Pediatric tracheostomy: epidemiology and characterization of tracheal secretion - a literature review

SUMMARY INTRODUCTION Despite the benefits, tracheostomized children are susceptible to respiratory infections, since the tube is located in a strategic region where there is colonization by several bacteria and biofilm formation. Biofilm is formed when the bacteria adhere strongly to the surfaces of the tubes, providing protection against various types of aggression, such as antibiotic treatment. OBJECTIVE To carry out a literature review of the last ten years on tracheostomized pediatric patients, in order to characterize the bacteria isolated in children's tracheal secretions, and verify which ones are the most frequent. METHODS Two authors searched the Lilacs, SciELO, Medline Plus, and PubMed databases. The MeSH terms used were: 'tracheostomy' and 'tracheotomy' associated with 'infections', 'children', 'child', and 'bacterial' as qualifiers. RESULTS Of the 512 studies on the subject, 19 were selected for review. The total number of children evaluated in the studies was 4,472, with a mean age of 7.5 years. As for the bacteria found in the secretions of tracheostomized children, 12 species of bacteria were more frequent, P. aeruginosa was the predominant bacterium, followed by S. aureus (63.1%), Klebsiella pneumoniae (57.8%), Streptococcus pneumoniae (47.3%), and Stenotrophomonas maltophilia (47.3%). CONCLUSION One of the main complications treated in tracheostomized patients were infections, since the respiratory system is colonized by several bacteria that can cause serious infections, which are associated with the formation of biofilms. The predominant bacterium in most of the studies was P. aeruginosa, and the second species commonly reported was S. aureus.

RESUMO INTRODUÇÃO Apesar dos benefícios, crianças traqueostomizadas estão suscetíveis a adquirir infecções respiratórias, pois o tubo se encontra em uma região estratégica, na qual existe colonização de diversas bactérias e formação de biofilme. O biofilme é formado quando as bactérias aderem fortemente às superfícies dos tubos, conferindo proteção contra diversos tipos de agressões, como o tratamento por antibióticos. OBJETIVO Realizar uma revisão de literatura dos últimos dez anos sobre pacientes pediátricos traqueostomizados, no intuito de caracterizar as bactérias isoladas em secreções traqueais de crianças, verificando-se quais são as mais frequentes. MÉTODOS Dois autores pesquisaram nas bases de dados do Lilacs, SciELO, Medline Plus e PubMed. Termos MeSH utilizados: tracheostomy e tracheotomy usados associados a infections, children, chlid e bacterial como qualificadores. RESULTADOS Dos 512 estudos relacionados ao tema, 19 foram selecionados para a revisão. O total de crianças avaliadas nos estudos foi de 4.472, com idade média de 7,5 anos. Quanto às bactérias encontradas nas secreções de crianças traqueostomizadas, 12 espécies de bactérias foram mais frequentes; P. aeruginosa foi a bactéria predominante, seguida de S. aureus (63,1%), Klebsiella pneumoniae (57,8%), Streptococcus pneumoniae (47,3%) e Stenotrophomonas maltophilia (47,3%). CONCLUSÃO Umas das principais complicações abordadas em pacientes traqueostomizados foram as infecções, já que o sistema respiratório é colonizado por diversas bactérias, que podem causar infecções graves, sendo estas associadas à formação de biofilmes. A bactéria predominante na maioria dos estudos foi a P. aeruginosa, e a segunda espécie comumente relatada foi a S. aureus.

Accuracy of a rapid molecular test for tuberculosis in sputum samples, bronchoalveolar lavage fluid, and tracheal aspirate obtained from patients with suspected pulmonary tuberculosis at a tertiary referral hospital / Acurácia do teste rápido molecular para tuberculose em amostras de escarro, lavado broncoalveolar e aspirado traqueal obtidos de pacientes com suspeita de tuberculose pulmonar em um hospital de referência terciária

ABSTRACT Tuberculosis continues to be a major public health problem worldwide. The aim of the present study was to evaluate the accuracy of the Xpert MTB/RIF rapid molecular test for tuberculosis, using pulmonary samples obtained from patients treated at the Júlia Kubitschek Hospital, which is operated by the Hospital Foundation of the State of Minas Gerais, in the city of Belo Horizonte, Brazil. This was a retrospective study comparing the Xpert MTB/RIF test results with those of standard culture for Mycobacterium tuberculosis and phenotypic susceptibility tests. Although the Xpert MTB/RIF test showed high accuracy for the detection of M. tuberculosis and its resistance to rifampin, attention must be given to the clinical status of the patient, in relation to the test results, as well as to the limitations of molecular tests.

