Microsphere-Enabled Micropillar Array for Whispering Gallery Mode Virus Detection

Rapid detection of pathogens and analytes at the point of care offers an opportunity for prompt patient management and public health control. This paper reports an open microfluidic platform coupled with active whispering gallery mode (WGM) microsphere resonators for the rapid detection of influenza viruses. The WGM microsphere resonators, precoated with influenza A polyclonal antibodies, are mechanically trapped in the open micropillar array, where the evaporation-driven flow continuously transports a small volume (∼μL) of sample to the resonators without auxiliaries. Selective chemical modification of the pillar array changes surface wettability and flow pattern, which enhances the detection sensitivity of the WGM resonator-based virus sensor. The optofluidic sensing platform is able to specifically detect influenza A viruses within 15 min using a few microliters of sample and displays a linear response to different virus concentrations.

Intracellular immunoglobulin A (icIgA) in protective immunity and vaccines

Virus neutralization at respiratory mucosal surfaces is important in the prevention of infection. Mucosal immunity is mediated mainly by extracellular secretory immunoglobulin A (sIgA) and its role has been well studied. However, the protective role of intracellular specific IgA (icIgA) is less well defined. Initially, in vitro studies using epithelial cell lines with surface expressed polymeric immunoglobulin receptor (pIgR) in transwell culture chambers have shown that icIgA can neutralize influenza, parainfluenza, HIV, rotavirus and measles viruses. This effect appears to involve an interaction between polymeric immunoglobulin A (pIgA) and viral particles within an intracellular compartment, since IgA is transported across the polarized cell. Co-localization of specific icIgA with influenza virus in patients' (virus culture positive) respiratory epithelial cells using well-characterized antisera was initially reported in 2018. This review provides a summary of in vitro studies with icIgA on colocalization and neutralization of the above five viruses. Two other highly significant respiratory infectious agents with severe global impacts viz. SARS-2 virus (CoViD pandemic) and the intracellular bacterium-Mycobacterium tuberculosis-are discussed. Further studies will provide more detailed understanding of the mechanisms and kinetics of icIgA neutralization in relation to viral entry and early replication steps with a specific focus on mucosal infections. This will inform the design of more effective vaccines against infectious agents transmitted via the mucosal route.

Colocalization of intracellular specific IgA (icIgA) with influenza virus in patients' nasopharyngeal aspirate cells

Inhibition of viral replication by icIgA antibodies has only been observed with in vitro studies using epithelial cell lines in transwell cultures. This effect appears to involve an interaction between polymeric immunoglobulin A (pIgA) and viral particles within an intracellular compartment, since IgA is transported across polarized cells. Polyclonal guinea pig antisera against purified influenza A virus and mouse antisera prepared against Influenza A/H3N2 hemagglutinin (HA₀) cleavage loop peptides, were used in confocal fluorescence microscopy to show specific staining of wild-type influenza H1N1 and H3N2 viruses in clinical specimens. The HA₀ cleavage loop peptides used for intranasal immunization of mice were designed and synthesized from specific conserved regions of influenza A/H1N1 & A/H3N2 viruses. Anti-human secretory IgA antibodies were used to show co-localisation of influenza A virus and icIgA. The results showed specific immunofluorescent staining of influenza A/H3N2 (X31) (HA₀ uncleaved)-infected MDCK cells and the presence of icIgA in respiratory exudate cells of infected patients. Both results confirm specific co-localisation and suggest interaction between influenza A virus and icIgA in patients' respiratory exudate cells. Importantly, antisera to the mouse anti-HA₀ cleavage site were specific for wild-type virus in clinical specimens, indicating that the conserved region of HA₀ was present in the uncleaved form. Similar staining and colocalization patterns between icIgA and virus were observed with polyclonal guinea pig antisera against influenza A virus. These are the first observations of co-localization of influenza A virus and intracellular IgA in clinical specimens. Role of icIgA: This report shows the co-localization of influenza A virus HA₀ and icIgA antibodies in respiratory exudate cells of patients who were culture and viral RNA positive, suggesting that icIgA directed against the conserved HA₀ site may have a privileged and unique opportunity to act on immature virus and thus prevent HA₀ cleavage, maturation and subsequent cycles of viral replication. The precise mechanism by which icIgA mediates intracellular viral neutralization remains to be fully elucidated.

