White blood cell and differential counts in acute respiratory viral and bacterial infections in children

Alterations in Patients' Clinical Outcomes and Respiratory Viral Pathogen Activity following the COVID-19 Pandemic

BACKGROUND

Before the COVID-19 pandemic, respiratory pathogens such as influenza, parainfluenza, and respiratory syncytial virus were the most commonly detected viruses among hospitalized patients with respiratory tract infections.

METHODS

This was a retrospective observational study of inpatients and outpatients who attended Jordan University Hospital and underwent Nasopharyngeal Aspiration (NPA) in the periods from December 2017 to December 2018 and from December 2021 to December 2022. The results of multiplex respiratory pathogen real-time PCR tests for nasopharyngeal swab specimens were extracted from the electronic-based molecular diagnostic laboratory record of JUH. We compared the prevalence of the detected viruses as well as the patients' characteristics and outcomes between the two periods.

RESULTS

The total number of included patients was 695. Our analysis showed that a higher percentage of patients with hypertension and diabetes presented before the pandemic compared to the same period after it (p-value < 0.001). The need for O2 devices, white blood cell counts, diastolic blood pressure, and the length of hospital stay were significantly higher among patients who presented before the pandemic (p-value < 0.050). Influenza H1N1 (8.70% vs. 4.03%), influenza B (1.67% vs. 0.25%), parainfluenza (1.00% vs. 0.00%), human metapneumovirus (5.35% vs. 0.76%), adenoviruses (6.35% vs. 3.02%), and coronaviruses (8.70% vs. 3.53%) were detected with higher frequency in the period before the pandemic (p-value = 0.011, 0.045, 0.045, 0.000, 0.035, 0.004). These results were similar in terms of changes in the detection rates of viruses after matching the number of tested patients between the periods before and after the pandemic.

CONCLUSIONS

We have demonstrated a reduction in the detection of several viruses, which might be due to the increase in public awareness toward infection protection measures after the COVID-19 pandemic.

Development of lab score system for predicting COVID-19 patient severity: A retrospective analysis

Aim

To develop an accurate lab score based on in-hospital patients’ potent clinical and biological parameters for predicting COVID-19 patient severity during hospital admission.

Methods

To conduct this retrospective analysis, a derivation cohort was constructed by including all the available biological and clinical parameters of 355 COVID positive patients (recovered = 285, deceased = 70), collected in November 2020-September 2021. For identifying potent biomarkers and clinical parameters to determine hospital admitted patient severity or mortality, the receiver operating characteristics (ROC) curve and Fischer’s test analysis was performed. Relative risk regression was estimated to develop laboratory scores for each clinical and routine biological parameter. Lab score was further validated by ROC curve analysis of the validation cohort which was built with 50 COVID positive hospital patients, admitted during October 2021-January 2022.

Results

Sensitivity vs. 1-specificity ROC curve (>0.7 Area Under the Curve, 95% CI) and univariate analysis (p<0.0001) of the derivation cohort identified five routine biomarkers (neutrophil, lymphocytes, neutrophil: lymphocytes, WBC count, ferritin) and three clinical parameters (patient age, pre-existing comorbidities, admitted with pneumonia) for the novel lab score development. Depending on the relative risk (p values and 95% CI) these clinical parameters were scored and attributed to both the derivation cohort (n = 355) and the validation cohort (n = 50). ROC curve analysis estimated the Area Under the Curve (AUC) of the derivation and validation cohort which was 0.914 (0.883–0.945, 95% CI) and 0.873 (0.778–0.969, 95% CI) respectively.

Conclusion

The development of proper lab scores, based on patients’ clinical parameters and routine biomarkers, would help physicians to predict patient risk at the time of their hospital admission and may improve hospital-admitted COVID-19 patients’ survivability.

Dynamics of COVID-19 Lockdown on Blood Indices and Its Impact on Individuals' Immunological Health Status: A Cohort Study in Madinah, Saudi Arabia

Objective

The complete blood count (CBC) is an essential blood test that has been used for decades to assess individuals’ overall health status. This study aimed to investigate the contributions of lockdown conditions to individuals’ overall health status using blood indices as biological markers. During lockdown, people are limited to confined spaces, have access to limited nutritional supply options, experience increased stress, and are exposed to other environmental factors.