RESUMO A tuberculose permanece como um grave problema de saúde pública. O objetivo deste estudo foi avaliar a acurácia do teste rápido molecular Xpert MTB/RIF em amostras pulmonares no Hospital Júlia Kubitschek, Fundação Hospitalar do Estado de Minas Gerais, localizado em Belo Horizonte (MG). Trata-se de um estudo descritivo retrospectivo, considerando-se como método padrão a cultura para o bacilo da tuberculose e o teste de sensibilidade fenotípico. O teste Xpert MTB/RIF apresentou ótima acurácia para a detecção da tuberculose e resistência à rifampicina, mas é necessária a atenção a dados clínicos do paciente em relação ao resultado do exame e às limitações dos testes moleculares.

Association between pathogens from tracheal aspirate and oral biofilm of patients on mechanical ventilation

Abstract The aim of this study was to detect possible associations between respiratory pathogens from tracheal aspirate and oral biofilm samples in intubated patients in an intensive care unit (ICU), and to identify the most common respiratory pathogens in oral biofilm, particularly in patients that developed ventilator-associated pneumonia (VAP). Two oral biofilm samples were collected from the tongue of intubated patients (at admission and after 48 hours) and analyzed by culture with the Antibiotic Sensitivity Test. The results from the tongue biofilm samples were compared with the tracheal secretions samples. A total of 59.37% of patients exhibited the same species of pathogens in their tracheal aspirate and oral biofilm, of which 8 (42.1%) developed VAP, 10 (52.63%) did not develop pneumonia and one (5.26%) had aspiration pneumonia. There was a statistically significant association between presence of microorganisms in the tracheal and mouth samples for the following pathogens: Klebsiella pneumoniae, Candida albicans, Pseudomonas aeruginosa, Enterobacter gergoviae, Streptococcus spp and Serratia marcescens (p < 0.05). Pathogens that are present in tracheal aspirates of intubated patients can be detected in their oral cavity, especially in those who developed VAP or aspiration pneumonia. Thus, the results indicate that an improved oral care in these patients could decrease ICU pneumonia rates.

Microbial investigation of biofilms recovered from endotracheal tubes using sonication in intensive care unit pediatric patients

Abstract Objectives To compare cultured microorganisms identified on endotracheal tubes biofilms through sonication technique with traditional tracheal aspirate collected at extubation of pediatric intensive care unit patients. Methods Demographic and epidemiological data were analyzed to identify factors possibly related with the microbiological profile of the two collection methods. Associations between categorical and continuous variables were analyzed using the chi-square or Fisher's exact test, or Student's t test. p-Value <0.05 were considered significant. Results Thirty endotracheal tubes and tracheal aspirates samples from 27 subjects were analyzed. Only one patient presented the clinical diagnosis of ventilator-associated pneumonia. Overall, 50% of bacteria were Gram-negative bacilli, followed by Gram-positive bacteria in 37%, and fungi in 10%. No statistically significant difference on the distribution of Gram-positive or Gram-negative bacteria (p = 0.996), and fungi (p = 0.985) were observed between the collection methods. Pseudomonas spp. was the most frequent microorganism identified (23.8%), followed by Streptococcus spp. (18.5%), Acinetobacter spp. (15.9%), coagulase-negative staphylococci (11.2%), and Klebsiella spp. (8.6%). Concordant results between methods amounted to 83.3%. Pseudomonas aeruginosa and Acinetobacter baumannii showed carbapenem resistance in 50% and 43.7% of the isolates, respectively. In general, cultures after endotracheal tubes sonication (non-centrifuged sonication fluid and centrifuged sonication fluid) yielded bacteria with higher rates of antimicrobial resistance compared to tracheal aspirates cultures. Additionally, in 12 subjects (40%), we observed discrepancies regarding microbiologic profiles of cultures performed using the collection methods. Conclusions Our study demonstrated that sonication technique can be applied to ET biofilms to identify microorganisms attached to their surface with a great variety of species identified. However, we did not find significant differences in comparison with the traditional tracheal aspirate culture approach.

