Yield of Anaerobic Blood Cultures in Pediatric Emergency Department Patients

Blood volume collected for cultures in infants with suspected neonatal sepsis

OBJECTIVES

To evaluate blood culture sample volumes, identify factors linked to insufficient samples, and compare volumes among neonates treated for culture-negative-sepsis, sepsis-rule-outs, and bloodstream infections (BSI).

METHODS

Observational cohort of blood cultures collected during NICU stay. Association of age, weight, gender, source, and collection time with lower-than-recommended volumes was determined by logistic regression. Blood culture inocula of patients with culture-negative-sepsis, sepsis rule-out, and BSI were compared using ANOVA.

RESULTS

742 blood cultures were obtained from 292 neonates. Median inoculum was 1 mL (IQR:0.6-1.4), and 259 bottles (35%) had inocula <0.9 mL. Night shift sample collection was associated with lower-than-recommended volumes (p = 0.006). No difference in sample volumes was observed between culture-negative-sepsis, sepsis-rule-outs, and BSI (p = 0.5).

CONCLUSIONS

Median NICU blood culture volumes align with recommendations. Night shift collections correlate with lower volumes. Sample volumes don't differ in patients with culture-negative-sepsis, BSI, and sepsis-rule-out, and should not be a justification for longer duration of antibiotics.

Clinical usefulness of anaerobic blood culture in pediatric patients with bacteremia

OBJECTIVES

The purpose of this study is to evaluate the usefulness of anaerobic blood culture in pediatric patients by comparing the detection rate and distribution of bacteria between aerobic and anaerobic blood culture bottles.

METHODS

A retrospective analysis was conducted on 11,664 blood cultures obtained from children under the age of 14 between January 2013 and June 2020. The positive rate of total, aerobic, and anaerobic blood culture, as well as the species distribution of each blood culture bottle, were investigated.

RESULTS

The positive rate of blood culture was 2.4 % (N = 281). Among them, 67 (23.8 %), 85 (30.3 %) and 129 (45.9 %) organisms were grown in only aerobic, only anaerobic, and both blood culture bottles, respectively. Gram-positive cocci were cultured on both, only aerobic, and only anaerobic blood culture bottles in proportions of 46.4 %, 23.4 %, and 30.2 %, respectively. Gram-negative bacilli were cultured on both, only aerobic, and only anaerobic blood culture bottles in proportions of 58.5 %, 12,3 %, and 29.2 %, respectively. Gram-positive bacilli grew best in aerobic bottle only. There were seven strains of obligate anaerobes.

CONCLUSION

Because many facultative anaerobic bacteria are recognized primarily from anaerobic blood culture bottles, combining aerobic and anaerobic blood culture bottles might be beneficial in pediatric patients with suspected blood stream infection.

Identification and distribution of anaerobic bacteria isolated from clinical specimens in a University Hospital: 4 years’ experience

Anaerobes, which are components of microbiota, can cause life-threatening infections. Because of their fastidious nature, they are difficult to isolate and are often overlooked. The goal of this study was to identify the anaerobic bacteria isolated from clinical specimens at the Central Laboratory of Hacettepe University Hospital in 2015-2018 and to evaluate the distribution of the isolated bacterial species among the different specimen types. The anaerobic bacteria isolated from the specimens were identified by the conventional methods and MALDI-TOF MS.

Overall, 15,300 anaerobic cultures were studied. Of these, 14,434 (94.3%) were blood samples and 866 (5.7%) were other clinical specimens. A total of 138 anaerobic bacteria were isolated: 62 (44.9%) were isolated from blood samples and 76 (55.1%) from other specimens. The most isolated anaerobes from blood cultures were Bacteroides spp. (41.9%), followed by Cutibacterium acnes (25.8%) and Clostridium spp. (9.7%). The most isolated anaerobes from the other specimens were Gram-negative bacilli, including Bacteroides spp. (15.8%), Fusobacterium spp. (14.5%), Prevotella spp. (14.5%), and Porphyromonas spp. (2.6%). Anaerobic Finegoldia magna represented the major species among the isolated Gram-positive bacteria (10.5%). Anaerobic growth was observed in 0.4% of all the blood cultures and in 5.8% of the positive blood cultures. The results of our study showed that the incidence of anaerobic bacteremia was stable during the 2015-2018 period.

