristics of AMS training programmes available and potential barriers to participation. METHODS: AMS training programmes available were identified by members of the ESCMID Study Group for Antimicrobial Stewardship (ESGAP) via an online survey and through an online search in 2018. Individual training programme course coordinators were then contacted (September-October 2018) for data on the target audience(s), methods of delivery, intended outcomes and potential barriers to accessing the training programme. RESULTS: A total of 166/250 ESGAP members (66%) responded to the survey, nominating 48 unique AMS training programmes. An additional 32 training programmes were identified through an online search. AMS training programmes were from around the world. Less than half (44.4%) of respondents were aware of one or more AMS training programmes available, with pharmacists more aware compared with medical doctors and other professionals (73% versus 46% and 25%, respectively). AMS training programmes were most commonly delivered online (59%) and aimed at medical doctors (46%). Training costs and a lack of recognition by health professional societies were the most frequently cited barriers to participation in AMS training programmes. CONCLUSIONS: The development of a systematic inventory of AMS training programmes around the globe identifies opportunities and limitations to current training available. Improving access and increasing awareness amongst target participants will support improved education in AMS.

Update on the epidemiology of carbapenemases in Latin America and the Caribbean.

INTRODUCTION: Carbapenemases are ß-lactamases able to hydrolyze a wide range of ß-lactam antibiotics, including carbapenems. Carbapenemase production in Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter spp., with and without the co-expression of other ß-lactamases is a serious public health threat. Carbapenemases belong to three main classes according to the Ambler classification: class A, class B, and class D. AREAS COVERED: Carbapenemase-bearing pathogens are endemic in Latin America. In this review, we update the status of carbapenemases in Latin America and the Caribbean. EXPERT OPINION: Understanding the current epidemiology of carbapenemases in Latin America and the Caribbean is of critical importance to improve infection control policies limiting the dissemination of multi-drug-resistant pathogens and in implementing appropriate antimicrobial therapy.

Advocacy for Increased International Efforts for Antimicrobial Stewardship Actions in Low-and Middle-Income Countries on Behalf of Alliance for the Prudent Use of Antimicrobials (APUA), Under the Auspices of the International Society of Antimicrobial Chemotherapy (ISAC).

Antimicrobial stewardship (AMS) is a set of coordinated strategies to improve the use of antimicrobials, to enhance patient outcomes, reduce antimicrobial resistance, and decrease unnecessary costs. The pioneer years of AMS were restricted to high-income countries (HIC), where overconsumption of antibiotics was associated with emergence of multidrug-resistant (MDR) bacteria. AMS in low- and middle-income countries (LMIC) is also necessary. However, programs effective in HIC may not perform as well in LMIC, because (i) While decreased consumption of antibiotics may be an appropriate target in overconsuming HIC, this may be dangerous in LMIC, where many patients die from the lack of access to antibiotics; (ii) although AMS programs in HIC can be designed and monitored through laboratory surveillance of resistance, surveillance programs are not available in many LMIC; (iii) the heterogeneity of health care systems implies that AMS programs must be carefully contextualized. Despite the need to individually tailor AMS programs in LMIC, international collaborations remain highly valuable, through the dissemination of high-quality documents and educational material, that may be shared, adapted where needed, and adopted worldwide. This process, facilitated by modern communication tools, combines many benefits, including: (i) saving time, a precious dimension for health care workers, by avoiding the duplication of similar works in different settings; (ii) taking advantage of colleagues skills, and initiatives, through open access to the work performed in other parts of the world; (iii) sharing experiences, so that we all learn from each others' successes and failures.

Antimicrobial stewardship in hospitals in Latin America and the Caribbean: a scoping review.