SIGNIFICANCE

The above findings in clinical specimens would contribute strongly to our understanding of the mechanisms and kinetics of icIgA neutralization in relation to viral entry and early replication steps of mucosal viral infections. A rapid, objective and sensitive assay - by ex vivo enumeration of respiratory epithelial cells that have co-localized influenza virus and icIgA - would contribute to further mucosal immunity studies and inform the design of more effective vaccines against influenza and other viral infections transmitted via the mucosal route e.g. respiratory syncytial virus, rotavirus.

Coxiella burnetii dormancy in a fatal ten-year multisystem dysfunctional illness: case report

BACKGROUND

In a previous study of a Q fever outbreak in Birmingham, our group identified a non-infective complex of Coxiella burnetii (C.b.) antigens able to survive in the host and provoked aberrant humoral and cell-mediated immunity responses. The study led to recognition of a possible pathogenic link between C.b. infection and subsequent long-term post Q fever fatigue syndrome (QFS). This report presents an unusually severe case of C.b. antigen and DNA detection in post-mortem specimens from a patient with QFS.

CASE PRESENTATION

We report a 19-year old female patient who became ill with an acute unexplained febrile encephalitis-like illness, followed by increasingly severe multisystem dysfunction and death 10 years later. During life, extensive clinical and laboratory investigations from different disciplinary stand points failed to deliver a definitive identification of a cause. Given the history of susceptibility to infection from birth, acute fever and the diagnosis of "post viral syndrome", tests for infective agents were done starting with C.b. and Legionella pneumophila. The patient had previously visited farms a number of times. Comprehensive neuropathological assessment at the time of autopsy had not revealed gross or microscopic abnormalities. The aim was to extend detailed studies with the post-mortem samples and identify possible factors driving severe disturbance of homeostasis and organ dysfunction exhibited by the course of the patient's ten-year illness. Immunohistochemistry for C.b. antigen and PCR for DNA were tested on paraffin embedded blocks of autopsy tissues from brain, spleen, liver, lymph nodes (LN), bone marrow (BM), heart and lung. Standard H&E staining of brain sections was unrevealing. Immuno-staining analysis for astrocyte cytoskeleton proteins using glial fibrillary acidic protein (GFAP) antibodies showed a reactive morphology. Coxiella antigens were demonstrated in GFAP immuno-positive grey and white matter astrocytes, spleen, liver, heart, BM and LN. PCR analysis (COM1/IS1111 genes) confirmed the presence of C.b. DNA in heart, lung, spleen, liver & LN, but not in brain or BM.

CONCLUSION

The study revealed the persistence of C. b. cell components in various organs, including astrocytes of the brain, in a post-infection QFS. The possible mechanisms and molecular adaptations for this alternative C.b. life style are discussed.

Molecular diagnosis of medical viruses

The diagnosis of infectious diseases has been revolutionized by the development of molecular techniques, foremost with the applications of the polymerase chain reaction (PCR). The achievable high sensitivity and ease with which the method can be used to detect any known genetic sequence have led to its wide application in the life sciences. More recently, real-time PCR assays have provided additional major contributions, with the inclusion of an additional fluorescent probe detection system resulting in an increase in sensitivity over conventional PCR, the ability to confirm the amplification product and to quantitate the target concentration. Further, nucleotide sequence analysis of the amplification products has facilitated epidemiological studies of infectious disease outbreaks, and the monitoring of treatment outcomes for infections, in particular with viruses which mutate at high frequency. This review discusses the applications of qualitative and quantitative real-time PCR, nested PCR, multiplex PCR, nucleotide sequence analysis of amplified products and quality assurance with nucleic acid testing (NAT) in diagnostic laboratories.