The value of antibody-coated bacteria in tracheal aspirates for the diagnosis of ventilator-associated pneumonia: a case-control study / Utilidade da avaliação de bactérias revestidas por anticorpos em aspirados traqueais para o diagnóstico de pneumonia associada à ventilação mecânica: um estudo caso-controle

ABSTRACT Objective: Ventilator-associated pneumonia (VAP) is the leading type of hospital-acquired infection in ICU patients. The diagnosis of VAP is challenging, mostly due to limitations of the diagnostic methods available. The aim of this study was to determine whether antibody-coated bacteria (ACB) evaluation can improve the specificity of endotracheal aspirate (EA) culture in VAP diagnosis. Methods: We conducted a diagnostic case-control study, enrolling 45 patients undergoing mechanical ventilation. Samples of EA were obtained from patients with and without VAP (cases and controls, respectively), and we assessed the number of bacteria coated with FITC-conjugated monoclonal antibodies (IgA, IgM, or IgG) or an FITC-conjugated polyvalent antibody. Using immunofluorescence microscopy, we determined the proportion of ACB among a fixed number of 80 bacteria. Results: The median proportions of ACB were significantly higher among the cases (n = 22) than among the controls (n = 23)-IgA (60.6% vs. 22.5%), IgM (42.5% vs. 12.5%), IgG (50.6% vs. 17.5%), and polyvalent (75.6% vs. 33.8%)-p < 0.001 for all. The accuracy of the best cut-off points for VAP diagnosis regarding monoclonal and polyvalent ACBs was greater than 95.0% and 93.3%, respectively. Conclusions: The numbers of ACB in EA samples were higher among cases than among controls. Our findings indicate that evaluating ACB in EA is a promising tool to improve the specificity of VAP diagnosis. The technique could be cost-effective and therefore useful in low-resource settings, with the advantages of minimizing false-positive results and avoiding overtreatment.

RESUMO Objetivo: A pneumonia associada à ventilação mecânica (PAVM) é o principal tipo de infecção adquirida no ambiente hospitalar em pacientes em UTIs. O diagnóstico de PAVM é desafiador, principalmente devido a limitações dos métodos diagnósticos disponíveis. O objetivo deste estudo foi determinar se a avaliação de bactérias revestidas por anticorpos (BRA) pode melhorar a especificidade de culturas de aspirado traqueal (AT) no diagnóstico de PAVM. Métodos: Estudo diagnóstico caso-controle envolvendo 45 pacientes sob ventilação mecânica. Amostras de AT foram obtidas de pacientes com e sem PAVM (casos e controles, respectivamente), e verificamos o número de bactérias revestidas com anticorpos monoclonais conjugados com FITC (IgA, IgM ou IgG) ou anticorpo polivalente conjugado com FITC. Utilizando microscopia de imunofluorescência, foi determinada a proporção de BRA em um número fixo de 80 bactérias. Resultados: A mediana das proporções de BRA foi significativamente maior nos casos (n = 22) que nos controles (n = 23) - IgA (60,6% vs. 22,5%), IgM (42,5% vs. 12,5%), IgG (50,6% vs. 17,5%) e polivalente (75,6% vs. 33,8%) - p < 0,001 para todos. A acurácia dos melhores pontos de corte para o diagnostico de PAVM em relação aos BRA monoclonais e polivalentes foi > 95,0% e > 93,3%, respectivamente. Conclusões: O número de BRA em amostras de AT foi maior nos casos que nos controles. Nossos achados indicam que a avaliação de BRA no AT é uma ferramenta promissora para aumentar a especificidade do diagnóstico de PAVM. A técnica pode ser custo-efetiva e, portanto, útil em locais com poucos recursos, com as vantagens de minimizar resultados falso-positivos e evitar o tratamento excessivo.

