Is Intermittent Abdominal Pressure Ventilation Still Relevant? A Multicenter Retrospective Pilot Study

Non-invasive ventilatory support (NVS) is a technique used to reduce respiratory work in neuromuscular diseases, preventing the progression of respiratory failure. NVS is usually administered via a nasal or an oronasal mask, causing discomfort, especially in patients ventilated for more than 16 h/day. Intermittent abdominal pressure ventilation (IAPV) differs completely from conventional NVS and consists of a portable ventilator and a corset with Velcro closures as the interface. In our study, the practicability and efficacy of IAPV were studied in three Italian centers monitoring 28 neuromuscular patients using IAPV who were then retrospectively analyzed. The primary outcomes were an improvement in hypoxemia and the normalization of hypercapnia, and the secondary outcome was an improvement in quality of life. Data were collected at baseline (T0) and after two hours of ventilation (T1), with follow-ups at three months (T2) and six months (T3). Statistical significance was found for PaCO₂ over time (F (2.42) = 7.63, p = 0.001) and PaO₂ (W = 0.539, p = 0.033). The time of NVS usage also significantly affected the quality of life (F (2.14) = 6.90, p = 0.010), as seen when comparing T0 and T3. As an alternative ventilation method, IAPV is still relevant today and could become a key part of daytime support, especially for patients who do not tolerate standard daytime NVS with an oral interface.

Importance of acute Mycoplasma pneumoniae and Chlamydia pneumoniae infections in children with wheezing

In order to evaluate the role of Mycoplasma pneumoniae and Chlamydia pneumoniae in reactive airway disease, 71 children aged 2-14 yrs with an acute episode of wheezing and 80 age-matched healthy children were studied. Sera for the determination of specific antibody levels and nasopharyngeal aspirates for the detection of M. pneumoniae and C. pneumoniae deoxyribonucleic acid were obtained on admission and after 4-6 weeks. All children with wheezing received a standard therapy with inhaled corticosteroids and bronchodilators for 5-7 days; when antibiotic was added on the basis of the judgement of the paediatrician in charge, clarithromycin 15 mg.kg body weight(-1).day(-1) for 10 days was used. Acute M. pneumoniae and C. pneumoniae infections were detected significantly more often in children with wheezing than in controls. In patients infected with one of the two pathogens, a history of recurrent wheezing was significantly more frequent than in those without either infection. During a 3-month follow-up period, among nonantibiotic-treated children, those with acute M. pneumoniae and/or C. pneumoniae infection showed a significantly higher recurrence of wheezing than those without acute M. pneumoniae and/or C. pneumoniae infection (p=0.03). These results highlight the apparently significant relationship of Mycoplasma pneumoniae and Chlamydia pneumoniae with wheezing in children, particularly in subjects with a history of recurrent episodes, and the possible improvement in the course of reactive airway disease within paediatric patients with acute Mycoplasma pneumoniae and/or Chlamydia pneumoniae infection.

Chlamydia pneumoniae detection in atherosclerotic plaques in Italy

Italian investigations have shown an association between Chlamydia pneumoniae infection and atherosclerosis. With the use of several diagnostic techniques, including serology, a microimmunofluorescence test, and nucleic acid amplification methods, a temporal association was found between acute C. pneumoniae reinfection and acute myocardial infarction, suggesting that an acute infection superimposed on a chronic or latent infection may trigger the onset of acute myocardial infarction. C. pneumoniae but not Helicobacter pylori or Mycoplasma pneumoniae was found in atherosclerotic plaques of abdominal aortic aneurysms and the carotid artery. A reverse transcriptase-polymerase chain reaction process confirmed the presence of viable C. pneumoniae in carotid atheromas. Nucleic amplification of peripheral blood mononuclear cells may enable the identification of subjects carrying C. pneumoniae in the vascular wall. Macrolide treatment reduced fibrinogen and C-reactive protein plasma levels and C. pneumoniae burden in patients with atherosclerotic diseases.

Chlamydia pneumoniae eradication from carotid plaques. Results of an open, randomised treatment study

OBJECTIVE

to determine the effect of specific antibiotic treatment with roxithromycin in the eradication of Chlamydia pneumoniae from carotid artery plaques.

DESIGN

prospective open randomised treatment study.