The anti-angiogenic effect of sinomenine

Sinomenine is an alkaloid extracted from the Chinese medicinal plant, Sinomenium acutum, which has been utilized to treat rheumatoid arthritis (RA) in China for over 2000 years. Sinomenine has been shown to mediate a wide range of pharmacological actions which includes anti-inflammatory and anti-rheumatic effects. RA has been classified as a chronic immune-mediated disease that exhibits overlapping manifestation of inflammatory, abnormal cellular and hormonal immune responses with synovial hyperplasia. Since, angiogenesis is recognized to play a critical role in the development of RA and anti-angiogenic therapy has been proposed as a new therapeutic strategy for treatment of RA, we would like to see if sinomenine possesses anti-angiogenic property. In this study, sinomenine inhibited bFGF-induced proliferation of human umbilical vein endothelial cells (HUVEC) and arrested its cell cycle in G1 phase. Sinomenine disrupted tube formation of HUVEC on Matrigel and suppressed the chemotaxis of HUVEC. In addition, sinomenine reduced neovascularization in Matrigel plug assay as well as microvascular outgrowth in rat aorta ring sprouting assay. These results suggest that sinomenine inhibited bFGF-induced angiogenesis in vitro and in vivo. As the leukocytes-endothelial adhesive interactions also play an important role in inflammation, we found that sinomenine reduced the transmigration of granulocytic differentiated HL60 cells across IL-1beta activated HUVEC monolayer. Therefore, the inhibition of leukocytes migration across blood vessel walls and the anti-angiogenic effect of sinomenine may contribute towards its therapeutic mechanisms in alleviating the pathogenesis of RA.

Rapid detection and simultaneous subtype differentiation of influenza A viruses by real time PCR

A real time RT-PCR, using the LightCycler, was developed and compared with rapid antigen enzyme immunoassay (AgEIA) and enhanced virus culture for rapid detection of influenza A viruses in stored and prospectively collected respiratory specimens. Specific hybridization probes were used for simultaneous detection and differentiation between H1N1 and H3N2 subtypes. The sensitivity of the RT-PCR for influenza A H1N1 was 120 copies and H3N2 350 copies of in vitro transcribed RNA. A specimen was considered positive for influenza A when it was culture positive or at least two methods yielded a positive test result. Using these criteria, with stored samples, the RT-PCR sensitivity, specificity, positive and negative predictive values were 82.9, 95.5, 98.9 and 52.5%, respectively. In specimens collected prospectively the RT-PCR sensitivity, specificity, positive and negative predictive values were 100, 87.9, 82.8 and 100%, respectively. There was complete concordance with subtype differentiation by hybridization probe melting temperature analysis and haemagglutination inhibition assay.

The mudskipper, Periophthalmodon schlosseri, actively transports NH4+ against a concentration gradient

Periophthalmodon schlosseri can maintain ammonia excretion rates and low levels of ammonia in its tissues when exposed to 8 and 30 mM NH4Cl, but tissue ammonia levels rise when the fish is exposed to 100 mM NH4Cl in 50% seawater. Because the transepithelial potential is not high enough to maintain the NH4+ concentration gradient between blood and water, ammonia excretion under such a condition would appear to be active. Branchial Na+-K+-ATPase activity is very high and can be activated by physiological levels of NH4+ instead of K+. Ammonia excretion by the fish against a concentration gradient is inhibited by the addition of ouabain and amiloride to the external medium. It is concluded that Na+-K+-ATPase and an Na+/H+ exchanger may be involved in the active excretion of ammonia across the gills. This unique ability of P. schlosseri to actively excrete ammonia is related to the special structure of its gills and allows the fish to continue to excrete ammonia while air exposed or in its burrow.

