Techniques for Oxygenation and Ventilation in Coronavirus Disease 2019.

This paper discusses mechanisms of hypoxemia and interventions to oxygenate critically ill patients with COVID-19 which range from nasal cannula to noninvasive and mechanical ventilation. Noninvasive ventilation includes continuous positive airway pressure ventilation (CPAP) and high-flow nasal cannula (HFNC) with or without proning. The evidence for each of these modalities is discussed and thereafter, when to transition to mechanical ventilation (MV). Various techniques of MV, again with and without proning, and rescue strategies which would include extra corporeal membrane oxygenation (ECMO) when it is available and permissive hypoxemia where it is not, are discussed.

Epidemiology of Gram-negative bacteria during coronavirus disease 2019. What is the real pandemic?

PURPOSE OF REVIEW: Bacterial infections play a key role in hospital outcomes during the coronavirus disease 2019 (COVID-19) pandemic. Nonetheless, the global impact on the epidemiology of Gram-negative bacteria (GNB) and antibiotic resistance has not been clearly established. RECENT FINDINGS: Multiple limitations exist in the current literature, in that substantial variability was observed with regard to methodology. Notwithstanding the heterogeneity, the evidence suggests that the COVID-19 pandemic had a substantial negative impact on global epidemiology with an increase in hospital-onset infections, associated with GNB. Similarly, an alarming increase in resistant GNB compared to prepandemic rates, was apparent. This was most evident for carbapenemase-producing Klebsiella pneumoniae (bloodstream infections), carbapenem-resistant Pseudomonas aeruginosa (ventilator-associated pneumonia), and carbapenem-resistant Acinetobacter baumannii (all infections). Significant variations were most apparent in the large, system-wide regional or national comparative assessments, vs. single-centre studies. Categorizing concurrent bacteria as co- or secondary-infections may be paramount to optimize standard of care. SUMMARY: The data from most studies signal the probability that COVID-19 accelerated resistance. However, multiple limitations intrinsic to interpretation of current COVID-19 data, prevents accurately quantifying collateral damage on the global epidemiology and antibiotic resistance amongst GNB. It is likely to be substantial and renewed efforts to limit further increases is warranted.

Development and internal validation of the HIV In-hospital Mortality Prediction (HIV-IMP) risk score.

BACKGROUND: Despite advances in availability and access to antiretroviral therapy (ART), HIV still ranks as a major cause of global mortality. Hence, the aim of this study was to develop and internally validate a risk score capable of accurately predicting in-hospital mortality in HIV-positive patients requiring hospital admission. METHODS: Consecutive HIV-positive patients presenting to the Charlotte Maxeke Johannesburg Academic Hospital adult emergency department between 7 July 2017 and 18 October 2018 were prospectively enrolled. Multivariate logistic regression was used to determine parameters for inclusion in the final risk score. Discrimination and calibration were assessed by means of the area under the receiver operating curve (AUROC) and the Hosmer-Lemeshow goodness-of-fit test, respectively. Internal validation was conducted using the regular bootstrap technique. RESULTS: The overall in-hospital mortality rate was 13.6% (n = 166). Eight predictors were included in the final risk score: ART non-adherence or not yet on ART, Glasgow Coma Scale < 15, respiratory rate > 20 breaths/min, oxygen saturation < 90%, white cell count < 4 × 109 /L, creatinine > 120 µmol/L, lactate > 2 mmol/L and albumin < 35 g/L. After internal validation, the risk score maintained good discrimination [AUROC 0.83, 95% confidence interval (CI): 0.78-0.88] and calibration (Hosmer-Lemeshow χ2 = 2.26, p = 0.895). CONCLUSION: The HIV In-hospital Mortality Prediction (HIV-IMP) risk score has overall good discrimination and calibration and is relatively easy to use. Further studies should be aimed at externally validating the score in varying clinical settings.

The role of multidrug and extensive-drug resistant Gam-negative bacteria in skin and soft tissue infections.