OBJECTIVES: To examine published antimicrobial stewardship (AMS) initiatives in hospitals in Latin America and the Caribbean (LAC) in order to characterize AMS terminology usage, geotemporality, and elements of structure (human resources), process (interventions), and outcomes, and to set priority areas for improving AMS reporting. METHODS: This was a scoping review that searched PubMed, LILACS, EMBASE, and 12 other databases, along with a manual search for academic and grey literature to identify documents on AMS initiatives in hospitals in 33 countries of LAC, up to August 2019. Keywords included 'antibiotic' or 'antimicrobial' AND 'stewardship, policy, strategies, management, control, rational use, appropriate use, surveillance, or interventions' and 33 country names. RESULTS: Selected articles totalled 147 studies published in 1985 - 2019; of those, 22% used 'antimicrobial stewardship' in the title. Eighteen countries published AMS hospital initiatives, one-half of which were implemented in capital cities. Brazil, Argentina, Colombia, Cuba, Mexico, and Chile, in descending frequency, made up > 59% of published initiatives. Educational interventions were the most frequently reported, followed by persuasive and restrictive strategies. Antimicrobial consumption was the most common outcome measure reported. About one-third of the studies (35%) referred to baseline measures-only in preparation for AMS interventions. Fifty-nine studies from 6 countries reported AMS comprehensively, using structure, process, and outcome (SPO) elements. CONCLUSIONS: Published hospital AMS initiatives have increased over time and have expanded across LAC. However, more programs need to be developed. Complete reporting of SPO elements is imperative to evaluating and replicating AMS actions.

The Lancet Infectious Diseases Commission on antimicrobial resistance: 6 years later.

In 2013, a Lancet Infectious Diseases Commission described the state of antimicrobial resistance worldwide. Since then, greater awareness of the public health ramifications of antimicrobial resistance has led to national actions and global initiatives, including a resolution at the high-level meeting of the UN General Assembly in 2016. Progress in addressing this issue has ranged from a ban on irrational drug combinations in India to commitments to ban colistin as a growth promoter in animals, improve hospital infection control, and implement better antimicrobial stewardship. Funds have been mobilised, and regulatory barriers to new antibiotic development have been relaxed. These efforts have been episodic and uneven across countries, however. Sustained funding for antimicrobial resistance and globally harmonised targets to monitor progress are still urgently needed. Except for in a few leading countries, antimicrobial resistance has not captured the sustained focus of national leaders and country-level actors, including care providers.

Ten key points for the appropriate use of antibiotics in hospitalised patients: a consensus from the Antimicrobial Stewardship and Resistance Working Groups of the International Society of Chemotherapy.

The Antibiotic Stewardship and Resistance Working Groups of the International Society for Chemotherapy propose ten key points for the appropriate use of antibiotics in hospital settings. (i) Get appropriate microbiological samples before antibiotic administration and carefully interpret the results: in the absence of clinical signs of infection, colonisation rarely requires antimicrobial treatment. (ii) Avoid the use of antibiotics to 'treat' fever: use them to treat infections, and investigate the root cause of fever prior to starting treatment. (iii) Start empirical antibiotic treatment after taking cultures, tailoring it to the site of infection, risk factors for multidrug-resistant bacteria, and the local microbiology and susceptibility patterns. (iv) Prescribe drugs at their optimal dosing and for an appropriate duration, adapted to each clinical situation and patient characteristics. (v) Use antibiotic combinations only where the current evidence suggests some benefit. (vi) When possible, avoid antibiotics with a higher likelihood of promoting drug resistance or hospital-acquired infections, or use them only as a last resort. (vii) Drain the infected foci quickly and remove all potentially or proven infected devices: control the infection source. (viii) Always try to de-escalate/streamline antibiotic treatment according to the clinical situation and the microbiological results. (ix) Stop unnecessarily prescribed antibiotics once the absence of infection is likely. And (x) Do not work alone: set up local teams with an infectious diseases specialist, clinical microbiologist, hospital pharmacist, infection control practitioner or hospital epidemiologist, and comply with hospital antibiotic policies and guidelines.

Antimicrobial stewardship in hospitals: Does it work and can we do it?

Selection of resistant pathogens by antimicrobial use is probably the most important cause of antimicrobial resistance. Antimicrobial stewardship (AMS) refers to a multifaceted approach to optimise prescribing. The benefits of AMS programmes have been widely demonstrated in terms of reductions in antimicrobial use, mortality, Clostridium difficile and other healthcare-associated infections, hospital length of stay and bacterial resistance. Several kinds of interventions (i.e. restriction of drugs, pre-authorisation of certain antimicrobials, joint clinical rounds with prescribers, implementation of guidelines and education) have shown positive results. Regrettably, in most hospitals in Latin America, Asia and Africa as well as in a significant proportion of institutions in Europe and North America, essential human and material resources are scarce or absent, and teams are neither developed nor well functioning. Despite current or potential barriers, we should start or improve our already ongoing initiatives on AMS by considering the main specific problems and act accordingly with the available human and material resources. From supervising the use of specific classes of drugs to implementing more sophisticated decision support programmes, there is a wide range of possible useful interventions.

