Comparison between nasopharyngeal swab and nasal wash, using culture and PCR, in the detection of potential respiratory pathogens

<p>Abstract</p> <p>Background</p> <p>Nasopharyngeal carriage of potential pathogens is important as it is both the major source of transmission and the prerequisite of invasive disease. New methods for detecting carriage could improve comfort, accuracy and laboratory utility. The aims of this study were to compare the sensitivities of a nasopharyngeal swab (NPS) and a nasal wash (NW) in detecting potential respiratory pathogens in healthy adults using microbiological culture and PCR.</p> <p>Results</p> <p>Healthy volunteers attended for nasal washing and brushing of the posterior nasopharynx. Conventional and real-time PCR were used to detect pneumococcus and meningococcus. Statistical differences between the two nasal sampling methods were determined using a nonparametric Mann-Whitney U test; differences between culture and PCR methods were determined using the McNemar test.</p> <p>Nasal washing was more comfortable for volunteers than swabbing (n = 24). In detection by culture, the NW was significantly more likely to detect pathogens than the NPS (<it>p </it>< 0.00001). Overall, there was a low carriage rate of pathogens in this sample; no significant difference was seen in the detection of bacteria between culture and PCR methods.</p> <p>Conclusions</p> <p>Nasal washing and PCR may provide effective alternatives to nasopharyngeal swabbing and classical microbiology, respectively.</p

Human Nasal Challenge with Streptococcus pneumoniae Is Immunising in the Absence of Carriage

Infectious challenge of the human nasal mucosa elicits immune responses that determine the fate of the host-bacterial interaction; leading either to clearance, colonisation and/or disease. Persistent antigenic exposure from pneumococcal colonisation can induce both humoral and cellular defences that are protective against carriage and disease. We challenged healthy adults intra-nasally with live 23F or 6B Streptococcus pneumoniae in two sequential cohorts and collected nasal wash, bronchoalveolar lavage (BAL) and blood before and 6 weeks after challenge. We hypothesised that both cohorts would successfully become colonised but this did not occur except for one volunteer. The effect of bacterial challenge without colonisation in healthy adults has not been previously assessed. We measured the antigen-specific humoral and cellular immune responses in challenged but not colonised volunteers by ELISA and Flow Cytometry. Antigen-specific responses were seen in each compartment both before and after bacterial challenge for both cohorts. Antigen-specific IgG and IgA levels were significantly elevated in nasal wash 6 weeks after challenge compared to baseline. Immunoglobulin responses to pneumococci were directed towards various protein targets but not capsular polysaccharide. 23F but not 6B challenge elevated IgG anti-PspA in BAL. Serum immunoglobulins did not increase in response to challenge. In neither challenge cohort was there any alteration in the frequencies of TNF, IL-17 or IFNγ producing CD4 T cells before or after challenge in BAL or blood. We show that simple, low dose mucosal exposure with pneumococci may immunise mucosal surfaces by augmenting anti-protein immunoglobulin responses; but not capsular or cellular responses. We hypothesise that mucosal exposure alone may not replicate the systemic immunising effect of experimental or natural carriage in humans

Is there a role for cough peak flow in assessment of patients with severe COPD?

Objective: To assess cough peak flow in patients with frequent infective exacerbations of COPD. Design: Cross-sectional controlled clinical study. Settings: Pulmonary function laboratory of the Chest Department of Ain Shams University Hospitals, Cairo, Egypt. Patients: Forty male patients with severe COPD; twenty with stable disease and twenty with more than two exacerbations in the last year were included in the study. Interventions: Spirometry and cough peak flows were measured at least six weeks after recovery from their last exacerbation. Results: Both groups were matched as regards demographics and lung functions. There was a statistically significant lower CPF in the frequent exacerbation group. Conclusion: Cough peak flow can guide respiratory physicians in fine tuning the management of patients with severe COPD to their particular needs

Bacteremia associated with bronchoscopy

Objective: To assess the incidence of bacteremia following bronchoscopy to determine whether the use of prophylactic antibiotics is warranted in patients at risk of endocarditis. Design: Prospective nonrandomized clinical study. Settings: Bronchoscopy Unit of Chest Department and Thoracic Surgery Department, and Microbiology Laboratory of Ain Shams University Hospitals, Cairo, Egypt. Patients: Forty-five patients undergoing diagnostic and therapeutic bronchoscopy. Interventions: Blood samples for culture were obtained before and immediately after the procedure. Results: There were no documented cases of bacterial growth in blood. Two culture bottles yielded contaminant. Conclusion: Bronchoscopy is a low-risk procedure for the development of bacteremia. This may bear on present practice regarding perioperative antibiotic prophylaxis for endocarditis in the high-risk groups