Quantitative culture of endotracheal aspirate and BAL fluid samples in the management of patients with ventilator-associated pneumonia: a randomized clinical trial / Cultura quantitativa de aspirado traqueal e lavado broncoalveolar no manejo de pacientes com pneumonia associada à ventilação mecânica: um ensaio clínico randomizado

OBJECTIVE: To compare 28-day mortality rates and clinical outcomes in ICU patients with ventilator-associated pneumonia according to the diagnostic strategy used. METHODS: This was a prospective randomized clinical trial. Of the 73 patients included in the study, 36 and 37 were randomized to undergo BAL or endotracheal aspiration (EA), respectively. Antibiotic therapy was based on guidelines and was adjusted according to the results of quantitative cultures. RESULTS: The 28-day mortality rate was similar in the BAL and EA groups (25.0% and 37.8%, respectively; p = 0.353). There were no differences between the groups regarding the duration of mechanical ventilation, antibiotic therapy, secondary complications, VAP recurrence, or length of ICU and hospital stay. Initial antibiotic therapy was deemed appropriate in 28 (77.8%) and 30 (83.3%) of the patients in the BAL and EA groups, respectively (p = 0.551). The 28-day mortality rate was not associated with the appropriateness of initial therapy in the BAL and EA groups (appropriate therapy: 35.7% vs. 43.3%; p = 0.553; and inappropriate therapy: 62.5% vs. 50.0%; p = 1.000). Previous use of antibiotics did not affect the culture yield in the EA or BAL group (p = 0.130 and p = 0.484, respectively). CONCLUSIONS: In the context of this study, the management of VAP patients, based on the results of quantitative endotracheal aspirate cultures, led to similar clinical outcomes to those obtained with the results of quantitative BAL fluid cultures. .

OBJETIVO: Comparar a mortalidade em 28 dias e desfechos clínicos em pacientes com pneumonia associada à ventilação mecânica (PAVM) internados em UTI conforme a estratégia diagnóstica utilizada. MÉTODOS: Ensaio clínico randomizado prospectivo. Dos 73 pacientes incluídos no estudo, 36 e 37, respectivamente, foram randomizados para a realização de LBA ou aspiração traqueal (AT). A antibioticoterapia inicial baseou-se em diretrizes e foi ajustada de acordo com os resultados das culturas quantitativas. RESULTADOS: A taxa de mortalidade em 28 dias foi semelhante nos grupos LBA e AT (25,0% e 37,8%, respectivamente; p = 0,353). Não houve diferenças entre os grupos em relação a duração da ventilação mecânica, antibioticoterapia, complicações secundárias, recidiva de PAVM ou tempo de permanência hospitalar e na UTI. A antibioticoterapia inicial foi considerada adequada em 28 (77,8%) e 30 (83,3%) dos pacientes nos grupos LBA e AT, respectivamente (p = 0,551). A mortalidade em 28 dias não se associou com a adequação da antibioticoterapia inicial nos grupos LBA e AT (tratamento apropriado: 35,7% vs. 43,3%; p = 0,553; e tratamento inapropriado: 62,5% vs. 50,0%; p = 1,000). O uso prévio de antibióticos não interferiu no rendimento das culturas nos grupos AT e LBA (p = 0,130 e p = 0,484, respectivamente). CONCLUSÕES: No contexto deste estudo, o manejo dos pacientes com PAVM, baseado nos resultados da cultura quantitativa do aspirado traqueal, resultou em desfechos clínicos semelhantes aos obtidos com os resultados da cultura quantitativa do LBA. (Registro Brasileiro de Ensaios ...

Antibiotic Sensitivity Pattern of Gram Negative Bacilli Isolated from the Lower Respiratory Tract of Ventilated Patients in the Intensive Care Unit.