Methods

Our study’s target population included all outpatients who were severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-negative and requested CBC assessments as part of their routine health checks. A total of 2414 CBC results were included, covering a period from February 2019 to December 2020. The average of different blood indices during the COVID-19 lockdown was compared to the 10-month period preceding the lockdown.

Results

The average counts of RBCs, hemoglobin, and hematocrit showed a significant increase during the lockdown period, which lasted from May 2020 to September 2020. Reductions were observed for the RBC distribution width, total white blood cell count, platelets, and platelet distribution width.

Conclusion

Our findings suggested that the overall health status of individuals improved during the lockdown period in the short term, but health status might be adversely affected under these conditions of a longer period. Both RDW and PDW could be used as indicators for the overall health status when assessed against other blood indices.

Effects of health status on pressure-induced changes in phocid immune function and implications for dive ability

The ability of marine mammals to cope with environmental challenges is a key determining factor in strandings and successful release of rehabilitated animals. Dive behavior is related to foraging and thus survival. While dive adaptations have been well studied, it is unknown how the immune system responds to diving and whether health status impacts immune function during diving. This study investigated the functional response of ex situ immune cells from stranded phocids to in vitro increased pressure, over the course of rehabilitation. Blood samples were drawn from stranded harbor seals (Phoca vitulina), gray seals (Halichoerus grypus) and harp seals (Phoca groenlandica) at the time of admit to the Mystic Aquarium, Mystic, CT and again after rehabilitation (pre-release). Phagocytosis, lymphocyte proliferation and immune cell activation were measured in vitro, with and without exposure to 2000 psi (simulated dive depth of 1360 m). Plasma epinephrine and norepinephrine, and serum cortisol were measured in vivo. All hormone values decreased between admit and release conditions. Under admit or release conditions, pressure exposures resulted in significant changes in granulocyte and monocyte phagocytosis, granulocyte expression of CD11b and lymphocyte expression of the IL2 receptor (IL2R). Overall, pressure exposures resulted in decreased phagocytosis for admit conditions, but increased phagocytosis in release samples. Expression of leukocyte activation markers, CD11b and IL2R, increased and the response did not differ between admit and release samples. Specific hematological and serum chemistry values also changed significantly between admit and release and were significantly correlated with pressure-induced changes in immune function. Results suggest (1) dive duration affects the response of immune cells, (2) different white blood cell types respond differently to pressure and (3) response varies with animal health. This is the first study describing the relationship between diving, immune function and health status in phocids.

A prospective, multi-centre US clinical trial to determine accuracy of FebriDx point-of-care testing for acute upper respiratory infections with and without a confirmed fever

BACKGROUND

FebriDx is a 10-minute disposable point-of-care test designed to identify clinically significant systemic host immune responses and aid in the differentiation of bacterial and viral respiratory infection by simultaneously detecting C-reactive protein (CRP) and myxovirus resistance protein A (MxA) from a fingerstick blood sample. FebriDx diagnostic accuracy was evaluated in the emergency room and urgent care setting.

METHODS

A prospective, multicentre, observational cohort study of acute upper respiratory tract infections (URIs), with and without a confirmed fever at the time of enrolment, was performed to evaluate the diagnostic accuracy of FebriDx to identify clinically significant bacterial infection with host response and acute pathogenic viral infection. The reference method consisted of an algorithm with physician override that included bacterial cell culture, respiratory PCR panels for viral and atypical pathogens, procalcitonin, and white blood cell count.

RESULTS

Among 220 patients enrolled, 100% reported fever 100.5°F within the last 72 hours while 55% had a measured hyperthermia (T > 100.4) at the time of enrolment. FebriDx demonstrated a sensitivity of 95% (95% CI: 77-100%), specificity of 94% (88-98%), PPV of 76% (59-87%), and a NPV of 99% (93-100%).

CONCLUSION

FebriDx may identify clinically significant bacterial URI's and supports outpatient antibiotic decisions. Key messages FebriDx is an outpatient POC test designed to identify a clinically significant systemic host immune response and aid in the differentiation of viral and bacterial infection through rapid measurement of MxA and CRP from a fingerstick blood sample. FebriDx test was determined to be an accurate test, with a 85% sensitivity, 93% specificity and 97% NPV to rule out bacterial infection for any patient presenting with symptoms and reported fever within the prior 3 days, and when confirming fever (hyperthermia) at the time of testing, the test was even more sensitive (95%) and specific (94%) with a 99% NPV. FebriDx may support antibiotic stewardship by rapidly identifying clinically significant bacterial URIs.