Fine structure of the gill epithelium of the terrestrial mudskipper, Periophthalmodon schlosseri

In this paper, we describe the fine structure of the branchial epithelium of the amphibious, air-breathing mudskipper Periophthalmodon schlosseri, and relate the observed structure to functions in gas exchange, and to the elimination of sodium chloride and ammonia. Also, we describe the fine structure of the opercular epithelimicrom. The gill lamellar epithelium is thickened by the presence of large mitochondria-rich (MR) cells. These MR cells are further characterized by an extensive tubular system that is continuous with the basolateral plasma membrane and by a deep apical crypt often lined with microvilli. There are very few specialized MR accessory cells, which are associated with NaCl excretion in marine teleosts. Instead, MR cells are commonly isolated from each other laterally by flattened cells rich in intermediate filaments. These filament-rich (FR) cells are interconnected by desmosomes and have unusual canaliculi. These branchial FR cells are unique to P. schlosseri and may have a structural role. Electron-dense pavement cells rich in vesicles and large vacuous mitochondria compose the superficial layer of the epithelium. The unusual morphology of P. schlosseri's gill lamellae may be related to the animal's ability to effectively eliminate ammonia during air exposure. The inner opercular lining and parts of the leading edge of the filament have intraepithelial capillaries, which provide a more suitable gas exchange surface than the thickened lamellae with its restricted interlamellar water spaces. The arrangement of respiratory and ion exchange epithelia is opposite to that found in all other fish in which the lamellae typically function in gas exchange and the gill filament in ion regulation.

Further characterization of HIV RNA synthesis early after cell-to-cell transmission infection

Using a one-step model for cell-to-cell transmission of HIV infection we have identified two distinct phases of HIV RNA synthesis. The first phase (4 h-12 h p.i.) was marked by an increase in only the full-length 9 kb RNA, while the second phase (24 h p.i. onwards) comprised a significant increase in the levels of all three species of viral RNA. We now report that while the continual presence of actinomycin D at 50 micrograms/ml abolished all detectable viral nucleic acid synthesis when virus donor H3B cells were pre-treated with 50 micrograms/ml of actinomycin D (AmD), washed free of unbound drug (a procedure which inhibited > 99% of total cellular RNA transcription) then mixed with untreated recipient Hut 78 cells, normal amounts of full length linear unintegrated viral DNA were produced and the first phase of viral RNA transcription was unaffected. Similarly, when both the virus donor cells and recipient cells were arrested in the late G1 phase of the cell cycle by aphidicolin and then mixed, linear unintegrated viral DNA was the major viral DNA species produced. The appearance of circular viral DNA and progeny virus was inhibited, but the first phase of induced viral RNA synthesis was unaffected. When AZT was added at 2 h or 4 h after cell-cell mixing, the level of 9 kb RNA detected was significantly lower, corresponding to reduction in the level of viral DNA. These and previous results indicate that the template for the first phase of viral RNA synthesis was likely to be newly synthesized, linear unintegrated viral DNA and not pre-existing proviral DNA present in the donor cells. Taken together, our results suggest that there exists a yet to be fully characterized pathway of concurrent viral DNA and RNA synthesis early after cell to cell transmission of HIV infection.

Comparison of rhabdomyosarcoma, buffalo green monkey kidney epithelial, A549 (human lung epithelial) cells and human embryonic lung fibroblasts for isolation of enteroviruses from clinical samples

BACKGROUND

Traditionally, primary monkey kidney (PMK) epithelial cells have been one of the more widely used cell types for the isolation of enteroviruses from clinical samples. For the isolation of coxsackie A viruses, intraperitoneal inoculation of newborn mice has been used in some laboratories.

OBJECTIVE

With the discontinued availability of PMK epithelial cells and the reported growth of coxsackie A viruses in rhabdomyosarcoma cells (RD), we compared the use of the latter cell line with our routinely used microwell cell cultures.

