Impact of delays to incubation and storage temperature on blood culture results: a multi-centre study

Improving the Treatment of Neonatal Sepsis in Resource-Limited Settings: Gaps and Recommendations

Neonatal sepsis causes significant global morbidity and mortality, with the highest burden in resource-limited settings where 99% of neonatal deaths occur. There are multiple challenges to achieving successful treatment of neonates in this setting. Firstly, reliable and low-cost strategies for risk identification are urgently needed to facilitate treatment as early as possible. Improved laboratory capacity to allow identification of causative organisms would support antimicrobial stewardship. Antibiotic treatment is still hampered by availability, but also increasingly by antimicrobial resistance - making surveillance of organisms and judicious antibiotic use a priority. Finally, supportive care is key in the management of the neonate with sepsis and has been underrecognized as a priority in resource-limited settings. This includes fluid balance and nutritional support in the acute phase, and follow-up care in order to mitigate complications and optimise long-term outcomes. There is much more work to be done in identifying the holistic needs of neonates and their families to provide effective family-integrated interventions and complete the package of neonatal sepsis management in resource-limited settings.

Predictive factors of infection in patients with chronic kidney disease using hemodialysis catheters

Background

Infection is the most frequent complication of central venous catheters used for hemodialysis.

Objectives

The purpose of this study was to the determine the central venous catheter-related infection rate at a dialysis center in the Brazilian state of Amazonas and to identify risk factors and the microbiological profile of the infections.

Methods

This was an observational study with prospective data collection over a 12-month period by chart analysis and face-to-face interviews with patients undergoing hemodialysis using central venous catheters at a dialysis center.

Results

96 central venous catheters were analyzed in 48 patients. 78 of these were non-tunneled central venous catheters (81.3%) and 18 were tunneled central venous catheters (18.7%), 53.1% of the catheters were exchanged because of infection and blood cultures were obtained from 35.2% of the patients who had catheter-related infections. Gram-negative bacteria were isolated from five of the nine blood cultures in which there was bacterial growth and Gram-positive bacteria were isolated from the other four. The most commonly isolated bacteria was Staphylococcus hominis, found in 22.2% of positive blood cultures.

Conclusion

The overall hemodialysis venous catheter infection rate was 10.1 episodes/1000 catheter days, 15.1 episodes/1000 catheters days in non-tunneled catheters and 3.3 episodes/1000 catheters days in tunneled catheters. The infection predisposing factors identified were use of non-tunneled catheters and having 2 hemodialysis sessions per week. Regarding the microbiological profile, over half of the bacteria isolated were Gram-negative.

An assessment of the downstream implications of blood culture collection and transit

The implications of the variables within the pre-analytical phase of blood culture processing are poorly understood. This study aims to explore the effect of transit times (TT) and culture volume, on time to microbiological diagnosis and patient outcomes. Blood cultures received between 1st March and 31st July 2020/21 were identified. TT, time in incubator (TII), and for positive samples, request to positivity times (RPT) were calculated. Demographic details were recorded for all samples, and culture volume, length of stay (LoS), and 30-day mortality for patients with positive samples. Statistical analysis examined how culture volume and TT effected culture positivity and outcome; in the context of the 4-h national TT target. Totally, 14,375 blood culture bottles were received from 7367 patients; 988 (13.4%) were positive for organisms. There was no significant difference between TT of negative and positive samples. The RPT was significantly lower for samples with TT < 4 h (p < 0.001). Culture bottle volume did not affect RPT (p = 0.482) or TII (p = 0.367). A prolonged TT was associated with a longer length-of-stay in those with a bacteraemia with a significant organism (p = 0.001). We found shorter blood culture transportation time was associated with a significantly faster time of positive culture reporting, while optimal blood culture volume did not make a significant impact. Delays in reporting for significant organisms correspond to a prolonged LoS. Laboratory centralisation makes achieving the 4-h target a logistical challenge; however, this data suggests such targets have significant microbiological and clinical impacts.