PURPOSE OF REVIEW: Whereas Staphylococcus aureus remains the leading cause of skin and soft tissue infections (SSTI), Gram-negative bacilli (GNB) are increasingly reported as a cause of monomicrobial or polymicrobial infections. This review examines the expanding role of GNB in SSTI and discusses the risks for and the frequency of multidrug-resistance (MDR) and extensive drug-resistance (XDR) and the implications with regard to outcome and therapy. RECENT FINDINGS: Although the global epidemiology and role of GNB in SSTIs have not been studied systematically, complicated SSTIs caused by resistant GNB are increasing particularly in vulnerable patients with long-standing infections, those in long-term care facilities, and those with a history of recent hospitalization or prior antibiotic therapy. Mixed infections also occur in up to 25% of SSTIs, and inappropriate therapy occurs in 40% of cases. Prompt identification of the causative pathogen requires that patients with SSTI be risk stratified according to the likelihood of resistance to enable early recognition and swift initiation of appropriate therapy. SUMMARY: For individual treatment decisions in SSTIs, institutional diagnostic and treatment algorithms based on local epidemiology and risk factors are pivotal to reducing the incidence of treatment failure and improving outcomes associated with resistant GNB.

Best practice: antibiotic decision-making in ICUs.

PURPOSE OF REVIEW: A major challenge in the ICU is optimization of antibiotic use. This review assesses current understanding of core best practices supporting and promoting astute antibiotic decision-making. RECENT FINDINGS: Limiting exposure to the shortest effective duration is the cornerstone of antibiotic decision-making. The decision to initiate antibiotics should include assessment of risk for resistance. This requires synthesis of patient-level data and environmental factors to determine whether delayed initiation could be considered in some patients with suspected sepsis until sensitivity data is available. Until improved stratification scores and clinically meaningful cut-off values to identify MDR are available and externally validated, decisions as to which empiric antibiotic is used should rely on syndromic antibiograms and institutional guidance. Optimization of initial and maintenance doses is another enabler of enhanced outcome. Stewardship practices must be streamlined by re-assessment to minimize negative effects, such as a potential increase in duration of therapy and increased risk of collateral damage from exposure to multiple, sequential antibiotics that may ensue from de-escalation. SUMMARY: Multiple challenges and research priorities for antibiotic optimization remain; however, the best stewardship practices should be identified and entrenched in daily practice. Reducing unnecessary exposure remains a vital strategy to limit resistance development.

Four decades of pulmonary tuberculosis in deceased South African miners: trends and determinants.

OBJECTIVE: We investigated trends and determinants of pulmonary tuberculosis (PTB) in deceased South African miners. METHODS: Statutory autopsies are performed on miners for occupational lung disease compensation, irrespective of cause of death. Data were extracted from the PATHAUT (Pathology Automation System) autopsy database. PTB trends were analysed and explanatory variables (year of autopsy, age at death, gold employment duration, silicosis and HIV) were evaluated using binary logistic regression modelling. Analyses were stratified by population group because of racial differences in socioeconomic status, employment patterns and access to facilities for autopsies. The analyses were segmented to represent the pre-HIV (1975-1989), rapid HIV spread (1990-2004) and antiretroviral therapy (2005-2014) periods. RESULTS: The proportions of men with PTB at autopsy increased from 4.62% in 1975 to 27.18% in 2014 in black miners, and from 2.07% to 5.19% in white miners, with peaks in 2007 (43.12% and 9.51%, respectively). The magnitude and significance of adjusted ORs of determinants differed by population group and calendar period. PTB was largely associated with silicosis, increasing gold employment duration and year of autopsy (a surrogate for unmeasured confounders, such as unknown HIV status and tuberculosis transmission). CONCLUSIONS: Changes in PTB time trends and determinants reflect the complex social and political environment in which mining occurs. Silica dust reduction remains a key intervention for tuberculosis reduction, together with tuberculosis and HIV treatment and management. The autopsy data provide reliable information to monitor progress towards the achievement of industry and national targets to reduce tuberculosis.

From guidelines to practice: a pharmacist-driven prospective audit and feedback improvement model for peri-operative antibiotic prophylaxis in 34 South African hospitals.

