Bacteremic Pneumococcal Pneumonia: a Longitudinal Study in 279 Adult Patients from a Single Center

Background: Bacteremic pneumococcal pneumonia (BPP) is the most common clinical presentation of invasive pneumococcal disease (IPD). Although it has been extensively studied, there is little knowledge in our region in relation to burden of disease, demographic and outcome features. Methods: We conducted a prospective, longitudinal, observational study from 1989 to 2015 in adult patients with BPP, in order to deepen our knowledge of the characteristics of this disease in our community hospital in Tandil, Argentina. Results: 279 patients were included. The mean incidence was 2.8/1000 admissions with a sharp decrease in the last two years, reaching 0.8/1000 admissions. Mean patient age was 60 years. Comorbidities were found in 65% of the cases. Non-respiratory symptoms occurred in 50% of cases. Infiltrates on chest x ray were predominantly unilateral (75%) and lobar (57%). Regarding severity, a low PSI score I-II-II was found in 178 patients (64%), 60 (22%) were admitted to ICU, 40 (14%) required mechanical ventilation, and 21 (8%) developed empyema. Penicillin resistance was not found. Mortality was 18% (49/279), and by a multivariate analysis it was associated with confusion (OR= 5.44), age>80 years (OR =5.72), leukopenia (OR =5.73) and dyspnea (OR=7.87). Conclusions: In this study of 279 bacteremic pneumococcal pneumonia we reinforce previous knowledge on this disease regarding incidence and clinical features and confirm a considerable an early mortality associated to age and severity of disease at onset. Recent changes in incidence of BPP in adults could be secondary to herd effect of PVC 13 a vaccine that is mandatory in children in our community since 2012. DOI: 10.18297/jri/vol2/iss1/10 Received Date: February 13, 2018 Accepted Date: March 29, 2018 Website: https://ir.library.louisville.edu/jri Affiliations: 1 Servicio de Infectología, Hospital Santamarina, Tandil, Argentina 2 Laboratorio de Microbiología, Hospital Santamarina, Tandil, Argentina 3 Area de Bioestadística, FCV-UNCPBA 4 Area de virología, FCV-UNCPBA, CIVETAN-CONICET ©2018, The Author(s). 47 ULJRI Vol 2, (1) 2018 ORIGINAL RESEARCH *Correspondence To: Dr. Jorge Gentile Work Address: Uriburu 950 Tandil CP 7000-Argentina, Work Email: gentilejorgeh@gmail.com treated in ambulatory setting between 1989 and 2015. Exclusion criteria: having been hospitalized in the last 30 days, or presented with any other evidence suggestive of nosocomial pneumonia, severe immunosuppression such in transplantation, AIDS or receiving chemotherapy or other immunosuppressive drugs. Study definitions/variables Pneumonia was defined as the presence of a new infiltrate on chest radiograph plus two or more of the following clinical manifestations including: fever (axillary temperature >37.8oC), cough, production of purulent sputum, pleuritic chest pain and dyspnoea. BPP was defined as a diagnosis of pneumonia with one or more positive blood cultures for S. pneumoniae. Identification of patients with BPP: one of the authors of this manuscript, (CH or JG), or a resident, reviewed admissions to the hospital daily, including holidays. The laboratory informed as soon as possible, when S. pneumoniae was isolated from blood culture. Data of chart was reviewed and a form was completed within 48-72h of admission. All patients were questioned, examined and followed exclusively by the authors. (JG or CH). When a patient with criteria of BPP was not admitted and sent home we strived to contact him in order to assist and include him in the study. Hospital based incidence was calculated dividing number of BPP/adult patients admitted annually to the hospital x 1000. Seasonal distribution was registered. Population incidence, was calculated during the period 20102015, adding to our series of patients with BPP admitted to the other two centres of the city, and considering population variations in the period. The following variables were recorded on admission directly from the subject, or from documentation in chart or interview with relatives: age, sex, duration of illness before consult, underlying chronic conditions such as diabetes, chronic renal failure, congestive heart failure, chronic lung