Detection, treatment, and prevention of carbapenemase-producing Enterobacteriaceae: recommendations from an International Working Group.

The prevalence of carbapenemase-producing Enterobacteriaceae (CPE) has increased during the past 10 years. Its detection is frequently difficult, because they do not always show a minimum inhibitory concentration (MIC) value for carbapenems in the resistance range. Both broth microdilution and agar dilution methods are more sensitive than disk diffusion method, Etest and automated systems. Studies on antimicrobial treatment are based on a limited number of patients; therefore, the optimal treatment is not well established. Combination therapy with two active drugs appears to be more effective than monotherapy. Combination of a carbapenem with another active agent--preferentially an aminoglycoside or colistin--could lower mortality provided that the MIC is ≤4 mg/l and probably ≤8 mg/l, and is administered in a higher-dose/prolonged-infusion regimen. An aggressive infection control and prevention strategy is recommended, including reinforcement of hand hygiene, using contact precautions and early detection of CPE through use of targeted surveillance.

[Inter-society consensus for the management of respiratory infections: acute bronchitis and chronic obstructive pulmonary disease]. / Consenso Intersociedades para el manejo de infecciones respiratorias: bronquitis aguda y enfermedad pulmonar obstructiva crónica.

The Argentine Society for Infectious Diseases and other national societies issued updated practical guidelines for the management of acute bronchitis (AB) and reactivations of chronic obstructive pulmonary disease (COPD) with the aim of promoting rational use of diagnostic and therapeutic resources. AB is a condition characterized by inflammation of the bronchial airways which affects adults and children without underlying pulmonary disease. It is usually caused by a virus. The diagnosis is based on clinical findings after community acquired pneumonia has been ruled out. Treatment of AB is mainly symptomatic. Antibiotics should be used in immune-compromised hosts, patients with chronic respiratory or cardiac diseases and in the elderly with co-morbidities. Reactivation of COPD is defined as an acute change in the patient's baseline clinical situation beyond normal day to day variations, with an increase in dyspnea, sputum production and/or sputum purulence, warranting a change in medication. An increase in one symptom is considered a mild exacerbation, two as moderate, and the presence of three symptoms is considered a severe exacerbation. An infectious agent can be isolated in sputum in 50 to 75% of COPD reactivations. Moderate and severe episodes must be treated with antibiotics, amoxicillin/ beta-lactamase inhibitor, macrolides and fluoroquinolones are first choice drugs.

Consenso Intersociedades para el manejo de infecciones respiratorias: bronquitis aguda y enfermedad pulmonar obstructiva crónica / [Inter-society consensus for the management of respiratory infections: acute bronchitis and chronic obstructive pulmonary disease].

The Argentine Society for Infectious Diseases and other national societies issued updated practical guidelines for the management of acute bronchitis (AB) and reactivations of chronic obstructive pulmonary disease (COPD) with the aim of promoting rational use of diagnostic and therapeutic resources. AB is a condition characterized by inflammation of the bronchial airways which affects adults and children without underlying pulmonary disease. It is usually caused by a virus. The diagnosis is based on clinical findings after community acquired pneumonia has been ruled out. Treatment of AB is mainly symptomatic. Antibiotics should be used in immune-compromised hosts, patients with chronic respiratory or cardiac diseases and in the elderly with co-morbidities. Reactivation of COPD is defined as an acute change in the patient’s baseline clinical situation beyond normal day to day variations, with an increase in dyspnea, sputum production and/or sputum purulence, warranting a change in medication. An increase in one symptom is considered a mild exacerbation, two as moderate, and the presence of three symptoms is considered a severe exacerbation. An infectious agent can be isolated in sputum in 50 to 75

of COPD reactivations. Moderate and severe episodes must be treated with antibiotics, amoxicillin/ beta-lactamase inhibitor, macrolides and fluoroquinolones are first choice drugs.

[Consensus guidelines for the management of upper respiratory tract infections]. / Consenso sobre diagnóstico y tratamiento de infecciones de vías respiratorias altas.

