Antibiotics for preventing respiratory tract infections in adults receiving intensive care

Gut to lung translocation and antibiotic mediated selection shape the dynamics of Pseudomonas aeruginosa in an ICU patient

Bacteria have the potential to translocate between sites in the human body, but the dynamics and consequences of within-host bacterial migration remain poorly understood. Here we investigate the link between gut and lung Pseudomonas aeruginosa populations in an intensively sampled ICU patient using a combination of genomics, isolate phenotyping, host immunity profiling, and clinical data. Crucially, we show that lung colonization in the ICU was driven by the translocation of P. aeruginosa from the gut. Meropenem treatment for a suspected urinary tract infection selected for elevated resistance in both the gut and lung. However, resistance was driven by parallel evolution in the gut and lung coupled with organ specific selective pressures, and translocation had only a minor impact on AMR. These findings suggest that reducing intestinal colonization of Pseudomonas may be an effective way to prevent lung infections in critically ill patients.

The potential impact of the COVID-19 pandemic on antimicrobial resistance and antibiotic stewardship

The rapid emergence and spread of antimicrobial resistance continue to kill an estimated 700,000 people annually, and this number is projected to increase ten-fold by 2050. With the lack of data, it is uncertain how the COVID-19 pandemic will affect antimicrobial resistance. Severe disruption of research, innovation, global health programs, and compromised antimicrobial stewardship, infection prevention and control programs, especially in low-and middle-income countries, could affect antimicrobial resistance. However, factors such as strict lockdown, social distancing, vaccination, and the extensive implementation of hand hygiene and face masks, with limited international travel and migration, may also contribute to decreasing AMR. Although the impact of COVID-19 on AMR is global, the adverse effect is likely to be worse in LMICs. In this article, we explore the possible impact of the current pandemic on antibiotic resistance.

Topical antibiotic prophylaxis to reduce respiratory tract infections and mortality in adults receiving mechanical ventilation

BACKGROUND

Patients treated with mechanical ventilation in intensive care units (ICUs) have a high risk of developing respiratory tract infections (RTIs). Ventilator-associated pneumonia (VAP) has been estimated to affect 5% to 40% of patients treated with mechanical ventilation for at least 48 hours. The attributable mortality rate of VAP has been estimated at about 9%. Selective digestive decontamination (SDD), which consists of the topical application of non-absorbable antimicrobial agents to the oropharynx and gastroenteric tract during the whole period of mechanical ventilation, is often used to reduce the risk of VAP. A related treatment is selective oropharyngeal decontamination (SOD), in which topical antibiotics are applied to the oropharynx only. This is an update of a review first published in 1997 and updated in 2002, 2004, and 2009.

