Page 216 - 2021_12-Haematologica-web

Letters to the Editor
Lower respiratory tract infection with Staphylococcus aureus in sickle-cell adult patients with severe acute chest syndrome - the STAPHACS Study
Acute chest syndrome (ACS) is the most common acute pulmonary complication of sickle cell disease (SCD).1 It may progress to a life-threatening event requir- ing the use of mechanical ventilation, with a mortality rate ranging from 3%1 to 50% when acute respiratory distress syndrome develops.2 Lung infection may account for 30% of the aetiologies of ACS.1 The causal relation- ship between Staphylococcus aureus (S. aureus) and ACS has been described for many years.3 However, this microorganism has been identified in only 4% of cases in the largest series published to date.1 To our knowledge, there is no specific study focusing on acute lower respira- tory tract infection (LRTI) associated with S. aureus in SCD adult patients with ACS, in the pneumococcal vac- cine era. The objectives of this pilot study were to describe S. aureus LRTI in SCD patients with severe ACS, in terms of prevalence, clinical and laboratory findings and outcomes.
We conducted a retrospective observational study from April 2015 to December 2017 in SCD patients with ACS admitted to the intensive care unit (ICU) of Tenon Hospital, Paris, France, a tertiary university hospital and referral center for SCD. The definition of ACS combined fever or chest pain and a new pulmonary infiltrate of at least one segment on thoracic imaging. ACS was consid- ered to be associated with S. aureus (alone or associated with another microorganism) when respiratory tract
samples or blood cultures yielded S. aureus, in the absence of any identifiable clinical source other than the lung. Patients with ACS associated with S. aureus (S. aureus group) were compared to patients with ACS in whom another microorganism was identified or in whom no microbiological documentation was obtained despite a comprehensive microbiological workup (control group). The workup included i) respiratory tract sam- plings (sputum, tracheal aspirate [TA], or bronchoalveolar lavage [BAL]) with Gram staining and quantitative cul- ture for bacterial microorganisms; ii) blood cultures; iii) urinary antigen testing for Streptococcus pneumoniae and Legionella pneumophila. Additionally, a respiratory multi- plex polymerase chain reaction (mPCR) test (FilmArrayTM Respiratory Panel system) has been avail- able in our unit since 2016.
This study was conducted in accordance with the French law, and was approved by the Ethical Review Board of the Société de Pneumologie de Langue Française (CEPRO 2019-021).
During the study period, 119 episodes of ACS were recorded in 114 patients. Forty-two episodes (40 patients) were excluded from the analysis because of incomplete microbiological investigation (Figure 1). Overall, S. aureus was identified in 29 of 119 episodes (24%), including respiratory tract samples cultures in 28 episodes, and blood culture in one episode (Table 1). Bacterial and viral co-infections were respectively diag- nosed in four (14 %) and three (10%) episodes in the S. aureus group. The overall distribution of the ACS episodes associated with S. aureus was sporadic through- out the year (Online Supplementary Figure S1). More
Table 1. Microbiological investigations.
Microbiological investigations performed, n (%)
Sputum
Tracheal aspirate
Broncho-alveolar lavage
Blood culture
Streptococcus pneumoniae urinary antigen test¤ Legionella pneumophila urinary antigen test¤ Chlamydophila pneumoniae serology Mycoplasma pneumoniae serology Nasopharyngeal swab (multiplex PCR)† Parvovirus B19 serology
Microbial identification, n (%) Respiratory tract
MSSA£
MRSA£
Other bacterial microorganism Respiratory virus†
Blood
S. aureus ACS group, N=29 26 (90)
1 (3)
1 (3) 28 (97) 24 (83) 26 (90) 7 (24) 8 (28) 19 (66) 11 (38)
27 (93)
2 (7)
4 (14)§
3 (10)¶
1 (3)
Control ACS group, N=48
47 (98) 7 (15) 3 (6) 47 (98) 47 (98) 47 (98) 8 (17) 9 (19) 31 (65) 14 (29)
N/A
N/A
10 (21)#
5 (10)‡
3 (7)$
P
0.15* 0.25* 0.99* 0.99* 0.03 0.15* 0.42 0.37* 0.93 0.43
0.44
0.99*
0.99*
Finally, all the patients had at least one respiratory tract sample,except 1 patient in the Staphylococcus aureus ( group (in whom S.aureus was identified in blood culture). ¤Urinary antigen testing for Streptococcus pneumoniae and Legionella pneumophila was the BinaxNOW kits (Alere, Jouy en Josas, France). £MSSA: Methicillin-sensitive S. aureus; MRSA: Methicillin-resistant S. aureus. §Streptococcus pneumoniae (n=2); Klebsiella pneumoniae (n=1); Mycoplasma pneumoniae (n=1). #Chlamydophila pneumo- niae (n=2); Streptococcus pneumoniae (n=2); Klebsiella pneumonia (n=1); Streptococcus alpha-hemolyticus (n=1); Streptococcus agalactiae (n=1); Enterobacter aerogenes (n=1);Citrobacter freundii (n=1);Salmonella typhimirium (n=1).†Respiratory viruses were detected using the respiratory multiplex polymerase chain recation (mPCR) panel (FilmArrayTM Respiratory Panel system, BioFire®, Salt Lake City, UT) including 17 respiratory viruses (coronaviruses, adenovirus, human metapneumovirus, human enterovirus/rhinovirus, respiratory syncytial virus, parainfluenza viruses and influenza viruses A and B) and 3 bacteria (Chlamydophila pneumoniae, Mycoplasma pneumo- niae, and Bordetella pertussis). ¶ Rhinovirus (n=1); Coronavirus 229E (n=1), Influenza B (n=1). ‡Rhinovirus (n=3); Enterovirus (n=1); Influenza A virus (n=1); Parvovirus B19 (n=1); one patient had 2 respiratory viruses (Enterovirus + Influenza A virus). $Salmonella typhimirium (n=1); Streptococcus pneumoniae (n=1); Citrobacter freundii (n=1). Data are presented as median [first through third quartiles] or number (%). Continuous variables are compared using a Wilcoxon method; categorical variables are com- pared either using a c2 test or Fisher’s exact test when followed by (*). ACS: acute chest syndrome.
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haematologica | 2021; 106(12)