Diagnostic Accuracy of FebriDx: A Rapid Test to Detect Immune Responses to Viral and Bacterial Upper Respiratory Infections

C-reactive protein (CRP) and myxovirus resistance protein A (MxA) are associated with bacterial and viral infections, respectively. We conducted a prospective, multicenter, cross-sectional study of adults and children with febrile upper respiratory tract infections (URIs) to evaluate the diagnostic accuracy of a rapid CRP/MxA immunoassay to identify clinically significant bacterial infection with host response and acute pathogenic viral infection. The reference standard for classifying URI etiology was an algorithm that included throat bacterial culture, upper respiratory PCR for viral and atypical pathogens, procalcitonin, white blood cell count, and bandemia. The algorithm also allowed for physician override. Among 205 patients, 25 (12.2%) were classified as bacterial, 53 (25.9%) as viral, and 127 (62.0%) negative by the reference standard. For bacterial detection, agreement between FebriDx and the reference standard was 91.7%, with FebriDx having a sensitivity of 80% (95% CI: 59–93%), specificity of 93% (89–97%), positive predictive value (PPV) of 63% (45–79%), and a negative predictive value (NPV) of 97% (94–99%). For viral detection, agreement was 84%, with a sensitivity of 87% (75–95%), specificity of 83% (76–89%), PPV of 64% (63–75%), and NPV of 95% (90–98%). FebriDx may help to identify clinically significant immune responses associated with bacterial and viral URIs that are more likely to require clinical management or therapeutic intervention, and has potential to assist with antibiotic stewardship.

Drivers of antibiotic prescribing in children and adolescents with febrile lower respiratory tract infections

BACKGROUND

Knowledge of key drivers for antibiotic prescribing in pediatric lower respiratory tract infection (LRTI) could support rational antibiotic use. Thus, we aimed to determine the impact of clinical and laboratory factors on antibiotic prescribing in children and adolescents with febrile LRTI.

METHODS

Pediatric patients from the standard care control group of a randomized controlled trial (ProPAED) investigating procalcitonin guided antibiotic treatment in febrile LRTI were included in a multivariate logistic regression analysis to evaluate the impact of laboratory and clinical factors on antibiotic prescribing.

RESULTS

The standard care control group of the ProPAED study comprised 165 LRTI patients (median age: 2.7 years, range: 0.1-16), out of which 88 (55%) received antibiotic treatment. Factors significantly associated with antibiotic prescribing in patients with complete clinical and laboratory documentation (n = 158) were C-reactive protein (OR 5.8 for a 10-fold increase, 95%CI 2.2-14.9), white blood count beyond age-dependent reference range (OR 3.9, 95%CI 1.4-11.4), body temperature (OR 1.7 for an increase by 1°C, 95%CI 1.02-2.68), and pleuritic pain (OR 2.8, 95%CI 1.1-7.6). Dyspnea (OR 0.3, 95%CI 0.1-0.7) and wheezing (OR 0.3, 95%CI 0.13-0.95) were inversely associated with antibiotic prescribing.

CONCLUSION

Laboratory markers were strong drivers of antibiotic prescribing in children with febrile lower respiratory tract infections, in spite of their known poor prediction of antibiotic need. Building on current guidelines for antibiotic treatment in children with febrile LRTI, a reliable decision algorithm for safe antibiotic withholding considering the laboratory and clinical factors evaluated in this study has the potential to further reduce antibiotic prescribing.