Contribution of the anaerobic blood culture vial for the recovery of Candida glabrata: a retrospective multicentric study

Although Candida spp are aerobic microorganisms, some Candida strains, mainly Candida glabrata, can be recovered from anaerobic blood culture vials. We assessed the contribution of the anaerobic vials for the diagnosis of candidemia, especially for C. glabrata. We conducted a multicenter retrospective study including eight University or regional hospitals. A single episode of monomicrobial candidemia per patient was included from September 1st, 2016, to August 31st, 2019. The characteristics of all aerobic and anaerobic blood culture vials sampled within 2 hours before and after the first positive blood culture vials were recorded (type of vials, result, and for positive vials time-to-positivity and Candida species). Overall, 509 episodes of candidemia were included. The main species were C. albicans (55.6%) followed by C. glabrata (17.1%), C. parapsilosis (4.9%), and C. tropicalis (4.5%). An anaerobic vial was positive in 76 (14.9%) of all episodes of which 56 (73.8%) were due to C. glabrata. The number of C. glabrata infections only positive in anaerobic vials was 1 (2.6%), 1 (11.1%), and 15 (37.5%) with the BACT/ALERT 3D the BACT/ALERT VIRTUO and the BACTEC FX instrument respectively (P &lt; 0.01). The initial positivity of an anaerobic vial was highly predictive of the isolation of C. glabrata with the BACTEC FX (sensitivity of 96.8%). C. glabrata time-to-positivity was shorter in anaerobic vial than aerobic vial with all instruments. Anaerobic blood culture vials improve the recovery of Candida spp mainly C. glabrata. This study could be completed by further analyzes including mycological and pediatric vials.

Case of infant invasive Streptococcus intermedius infection suggesting the need for anaerobic cultures

We report the case of an immunocompetent 6-month-old boy with a lung abscess and empyema caused by Streptococcus intermedius detected only from anaerobic cultures. Invasive S. intermedius infection in infants is rare. S. intermedius has been infrequently reported as a causative microorganism of lung abscess and empyema as most of the S. intermedius infections in children have been head and neck infections. While anaerobic cultures are often not performed for infant patients, we suggest the need for these cultures, including blood cultures, especially in cases of pediatric empyema, brain abscess, and liver abscess, which can be caused by S. intermedius.

An unusual case of abdominal pain and splenomegaly in a paediatric patient

Fusobacterium species are members of the oral microbiota and have been found to cause a wide spectrum of opportunistic infections. We describe the case of a previously healthy teenager with a large splenic abscess secondary to Fusobacterium nucleatum, successfully managed with percutaneous drainage and intravenous antibiotics. Identification of the organism was achieved using anaerobic culture of the aspirated fluid and matrix-assisted laser desorption/ionization time of flight, later confirmed by 16S ribosomal RNA metagenomic sequencing of the fluid. Fusobacteria are typically associated with oropharyngeal infections but are very rarely implicated in splenic abscesses. Aerobic and anaerobic blood cultures should be drawn when an intra-abdominal infection is suspected in a paediatric patient, and empiric antimicrobial therapy should be administered with coverage for gram-positive, gram-negative, and anaerobic bacteria.

Microbiology of Bloodstream Infections in Children After Hematopoietic Stem Cell Transplantation: A Single-Center Experience Over Two Decades (1997-2017)

Background

Bloodstream infections (BSIs) occur frequently after hematopoietic stem cell transplantation (HSCT). We examined the microbiology of BSI in pediatric HSCT recipients over a 2-decade period at our institution to inform empirical antimicrobial prescribing and infection prevention strategies.

Methods

We conducted a retrospective cohort study of children (<18 years) who underwent HSCT at Duke University between 1997 and 2015. We used recurrent-event gap-time Cox proportional hazards models to determine the hazards of all-cause and cause-specific BSI according to HSCT year. We compared the median time to BSI by causative organism type and evaluated for temporal trends in the prevalence of antibiotic resistance among causative organisms.

Results

A total of 865 BSI occurred in 1311 children, including 412 (48%) Gram-positive bacterial, 196 (23%) Gram-negative bacterial, 56 (6%) fungal, 23 (3%) mycobacterial, and 178 (21%) polymicrobial BSI. The hazard of all BSIs did not change substantially over time during the study period, but the hazard of fungal BSIs declined over time during the study period (P = .04). Most fungal BSIs (82%) occurred in the first 100 days after HSCT, whereas mycobacterial BSIs occurred later after HSCT than BSIs caused by other organisms (P < .0001). The prevalence of vancomycin resistance among BSIs caused by Enterococcus faecium increased during the study period (P = .0007). The risk of 2-year mortality in children was increased with BSI (P = .02), Gram-negative bacterial BSI (P = .02), and fungal BSI (P < .0001).

Conclusions

Despite expanded practices for BSI prevention over the past several decades, the incidence of BSI remains high in pediatric HSCT recipients at our institution. Additional strategies are urgently needed to effectively prevent BSIs in this high-risk population.

Modern Blood Culture: Management Decisions and Method Options

The optimal care of septic patients depends on the successful recovery of clinically relevant microorganisms from blood cultures and the timely reporting of organism identification and antimicrobial susceptibility testing (AST) results. Many preanalytic factors play a critical role in culturing microorganisms, and advancements in blood culture instrument technology have reduced the time to positive results. Additionally, rapid organism identification and AST results directly from positive blood culture broth via new methods help to further shorten the time from empiric to targeted treatment. This article summarizes the current state of blood culture methods, including preanalytic, analytical, and postanalytic factors that are available to clinical microbiology laboratories.