STUDY DESIGN

Microwell cell cultures of buffalo green monkey epithelial cell line (BGM), human lung carcinoma epithelial cell line (A549) and human embryonic lung (HEL) fibroblasts were compared with RD cell line for the isolation of enteroviruses from clinical samples.

RESULTS

A total of 39 enteroviruses was isolated from 3517 specimens. The HEL fibroblasts yielded 28 (72%) enteroviruses, followed by A549 (25 isolates, 64%), BGM (23 isolates, 59%) and RD cells (18 isolates, 46%).

CONCLUSIONS

All isolates which grew in RD cells showed specific cytopathic effects in one or more of the other inoculated cell cultures. Quantitative determinations (TCID50) with five different enteroviruses showed that the HEL fibroblasts and RD cell line to be the most sensitive cell types, followed by BGM and A549 cell lines. However, integrity of the inoculated cell monolayers was best with HEL fibroblasts and A549 cells but morphology was not optimal with RD cells during the incubation period of 14 days.

AZT blocks down-regulation of IL-2 and IFN-gamma gene expression in HIV acutely infected cells

HIV infection causes dysregulation of cytokine gene expression in CD4+ T cells of the infected host. Azidothymidine (AZT) inhibits HIV replication by blocking reverse transcription. Using a one-stop cell-to-cell HIV infection model, we have investigated the expression of several key cytokines in HIV infected T cells in the absence or presence of AZT treatment. Acute HIV infection of T cells resulted in dramatic down regulation of the expression of IL-2 and INF-gamma mRNA. While beta-actin mRNA levels remained constant in both AZT-free and AZT treated cultures after HIV infection, it was found that AZT blocked the down regulation of IL-2 mRNA and INF-gamma mRNA in CD4+ T cells acutely infected with HIV.

Recognition of adenovirus types in faecal samples by southern hybridization in South Australia

The distribution of adenovirus types in faecal samples of patients with suspected viral gastroenteritis from South Australia was determined during the 12-month period, July 1991-June 1992. There were 3299 samples tested and 226 (6.9%) were positive for adenovirus by enzyme immunoassay. Of these 226 samples, 154 (68%) were typed directly using virus DNA extracted from the faecal samples according to the Sma I, Hind III and BstE II restriction patterns and Southern hybridization analysis with pooled viral genomic DNA probes. In this group, 86% of the samples were from patients who were < 3 years of age. Enteric adenovirus types 40 and 41 accounted for 20 and 40% respectively, of these samples, and types 1, 2, 3, 5, 6, 7 and 31 comprised the remainder. Type 40 was detected mainly in the winter and spring periods, and type 41 predominated in the autumn period. The majority of the non-enteric types were found during the late winter and spring periods.

Experience with newer techniques for the laboratory detection of Mycoplasma pneumoniae infection: Adelaide, 1978-1992

Efforts to improve laboratory diagnostic methods for infection due to Mycoplasma pneumoniae have involved the use of a cell-sheet culture method and a modified indirect hemagglutination method for IgM antibody, while direct detection of mycoplasma has employed antigen capture-enzyme immunoassay (Ag-EIA) and polymerase chain reaction (PCR) amplification of sequences within the P1 and 16S ribosomal RNA genes and quantification of the amplified DNA by dot blot hybridization (DBH). Cell-sheet culture was slightly more sensitive and more rapid than culture with cell-free diphasic medium. Indirect hemagglutination detection of IgM antibody to M. pneumoniae was more sensitive than CF and EIA for detection of IgM antibody to mycoplasma. Ag-EIA gave a rapid and reasonably sensitive indication of infection and correlated well with a serological response of patients indicating a current infection. PCR-DBH was a highly sensitive substitute for culture of mycoplasma. Both Ag-EIA and PCR-DBH require confirmation by assessment of serological response to verify that the infection is current and that positive results of PCR-DBH, in particular, are not the result of continuing carriage of the organism from a previous infection, unrelated to the current episode under investigation.