Neutrophil CD64 as a Marker of Bacterial Infection in Acute Exacerbations of Chronic Obstructive Pulmonary Disease

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are responsible for most mortality in patients with chronic obstructive pulmonary disease (COPD) and are caused mainly by bacterial infection. We analyzed and compared neutrophil CD64 expression (using the ratio of CD64 level in neutrophils to that in lymphocytes as an index), serum C-reactive protein (CRP), procalcitonin (PCT) levels, white blood cell (WBC) count, and neutrophil percentage among healthy subjects and patients with stable COPD or AECOPD. Compared with patients with COPD and healthy subjects, patients with AECOPD demonstrated significantly increased CD64 index, CRP, PCT, WBC count, and neutrophil percentage. Interestingly, CD64 index and PCT were both significantly higher in patients with AECOPD with positive bacterial sputum culture than those with negative culture. Furthermore, CD64 index and PCT were positively correlated in AECOPD, and there was also correlation between CD64 index and CRP, WBC, and neutrophil percentage. These data suggest that CD64 index is a relevant marker of bacterial infection in AECOPD. We divided patients with AECOPD into CD64-guided group and conventional treatment group. In CD64-guided group, clinicians prescribed antibiotics based on CD64 index; while in the conventional treatment group, clinicians relied on experience and clinical symptoms to determine the necessity for antibiotics. We found that the efficacy of antibiotic treatment in CD64-guided group was significantly improved compared with the conventional treatment group, including reduction of hospital stays and cost and shortened antibiotic treatment duration. Thus, the CD64 index has important diagnostic and therapeutic implications for antibiotic treatment of patients with AECOPD.

Association of Mycoplasma pneumoniae and asthma among Indian children

The role of Mycoplasma pneumoniae infection as a trigger for asthma exacerbations is well supported in previous studies. This study was designed to investigate the role of M. pneumoniae infection in acute exacerbation of asthma in children. A total of 150 patients (110 males, 40 females) were studied and immunoglobulin M (IgM) antibodies to M. pneumoniae were detected by enzyme-linked immunosorbent assay (ELISA), and PCR amplification was performed for the P1 gene to associate M. pneumoniae infection with asthma. As compared with 33 children with asthma, only two of the control subjects had positive IgM titers for M. pneumoniae, which was statistically significant (P=0.002). A total of 15 children with asthma were positive by PCR for the P1 gene while none of the controls had a positive PCR. Of these positive cases, 24 cases were positive only by ELISA, six were positive only by PCR and nine patients were found to be positive by both ELISA and PCR. All the clinical characteristics of the patients at baseline were comparable between the moderate and the severe group of patients statistically, except for the peak expiratory flow rate. Mycoplasma pneumoniae infection was found to have a significant association with acute exacerbation in the moderate group of asthma patients by PCR (P=0.01). These data suggest that M. pneumoniae infection may contribute to asthma exacerbation.

Differentiation of bacterial and viral community-acquired pneumonia in children

BACKGROUND

Microbe-specific diagnosis of pediatric community-acquired pneumonia (CAP) and the distinction between typical-bacterial, atypical-bacterial and viral cases are difficult. The aim of the present study was to evaluate the role of four serum non-specific inflammatory markers and their combinations, supplemented by chest radiological findings, in the screening of bacterial etiology of pediatric CAP.

METHODS

Serum procalcitonin (PCT), serum C-reactive protein (CRP), blood erythrocyte sedimentation rate (ESR) and white blood cell (WBC) counts were determined in 101 children with CAP, all confirmed on chest radiograph. Evidence of etiology was achieved in 68 patients (67%) mainly using a serologic test panel including 15 pathogens.

RESULTS

For the combination of CRP > 100 mg/L, WBC count > 15 x 10(9)/L, PCT > 1.0 ng/mL and ESR > 65 mm/h, the likelihood ratio for a positive test result (LR+) was 2.7 in the distinction between pneumococcal and viral CAP and 3.9 between atypical and viral CAP. If there was a higher value in one of these four parameters (CRP > 200 mg/L, WBC count > 22 x 10(9)/L, PCT > 18 ng/mL or ESR > 90 mm/h) LR+ changed to >or=3.4, which means a significant increase from pre-test to post-test disease probability. An alveolar radiological infiltration was associated with higher values in non-specific inflammatory markers when compared with interstitial infiltrates, but there were no significant associations between radiological and etiological findings.

CONCLUSIONS

CRP, WBC count, PCT and ESR or their combinations have a limited role in screening between bacterial and viral pediatric CAP. If all or most of these markers are elevated, bacterial etiology is highly probable, but low values do not rule out bacterial etiology.