The Addition of Anaerobic Blood Cultures for Pediatric Patients with Concerns for Bloodstream Infections: Prevalence and Time to Positive Cultures

Anaerobes are an important but uncommon cause of bloodstream infections (BSIs). For pediatric patients, routine inclusion of an anaerobic blood culture alongside the aerobic remains controversial. We implemented automatic anaerobic blood culture alongside aerobic blood cultures in a pediatric emergency department (ED) and sought to determine changes in recovery of obligate and facultative anaerobes. This was a cohort study in a pediatric ED (August 2015 to July 2018) that began in February 2017. Blood culture positivity results for true pathogens and contaminants were assessed, along with a secondary outcome of time to positivity (TTP) of blood culture. A total of 14,180 blood cultures (5,202 preimplementation and 8,978 postimplementation) were collected, with 8.8% (456) and 7.1% (635) positive cultures in the pre- and postimplementation phases, respectively. Of 635 positive cultures in the postimplementation phase, aerobic blood cultures recovered 7.6% (349/4,615), whereas anaerobic blood cultures recovered 6.6% (286/4,363). In 211/421 (50.0%) paired blood cultures, an organism was recovered in both cultures. The number of cases where organisms were only recovered from an aerobic or an anaerobic bottle in the paired cultures were 126 (30.0%) and 84 (20.0%), respectively. The TTP was comparable regardless of bottle type. Recovery of true pathogens from blood cultures was approximately 7 h faster than recovery of contaminants. Although inclusion of anaerobic blood cultures only recovered 2 (0.69%) obligate anaerobes, it did allow for recovery of clinically significant pathogens that were negative in aerobic blood cultures and supports the routine collection of both bottles in pediatric patients with a concern of bloodstream infections.

Metronidazole-sensitive organisms in children with severe acute malnutrition: an evaluation of the indication for empiric metronidazole treatment

OBJECTIVES

Children with severe acute malnutrition (SAM) are treated with empiric amoxicillin or penicillin and gentamicin because of the high risk of severe infections. Experts have suggested, based on available evidence, adding metronidazole to cover anaerobic bacteraemia and diarrhoea caused by Giardia duodenalis or Clostridium difficile. The objective of this study was to assess the importance of these infections in children with SAM.

METHODS

Children from 6 months to 15 years with SAM were enrolled and followed clinically. Aerobic and, when patient weight permitted, anaerobic blood cultures were done using Bactec® system, and isolates identified with matrix-assisted laser desorption ionization-time of flight mass spectrometry. Stool samples were tested for C. difficile, G. duodenalis and Entamoeba histolytica by PCR.

RESULTS

A total of 334 children were enrolled and 174 out of 331 (53%) for which data on this was available had diarrhoea. Of 273 patients tested by blood culture, 11 had bacteraemia (4.0%, 95% CI 2.3-7.1%) but none with strict anaerobic bacteria (0/153, 95% CI 0-2.4%). There was no difference in the prevalence of C. difficile between children with (5/128, 4%) and without (7/87, 8%) diarrhoea (OR 0.47, 95% CI 0.14-1.53), and no difference in the prevalence of Giardia between these groups (78/138, 60% vs. 46/87, 53%; OR 1.34, 95% CI 0.77-2.32). Children with C. difficile had higher mortality than those without this infection (3/11, 27%, vs. 7/186, 4%; OR 43, 95% CI 3.9-483).

CONCLUSION

Our results do not provide support for empiric metronidazole to cover for anaerobic bacteraemia. Trials evaluating the effect of empiric treatment and its effect on G. duodenalis and C. difficile are warranted.

Using anaerobic blood cultures for infants younger than 90 days rarely showed anaerobic infections but increased yields of bacterial growth

AIM

The use of anaerobic blood cultures in infants suspected of bacteraemia is controversial. Our children's hospital uses both aerobic and anaerobic media, regardless of the risk of anaerobic infection, and the aim of this study was to re-evaluate the use of anaerobic cultures in infants.

METHODS

We collected retrospective data from 2002 to 2016 on all blood cultures taken from infants younger than 90 days in the Hadassah-Hebrew University Medical Centre, Jerusalem, Israel. The incidence and characteristics of infants with positive anaerobic blood cultures were assessed.

RESULTS

During the study period, 51 035 blood cultures were drawn from 44 304 infants. Of these, 1496 (2.9%) were clinically significant positive cultures. Pathogenic obligatory anaerobic bacteraemia was extremely rare, with only 37 positive cultures (0.07%) from all of the cultures drawn. No specific risk factors for obligatory anaerobic bacteraemia could be defined, but as many as 174 (11.6%) clinically significant isolates were only detected in the anaerobic culture bottle.

CONCLUSION

True anaerobic bacteraemia was extremely rare in neonates. Nevertheless, using anaerobic culture media may increase the overall yield of bacterial culture growth by isolating anaerobic-facultative bacteria. This should be weighed up against increasing the volume of blood used for the aerobic culture.