Abstract / Summary
Abstract Background The presence of opportunistic bacterial pathogens may complicate patients with coronavirus disease-2019 (COVID-19), and characterizing their prevalence and spectrum during the early phase of the pandemic is epidemiologically relevant. This study estimated the frequency and distribution of respiratory bacterial pathogens detected by polymerase chain reaction (PCR) in hospitalized COVID-19 patients during the first period of the pandemic in Golestan Province, Iran. Methods This retrospective study was performed on patients with COVID-19 confirmed by real-time reverse transcription (RT-PCR) who were hospitalized between June and November 2020. Nasal and nasopharyngeal swabs were tested by PCR for eight respiratory bacterial pathogens. Demographic, clinical, laboratory, and outcome data were extracted from medical records. Because upper-airway PCR cannot detect colonization, non-viable DNA, and true lower-respiratory tract infection, all positive results were interpreted as bacterial detection, not clinically confirmed co-infection. Results Among 254 hospitalized patients with confirmed COVID-19, 154 patients (60.6%) had detectable DNA from at least one bacterial target. Monobacterial and polybacterial detection was found in 111 (43.7%) and 43 (16.9%) patients, respectively. Staphylococcus aureus was the most common (22.8%) detected organism, followed by Streptococcus pneumoniae (21.3%), Stenotrophomonas maltophilia (20.5%), and Pseudomonas aeruginosa (11.4%). No significant associations were found between overall bacterial detection and age group, gender, clinical severity, ICU admission, mortality, length of hospital stay, or major laboratory parameters. In the unadjusted organism-specific analyses, P. aeruginosa detection was significantly associated with age group (P = 0.006), COVID-19 severity (P = 0.032), fever (P = 0.028), and ICU admission (P = 0.04). After multivariable adjustment, severe or critical COVID-19 remained independently associated with P. aeruginosa compared with mild disease (adjusted odds ratio [AOR] = 6.88; 95% confidence interval [CI], 1.02–46.46; P = 0.048). Hypertension was identified as a suggestive marker for polybacterial detection (AOR = 3.08; 95% CI, 0.98–9.7; P = 0.054). Mild COVID-19 was associated with lower odds of polybacterial presence compared with severe or critical COVID-19 (AOR = 0.16; 95% CI, 0.03–0.95; P = 0.04). Conclusions Bacterial DNA of several respiratory organisms was frequently detected by PCR in upper-airway specimens from hospitalized COVID-19 patients during the early pandemic. However, these results should be interpreted cautiously; the observational nature of the study precludes causal interpretation. Because respiratory sampling occurred at variable times during hospitalization and PCR positivity cannot distinguish colonization from infection, our findings suggest a prevalence of bacterial DNA detected during the hospital stay rather than active infection. Prospective studies using lower-respiratory specimens when clinically indicated, culture and susceptibility testing are needed.