PATIENTS AND METHODS

we analysed 32 patients (16 females, mean age 70.1+/-14.7 years) who underwent surgery for the removal of atherosclerotic plaques from carotid arteries. During surgery samples of lingual vein and superior thyroid artery were also taken. Before surgery, patients were randomised to receive either roxithromycin 150 mg twice daily or no treatment. Sixteen patients were treated with antibiotic for a mean of 26 days (range 17-35 days). The two groups of patients were comparable in terms of age, sex, risk factors, and seroprevalence for C. pneumoniae. We applied a semi-nested polymerase chain reaction (PCR) technique to the carotid plaques, lingual vein, and thyroid artery samples. Blood samples were obtained from the patients for the determination of C. pneumoniae IgG, IgA, and IgM antibody titres by a microimmunofluorescence technique.

RESULTS

in twelve out of sixteen non-treated patients we found evidence of C. pneumoniae DNA in the carotid plaques. Conversely, C. pneumoniae DNA was detected in only five out of sixteen treated patients (p=0.034, Chi-squared test). In all cases PCR was negative for the lingual vein and thyroid artery samples.

CONCLUSIONS

Roxithromycin seems effective in reducing the bacterial burden of C. pneumoniae within atherosclerotic plaques, although extended follow-up is needed to determine whether antibiotic treatment benefits long-term patient outcome.

Demonstration of viable Chlamydia pneumoniae in atherosclerotic plaques of carotid arteries by reverse transcriptase polymerase chain reaction

The presence of Chlamydia pneumoniae in atheromas has been demonstrated in several studies. Culture of the organism from arterial tissue has been difficult. We report the use of a reverse transcriptase polymerase chain reaction to detect viable Chlamydia pneumoniae in carotid atheromas. We analyzed 30 patients (14 females, mean age 69.6 +/- 8.8 years) who underwent surgery for the removal of atherosclerotic plaques from carotid arteries. During surgery, samples of lingual vein and superior thyroideal artery were also taken. We applied two molecular biology techniques to the carotid plaques on lingual vein or thyroideal artery samples: 1) polymerase chain reaction (PCR) and 2) reverse transcriptase-PCR (RT-PCR) for the detection of bacterial mRNA, employing PCR primers designed to detect a fragment of the 16S rRNA gene. Blood samples were obtained from the patients for determination of Chlamydia pneumoniae IgG, IgA, and IgM antibody titers by a microimmunofluorescence technique. The results of the present study confirmed the presence of viable Chlamydia pneumoniae in atheromas and support the hypothesis that the organism may be an active factor in the pathogenesis of atherosclerosis.

Incidence of Chlamydia pneumoniae infection in vertically HIV-1 infected children

The rate of seroconversion for antibody to Chlamydia pneumoniae was analysed in blood samples of 26 vertically HIV-1 infected children and 14 seroreverter children (HIV-negative children born to HIV-positive mothers) during a 3-year study period. Seroconversion for Chlamydia pneumoniae was found in 13 of 26 HIV-1 infected children and in 1 of 14 in the seroreverter group (P=0.013). A lower mean CD4+ cell count and p24 antigen positivity at enrolment were significantly associated with seroconversion for Chlamydia pneumoniae. Signs and symptoms of acute respiratory infection were recorded in the 30 to 40 days preceding collection of the blood samples showing seroconversion for Chlamydia pneumoniae in 8 of 13 HIV-1 infected children and in the single seroreverter. This study confirms the potential role of Chlamydia pneumoniae in the pathogenesis of respiratory tract infections in HIV-1 infected subjects.