Urine and the laboratory diagnosis of Chlamydia trachomatis in males

OBJECTIVE

To determine whether the use of urine samples from male patients can replace urethral swabs for the rapid detection of Chlamydia trachomatis by the Pharmacia EIA.

SETTING

The STD clinic, Adelaide, South Australia.

PATIENTS

There were two separate groups of male patients. Group A (398) patients provided urethral specimens for the EIA and culture tests. The patients in Group B (356) provided an urethral swab and a urine sample for the EIA test.

METHODS

The urine samples and urethral swabs were tested for the presence of C trachomatis by the Pharmacia Chlamydia EIA. In addition, the urethral swabs from Group A patients were cultured for the organism by standard cell cultures. The infected cell cultures were identified by an immunofluorescence test using a FITC-monoclonal antibody to C trachomatis (Kallestad).

RESULTS

When the EIA was validated against culture, it showed a sensitivity of 100% and a specificity of 95% with the urethral swabs from Group A patients. The urine specimens were positive in 24% of those patients who yielded a positive EIA result in the urethral swabs.

CONCLUSIONS

Although the EIA test on urethral swabs showed high sensitivity and specificity when validated against culture, our results showed that the use of urine samples cannot replace urethral swabs for the laboratory diagnosis of this sexually transmitted disease.

Laboratory diagnosis of Mycoplasma pneumoniae infection. 4. Antigen capture and PCR-gene amplification for detection of the Mycoplasma: problems of clinical correlation

Direct detection assays for Mycoplasma pneumoniae were established by PCR amplification of short sequences within the foot protein/adhesin (P1) gene and the 16S ribosomal RNA gene. Specificity and sensitivity was excellent, no hybridization was observed with M. genitalium and other human Mycoplasma species. In nose and throat washings from subjects with respiratory infection a pattern of high counts (c.f.u./ml) of M. pneumoniae (deduced from the amount of amplified PCR product), and a positive antigen capture assay, was found in 83% of subjects with serological evidence of current infection with M. pneumoniae. A small proportion of subjects with serological patterns suggesting infection in the more distant past had positive PCR assays. This was considered to represent either persistence of the organism from a previous infection or perhaps transient carriage during a reinfection, without substantial change in antibody response. PCR-based assay of M. pneumoniae offers a powerful, rapid, and sensitive substitute for culture of the mycoplasma. Antigen capture, while less sensitive than PCR, offers the advantage that it is more often positive with samples from current infection and requires less stringent laboratory organization to contain false positive results. We conclude however that the laboratory diagnosis of a chosen clinical episode should not rest on the PCR or Ag-EIA assays alone, but must also include antibody assays to confirm whether infection is current or represents persistence from past exposure.

A survey of nosocomial respiratory viral infections in a children's hospital: occult respiratory infection in patients admitted during an epidemic season

OBJECTIVE

To define the extent of shedding of respiratory viruses and Mycoplasma pneumoniae among a population of pediatric patients admitted to the hospital during a winter epidemic period and to identify nosocomial infections within this population.

DESIGN

An open, prospective survey of patients admitted to three wards (General Medical, Respiratory Infectious, and Infectious Diseases) of a pediatric hospital during a defined three-month period.

PATIENTS

All patients with medical, respiratory, and infectious conditions admitted to three wards of the Adelaide Children's Hospital had nasopharyngeal aspirations performed at the time of admission with the purpose of documenting viral and M pneumoniae shedding. Patients were monitored daily for the development of symptoms of respiratory infection or new symptoms of respiratory disease. Such patients underwent a further nasopharyngeal aspiration for the purpose of diagnosing hospital-acquired infection.