OBJECTIVES

To assess the effect of topical antibiotic regimens (SDD and SOD), given alone or in combination with systemic antibiotics, to prevent mortality and respiratory infections in patients receiving mechanical ventilation for at least 48 hours in ICUs.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Acute Respiratory Infections (ARI) Group's Specialised Register, PubMed, and Embase on 5 February 2020. We also searched the WHO ICTRP and ClinicalTrials.gov for ongoing and unpublished studies on 5 February 2020. All searches included non-English language literature. We handsearched references of topic-related systematic reviews and the included studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and cluster-RCTs assessing the efficacy and safety of topical prophylactic antibiotic regimens in adults receiving intensive care and mechanical ventilation. The included studies compared topical plus systemic antibiotics versus placebo or no treatment; topical antibiotics versus no treatment; and topical plus systemic antibiotics versus systemic antibiotics.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We included a total of 41 trials involving 11,004 participants (five new studies were added in this update). The minimum duration of mechanical ventilation ranged from 2 (19 studies) to 6 days (one study). Thirteen studies reported the mean length of ICU stay, ranging from 11 to 33 days. The percentage of immunocompromised patients ranged from 0% (10 studies) to 22% (1 study). The reporting quality of the majority of included studies was very poor, so we judged more than 40% of the studies as at unclear risk of selection bias. We judged all studies to be at low risk of performance bias, though 47.6% were open-label, because hospitals usually have standardised infection control programmes, and possible subjective decisions on who should be tested for the presence or absence of RTIs are unlikely in an ICU setting. Regarding detection bias, we judged all included studies as at low risk for the outcome mortality. For the outcome RTIs, we judged all double-blind studies as at low risk of detection bias. We judged five open-label studies as at high risk of detection bias, as the diagnosis of RTI was not based on microbiological exams; we judged the remaining open-label studies as at low risk of detection bias, as a standardised set of diagnostic criteria, including results of microbiological exams, were used. Topical plus systemic antibiotic prophylaxis reduces overall mortality compared with placebo or no treatment (risk ratio (RR) 0.84, 95% confidence interval (CI) 0.73 to 0.96; 18 studies; 5290 participants; high-certainty evidence). Based on an illustrative risk of 303 deaths in 1000 people this equates to 48 (95% CI 15 to 79) fewer deaths with topical plus systemic antibiotic prophylaxis. Topical plus systemic antibiotic prophylaxis probably reduces RTIs (RR 0.43, 95% CI 0.35 to 0.53; 17 studies; 2951 participants; moderate-certainty evidence). Based on an illustrative risk of 417 RTIs in 1000 people this equates to 238 (95% CI 196 to 271) fewer RTIs with topical plus systemic antibiotic prophylaxis. Topical antibiotic prophylaxis probably reduces overall mortality compared with no topical antibiotic prophylaxis (RR 0.96, 95% CI 0.87 to 1.05; 22 studies, 4213 participants; moderate-certainty evidence). Based on an illustrative risk of 290 deaths in 1000 people this equates to 19 (95% CI 37 fewer to 15 more) fewer deaths with topical antibiotic prophylaxis. Topical antibiotic prophylaxis may reduce RTIs (RR 0.57, 95% CI 0.44 to 0.74; 19 studies, 2698 participants; low-certainty evidence). Based on an illustrative risk of 318 RTIs in 1000 people this equates to 137 (95% CI 83 to 178) fewer RTIs with topical antibiotic prophylaxis. Sixteen studies reported adverse events and dropouts due to adverse events, which were poorly reported with sparse data. The certainty of the evidence ranged from low to very low.

AUTHORS' CONCLUSIONS

Treatments based on topical prophylaxis probably reduce respiratory infections, but not mortality, in adult patients receiving mechanical ventilation for at least 48 hours, whereas a combination of topical and systemic prophylactic antibiotics reduces both overall mortality and RTIs. However, we cannot rule out that the systemic component of the combined treatment provides a relevant contribution in the observed reduction of mortality. No conclusion can be drawn about adverse events as they were poorly reported with sparse data.

Detection of respiratory viruses in adults with respiratory tract infection using a multiplex PCR assay at a tertiary center

Background

Respiratory viruses (RVs) are among the most common pathogens for both upper and lower respiratory tract infections (RTIs). However, the viral epidemiology of RV-associated RTIs in adults has long been under-recognized. Through a sensitive molecular assay, it would be possible to have a better understanding of the epidemiology of RV-associated RTIs.

Material and methods

Respiratory tract (RT) specimens from adults hospitalized due to RTIs were tested for RVs, using the multiplex PCR-based Luminex xTAG® Respiratory Viral Panel assay. A total of nineteen RVs, including influenza viruses and non-influenza respiratory viruses (NIRVs) were detected. Positive rates were compared using a chi-square test.

Results

A total of 2292 samples from adult patients hospitalized with RTIs were screened for RVs. The overall positive rate was 22%, with 17.8% samples positive for at least one NIRV. NIRVs had a higher positive rate in non-winter seasons. As many as 12.7% (46/363) of the samples collected through broncho-alveolar lavage and 20.5% (176/859) of the samples collected in ICUs were positive for RVs. Distribution of corona virus (CoV), human metapneumovirus (hMPV) and parainfluenza virus (PIV) demonstrated seasonal variation. Also, temperature was associated with the positive rates of specific viruses, including CoV, respiratory syncytial virus (RSV), hMPV and PIV.

Conclusion

Respiratory viruses, notably NIRVs, were frequently detected in adults hospitalized with RTIs. Several RVs were detected with distinctive seasonal variations. A substantial number of RVs were identified in lower RT specimens or from patients admitted to ICU, highlighting their important role in causing severe respiratory infection.