Diagnostics for Typhoid Fever: Current Perspectives and Future Outlooks for Product Development and Access

Typhoid is an enteric disease caused by Salmonella Typhi. Like many febrile illnesses, typhoid presents with nonspecific symptoms. In routine healthcare settings in low- and middle-income countries, typhoid fever is suspected and treated empirically. Though many diagnostic tests are available for typhoid diagnosis, there are currently no diagnostic tests that meet ideal requirements for sensitivity, specificity, speed, and cost-effectiveness. With introduction of typhoid conjugate vaccine, it is essential to explore the current and future typhoid approach in the context of use case and access to ensure their utilization for disease control.

Bloodstream infections and antibiotic resistance at a regional hospital, Colombia, 2019-2021

Objectives

To assess antibiotic susceptibility of World Health Organization (WHO) priority bacteria (Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Salmonella spp., Staphylococcus aureus, and Streptococcus pneumoniae) in blood cultures at the Orinoquía regional hospital in Colombia.

Methods

This was cross-sectional study using routine laboratory data for the period 2019-2021. Data on blood samples from patients suspected of a bloodstream infection were examined. We determined: the total number of blood cultures done and the proportion with culture yield; the characteristics of patients with priority bacteria; and the type of bacteria isolated and antibiotic resistance patterns.

Results

Of 25 469 blood cultures done, 1628 (6%) yielded bacteria; 774 (48%) of these bacteria were WHO priority pathogens. Most of the priority bacteria isolated (558; 72%) were gram-negative and 216 (28%) were gram-positive organisms. Most patients with priority bacteria (666; 86%) were hospitalized in wards other than the intensive care unit, 427 (55%) were male, and 321 (42%) were ≥ 60 years of age. Of the 216 gram-positive bacteria isolated, 205 (95%) were Staphylococcus aureus. Of the 558 gram-negative priority bacteria isolated, the three most common were Escherichia coli (34%), Klebsiella pneumoniae (28%), and Acinetobacter baumannii (20%). The highest resistance of Staphylococcus aureus was to oxacillin (41%). For gram-negative bacteria, resistance to antibiotics ranged from 4% (amikacin) to 72% (ampicillin).

Conclusions

Bacterial yield from blood cultures was low and could be improved. WHO priority bacteria were found in all hospital wards. This calls for rigorous infection prevention and control standards and continued surveillance of antibiotic resistance.

Incorporation of plasma Vitamin C levels to modified nutritional risk in critically ill score as the novel Vitamin C nutritional risk in critically ill score in sepsis subjects as an early predictor of multidrug-resistant bacteria: A prospective observational study

Background

On intensive care unit (ICU) admission, it is difficult to predict which patient may harbor multidrug-resistant (MDR) bacteria. MDR is the nonsusceptibility of bacteria to at least one antibiotic in three or more antimicrobial categories. Vitamin C inhibits bacterial biofilms, and its incorporation into the modified nutritional risk in critically ill (mNUTRIC) scores may help predict MDR bacterial sepsis early.

Methods

A prospective observational study was conducted on adult subjects with sepsis. Plasma Vitamin C level was estimated within 24 h of ICU admission, and it was incorporated into the mNUTRIC score (designated as Vitamin C nutritional risk in critically ill [vNUTRIC]). Multivariable logistic regression was performed to determine if vNUTRIC was an independent predictor of MDR bacterial culture in sepsis subjects. The receiver operating characteristic curve was plotted to determine the vNUTRIC cutoff score for predicting MDR bacterial culture.

Results

A total of 103 patients were recruited. The bacterial culture-positive sepsis subjects were 58/103, with 49/58 culture-positive subjects having MDR. The vNUTRIC score on ICU admission in the MDR bacteria group was 6.71 ± 1.92 versus 5.42 ± 2.2 in the non-MDR bacteria group (P = 0.003, Independent Student's t-test). High vNUTRIC score ≥6 on admission is associated with MDR bacteria (P = 0.042 Chi-Square test), and is a predictor of MDR bacteria (P = 0.003, AUC 0.671, 95% confidence interval [0.568-0.775], sensitivity 71%, specificity 48%). Logistic regression showed that the vNUTRIC score is an independent predictor of MDR bacteria.

CONCLUSION

High vNUTRIC score (≥6) on ICU admission in sepsis subjects is associated with MDR bacteria.

Equine blood cultures: Can we do better?

