Dissemination of Bacillus cereus in a paediatric intensive care unit traced to insufficient disinfection of reusable ventilator air-flow sensors

Neuroinvasive Bacillus cereus Infection in Immunocompromised Hosts: Epidemiologic Investigation of 5 Patients With Acute Myeloid Leukemia

Background

Bacillus cereus is a ubiquitous gram-positive rod-shaped bacterium that can cause sepsis and neuroinvasive disease in patients with acute leukemia or neutropenia.

Methods

A single-center retrospective review was conducted to evaluate patients with acute leukemia, positive blood or cerebrospinal fluid test results for B cereus, and abnormal neuroradiographic findings between January 2018 and October 2022. Infection control practices were observed, environmental samples obtained, a dietary case-control study completed, and whole genome sequencing performed on environmental and clinical Bacillus isolates.

Results

Five patients with B cereus neuroinvasive disease were identified. All patients had acute myeloid leukemia (AML), were receiving induction chemotherapy, and were neutropenic. Neurologic involvement included subarachnoid or intraparenchymal hemorrhage or brain abscess. All patients were treated with ciprofloxacin and survived with limited or no neurologic sequelae. B cereus was identified in 7 of 61 environmental samples and 1 of 19 dietary protein samples-these were unrelated to clinical isolates via sequencing. No point source was identified. Ciprofloxacin was added to the empiric antimicrobial regimen for patients with AML and prolonged or recurrent neutropenic fevers; no new cases were identified in the ensuing year.

Conclusions

B cereus is ubiquitous in the hospital environment, at times leading to clusters with unrelated isolates. Fastidious infection control practices addressing a range of possible exposures are warranted, but their efficacy is unknown and they may not be sufficient to prevent all infections. Thus, including B cereus coverage in empiric regimens for patients with AML and persistent neutropenic fever may limit the morbidity of this pathogen.

Bacillus cereus Invasive Infections in Preterm Neonates: an Up-to-Date Review of the Literature

Bacillus cereus group species are widespread, Gram-positive, spore-forming environmental bacteria. B. cereus sensu stricto is one of the major causes of food poisoning worldwide. In high-risk individuals, such as preterm neonates, B. cereus infections can cause fatal infections. It is important to note that the phenotypic identification methods commonly used in clinical microbiology laboratories make no distinction between B. cereus sensu stricto and the other members of the group (Bacillus anthracis excluded). As a result, all the invasive infections attributed to B. cereus are not necessarily due to B. cereus sensu stricto but likely to other closely related species of the B. cereus group. Next-generation sequencing (NGS) should be used to characterize the whole genome of the strains belonging to the B. cereus group. This could confirm whether the strains involved in previously reported B. cereus invasive infections preferentially belong to formerly known or emerging individual species. Moreover, infections related to B. cereus group species have probably been overlooked, since their isolation in human bacteriological samples has for a long time been regarded as an environmental contaminant of the cultures. Recent studies have questioned the emergence or reemergence of B. cereus invasive infections in preterm infants. This review reports our current understanding of B. cereus infections in neonates, including taxonomical updates, microbiological characteristics, bacterial identification, clinical features, host-pathogen interactions, environmental sources of contamination, and antimicrobial resistance.

Rapidly fatal infection with Bacillus cereus/thuringiensis: genome assembly of the responsible pathogen and consideration of possibly contributing toxins

Bloodstream infection with Bacillus cereus/thuringiensis can be life threatening, particularly in patients who are severely immunocompromised. In this report we describe a case that progressed from asymptomatic to fatal over approximately 5 hours despite extensive resuscitation efforts. We identify the pathogen and assemble its genome, in which we find genes for toxins that may have contributed to the precipitous demise. In the context of this and other cases we discuss the possible indication for rapid appropriate antibiotic administration and potentially antitoxin treatment or toxin removal in fulminant illness in immunocompromised patients.

Investigation of a cluster of Bacillus cereus bacteremia in neonatal care units

BACKGROUND

Bacillus cereus is a well-known pathogen for self-limited foodborne illness, and rarely an opportunistic pathogen associated with invasive infections among immunocompromised patients. Nosocomial outbreaks have been rarely reported.

METHODS

Between August and November 2019, four preterm neonates in neonatal care units of a medical center developed late-onset B. cereus bacteremia. An investigation was carried out. Forty-eight environmental specimens were obtained from these neonatal units, skin surface and environmental objects of Patient 4 for the detection of this organism 19 days after the onset of illness of Patient 4. B. cereus isolates from Patient 4, five unrelated patients and environmental objects if identified were further characterized by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

RESULTS

All four infants survived after vancomycin-containing treatment. Patient 4 developed diffuse cerebritis, brain abscess with severe neurologic sequelae. Of the 48 environmental samplings, 26 specimens showed positive for B. cereus, with one major clone (sequence type 365) accounting for 73%. The isolate from Patient 4 (ST427) was identical to one isolate collected from environmental objects in the same unit. After extensive cleaning of the environment and re-institution of the sterilization procedure of hospital linens, which was ceased since two months before the outbreak, no more cases was identified in these units for at least one year.