Antibiotic stewardship programmes in intensive care units: Why, how, and where are they leading us

Antibiotic usage and increasing antimicrobial resistance (AMR) mount significant challenges to patient safety and management of the critically ill on intensive care units (ICU). Antibiotic stewardship programmes (ASPs) aim to optimise appropriate antibiotic treatment whilst minimising antibiotic resistance. Different models of ASP in intensive care setting, include “standard” control of antibiotic prescribing such as “de-escalation strategies”through to interventional approaches utilising biomarker-guided antibiotic prescribing. A systematic review of outcomes related studies for ASPs in an ICU setting was conducted. Forty three studies were identified from MEDLINE between 1996 and 2014. Of 34 non-protocolised studies, [1 randomised control trial (RCT), 22 observational and 11 case series], 29 (85%) were positive with respect to one or more outcome: These were the key outcome of reduced antibiotic use, or ICU length of stay, antibiotic resistance, or prescribing cost burden. Limitations of non-standard antibiotic initiation triggers, patient and antibiotic selection bias or baseline demographic variance were identified. All 9 protocolised studies were RCTs, of which 8 were procalcitonin (PCT) guided antibiotic stop/start interventions. Five studies addressed antibiotic escalation, 3 de-escalation and 1 addressed both. Six studies reported positive outcomes for reduced antibiotic use, ICU length of stay or antibiotic resistance. PCT based ASPs are effective as antibiotic-stop (de-escalation) triggers, but not as an escalation trigger alone. PCT has also been effective in reducing antibiotic usage without worsening morbidity or mortality in ventilator associated pulmonary infection. No study has demonstrated survival benefit of ASP. Ongoing challenges to infectious disease management, reported by the World Health Organisation global report 2014, are high AMR to newer antibiotics, and regional knowledge gaps in AMR surveillance. Improved AMR surveillance data, identifying core aspects of successful ASPs that are transferable, and further well-conducted trials will be necessary if ASPs are to be an effective platform for delivering desired patient outcomes and safety through best antibiotic policy.

Antibiotic prophylaxis to reduce respiratory tract infections and mortality in adults receiving intensive care

BACKGROUND

Pneumonia is an important cause of mortality in intensive care units (ICUs). The incidence of pneumonia in ICU patients ranges between 7% and 40%, and the crude mortality from ventilator-associated pneumonia may exceed 50%. Although not all deaths in patients with this form of pneumonia are directly attributable to pneumonia, it has been shown to contribute to mortality in ICUs independently of other factors that are also strongly associated with such deaths.

OBJECTIVES

To assess the effects of prophylactic antibiotic regimens, such as selective decontamination of the digestive tract (SDD) for the prevention of respiratory tract infections (RTIs) and overall mortality in adults receiving intensive care.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, issue 1), which contains the Cochrane Acute Respiratory Infections (ARI) Group's Specialised Register; MEDLINE (January 1966 to March 2009); and EMBASE (January 1990 to March 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of antibiotic prophylaxis for RTIs and deaths among adult ICU patients.

DATA COLLECTION AND ANALYSIS

At least two review authors independently extracted data and assessed trial quality.

MAIN RESULTS

We included 36 trials involving 6914 people. There was variation in the antibiotics used, patient characteristics and risk of RTIs and mortality in the control groups. In trials comparing a combination of topical and systemic antibiotics, there was a significant reduction in both RTIs (number of studies = 16, odds ratio (OR) 0.28, 95% confidence interval (CI) 0.20 to 0.38) and total mortality (number of studies = 17, OR 0.75, 95% CI 0.65 to 0.87) in the treated group. In trials comparing topical antimicrobials alone (or comparing topical plus systemic versus systemic alone) there was a significant reduction in RTIs (number of studies = 17, OR 0.44, 95% CI 0.31 to 0.63) but not in total mortality (number of studies = 19, OR 0.97, 95% CI 0.82 to 1.16) in the treated group.

AUTHORS' CONCLUSIONS

A combination of topical and systemic prophylactic antibiotics reduces RTIs and overall mortality in adult patients receiving intensive care. Treatment based on the use of topical prophylaxis alone reduces respiratory infections but not mortality. The risk of resistance occurring as a negative consequence of antibiotic use was appropriately explored only in one trial which did not show any such effect.