The causative organisms vary according to the patients’ demographics in the ICU, methods of diagnosis, the durations of hospital and ICU stay. It is necessary to study different etiological organisms and their antimicrobial susceptibility pattern for generating local antibiotic policy. Aims: To study the causative organisms and determine the antibiotic susceptibility pattern of the lower respiratory tract isolates from patients admitted to ICU. Methods and Material: Endotracheal aspirates from 200 patients admitted to the ICU were cultured, identified and antimicrobial susceptibility testing was performed by standard methods. Results: From 200 specimens, 69(34.5%) were culture positive. Total 96 isolates were recovered, from these 92 (96.87%) isolates were gram negative bacilli (GNB). In 34.78% specimens, two isolates were recovered. The most common Gram- negative organism being Acinetobacter spp. (31.25%) followed by Klebsiella spp. (21.87%), E-coli (21.87%) and Pseudomonas Spp. (17.7%). All GNBs were 100% sensitive to polymyxin B and colistin and resistant to piperacillin, ceftazidime and cotrimoxazole. 50% E-coli and 38% of Klebsiella pneumoniae strains were ESBL (extendedspectrum b-lactamase) producers. Conclusions: This study demonstrates the trend in antimicrobial susceptibility pattern of gram negative bacilli in intensive care unit. It is the most important for specific treatment of ventilator associated pneumonia patients and to generate local data periodically to decide empiric antimicrobial therapy.

Fulminating septicemia due to persistent pan-resistant community-acquired metallo-β-lactamase (IMP-1)-positive Acinetobacter baumannii

Acinetobacter baumannii is considered as an emerging nosocominal pathogen and is renowned for its multi-drug resistance. We report a case of community-acquired pan-resistant A. baumannii strain isolated from blood, pus , urine and tracheal aspirate was confirmed by 16S r-RNA sequence homology and found positive for metallo-ß-lactamase IMP-1, and was found to be a strong biofilm producer The isolate was only susceptible (moderately) to colistin.

Usefulness of Quantitative Endotracheal Aspirate Cultures in Intensive Care Unit Patients with Suspected Pneumonia

It is difficult to differentiate pathogens responsible for pneumonia or colonization in patients with an endotracheal tube or in patients that have undergone tracheostomy. We evaluated the clinical usefulness of quantitative endotracheal aspirates cultures and sought to determine the result threshold level for positivity. The authors performed this retrospective cohort study between December 1, 2004 and January 31, 2006. Forty-five suspected pneumonia patients admitted to an intensive care unit (ICU) with quantitative bronchoalveolar lavage (BAL) and endotracheal aspirate (EA) culture results were enrolled. Using a threshold of 10(5) cfu/mL, 10 of the 45 (22.2%) quantitative EA cultures were positive, as compared with 7 (15.6%) BAL cultures. When BAL culture findings were used as the reference, the sensitivity and specificity of quantitative EA cultures were 85.7% and 89.5%, respectively, at a threshold of 10(5) cfu/mL, and 85.7% and 94.7%, respectively, at a threshold of 10(6) cfu/mL. Of the 10 EA culture positive patients, 2 patients with a result of -10(5) cfu/mL were BAL culture negative. The quantitative EA culture is a useful non-invasive tool for the diagnosis of pneumonia pathogens. It is suggested that a threshold level of 10(6) cfu/mL is appropriate.

Clinical significance of airways colonization with Ureaplasma urealyticum in premature (<34 wk) neonates.

BACKGROUND & OBJECTIVE: Ureaplasma urealyticum has been implicated in various neonatal morbidities in preterm infants. Its association with chronic lung disease (CLD) remains controversial. The aim of this prospective study was to investigate colonization of U. urealyticum in preterm infants (with gestational age <34 wk) and to evaluate the relationship between U. urealyticum colonization and neonatal morbidity including CLD. METHODS: U. urealyticum was cultured from nasopharyngeal or endotracheal aspirates collected within 24 h of birth from infant <or=34 wk gestation weighing <1800 g admitted to a Neonatal Intensive Care Unit of a tertiary care hospital in north India, and PCR was performed on the DNA extracted from these samples. RESULTS: Twenty per cent of the study infants were colonized with U. urealyticum. The mean gestational age of the infants in the colonized group was less than that of non colonized infants (P<0.05). The peripheral total leukocyte counts and mortality rate were higher in infants with U. urealyticum colonization than in non-colonized infants (P<0.05). There was no significant difference between the colonized and non colonized groups with regard to the antenatal use of steroids, sex, cause of respiratory distress, use of surfactant, duration of ventilation. INTERPRETATION & CONCLUSION: None of the 20 babies colonized with U. urealyticum developed CLD as compared with two (2.5%) of the non colonized group. Colonization of the airways with U. urealyticum had no significant role in development of CLD in Indian preterm infants.