Airway infectious disease emergencies

Upper and lower respiratory infections are encountered commonly in the emergency department. Visits resulting from occurrences of respiratory disease account for 10% of all pediatric emergency department visits and 20% of all pediatric hospital admissions. Causes of upper airway infections include croup, epiglottitis, retropharyngeal abscess, cellulitis, pharyngitis, and peritonsillar abscesses. Lower airway viral and bacterial infections cause illnesses such as pneumonia and bronchiolitis. Signs and symptoms of upper and lower airway infections overlap, but the differentiation is important for appropriate treatment of these conditions. This article reviews the varied clinical characteristics of upper and lower airway infections.

Non-specific host response markers in the differentiation between pneumococcal and viral pneumonia: what is the most accurate combination?

BACKGROUND

Serum C-reactive protein (CRP), blood white cell count (WBC), serum procalcitonin (PCT) and erythrocyte sedimentation rate (ESR) were measured in 132 children hospitalized for community-acquired pneumonia. Serological evidence for viral infection was found in 38 cases and for pneumococcal infection in 41 cases, and the infiltrate was alveolar in 46 cases and interstitial in 86 cases. The aim of the present paper was to determine if there is a combination of these four host response markers and chest radiograph findings suitable for differentiating pneumococcal from viral etiology of pneumonia.

METHODS

The 50th, 75th and 90th percentiles of CRP, WBC, ESR and PCT in the total group of 132 patients were calculated. By using these cut-off limits, the likelihood ratios of a positive test result were calculated for the possible combinations of CRP, WBC, ESR and PCT, and the likelihood ratio was 1.50 or more for six combinations.

RESULTS

The highest likelihood ratio (1.74) was achieved with the combination CRP > 90th (80 mg/L) or WBC > 75th (17.0 x 10(9)/L) or PCT > 75th (0.84 microg/L) or ESR > 90th (63 mm/h) percentile. For this combination, the sensitivity was 61% and the specificity 65%. When the 90th percentile cut-off limit was applied also for WBC (>22 x 10(9)/L) and PCT (>1.8 microg/L), the specificity increased to 76%, but the sensitivity decreased to 37%. When the presence of an alveolar infiltration was included in the combination, the likelihood ratio was 1.89; the specificity was as high as 82% and the sensitivity as low as 34%.

CONCLUSIONS

CRP, PCT, WBC and ESR have only limited value in differentiating pneumococcal or other bacterial pneumonia from viral pneumonia. If there was a high value in at least one of the markers (CRP > 80 mg/L, PCT > 1.8 microg/L, WBC > 22 x 10(9)/L or ESR > 60 mm/h), viral infections were rare. There was no combination of these markers which was sufficiently sensitive and specific to be used in clinical pediatric practice.

Pediatric pneumonia

Respiratory disease is common in pediatrics and diagnosing pneumonia may be clinically challenging. Changes in pneumococcal resistance and immunization practices continue to change the incidence and etiologies of pneumonia. Careful attention to epidemiologic, seasonal, and specific pediatric clinical factors and using adjunct radiographs and laboratory tests should guide the emergency physician in his or her management strategy, including selection of antibiotics and inpatient or outpatient disposition.

White blood cell count can aid judicious antibiotic prescribing in acute upper respiratory infections in children

Fifty percent or more of children with upper respiratory infections (URIs) and nonspecific febrile illnesses (e.g., children febrile, anorexic, decreased activity, irritable) receive unnecessary antibiotics from community-based physicians. This study was undertaken to show that white blood cell (WBC) count testing can aid physicians in avoiding antibiotic prescribing when managing children with URIs, and nonspecific febrile illnesses. A prospective, 3-year study was conducted in a community-based pediatric practice. A weekly convenience sample (Tuesdays) of acute URI and febrile patients ages 3 months to 21 years was studied. Data collected on enrollment included: age, gender, duration of illness, recent/current antibiotic use, temperature, symptoms, signs, laboratory testing (WBC count, cultures), diagnosis and treatment. Similar data on any illness visits in the previous 2 weeks and the subsequent 2 weeks after enrollment were collected. Viral culture specimens were obtained on a subset. The use of the WBC count was assessed, including obviating antibiotic prescription, frequency of related follow-up visits, and the occurrence of subsequent bacterial infections. Of 1,956 patients with respiratory or febrile illness enrolled, 1,219 (62%) had a diagnosis established by history and examination (e.g., acute otitis media) and 737 (38%) did not. Of the 737 patients without an established diagnosis, 386 (52%) did not receive an antibiotic because they did not appear particularly ill, their temperature was less than 101 degrees F, and parents were not demanding antibiotics, leaving 351 (48%) patients who appeared ill, had a temperature greater than 101 degrees F, and parents were demanding an antibiotic or physicians were inclined to give an antibiotic. A WBC count was performed on these 351 children; 337 children (96%) had a WBC count less than 15,000/mm3, and 14 (4%) had a WBC 15,000/mm3 or greater. An antibiotic was prescribed for 13 of the 14 children with a WBC count greater than 15,000/mms. With this approach, return office visits in the following 2 weeks were infrequent (13% of 737 patients), and no child had significant bacterial illness that was missed. With selective use of WBC count testing