High prevalence of respiratory viral infections in patients hospitalized in an intensive care unit for acute respiratory infections as detected by nucleic acid-based assays

Forty-seven bronchoalveolar lavages (BAL) were obtained from 41 patients with acute pneumonia attending an intensive care unit. By molecular diagnosis, 30% of total BAL and 63% of bacteria-negative BAL were positive for respiratory viruses. Molecular detection allows for high-rate detection of respiratory viral infections in adult patients suffering from severe pneumonia.

Nosocomial infections in adult intensive-care units

Nosocomial infections affect about 30% of patients in intensive-care units and are associated with substantial morbidity and mortality. Several risk factors have been identified, including the use of catheters and other invasive equipment, and certain groups of patients-eg, those with trauma or burns-are recognised as being more susceptible to nosocomial infection than others. Awareness of these factors and adherence to simple preventive measures, such as adequate hand hygiene, can limit the burden of disease. Management of nosocomial infection relies on adequate and appropriate antibiotic therapy, which should be selected after discussion with infectious-disease specialists and adapted as microbiological data become available.

Multiple organ dysfunction syndrome: a narrative review

PURPOSE

To review multiple organ dysfunction syndrome with respect to: 1) clinical measurement systems; 2) molecular mechanisms; and 3) therapeutic directions based upon molecular mechanisms.

METHODS

The Medline, Cochrane, and Best Evidence databases (1996 to 2000), conference proceedings, bibliographies of review articles were searched for relevant articles. Key index words were multiple organ failure, multiple system organ dysfunction, sepsis, septic shock, shock, systemic inflammatory response syndrome. Outcomes prospectively defined were death and physiological reversal of end organ failure.

RESULTS

Multiple organ dysfunction/failure (MODS) is the most common cause for death in intensive care units. The recognition of this syndrome in the last 30 yr may be due to advances in early resuscitation unmasking these delayed sequelae in those that would have died previously. Multiple organ dysfunction occurs after shock of varied etiologies and may be the result of unbridled systemic inflammation. As yet, therapy directed to prevent or improve MODS has not dramatically altered outcomes.

CONCLUSION

Multiple organ dysfunction may serve as useful measure of disease severity for risk adjustment and outcome marker for quality of care and therapy provided. Anesthesiologists treating shock patients will note the subsequent development of MODS in the critical care unit and may be required to provide anesthetic support to these patients.

Antibiotics for preventing respiratory tract infections in adults receiving intensive care

OBJECTIVES

Pneumonia is an important cause of mortality in intensive care units. The objective of this review was to assess the effects of antibiotics for preventing respiratory tract infections and overall mortality in adults receiving intensive care.

SEARCH STRATEGY

We searched MEDLINE, proceedings of scientific meetings and reference lists of articles from January 1984 to September 1997. We also contacted investigators in the field.

SELECTION CRITERIA

Randomised trials of antibiotic prophylaxis for respiratory tract infections and deaths among adult intensive care unit patients.

DATA COLLECTION AND ANALYSIS

Trials were assessed for quality and investigators contacted for additional information.

MAIN RESULTS

Overall 33 trials involving 5727 people were included. There was variation in the antibiotics used, patient characteristics and the risk of respiratory tract infections and mortality in the control groups. In 16 trials (involving 3493 patients) of a topical and systemic antibiotic combination, the average rates of respiratory tract infections and deaths in the control group were 33% and 28% respectively. There was a significant reduction of both respiratory tract infections (odds ratio 0.36, 95% confidence interval 0.30 to 0. 43) and total mortality (odds ratio 0.80, 95% confidence interval 0. 68 to 0.93). On average five patients needed to be treated to prevent one infection and 23 treated to prevent one death. In 17 trials (involving 2366 patients) of topical antimicrobials the rates of respiratory tract infections and deaths in the control groups were 30% and 24% respectively. There was a significant reduction of respiratory tract infections (odds ratio 0.57, 95% confidence interval 0.46 to 0.69) but not in total mortality (odds ratio 1.01, 95% confidence interval 0.84 to 1.22).

REVIEWER'S CONCLUSIONS

A combination of topical and systemic prophylactic antibiotics can reduce respiratory tract infections and overall mortality in adult patients receiving intensive care. [This abstract has been prepared centrally.]