Bacteriology of granulation tissue in laryngotracheal stenosis patients.

BACKGROUND: The formation of granulation tissue is an important factor promoting recurrence after surgical treatment of laryngotracheal stenosis. Bacterial infection was claimed to be the cause. OBJECTIVE: The present study aimed to identify the bacteriology of granulation tissue in laryngotracheal stenosis patients. MATERIAL AND METHOD: Data was collected prospectively. Granulation tissue found in the site of laryngotracheal stenosis was removed and sent to the microbiologic study to identify the organisms. RESULTS: Twenty-four specimens from 17 patients were included in the present study. Coagulase-positive Staphylococcus (45.8%) was the most common gram-positive organism and Pseudomonas aeruginosa as well as Enterobacter species (16.7%) were the most common gram-negative bacteria. Ciprofloxacin may be the oral antibiotic that should be recommended. CONCLUSION: Coagulase-positive Staphylococcus, Pseudomonas aeruginosa as well as Enterobacter species were the common organisms identified from the granulation tissue in recurrent laryngotracheal stenosis. Oral antibiotics, such as ciprofloxacin, may have benefit in reducing the formation of this granulation tissue.

Cryptosporidium sp. em intestinos, bursa de Fabricius e traquéia de frangos (Gallus gallus sp) / Cryptosporidium sp. in intestines, bursa of Fabricius and poultry trachea (Gallus gallus sp)

Parasitas do gênero Cryptosporidium infectam várias espécies de animais, e a enfermidade resultante é a criptosporidiose, importante zoonose de distribuição mundial. Em aves, a infecção tem sido reportada em várias espécies. Este trabalho objetivou identificar a presença do parasita em 208 amostras de bursa de Fabricius, 208 amostras de intestino e 208 de traquéia, coletadas de frangos (Gallus gallus sp) de diferentes idades, abatidos em três propriedades rurais do município de Santa Maria, RS. Foram feitas três impressões de cada amostra em lâminas para microscopia, coradas pelas técnicas de Ziehl Neelsen modificada com Dimetil Sulfóxido (DMSO), Ziehl Neelsen modificada por Henriksen e Pohlens (HP), Ziehl Neelsen (ZN) e Kinyoun (K), perfazendo 1872 impressões analisadas em microscopia óptica (1000 x). Neste total, nas diferentes colorações empregadas, oocistos do parasita Cryptosporidium sp. foram visualizados em 18 impressões de traquéia, 42 de bursa de Fabricius e 29 de intestino, resultando positivas, portanto, 89 impressões. Destas, 44 foram identificadas pela técnica de DMSO, 32 por HP, três por ZN e 10 por K. Pode-se concluir que os oocistos do parasita Cryptosporidium sp. foram visualizados com maior freqüência nas impressões de bursa de Fabricius, e que o método de coloração, dentre os utilizados, que proporcionou a maior visualização dos oocistos foi o DMSO.

The role of quantitative cultures of non-bronchoscopic samples in ventilator associated pneumonia.