Blood culture is considered the gold standard test for documenting bacteraemia in patients with suspected bacterial sepsis in veterinary and human medicine. However, blood culture often fails to yield bacterial growth even though the clinical picture is strongly suggestive of bacterial sepsis, or contaminating organisms can overgrow the true pathogen, making accurate diagnosis and appropriate management of this life-threatening condition very challenging. Methodology for collecting blood cultures in equine medicine, and even in human hospitals, is not standardised, and many variables can affect the yield and type of microorganisms cultured. Microbiological culture techniques used in the laboratory and specific sample collection techniques, including volume of blood collected, aseptic technique utilised, and the site, timing and frequency of sample collection, all have substantial impact on the accuracy of blood culture results. In addition, patient-specific factors such as husbandry factors, the anatomical site of the primary infection, and changing microflora in different geographic locations, also can impact blood cultures. Thus, blood cultures obtained in practice may not always accurately define the presence or absence of, or specific organisms causing, bacteraemia in horses and foals with suspected sepsis. Erroneous blood culture results can lead to inappropriate antimicrobial use, which can result in poor outcomes for individual patients and contribute to the development of antimicrobial resistance in the patient's microflora and the environmental microcosm. This review summarises current indications and methodology, and specific factors that may be optimised, for equine blood culture, with particular focus on available literature from neonatal foals with suspected bacterial sepsis. To standardise and optimise blood culture techniques in horses and foals, future research in this area should be aimed at determining the optimal volume of blood that should be collected for culture, and the ideal site, timing, and frequency of sample collection.

Impact of delayed processing of positive blood cultures on organism detection: a prospective multi-centre study

Background

Blood cultures remain the gold standard investigation for the diagnosis of bloodstream infections. In many locations, quality-assured processing of positive blood cultures is not possible. One solution is to incubate blood cultures locally, and then transport bottles that flag positive to a central reference laboratory for organism identification and antimicrobial susceptibility testing. However, the impact of delay between the bottle flagging positive and subsequent sub-culture on the viability of the isolate has received little attention.

Methods

This study evaluated the impact of delays to sub-culture (22 h to seven days) in three different temperature conditions (2–8 °C, 22–27 °C and 35 ± 2 °C) for bottles that had flagged positive in automated detection systems using a mixture of spiked and routine clinical specimens. Ninety spiked samples for five common bacterial causes of sepsis (Escherichia coli, Haemophilus influenzae, Staphylococcus aureus, Streptococcus agalactiae and Streptococcus pneumoniae) and 125 consecutive positive clinical blood cultures were evaluated at four laboratories located in Cambodia, Lao PDR and Thailand. In addition, the utility of transport swabs for preserving organism viability was investigated.

Results

All organisms were recoverable from all sub-cultures in all temperature conditions with the exception of S. pneumoniae, which was less likely to be recoverable after longer delays (> 46–50 h), when stored in hotter temperatures (35 °C), and from BacT/ALERT when compared with BACTEC blood culture bottles. Storage of positive blood culture bottles in cooler temperatures (22–27 °C or below) and the use of Amies bacterial transport swabs helped preserve viability of S. pneumoniae.

Conclusions

These results have practical implications for the optimal workflow for blood culture bottles that have flagged positive in automated detection systems located remotely from a central processing laboratory, particularly in tropical resource-constrained contexts.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07504-1.

The drop in reported invasive pneumococcal disease among adults during the first COVID-19 wave in the Netherlands explained

Objectives: Streptococcus pneumoniae is the leading bacterial pathogen causing respiratory infections. Since the COVID-19 pandemic emerged, less invasive pneumococcal disease (IPD) was identified by surveillance systems worldwide. Measures to prevent transmission of SARS-CoV-2 also reduce transmission of pneumococci, but this would gradually lead to lower disease rates. Design: Here, we explore additional factors contributing to the instant drop in pneumococcal disease cases captured in surveillance. Results: Our observations on referral practices and other impediments to diagnostic testing indicate that residual IPD has likely occurred but remained undetected by conventional hospital-based surveillance. Conclusions: Depending on the setting, we discuss alternative monitoring strategies that could improve understanding of pneumococcal disease dynamics.