Characteristics of Streptococcus pneumoniae and atypical bacterial infections in children 2-5 years of age with community-acquired pneumonia

The characteristics of community-acquired pneumonia associated with Streptococcus pneumoniae infection were compared with those associated with atypical bacterial infection and with mixed S. pneumoniae-atypical bacterial infection in 196 children aged 2-5 years. S. pneumoniae infections were diagnosed in 48 patients (24.5%); atypical bacterial infections, in 46 (23.5%); and mixed infections, in 16 (8.2%). Although white blood cell counts and C-reactive protein levels were higher in patients with pneumococcal infections, no other clinical, laboratory, or radiographic characteristic was significantly correlated with the different etiologic diagnoses. There was no significant difference in the efficacy of the different treatment regimens followed by children with S. pneumoniae infection, whereas clinical failure occurred significantly more frequently among children with atypical bacterial or mixed infection who were not treated with a macrolide. This study shows the major role of both S. pneumoniae and atypical bacteria in the development of community-acquired pneumonia in young children, the limited role of clinical, laboratory, and radiological features in predicting etiology, and the importance of the use of adequate antimicrobial agents for treatment.

Emerging resistance to antibiotics against respiratory bacteria: impact on therapy of community-acquired pneumonia in children

Perhaps because of its etiologic complexity, community-acquired pneumonia (CAP) in infants and children remains a significant problem worldwide. Over the last few years, difficulties related to CAP treatment in children have greatly increased because of the emergence of resistance to the most widely used antibiotics against some of the bacterial pathogens involved in the development of the disease. There are few data describing the impact of antibiotic resistance on clinical outcomes in CAP, but many experts believe that the clinical impact is limited. We here discuss the prevalence of different etiologic agents in CAP of children, the diagnostic criteria, problems related to antibiotic resistance, therapeutic strategies, and future implications.

Mycoplasma pneumoniae and Chlamydia pneumoniae infections in children with pneumonia. Mowgli Study Group

The most common clinical signs, host responses and radiographic patterns were studied in 203 Italian children hospitalized for community-acquired pneumonia in order to clarify the role of clinical and radiological characteristics in the diagnosis of Mycoplasma pneumoniae and/or Chlamydia pneumoniae infections. Antibody measurements in paired sera and polymerase chain reaction on nasopharyngeal aspirates were used to establish the diagnoses of acute M. pneumoniae and C. pneumoniae infection, and the aetiologic data were correlated with the clinical, laboratory and radiographic data obtained on admission. No significant association was observed between evidence of M. pneumoniae and/or C. pneumoniae infection and periods of episode during the year, mean age of the study subjects, individual symptoms, physical findings or laboratory test results. Furthermore, no significant correlation was observed in relation to the radiological findings and M. pneumoniae and/or C. pneumoniae infection. This study shows that neither clinical findings nor laboratory parameters distinguished Mycoplasma pneumoniae and/or Chlamydia pneumoniae infection in children with pneumonia. Radiological findings also have a limited capacity to differentiate aetiologic agents. The priorities for future research include the development of rapid, easily accessible and cost-effective diagnostic tests useful for each episode of pneumonia in children.

The common cold

The common cold is characterized by symptoms of rhinorrhea, nasal obstruction, sneezing, throat clearing, postnasal drip, and cough. Some of the many viruses that cause colds may cause mild additional symptoms such as sore throat, weakness, dizziness, and tearing. This article presents data concerning the cause, pathogenesis, and treatment of the common cold as well as discussion of the available diagnostic tests and their use in formulating differential diagnoses.