To the Editor—In the global coronavirus disease 2019 (COVID-19) pandemic, up to 80% of the patients in intensive-care units (ICUs) have required invasive mechanical ventilation (IMV). ^{Reference Maes, Higginson and Pereira-Dias1} Inpatients receiving endotracheal intubation and IMV have increased risk of ventilator-associated pneumonia (VAP). ^{Reference Maes, Higginson and Pereira-Dias1,Reference Blonz, Kouatchet and Chudeau2}

Oral hygiene with chlorhexidine-based mouthwash is an important prevention measure for VAP ^{Reference Hocková, Riad and Valky3} ; however, outbreaks of Burkholderia cepacia complex associated with these products have been reported. ^{Reference Tavares, Kozak, Balola and Sá-Correia4,Reference Shaban, Sotomayor-Castillo and Nahidi5} To our knowledge, this is the first report of a VAP outbreak caused by B. cepacia complex in COVID-19 patients admitted in ICUs involving 2 hospitals.

In November and December 2020, in a tertiary-care university hospital (hospital 1) in southern Brazil, 7 patients in a COVID-19 ICU and 3 patients in an adult ICU had positive cultures for B. cepacia complex (>10⁶ CFU/mL) from endotracheal aspirate (ETA). During this period, 6 other patients in a mixed ICU in a private hospital (hospital 2) in the same region showed B. cepacia complex–positive cultures (Fig. 1).

Fig. 1. Schematic description of B. cepacia complex isolates recovered from mechanically ventilated patients and unopened mouthwash bottles in an intra- and interhospital outbreak. (a) Time (in days) between the beginning of invasive mechanical ventilation (IMV) and B. cepacia complex detection (collection of clinical sample). (b) Patients with and without COVID-19 are admitted to the mixed ICU. Note. ICU, intensive care unit; IGS, Instability after gastrointestinal surgery; CA, cardiac arrest; ARpI, acute respiratory insufficiency; ETA, endotracheal aspirate; ERIC, Enterobacterial repetitive intergenic consensus polymerase chain reaction.

As part of the intervention, contact-isolation precautions were implemented for all patients with B. cepacia complex–positive cultures. Microbiological data were reviewed to track the source of this contamination, and as reported previously, hospital 1 had experienced consecutive outbreaks of B. cepacia complex as a result of the use of intrinsically contaminated mouthwash, so this source was investigated first. ^{Reference Saalfeld, Shinohara and Szczerepa6}

Burkholderia cepacia complex isolates recovered from ETA and mouthwashes at hospital 1 were characterized phenotypically using the BD-Phoenix automated system (Becton-Dickinson, Franklin Lakes, NJ). Hospital 2 used the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) system (Bruker Daltonics GmbH, Leipzig, Germany). All isolates (hospitals 1 and 2) were typed using the enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) technique. ^{Reference Silbert, Pfaller and Hollis7} BioNumerics 6.5 software (Applied Maths, Sint-Martens-Latem, Belgium) was used to analyze band patterns.

In total, 16 patients had B. cepacia complex–positive cultures recovered from ETA; 12 (75%) these patients were hospitalized with COVID-19 (positive RT-PCR for severe acute respiratory coronavirus virus 2 [SARS-CoV-2]) (Fig. 1). The mean age of these patients was 66 years, and 69% were male. All patients received IMV from the first day of ICU admission. The median time between the beginning of IMV and the first isolation of B. cepacia complex was 14 days (interquartile range [IQR], 9–16).

Burkholderia cepacia complex was recovered (>2.7×10⁵ CFU/mL) in unopened mouthwash bottles containing 0.12% chlorhexidine used in both hospital 1 (batch C9252, 250 mL) and hospital 2 (batch C9275, 1000 mL), all from the same company. This company’s mouthwashes had been used at hospital 1 since January 2020 without isolation of B. cepacia complex in infections.

All isolates evaluated showed 100% genetic similarity, characterizing a monoclonal outbreak involving 3 ICUs and 2 hospitals caused by B. cepacia (confirmed by MALDI-TOF MS).

The manufacturer of these contaminated batches was implicated in a previous B. cepacia complex outbreak at hospital 1, 4 years prior (data reported by our research group). ^{Reference Saalfeld, Shinohara and Szczerepa6} In the current outbreak, the hospitals notified again the National Health Surveillance Agency (ANVISA) and the manufacturer. More effectively, a voluntary national recall on December 16, 2020, by the manufacturer resulted in removal of all affected batches. According to the FDA, a likely source of B. cepacia complex contamination in aqueous products appears to be contaminated water used in manufacturing. ^{Reference Tavares, Kozak, Balola and Sá-Correia4} The presence of B. cepacia complex in unopened bottles from different batches of mouthwash strongly suggests contamination during the manufacturing process, and as with B. lata in a study conducted by Leong et al ^{Reference Leong, Lagana and Carter8} , our findings also suggest contamination during manufacturing.

Nosocomial cross transmission between patients with B. cepacia complex appears unlikely in this case. In hospital 1, the facilities and staff are not shared between the ICUs, and the adult ICU has single-bed rooms and the COVID-19 ICU 2-bed rooms. In hospital 2, inpatients with COVID-19 are single-bed rooms.

Of the total of 12 patients with VAP by B. cepacia complex and with COVID-19, 9 (75%) died. Of the 4 patients with VAP by B. cepacia complex and without COVID-19, only 1 (25%) died (Fig. 1). The time of IVM of these patients (without COVID-19) was 54.8% shorter than the patients with B. cepacia complex and SARS-CoV-2 coinfection. The median times of IVM were 31 for patients with COVID-19 and 17 days for patients without COVID-19. These results suggest that coinfection with SARS-CoV-2 and B. cepacia complex may increase the time of IMV, similarly to the case reported by Osman and Nguyen. ^{Reference Osman and Nguyen9}

Another observation here was the high number of deaths, although attributable mortality was not calculated. Although data on coinfection between SARS-CoV-2, fungi or bacteria, including B. cepacia complex, were reported, ^{Reference Yang, Hua and Liu10} data on the time of IMV and mortality attributed to these patients are still little explored and require further investigation.

Outbreaks of B. cepacia complex PAV caused by intrinsically contaminated chlorhexidine-based mouthwashes have been well reported. ^{Reference Tavares, Kozak, Balola and Sá-Correia4-Reference Saalfeld, Shinohara and Szczerepa6} The ability of B. cepacia complex to remain viable in chlorhexidine appears to result from a combination of efflux pump activity, biofilm formation, and cell-wall impermeability. ^{Reference Leong, Lagana and Carter8} These factors in themselves are extremely important because these products are used for critically ill patients. However, in the context of the COVID-19 pandemic, an outbreak appears to have even more serious consequences. The few cases reported in hospital 2 showed that VAP occurred in a short period, with a high incidence (50%) of bacteremia secondary to VAP and 100% mortality of affected patients.

In conclusion, effective surveillance with practical monitoring by a multidisciplinary team and rapid implementation of outbreak control are even more necessary in mixed ICUs and COVID-19 ICUs. We strongly suggest that national regulatory authorities establish protocols for the detection of B. cepacia complex in chlorhexidine-based products, ensuring microbiological quality of the finished product in addition to patient safety, so that similar outbreaks can be prevented.