Background: Few data exist on the implementation of process measures to facilitate adherence to peri-operative antibiotic prophylaxis (PAP) guidelines in Africa. Objectives: To implement an improvement model for PAP utilizing existing resources, in order to achieve a reduction in surgical site infections (SSIs) across a heterogeneous group of 34 urban and rural South African hospitals. Methods: A pharmacist-driven, prospective audit and feedback strategy involving change management and improvement principles was utilized. This 2.5 year intervention involved a pre-implementation phase to test a PAP guideline and a 'toolkit' at pilot sites. Following antimicrobial stewardship committee and clinician endorsement, the model was introduced in all institutions and a survey of baseline SSI and compliance rates with four process measures (antibiotic choice, dose, administration time and duration) was performed. The post-implementation phase involved audit, intervention and monthly feedback to facilitate improvements in compliance. Results: For 70 weeks of standardized measurements and feedback, 24 206 surgical cases were reviewed. There was a significant improvement in compliance with all process measures (composite compliance) from 66.8% (95% CI 64.8-68.7) to 83.3% (95% CI 80.8-85.8), representing a 24.7% increase ( P < 0.0001). The SSI rate decreased by 19.7% from a mean group rate of 2.46 (95% CI 2.18-2.73) pre-intervention to 1.97 post-intervention (95% CI 1.79-2.15) ( P = 0.0029). Conclusions: The implementation of process improvement initiatives and principles targeted to institutional needs utilizing pharmacists can effectively improve PAP guideline compliance and sustainable patient outcomes.

Therapeutic drug monitoring: linezolid too?

Numerous factors interfere with the ability to achieve optimal pharmacokinetic and pharmacodynamic targets and this has been associated with greater mortality and lower cure rates. The recent study by Zoller and colleagues examining linezolid levels in critically ill patients emphasises this point. Their study is unique in the description of the intra-patient and inter-patient variability that occurs and in the degree to which therapy is inadequate; 63% of patients had insufficient levels and only 17% maintained optimal trough values (between 2 and 10 mg/l) throughout the 4 study days. Precisely why this result occurred is uncertain because albumin levels, free linezolid pharmacokinetics and the presence of augmented renal clearance were not recorded in the current study. The extent of this variability makes the case for therapeutic drug monitoring since an area under the inhibitory curve greater than 80 to 120 and the time above the minimum inhibitory concentration over the entire dosing interval strongly correlate with linezolid treatment efficacy. Accordingly, therapeutic drug monitoring where available or, if not available, alternative approaches to drug delivery such as continuous infusion or a dose increase--but particularly the former--may be the answer.

Limitations of life-sustaining therapies in South Africa.

PURPOSE: Limitations of life sustaining therapies (LLST) are frequent in intensive care units (ICUs), but no previous studies have examined end-of-life (EOL) care and LLST in South Africa (SA). MATERIALS AND METHODS: This study evaluated LLST in SA from the data of a prospective, international, multicentre, observational study (Ethicus-2) and compared practices with countries in the rest of the world. RESULTS: LLST was relatively common in SA, and withholding was more frequent than withdrawing therapy. However, withdrawing and withholding therapy were less common, while failed CPR was more common, than in many other countries. No patients had an advance directive. Primary reasons for LLST in SA were poor quality of life, multisystem organ failure and patients' unresponsiveness to maximal therapy. Primary considerations for EOL decision-making were good medical practice and patients' best-interest, with the need for an ICU bed only rarely considered. CONCLUSIONS: Withholding was more common than withdrawing treatment both in SA and worldwide, although both were significantly less frequent in SA compared with the world average.

Critical illness due to infection in people living with HIV.