Upper respiratory tract infections are the most common source of antibiotic prescriptions. Acute pharyngitis is caused mainly by viruses, viral cases can be distinguished from acute streptococcal pharyngitis using Centor clinical epidemiological criteria, by rapid antigen tests or throat culture. Treatment of choice for streptococcal infection is penicillin V given in two daily doses. In children, acute otitis media (AOM) is the infection for which antibiotics are most often prescribed. Predominant causative pathogens include Streptococcus pneumoniae, Haemophilus influenzae non-type b and Moraxella catarrhalis. Diagnosis is based on history, physical examination and otoscopic exam. Antibiotic treatment should be initiated promptly in all children<2 years of age, and in older children presenting bilateral AOM, otorrhoea, co-morbidities or severe illness. In Argentina, amoxicillin is the drug of choice given the low penicillin resistance rates for S. pneumoniae. In children who fail amoxicillin therapy, amoxicillin/clavulanate provides better coverage against beta-lactamase producing H. influenzae and M. catarrhalis. Rhinosinusitis is caused mainly by viruses, secondary bacterial complication occurs in less than 5% of cases. Diagnosis is based on physical examination and additional studies are not usually required. Acute bacterial sinusitis is caused by the same pathogens that cause AOM and amoxicillin is the drug of choice.

Consenso sobre diagnóstico y tratamiento de infecciones de vías respiratorias altas / Consensus guidelines for the management of upper respiratory tract infections

Las infecciones respiratorias altas son la primera causa de prescripción de antibióticos. La faringitis aguda es de origen viral en la mayoría de los casos; los episodios virales pueden diferenciarse de los de origen bacteriano producidos por Streptococcus pyogenes por criterios clínico-epidemiológicos (criterios de Centor), por pruebas diagnósticas rápidas o por el cultivo de fauces. Cuando la etiología es estreptocócica, la droga de elección es penicilina V (cada 12 horas). La otitis media aguda (OMA) es una de las causas más frecuentes de prescripción de antibióticos en niños. Los patógenos principales son Streptococcus pneumoniae, Haemophilus influenzae no tipable y Moraxella catarrhalis. Los antecedentes, la evaluación clínica junto con la otoscopía permiten establecer el diagnóstico. En niños menores de 2 años se recomienda tratamiento antibiótico precoz al igual que en niños mayores de 2 años con otitis bilateral, otorrea, presencia de comorbilidad o cuadro clínico grave. En la Argentina, debido a los bajos niveles de resistencia de S. pneumoniae a penicilina la droga de elección es amoxicilina; ante falta de respuesta al tratamiento puede utilizarse amoxicilina/clavulánico para cubrir cepas de H. influenzae y de M. catarrhalis productoras de betalactamasas. Las rinosinusitis son virales en la mayoría de los casos y menos del 5% se complican con sinusitis bacteriana. El diagnóstico es clínico y en general no se requieren estudios complementarios. Los patógenos bacterianos implicados son los mismos que causan OMA, por esta razón también se recomienda la amoxicilina como droga de elección.

Upper respiratory tract infections are the most common source of antibiotic prescriptions. Acute pharyngitis is caused mainly by viruses, viral cases can be distinguished from acute streptococcal pharyngitis using Centor clinical epidemiological criteria, by rapid antigen tests or throat culture. Treatment of choice for streptococcal infection is penicillin V given in two daily doses. In children, acute otitis media (AOM) is the infection for which antibiotics are most often prescribed. Predominant causative pathogens include Streptococcus pneumoniae, Haemophilus influenzae non-type b and Moraxella catarrhalis. Diagnosis is based on history, physical examination and otoscopic exam. Antibiotic treatment should be initiated promptly in all children < 2 years of age, and in older children presenting bilateral AOM, otorrhoea, co-morbidities or severe illness. In Argentina, amoxicillin is the drug of choice given the low penicillin resistance rates for S. pneumoniae. In children who fail amoxicillin therapy, amoxicillin/clavulanate provides better coverage against beta-lactamase producing H. influenzae and M. catarrhalis. Rhinosinusitis is caused mainly by viruses, secondary bacterial complication occurs in less than 5% of cases. Diagnosis is based on physical examination and additional studies are not usually required. Acute bacterial sinusitis is caused by the same pathogens that cause AOM and amoxicillin is the drug of choice.