BAL in COVID-19 in the critically ill patients.
Several studies have evaluated the utility of BAL in the critically ill
patients, two were prospective.18,19,33-36 A summary
of BAL findings in critically ill patients is reported in Table 1 and 2.
The highest positivity for SARS-Cov-2 detection in BAL performed in
critically ill patients has been reported by Wang W et al, 93% (95%CI
074-1.00; N total BAL = 15) and Yang Y et al, 68% (95% CI 056-0.79; N
total BAL = 44).7,19,37 The latter study reported a
100% SARS-Cov-2 positivity in the more severe patients in whom BAL was
collected within the first 2 weeks. After 15 days the positivity od
nasopharyngeal and oropharyngeal swabs decreased while BAL maintained a
high positive rate of 63%.37 Gao et al designed a
retrospective study to evaluate the diagnostic accuracy of
nasopharyngeal swab (NP) compared to BAL for the detection of
SARS-Cov-2.38 They reviewed 123 intubated patients who
underwent both tests (time interval median 1day, IQr 1-2.75 days)
showing that 9 cases with negative NS had positive BAL, 7% of the
total. The remaining cases were: 70 positive for both, 39 negatives for
both, and 5 cases with positive NS and negative BAL. Bacterial pneumonia
was identified in 34% of total cases, with significantly more bacterial
coinfections in the non-COVID-19 (24/44, 54%) than in the COVID
patients (18/79, 23%).38 Similar results were
achieved by Mahmood et al in 55 critically ill patients, in the subgroup
of 37 negative NS they found one positive BAL for SARS-Cov-2 (3%) and
in the overall cohort found 16% of positive cultures other than
COVID-19 (Staphylococcus, Pseudomonas, Fungi, Mycobacterium avium
and Pneumocysist jirovecii ).39 In the ICU setting BAL
allows the detection of coinfections in a significant proportion of
COVID-19 (Table 2). In several studies conducted in the ICU setting BAL
was mainly performed for a microbiological purpose, with a significant
impact in subsequent medical decisions. Baron et al performed BAL in 24
patients for microbiological purposes and only in 2 (7%) BAL was
performed to confirm COVID-19 after negative NS.40 The
Authors describe the use of BAL mainly for a suspicion of ventilator
associated pneumonia (N=11, 39%), invasive aspergillosis (N=4, 14%)
and to rule out superinfection before starting a steroid course. In this
study, BAL had an impact on medical decisions in 20 cases (71%), with
introduction (n = 6), continuation (n = 3), switch (n = 2), or
withdrawal (n = 4) of antimicrobial therapy in 14 cases (50%) and/or
decision to start (n = 6; 21%), or not (n = 6, 21%), corticosteroid
therapy.40 Pickens et al conducted a retrospective
single centre study in COVID-19 mechanically ventilated patients,
documenting by early BAL (48h within intubation) 21% (28/133) of
bacterial superinfection pneumonia. Streptococcus species and
methicillin-susceptible S. aureus (MSSA) combined accounted for
79% (22/28) of cases.33 Polymicrobial infections were
common, three patients, previously treated with antibiotics had
pathogens resistant to standard CAP antibiotics—oneStenotrophomonas maltophilia and two methicillin-resistantS. aureus (MRSA) and Pneumocystis was found in one patient with
HIV on antiretroviral treatment. For each day of mechanical ventilation
they measured the Narrow Antibiotic Treatment (NAT) score and found a
clinically and statistically significant difference between positive and
negative BAL results (NAT score median difference -1, 95% CI -1 to 0;
p=0.001). These findings suggest that negative BAL analysis was used to
narrow or discontinue antibiotic treatment and that in the absence of
BAL ventilator associated pneumonia may be underrecognized yet
overtreated with unnecessary broad antibiotics.33