disease, neurologic disease, malignancies, HIV infection, alcoholism, hepatic disease, smoking, prior antimicrobial therapy as well as clinical signs and symptoms. Living in nursing home or homelessness was registered too. Patients with dull percussion and bronchial breathing sounds on auscultation were considered as having clinical consolidation. Hypotension was defined as systolic arterial tension below 90mmHg. Abdominal pain, vomiting, hypotension, and confusion were considered nonpulmonary symptoms. Classical pneumococcal infection was considered if patients had all four of the following features: fever, pleuritic chest pain, lobar consolidation on chest X ray and leucocytosis. Pleural fluid examination was performed in all patients with pleural effusion. Empyema was considered when macroscopic pus or bacteria were identified in pleural fluid. History of pneumococcal vaccination was recorded in all cases and considered positive in patients who had received at least a single dose of 23-valent pneumococcal polysaccharide vaccine within the last 5 years. On admission, patients were stratified into risk classes I to V based on Pneumonia Severity Index (PSI) score [6]. Laboratory Leukocytosis was considered when white blood cells were more than 12,000/ml and leukopenia when WBC <4,000/ml Microbiological Testing S. pneumoniae was identified using standard microbiology procedures. One set of blood cultures were collected from each patient at entry, which is considered standard of care for patients with CAP admitted to the hospital. Conventional broth culture using nutritionally enriched media was used until 1997, after which fully automated, continuous blood culture monitoring equipment (BacT/ALERT® 3D BioMérieux, Inc. 100 Rodolphe Street, Durham, NC) became available. High quality sputum specimens (containing <10 squamous epithelial cells and >25 Polymorph Nuclear cells per low power field) were processed for bacterial diagnosis. Briefly, sputum was homogenized in 1.2 ml of sterile saline, spread onto a glass slide, air dried and heat fixed. Strains were identified based on Gram stains and morphology: gram-positive cocci found in singles, in pairs or in short chains were indicative of pneumococci infection. Sputum samples were inoculated on blood agar and chocolate agar plates and incubated at 35oC with 5-10% CO2 for 72 hours. All S. pneumoniae isolates were tested for penicillin susceptibility by diffusion, using 1 μg oxacillin disks and by broth micro-dilution test. Isolates were also screened for susceptibility to erythromycin, tetracycline, and levofloxacin using disk diffusion method. In addition, minimum inhibitory concentration (MIC) tests were used to determine susceptibility to erythromycin, extended spectrum cephalosporins, fluoroquinolones, tetracycline, trimethoprim sulfametoxazol, clindamycin, cefuroxime and vancomycin, in accordance to Clinical and Laboratory Standards Institute (CLSI, 2012) established guidelines [7]. Radiology Images on chest radiograph were classified by one of the investigators (JG) according to pattern (lobar consolidation, interstitial infiltrate, bronchopneumonia, pleural effusion) and extension (number of lobes affected, bilateral involvement) Outcome Patient were followed for 30 days after diagnosis, and complications were recorded, namely: pleural effusion, empyema, admission to ICU and need of mechanical ventilation. Overall case fatality rate was defined as death due to any cause within 30 days of hospitalization. Overall case fatality rate was defined as death due to any cause within 30 days of hospitalization. Statistical Analysis Qualitative variables are presented as the mean and range(minmax), while categorical variables are presented as frequency and percent. Contingency tables were used to measure associations with calculation of the chi-squared or Fisher’s exact test, and odds ratio (OR) were estimated. Multiple logistic regression analyses was performed to evaluate those factors found to be significant by univariate analysis and previously hypothesized to affect mortality. Two-tailed p-values are reported, with statistical significance when p<0.05. SAS V9.3 statistical software was used for calculations (SAS, Institute Inc. Cary, NC, USA). 48 ULJRI Vol 2, (1) 2018