Increased IgG but normal IgA anti-pneumococcal protein antibodies in lung of HIV-infected adults

PspA and pneumolysin (Ply) are important protein vaccine candidates. HIV infection is associated with increased susceptibility to pneumococcal pneumonia and concomitantly high pneumococcal carriage rates. Pneumococcal exposure is immunizing at the mucosa in healthy adults and so we wished to determine if the increased pneumococcal exposure in HIV-infected adults would be associated with altered pneumococcal specific antibody responses. We measured serum and bronchoalveolar lavage (BAL) fluid immunoglobulin (Ig)G and IgA to PspA and Ply in HIV-infected and healthy age-matched adults. Naturally generated anti-Ply and anti-PspA IgG levels but not IgA were significantly increased in HIV-infected subjects in BAL independent of the hyperglobulinaemia commonly associated with HIV. There was therefore no evidence of a defect in mucosal responses to pneumococcal protein antigens among HIV-infected adults. With regard to future vaccination strategies, simply increasing mucosal anti-pneumococcal protein Ig levels, without addressing functional protective response, is not likely to be effective in preventing pneumococcal pneumonia in HIV-infected individuals

rhIL-12 as adjuvant augments lung cell cytokine responses to pneumococcal whole cell antigen

Conjugate pneumococcal vaccines offer suboptimal protection against mucosal infections and are restricted in serotype and geographical coverage.New protein-based vaccines using conserved pneumococcal antigens and better mucosal adjuvant technology are urgently needed. Interleukin-12(IL-12) has shown efficacy as a pneumococcal protein vaccine adjuvant in murine models of pneumococcal linfection. Systemic administration of recombinant human (rh) IL-12 to humans, however, has been associated with adverse clinical and laboratory side effects. Inhaled forms of IL-12 have improved the safety profiles in humans, as suggested by animal models. Here we evaluated rhIL-12 as an adjuvant on ex vivo human BAL cells when stimulated with pneumococcal whole cells. We show that co-incubation of ex vivo human BAL cells with pneumococcal whole cell antigen (WCA) and a low dose of rhIL-12 (2ng) can elevate TNF production compared to treatment with WCA (p = 0.06 )or rhIL-12 (p = 0.03) alone. The production of IFN _ was also increased but not in an antigen specific manner, suggesting perhaps a predominant Th1 response. Our data suggest that 100–200-fold lower doses of inhaled rhIL-12 than those previously tested for systemic use may be adequate in a phase 1 study and commend further evaluation of rhIL-12 as a potential mucosal adjuvant in human vaccine studie

Nasal wash IgG response to pneumococcal purified protein antigens.

<p>ELISAs were performed using pneumococcal antigens PspA (A), PspC (B), PdB (C) and PsaA (D) to determine specific IgG in subject's pre and post 23F (<i>n</i> = 7) or 6B (<i>n</i> = 8) pneumococcal challenge (x-axis). Values shown are the mean antibody concentration (of triplicates). Antibodies to PspA and PspC are expressed in µg/ml and antibodies to PdB and PsaA are expressed in arbitrary units/ml (y-axis). *represents statistical significance between pre- and post-challenge antibody levels.</p

IgG and IgA responses to whole cell 23F or 6B pneumococci following 23F or 6B challenge, respectively.

<p>ELISAs were performed using 23F or 6B pneumococci as targets to measure specific IgG (A, C and E) and IgA (B, D and F) titers in serum (A and B), NW (C and D) and BAL (E and F). Values shown are the mean antibody titers (of triplicates), pre and post 23F (<i>n</i> = 7) or 6B (<i>n</i> = 8) challenge (x-axis). *represents statistical significance between pre- and post-inoculation antibody titers.</p

Nasal wash IgG binding to pneumococcal proteins before and after 23F pneumococcal challenge by Western blot.

<p>Pre- and post- 23F challenge NW samples from 8 volunteers were used to detect pneumococcal proteins present in whole cell (WCE) and choline chloride extracts (CCE) of the challenge strain.</p

Frequency of antigen specific CD4 T cell responses before and after 23F or 6B challenge.

<p>Blood (A and C) and BAL (B and D) responses are shown pre and post 23F (A and B) or 6B (C and D) challenge. The proportion of flu and pneumococcal specific (x-axis) CD4+CD45RO+ T cells producing either TNF ± IFNγ ± IL-17 (or combinations thereof) (y-axis) were analysed by multi-parameter flow cytometry. Shown are mean values ± SD of at least 6 paired samples.</p