People living with HIV comprise a substantial number of the patients admitted to intensive care. This number varies according to geography, but all areas of the world are affected. In lower-income and middle-income countries, the majority of intensive care unit (ICU) admissions relate to infections, whereas in high-income countries, they often involve HIV-associated non-communicable diseases diagnoses. Management of infections potentially resulting in admission to the ICU in people living with HIV include sepsis, respiratory infections, COVID-19, cytomegalovirus infection, and CNS infections, both opportunistic and non-opportunistic. It is crucial to know which antiretroviral therapy (ART) is appropriate, when is the correct time to administer it, and to be aware of any safety concerns and potential drug interactions with ART. Although ART is necessary for controlling HIV infections, it can also cause difficulties relevant to the ICU such as immune reconstitution inflammatory syndrome, and issues associated with ART administration in patients with gastrointestinal dysfunction on mechanical ventilation. Managing infection in people with HIV in the ICU is complex, requiring collaboration from a multidisciplinary team knowledgeable in both the management of the specific infection and the use of ART. This team should include intensivists, infectious disease specialists, pharmacists, and microbiologists to ensure optimal outcomes for patients.

Emergence of OXA-48 and OXA-181 carbapenemases among Enterobacteriaceae in South Africa and evidence of in vivo selection of colistin resistance as a consequence of selective decontamination of the gastrointestinal tract.

This study reports on the emergence of OXA-48-like carbapenemases among isolates of Enterobacteriaceae in South Africa. In addition, the emergence during therapy of a colistin-resistant OXA-181-producing Klebsiella pneumoniae isolate was documented following selective digestive tract decontamination with oral colistin, which is therefore strongly discouraged.

Comparison of the effects of electronic cigarette vapours and tobacco smoke extracts on human neutrophils in vitro.

Background: Electronic cigarettes (ECs) are electronic aerosol delivery systems composed of nicotine and various chemicals, which are widely used to facilitate smoking cessation. Although ECs are considered safer than cigarettes, they do, however, contain chemical toxicants, some of which may interact with cells of the host's innate immune system of which neutrophils constitute a key component. Methods: The current study was designed to compare the effects of aqueous EC aerosol extracts (ECEs; with or without nicotine) with those of cigarette smoke extract (CSE) on neutrophil and platelet reactivity in vitro. Neutrophil reactivity is characterised by the generation of reactive oxygen species (ROS), degranulation (elastase release) and the release of extracellular DNA (neutrophil extracellular trap (NET) formation: NETosis), which were measured using chemiluminescence, spectrophotometric and microscopic procedures, respectively. Platelet reactivity was measured according to the magnitude of upregulated expression of the adhesion molecule CD62P on activated cells using a flow cytometric procedure. Results: Exposure of neutrophils to either ECEs or CSE caused a significant inhibition of ROS generation and elastase release by N-formyl-l-methionyl-l-leucyl-l-phenylalanine (1 µM)-activated neutrophils. Pre-treatment of neutrophils with CSE also resulted in a marked attenuation of phorbol 12-myristate 13-acetate (6.25 nM)-mediated release of extracellular DNA, which was unaffected by the ECEs. Similarly, CSE, but not the ECEs, inhibited the expression of CD62P by platelets activated with ADP (100 µM). Conclusions: These observations suggest that ECE aerosols may inhibit some of the immuno-protective activities of neutrophils such as ROS production and elastase release by activated cells, the effect of which was not enhanced by inclusion of nicotine. The inhibitory effects of CSE were significantly more pronounced than those of ECEs, especially so for suppression of NET formation and platelet activation. If operative in vivo, these harmful immunosuppressive effects of ECEs may compromise intrinsic pulmonary antimicrobial defence mechanisms, albeit less so than cigarette smoke.

Peri-operative pharmacokinetics of cefazolin prophylaxis during valve replacement surgery.