RESULTS

Nasopharyngeal aspirations were obtained from 601 patients. Forty-seven percent of asymptomatic patients were positive for a respiratory virus or M pneumoniae, and 61% of patients with respiratory symptoms were also positive. Gastroenteritis patients shed viruses in 66% of cases. Respiratory symptoms were initially overlooked by admitting physicians but subsequently identified in 110 cases, and 46% of these were found to be positive for a respiratory virus or M pneumoniae. There were 18 possible hospital acquired infections among the 293 initially virus-negative patients. Multiple isolates were obtained from a substantial number of patients, especially those with respiratory symptoms.

CONCLUSIONS

A substantial proportion of all patients admitted to a pediatric hospital during winter represent a potential source of infection, and strict infection control measures should be enacted to limit the spread of these infections.

Laboratory diagnosis of Mycoplasma pneumoniae infection. 3. Detection of IgM antibodies to M. pneumoniae by a modified indirect haemagglutination test

The indirect haemagglutination (IHA) test was compared with the complement-fixation (CF) test for the measurement of antibodies to Mycoplasma pneumoniae. A modification of the IHA was used to measure M. pneumoniae IgM antibodies. Sera were obtained from various groups of patients who were either culture or antigen positive for M. pneumoniae in nasopharyngeal aspirates or who had fourfold or greater increase in CF antibody or a titre greater than or equal to 320. The results of these comparisons showed that the modified IHA test was specific and more sensitive (89% as opposed to 64%) than the CF test. The modified IHA test for the detection of IgM antibody was highly effective in the recognition of recent or current infection with the mycoplasma. It was also of equal sensitivity to an indirect enzyme immunoassay for the detection of IgM antibodies to M. pneumoniae.

Comparison of five enzyme immunoassays, electron microscopy, and latex agglutination for detection of rotavirus in fecal specimens

Five different enzyme immunoassays, electron microscopy, and latex agglutination (Slidex; bioMerieux) were compared for the rapid detection of human rotavirus in fecal specimens. The enzyme immunoassay using rotavirus polyclonal antiserum (Dakopatts) with simple in-house modifications was shown by the use of confirmatory tests to be the most sensitive and specific procedure.

Laboratory diagnosis of Mycoplasma pneumoniae infection. 1. Direct detection of antigen in respiratory exudates by enzyme immunoassay

Direct and indirect antigen capture enzyme immunoassays (Ag-EIA) have been developed for the detection of Mycoplasma pneumoniae in nasopharyngeal aspirates or sputum from respiratory infection. The sensitivity of the two Ag-EIA were similar, but the indirect method using polyclonal rabbit and guinea-pig antisera was more convenient. The Ag-EIA had a detection limit of 10(4-4.5) colony-forming units/ml of sample. It was specific for M. pneumoniae and gave a low level response with M. genitalium. There were no cross-reactions with 10 other species of mycoplasmas. Tests with a wide range of bacteria and chlamydia group antigen, representing agents sometimes found in the respiratory tract, were also negative. At the current level of development, the Ag-EIA detected about 90% of specimens that were also positive for culture; 43% of specimens from culture-negative--seropositive patients gave a positive result. The overall pattern of results indicated that while antigen detection is a quick and effective substitute for the slow culture method, serological examination for specific IgM antibody is also necessary to give a complete diagnostic coverage.

Mycoplasma pneumoniae: acute illness, antibiotics, and subsequent pulmonary function

One hundred and eight children presenting with Mycoplasma pneumoniae infection were assessed during the acute illness and followed for three years. The incidence of wheezing with the acute infection (40%) was greater than expected in a normal childhood population. The initial illness precipitated wheezing for the first time in some subjects but others wheezed only with the acute illness. In non-asthmatic subjects significant bronchodilator responsiveness was present one month after infection. Children given erythromycin during the first seven days of their illness had a significantly shorter fever duration compared with those treated inappropriately. No significant effects of treatment were noted on pulmonary function three years later but non-asthmatic children had abnormal mean forced expiratory volume in one second and forced expiratory flow after 50% of the expired vital capacity compared with 64 healthy controls. These findings indicate impaired function three years after initial infection.