Epidemiology of Chlamydia pneumoniae

Chlamydia pneumoniae is the most commonly occurring intracellular bacterial pathogen. It is frequently involved in respiratory tract infections and to a lesser degree in extrapulmonary diseases. According to seroepidemiologic surveys, C. pneumoniae infection seems to be both endemic and epidemic. Such studies indicate that C. pneumoniae infection is widespread, with frequent reinfection during a lifetime. In Western countries the highest rate of new infections occurs between the ages of 5 and 15. The antibody prevalence worldwide is higher in adult males than in females. Currently available data suggest that C. pneumoniae is primarily transmitted from human to human without any animal reservoir. Transmission seems to be inefficient, although household outbreaks with high transmission rates are reported. Most reports rank C. pneumoniae among the three most common etiologic agents of community-acquired pneumonia, with an incidence ranging from 6% to 25%, and generally presenting a mild and, in some cases, self-limiting clinical course. Recent reports also indicate a possible role for C. pneumoniae in severe forms of community-acquired pneumonia and in respiratory infections in immunocompromised patients. C. pneumoniae infection has also been implicated in the pathogenesis of asthma in both adults and children. The hypothesis that C. pneumoniae infection could lead to asthma is based on clinical studies and on the evidence of specific IgE production, direct epithelial damage, induction of T-cell immunopathologic diseases, and vascular smooth cell infection. Chronic C. pneumoniae infection seems to be common in patients with chronic bronchitis whether exacerbated or not, and is characterized by a strong humoral immune response to this intracellular microorganism, which is present in the majority of patients with severe chronic bronchitis. More than 60% of subjects with chronic bronchitis have specific C. pneumoniae antibody titers, and the microorganism may be identified by culture or PCR in almost 40% of these patients. This pathogen has also been recently associated with atherosclerosis and coronary heart disease (CHD). Seroepidemiological evidence indicates that the majority of patients with CHD present an anti-C. pneumoniae antibody pattern consistent with chronic infection. Furthermore, C. pneumoniae has been detected in atherosclerotic coronary plaques by several methods, including immunocytochemistry, transmission electron microscopy and molecular biology techniques. Recently, we detected C. pneumoniae DNA in a high percentage (51%) of aortic aneurysm plaques. Moreover, our serologic data support the hypothesis that a chronic C. pneumoniae antibody pattern may be a possible risk marker for atherosclerosis. Recently, C. pneumoniae has been isolated by culture from the coronary artery of a patient with coronary atherosclerosis, providing direct evidence of the presence of viable organisms in atheromatous lesions. Moreover, we recently demonstrated an association between C. pneumoniae reinfection and acute myocardial infarction.

Failure to detect the presence of Chlamydia pneumoniae in sarcoid pathology specimens

The pathogenesis of sarcoidosis is not yet known. On the basis of seroepidemiological data, an association between Chlamydia pneumoniae infection and sarcoidosis has been suggested, but so far no study has addressed the direct detection of this agent in the affected tissues. The aim of the present study was to detect C. pneumoniae deoxyribonucleic acid (DNA) within sarcoid tissue specimens by means of a two-step polymerase chain reaction. Lung biopsy specimens of 33 patients with histologically confirmed pulmonary sarcoidosis and 21 control lung biopsies or pathology specimens of patients with pulmonary carcinoma or emphysema were retrospectively analysed. A nested polymerase chain reaction was applied using two sets of primers designed to detect a fragment of the 16 strand ribosomal ribonucleic acid (rRNA) gene of C. pneumoniae. The results of the study failed to demonstrate the presence of C. pneumoniae in biopsy specimens of sarcoid tissue and in the control lung biopsies or pathology specimens. Our results, therefore, tend to rule out the possibility of a direct involvement of Chlamydia pneumoniae in the pathogenesis of sarcoidosis.

Detection of Chlamydia pneumoniae but not Helicobacter pylori in atherosclerotic plaques of aortic aneurysms

Recent reports suggest an association between Chlamydia pneumoniae and Helicobacter pylori bacteria and atherosclerosis. We studied 51 patients (mean age, 68.3 years) who underwent abdominal aortic aneurysm surgery. For each patient we performed a microimmunofluorescence test for immunoglobulin G (IgG), IgA, and IgM antibodies to C. pneumoniae specific antigen (TW-183). Anti-H. pylori antibodies were determined by means of an EIA-G test. Each aortic aneurysm surgical specimen was sampled into multiple sections of 0.3 cm2 each and frozen at -20 degrees C. Two samples of each aneurysm were used for a nested PCR with two sets of C. pneumoniae and two sets of H. pylori specific primers. Specimens were treated with a solution containing 20 mM Tris-HCl, Tween 20-Nonidet P-40 (0.5% [vol/vol] each), and 100 micrograms of proteinase K per ml and incubated at 60 degrees C for 1 h and at 98 degrees C for 10 min. DNA was extracted twice with phenol-chloroform-isoamylic alcohol and precipitated with sodium acetate-ethanol by standard methods. Forty-one patients were seropositive for C. pneumoniae with past-infection patterns in 32 patients (16 < or = IgG < 512; 32 < or = IgA < 256) and high antibody titers in 9 patients (IgG > or = 512). In 26 of 51 patients, C. pneumoniae DNA was detected in aortic aneurysm plaque specimens. Of these patients, 23 had a serologic past-infection pattern, 2 had an acute reinfection pattern, and 1 was seronegative. Forty-seven of 51 patients were seropositive for H. pylori. In all cases PCR showed no evidence of H. pylori presence in plaque specimens. This study provides data on a possible C. pneumoniae involvement in the pathogenesis of aortic aneurysm and additional evidence for an association between this agent and atherosclerosis. Conversely, notwithstanding a high H. pylori seroprevalence observed, our results tend to rule out the possibility of a direct involvement of H. pylori in atherosclerosis.