OBJECTIVE: There is little prospective data to guide effective dosing for antibiotic prophylaxis during surgery requiring cardiopulmonary bypass (CPB). We aim to describe the effects of CPB on the population pharmacokinetics (PK) of total and unbound concentrations of cefazolin and to recommend optimised dosing regimens. METHODS: Patients undergoing CPB for elective cardiac valve replacement were included using convenience sampling. Intravenous cefazolin (2g) was administered pre-incision and re-dosed at 4 hours. Serial blood and urine samples were collected and analysed using validated chromatography. Population PK modelling and Monte-Carlo simulations were performed using Pmetrics® to determine the fractional target attainment (FTA) of achieving unbound concentrations exceeding pre-defined exposures against organisms known to cause surgical site infections for 100% of surgery (100% fT>MIC). RESULTS: From the 16 included patients, 195 total and 64 unbound concentrations of cefazolin were obtained. A three-compartment linear population PK model best described the data. We observed that cefazolin 2g 4-hourly was insufficient to achieve the FTA of 100% fT>MIC for Staphylococcus aureus and Escherichia coli at serum creatinine concentrations ≤ 50 µmol/L and for Staphylococcus epidermidis at any of our simulated doses and serum creatinine concentrations. A dose of cefazolin 3g 4-hourly demonstrated >93% FTA for S. aureus and E. coli. CONCLUSIONS: We found that cefazolin 2g 4-hourly was not able to maintain concentrations above the MIC for relevant pathogens in patients with low serum creatinine concentrations undergoing cardiac surgery with CPB. The simulations showed that optimised dosing is more likely with an increased dose and/or dosing frequency.

Allergic rhinitis: Review of the diagnosis and management: South African Allergic Rhinitis Working Group.

BACKGROUND: Allergic rhinitis (AR) has a significant impact on the community as a whole with regard to quality of life and its relationship to allergic multi-morbidities. Appropriate diagnosis, treatment and review of the efficacy of interventions can ameliorate these effects. Yet, the importance of AR is often overlooked, and appropriate therapy is neglected. The availability of effective medications and knowledge as to management are often lacking in both public and private health systems. METHODS: This review is based on a comprehensive literature search and detailed discussions by the South African Allergic Rhinitis Working Group (SAARWG). RESULTS: The working group provided up-to-date recommendations on the epidemiology, pathology, diagnosis and management of AR, appropriate to the South African setting. CONCLUSION: Allergic rhinitis causes significant, often unappreciated, morbidity. It is a complex disease related to an inflammatory response to environmental allergens. Therapy involves education, evaluation of allergen sensitisation, pharmacological treatment, allergen immunotherapy (AIT) and evaluation of the success of interventions. Regular use of saline; the important role of intranasal corticosteroids, including those combined with topical antihistamines and reduction in the use of systemic steroids are key. Practitioners should have a thorough knowledge of associated morbidities and the need for specialist referral.Contribution: This review summarises the latest developments in the diagnosis and management of AR such that it is a resource that allows easy access for family practitioners and specialists alike.

Emergence of New Delhi metallo-beta-lactamase (NDM-1) and Klebsiella pneumoniae carbapenemase (KPC-2) in South Africa.

This report documents emergence of New Delhi metallo-beta-lactamase (NDM-1) and Klebsiella pneumoniae carbapenemase (KPC-2) in K. pneumoniae and Enterobacter cloacae in South Africa. NDM-1 producers have not been described in South Africa, and this is the first instance that KPC producers have been identified in Africa. The two patients infected with these carbapenemase-producing bacteria demised.

Calcium-dependent potentiation of the pro-inflammatory functions of human neutrophils by tigecycline in vitro.

OBJECTIVES: Tigecycline is the prototype of the recently introduced, intravenously administered glycylcycline class of antibiotics, developed in response to the increasing problem of antibiotic resistance in Gram-positive bacteria, especially Staphylococcus aureus, as well as Gram-negative bacteria and anaerobes. However, relatively little is known about the immunomodulatory potential of tigecycline, specifically its interactions with human neutrophils. In the current study we investigated the effects of tigecycline at therapeutically relevant concentrations and greater (0.625-10 mg/L) on alterations in cytosolic Ca(2+) concentrations, generation of antimicrobial reactive oxygen species (ROS) and release of granule proteases [elastase, matrix metalloproteinase-8 (MMP-8) and matrix metalloproteinase-9 (MMP-9)] by human blood neutrophils activated with the chemoattractant N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP; 1 µM). METHODS: Cytosolic Ca(2+) concentrations were measured using fura-2/AM-based spectrofluorimetry and radiometric procedures, generation of ROS by oxygen consumption and myeloperoxidase-mediated auto-iodination, and protease release by ELISA procedures. RESULTS: Exposure of the cells to fMLP resulted in activation of the generation of ROS, as well as release of the granule proteases, all of which were significantly increased by pre-incubation of the cells with tigecycline in a dose-dependent manner. Tigecycline-mediated enhancement of these neutrophil functions was associated with elevations in the concentrations of cytosolic Ca(2+), which appeared to result from the Ca(2+) ionophore activity of tigecycline. CONCLUSIONS: Tigecycline, by functioning as a Ca(2+) ionophore, and independent of antimicrobial activity, potentiates the pro-inflammatory functions of human neutrophils in vitro.