PURPOSE: The objective of this study is to determine the role of quantitative cultures of non-bronchoscopic samples such as blinded bronchial sampling (BBS) and endotracheal aspirates (ETA) in the management of ventilator associated pneumonia (VAP). The study also evaluates the clinical diagnosis of VAP based on the inclusion of Gram stain results of BBS/ETA samples into modified clinical pulmonary infection score (CPIS). METHODS: Fifteen out of the 120 patients admitted to respiratory intensive care unit under mechanical ventilation for more than 48 hours with a clinical suspicion of VAP, were included in this study. Quantitative cultures of BBS and ETA were performed from all the 15 patients. RESULTS: VAP was confirmed in 11 out of 15 cases by quantitative cultures of either the BBS or ETA samples. The condition of 8/11 VAP confirmed patients improved significantly with the change in antibiotic therapy. The overall mortality rate was found to be 18%. The agreement between BBS and ETA results was found to be 83.3%. Modified-clinical pulmonary infection score (CPIS) increased significantly when Gram stain results of BBS/ETA samples were included, thereby strengthening the clinical diagnosis of VAP. CONCLUSIONS: Quantitative culture of lower respiratory tract samples obtained by non-bronchoscopic methods may be a useful alternative to bronchoscopy, in the diagnosis of VAP. Inclusion of Gram stain results of BBS/ETA into modified-CPIS may augment the diagnostic evaluation of VAP.

A clinicomicrobiological study on the importance of pseudomonas in nosocomially infected ICU patients, with special reference to metallo beta1-lactamase production.

The present study was conducted with a view to assess the burden of pseudomonal infection in ICU patients of a tertiary care teaching hospital in Uttaranchal. Of the 525 patients selected for the study, during a 1-year period, 60 patients developed features of nosocomial infection and among them Pseudomonas was isolated from one or more samples in 18 patients. The isolated strains were speciated and further characterized for determining their antibiogram and for production of beta-lactamase, extended spectrum beta-lactamase and metallo-beta-lactamase enzymes. Pseudomonas aeruginosa was the commonest species isolated (54.54%) and endotracheal suction material showed the highest bacterial yield. Polymyxin B was found to be the most effective antibiotic followed by imipenem and carbenicillin. Though no strain was found to be producing beta-lactamase and extended spectrum beta-lactamase enzymes, a total of 12 strains (54.54%) were metallo-beta-lactamase producers. For all the beta lactam antibiotics, excepting aztreonam, the metallo-beta-lactamase producers showed more resistance compared to the non-producers.

Monitoramento microbiológico seqüencial da secreção traqueal em pacientes intubados internados em unidade de terapia intensiva pediátrica / Sequential microbiological monitoring of tracheal aspirates in intubated patients admitted to a pediatric intensive care unit

OBJETIVO: Estudar seqüencialmente a flora traqueal em pacientes internados em unidade de terapia intensiva pediátrica e associar esta flora com o tempo de internação, a utilização prévia de antimicrobianos e o diagnóstico de pneumonia associada à ventilação mecânica. MÉTODOS: A população estudada foi constituída de pacientes pediátricos admitidos em uma unidade de terapia intensiva pediátrica entre novembro de 2002 e dezembro de 2003 e submetidos a ventilação mecânica. Foram coletadas três amostras seriadas de secreção traqueal de cada paciente. A primeira coleta foi realizada dentro das primeiras 6 horas após a admissão, e as amostras seguintes, depois de 48 e 96 horas. RESULTADOS: Foram estudados 100 pacientes com idade entre 1 dia e 14 anos. Nas três coletas realizadas, observou-se um aumento do percentual de culturas positivas para Pseudomonas aeruginosa, de 6 para 22 por cento (p = 0,002), e também uma diminuição das culturas positivas para Staphylococcus aureus, de 23 para 8 por cento (p = 0,009). No grupo com uso prévio de antimicrobianos, houve maior freqüência de isolamento de Candida spp (p < 0,05). Dezesseis (23,5 por cento) dos 68 pacientes que foram internados sem diagnóstico de pneumonia desenvolveram pneumonia associada à ventilação mecânica. Em relação à cultura de secreção traqueal desses pacientes, foram obtidas culturas positivas em 10 casos: seis S. aureus (com três Acinetobacter baumanni concomitantes), dois Klebsiella spp. (com um Enterobacter spp. concomitante), um Candida spp. e um P. aeruginosa. CONCLUSÃO: O monitoramento seqüencial da secreção traqueal pode ser útil na avaliação das alterações da flora microbiana nas unidades de terapia intensiva pediátrica.