CONCLUSIONS

We documented a cluster of B. cereus bacteremia involving four preterm infants, which might be associated with cessation of the procedure for linen sterilization and was successfully controlled by re-institution of this procedure.

Availability and use of continuous positive airway pressure (CPAP) for neonatal care in public health facilities in India: a cross-sectional cluster survey

OBJECTIVES

To determine the availability of continuous positive airway pressure (CPAP) and to provide an overview of its use in neonatal units in government hospitals across India.

SETTING

Cross-sectional cluster survey of a nationally representative sample of government hospitals from across India.

PRIMARY OUTCOMES

Availability of CPAP in neonatal units.

SECONDARY OUTCOMES

Proportion of hospitals where infrastructure and processes to provide CPAP are available. Case fatality rates and complication rates of neonates treated with CPAP.

RESULTS

Among 661 of 694 government hospitals with neonatal units that provided information on availability of CPAP for neonatal care, 68.3% of medical college hospitals (MCH) and 36.6% of district hospitals (DH) used CPAP in neonates. Assessment of a representative sample of 142 hospitals (79 MCH and 63 DH) showed that air-oxygen blenders were available in 50.7% (95% CI 41.4% to 60.9%) and staff trained in the use of CPAP were present in 56.0% (45.8% to 65.8%) of hospitals. The nurse to patient ratio was 7.3 (6.4 to 8.5) in MCH and 6.6 (5.5 to 8.3) in DH. Clinical guidelines were available in 31.0% of hospitals (22.2% to 41.4%). Upper oxygen saturation limits of above 94% were used in 72% (59.8% to 81.6%) of MCH and 59.3% (44.6% to 72.5%) of DH. Respiratory circuits were reused in 53.8% (42.3% to 63.9%) of hospitals. Case fatality rate for neonates treated with CPAP was 21.4% (16.6% to 26.2%); complication rates were 0.7% (0.2% to 1.2%) for pneumothorax, 7.4% (0.9% to 13.9%) for retinopathy and 1.4% (0.7% to 2.1%) for bronchopulmonary dysplasia.

CONCLUSIONS

CPAP is used in neonatal units across government hospitals in India. Neonates may be overexposed to oxygen as the means to detect and treat consequences of oxygen toxicity are insufficient. Neonates may also be exposed to nosocomial infections by reuse of disposables. Case fatality rates for neonates receiving CPAP are high. Complications might be under-reported. Support to infrastructure, training, guidelines implementation and staffing are needed to improve CPAP use.

Bacillus species pseudo-outbreak: construction works and collateral damage

We describe the investigation and management of a pseudo-outbreak of Bacillus spp. bacteraemia associated with construction work in an emergency department (ED). During the pseudo-outbreak period 59 out of 3469 (1.7%) blood cultures yielded Bacillus spp. versus 24 out of 7628 (0.31%) in 2012. Material, surfaces, and air samples showed environmental contamination. Cases rapidly declined following the implementation of infection control measures and the end of construction. Construction works at the ED caused environmental contamination that most probably led to the pseudo-outbreak of Bacillus bacteraemia. In hospital settings, the lack of correctly implemented effective barriers during construction may place patients and healthcare providers at risk as well as lead to pseudo-outbreaks.

Use of Peripheral Parenteral Nutrition Solutions as a Risk Factor for Bacillus cereus Peripheral Venous Catheter-Associated Bloodstream Infection at a Japanese Tertiary Care Hospital: a Case-Control Study

The risk factors are unclear for peripheral venous catheter-associated bloodstream infections (PVCBSIs) caused by Bacillus cereus. We aimed to examine for these risk factors in patients with B. cereus PVCBSI by conducting a 2-year case-control study in a large teaching hospital. We analyzed all adult cases of B. cereus PVCBSI (37 patients) and 180 controls who were randomly selected from among patients who had a PVC in place for at least 2 days. Multivariate analysis using a conditional logistic regression model indicated that independent risk factors were use of a peripheral parenteral nutrition (PPN) solution with an adjusted odds ratio (OR) of 88.7 (95% confidence interval [CI], 17.4-451.9), and steroid therapy (adjusted OR, 5.7 [95% CI, 1.3-24.4]). In conclusion, use of PPN solutions or steroids was an independent risk factor for B. cereus PVCBSI. Appropriate use of PPN solutions may help prevent B. cereus PVCBSI. Prospective studies are needed to confirm these results.

Bacterial Contamination of an Automated Pharmacy Robot Used for Intravenous Medication Preparation

Multiple cultures were positive forBacillus cereusduring routine quality assurance testing of a pharmacy robot that prepares intravenous medications. An investigation confirmed bacterial contamination of the robot as well as drug product made by the robot. The process and outcomes of the investigation are described in this report.

Association ofBacillus cereusInfection with Contaminated Alcohol Prep Pads

Background.

Bacillusspecies have caused healthcare-associated outbreaks of invasive disease as well as pseudo-outbreaks. We report an outbreak investigation of blood cultures positive forBacillus cereusassociated with alcohol prep pads (APPs) contaminated withB. cereusandBacillusspecies resulting in a rapid internal product recall and subsequent international product recall.