Hypernatremia at a Tertiary Hospital Intensive Care Unit in South Africa.

Background Hypernatremia in the critical care setting is a major cause of morbidity and mortality. However, data pertaining to this has not been evaluated in South African hospitals. The aim of this study was to evaluate hypernatremia with regards to its prevalence, associated factors, and outcomes at an academic hospital intensive care unit (ICU) in Johannesburg, South Africa. Methods The ICU charts of patients admitted to the Charlotte Maxeke Johannesburg Academic Hospital adult general ICU from June 1, 2016 to May 31, 2017 were retrospectively reviewed. Subjects were categorized into three groups namely, ICU-acquired hypernatremia (IAH), pre-admission hypernatremia (PAH), and normonatremia. Data was compared between the three groups. Results Of the 833 subjects that were enrolled, 310 (37.2%) were hypernatremic. IAH was present in 144 (17.2%) and PAH in 166 (19.9%) subjects. Hypernatremia was significantly (p <0.05) associated with a higher rate of altered mental status, higher Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II) scores, a higher rate and duration of mechanical ventilation, a greater need for inotropic/vasopressor support, longer ICU stay and higher ICU mortality. Conclusion Hypernatremia in ICU patients remains a significant contributor to morbidity, mortality, and ICU length of stay. The prevalence of hypernatremia was much higher than that reported in higher-income countries.

Antimicrobial Stewardship: Leveraging the "Butterfly Effect" of Hand Hygiene.

It is vital that there are coordinated, collaborative efforts to address the threat of antimicrobial resistance (AMR) and to prevent and control the spread of hospital-onset infections, particularly those due to multidrug-resistant (MDR) pathogens. The butterfly effect is a concept in which metaphorically speaking, small, seemingly trivial events ultimately cascade into something of far greater consequence, more specifically by having a non-linear impact on very complex systems. In this regard, antimicrobial stewardship programs (ASP), when implemented alongside infection prevention control (IPC) interventions in hospitals, particularly hand hygiene (HH), are significantly more effective in reducing the development and spread of AMR bacteria than implementation of ASP alone. In this perspective, we briefly review the evidence for the combined effect, and call for closer collaboration between institutional IPC and ASP leadership, and for well-functioning IPC programs to ensure the effectiveness of ASP.

Best practices: Appropriate use of the new ß-lactam/ß-lactamase inhibitor combinations, ceftazidime-avibactam and ceftolozane-tazobactam in South Africa.

Antibiotic stewardship of hospital-acquired infections because of difficult-to-treat resistant (DTR) Gram-negative bacteria is a global challenge. Their increasing prevalence in South Africa has required a shift in prescribing in recent years towards colistin, an antibiotic of last resort. High toxicity levels and developing resistance to colistin are narrowing treatment options further. Recently, two new ß-lactam/ß-lactamase inhibitor combinations, ceftazidime-avibactam and ceftolozane-tazobactam were registered in South Africa, bringing hope of new options for management of these life-threatening infections. However, with increased use in the private sector, increasing levels of resistance to ceftazidime-avibactam are already being witnessed, putting their long-term viability as treatment options of last resort, in jeopardy. This review focuses on how these two vital new antibiotics should be stewarded within a framework that recognises the resistance mechanisms currently predominant in South Africa's multi-drug and DTR Gram-negative bacteria. Moreover, the withholding of their use for resistant infections that can be treated with currently available antibiotics is a critical part of stewardship, if these antibiotics are to be conserved in the long term.