Design.

Epidemiologic and microbiologic outbreak investigation.

Setting.

A 300-bed tertiary care children's hospital in Aurora, Colorado.

Patients.

Patients with blood or cerebrospinal fluid cultures positive forB. cereus.

Methods.

Three patients with blood cultures positive forB. cereuswere identified in late 2010. Breaches in procedural and surgical techniques, common interventions, and products were explored. The following 3 common products were cultured: sterile saline syringes, chlorhexidine/alcohol skin preparation solution, and APPs. Repetitive sequence-based polymerase chain reaction (Rep-PCR) was used to compare isolates obtained from patients and from APPs and was confirmed by independent pulsed-field gel electrophoresis.

Results.

There appeared to be a significant increase in blood cultures positive forB. cereusduring 2009-2010.B. cereusand otherBacillusspecies were cultured from the internal contents of 63.3% of APPs not labeled as sterile, and 8 of the 10 positive lots were manufactured after 2007. None of the isolates obtained from the patients matched strains isolated from the APPs. However, some lots of APPs had strains that were indistinguishable from one another.

Conclusions.

APPs that were not labeled as sterile were contaminated withBacillusspecies. The product was immediately recalled internally and replaced with APPs from another manufacturer that were labeled as sterile. On January 3, 2011, the manufacturer voluntarily recalled its APPs. Healthcare facilities, healthcare providers, and users of APPs should avoid the use of APPs not specifically labeled as sterile.

Role of TLR5 and flagella in bacillus intraocular infection

B. cereus possesses flagella which allow the organism to migrate within the eye during a blinding form of intraocular infection called endophthalmitis. Because flagella is a ligand for Toll-like receptor 5 (TLR5), we hypothesized that TLR5 contributed to endophthalmitis pathogenesis. Endophthalmitis was induced in C57BL/6J and TLR5−/− mice by injecting 100 CFU of B. cereus into the mid-vitreous. Eyes were analyzed for intraocular bacterial growth, retinal function, and inflammation by published methods. Purified B. cereus flagellin was also injected into the mid-vitreous of wild type C57BL/6J mice and inflammation was analyzed. TLR5 activation by B. cereus flagellin was also analyzed in vitro. B. cereus grew rapidly and at similar rates in infected eyes of C57BL/6J and TLR5−/− mice. A significant loss in retinal function in both groups of mice was observed at 8 and 12 hours postinfection. Retinal architecture disruption and acute inflammation (neutrophil infiltration and proinflammatory cytokine concentrations) increased and were significant at 8 and 12 hours postinfection. Acute inflammation was comparable in TLR5−/− and C57BL/6J mice. Physiological concentrations of purified B. cereus flagellin caused significant inflammation in C57BL/6J mouse eyes, but not to the extent of that observed during active infection. Purified B. cereus flagellin was a weak agonist for TLR5 in vitro. These results demonstrated that the absence of TLR5 did not have a significant effect on the evolution of B. cereus endophthalmitis. This disparity may be due to sequence differences in important TLR5 binding domains in B. cereus flagellin or the lack of flagellin monomers in the eye to activate TLR5 during infection. Taken together, these results suggest a limited role for flagellin/TLR5 interactions in B. cereus endophthalmitis. Based on this and previous data, the importance of flagella in this disease lies in its contribution to the motility of the organism within the eye during infection.

Bacillus cereus and severe intestinal infections in preterm neonates: Putative role of pooled breast milk

BACKGROUND

Bacillus cereus is an environmental pathogen whose spores resist the usual cleaning procedure applied by the food industry and hospitals. We reported a cluster of severe intestinal infections due to B cereus in 2 very low birth weight neonates from a neonatal intensive care unit.

METHODS

Environmental sampling and bacteriological analysis of pooled breast milk (PBM) were performed. Practices for preparation and administration of milk were observed and additional laboratory experiments performed. Strains were typed using M13-polymerase chain reaction and their virulence tested using cellular and insect models.

RESULTS

B cereus strains were exclusively isolated from intestinal tracts and PBM. No environmental culture yielded any viable B cereus. Although genotypically diverse, both clinical and food strains exhibited high virulence potency. These findings pointed out the pathogenic potency of B cereus in neonates; the putative role of PBM as a reservoir for pathogenic B cereus and the triggered effect of a defective care procedure, which allowed the growth of bacteria in pasteurized PBM. Well described from dried formula, the presence of pathogenic B cereus strains in PBM was not previously reported.

CONCLUSIONS

Careful monitoring of conditions during collection, conservation, and administration of PBM should be implemented in high-risk populations such as premature neonates.

Contaminated ventilator air flow sensor linked to Bacillus cereus colonization of newborns

We investigated Bacillus cereus–positive tracheal aspirates from infants on ventilators in a neonatal intensive care unit. Multilocus sequence typing determined a genetic match between strains isolated from samples from a case-patient and from the air flow sensor in the ventilator. Changing the sterilization method for sensors to steam autoclaving stopped transmission.