Concordância entre o aspirado traqueal e o lavado broncoalveolar no diagnóstico das pneumonias associadas à ventilação mecânica / Concordance between tracheal aspirate and bronchoalveolar lavage in the diagnosis of ventilator associated pneumonia

INTRODUÇAO: Os exames de cultura e o exame bacterioscópico pelo método de coloração de Gram (GRAM) do aspirado traqueal ainda são objeto de controvérsias com relação ao diagnóstico etiológico na pneumonia associada à ventilação mecânica (PAV). OBJETIVO: Avaliar a concordância entre os resultados do GRAM e da cultura quantitativa do aspirado traqueal e do lavado broncoalveolar nos pacientes com PAV. MÉTODO: Foram estudados de modo prospectivo os pacientes internados no período de outubro de 2001 a agosto de 2002, que estavam há mais de 48hs sob ventilação mecânica, e que apresentavam suspeita clínica de PAV. No momento da suspeita clínica foi realizado o aspirado traqueal seguido do lavado broncoalveolar. O diagnóstico de PAV foi confirmado com a suspeita clínica associada à cultura quantitativa do lavado broncoalveolar 10(4)ufc/ml. RESULTADOS: Dos 119 pacientes sob ventilação mecânica, 32 (26,8 por cento) tiveram suspeita clínica de PAV, com confirmação diagnóstica em 25 (78 por cento) deles. A comparação entre o GRAM do aspirado traqueal e a cultura do lavado broncoalveolar mostrou uma moderada concordância (coeficiente de Kappa de 0,56). Houve concordância entre a cultura quantitativa do aspirado traqueal e do lavado broncoalveolar em 22/25 (88 por cento) e discordância em 3/25 (12 por cento) casos (coeficiente de Kappa de 0,71). A sensibilidade e a especificidade do aspirado traqueal para o diagnóstico de PAV com o ponto de corte 10 6 ufc/ml foram de 71 por cento e 72 por cento, respectivamente. CONCLUSAO: A combinação do GRAM com a cultura quantitativa do aspirado traqueal pode contribuir para a avaliação diagnóstica da PAV.

Experimental pathogenicity evaluation of Mycoplasma canadense from bovine mastitis in vitro and in vivo laboratory models.

Mycoplasma canadense, a clinical isolate from milk of a mastitic buffalo, was experimentally tested for its pathogenic potential in hamster tracheal ring and rabbit fallopian tube explant organ cultures (in vitro) and rat and rabbit mammary gland (in vivo) models. The activity percentage reduction in M. canadense infected hamster tracheal rings was 99.1% in comparison to 16.4% in control rings. Mycoplasma canadense, also induced complete ciliostasis at 11-day post-infection in rabbit fallopian tube explants. Histopathological lesions in these infected organ cultures were loss of cilia, desquamation or denudation of epithelium, infiltration of inflammatory cells and proliferation of macrophages as well as oedema in lamina propria. At the end of the experiments, M. canadense organisms were reisolated in pure colonies from the infected but not the control organ cultures. In the rat and rabbit mammary glands, M. canadense organisms persisted upto 6-day and 7-day postinfection, respectively and caused histopathological changes suggestive of subacute to chronic mastitis during the experimental period. The results indicate that the tested M. canadense clinical isolate was virulent.

Microbial flora variations in the respiratory tract of mice

A stable microbial system in the respiratory tract acts as an important defense mechanism against pathogenic microorganisms. Perturbations in this system may allow pathogens to establish. In an ecological environment such as the respiratory tract, there are many diverse factors that play a role in the establishment of the indigenous flora. In the present work we studied the normal microbial flora of different areas of the respiratory tract of mice and their evolution from the time the mice were born. Our interest was to know which were the dominant groups of microorganisms in each area, which were the first capable of colonizing and which dominated over time to be used as probiotic microorganisms. Our results show that Gram negative facultatively anaerobic bacilli and strict anaerobic microorganisms were the last ones to appear in the bronchia, while aerobic and Gram positive cocci were present in all the areas of the respiratory tract. The number of facultative aerobes and strict anaerobes were similar in the nasal passage, pharynx instilled and trachea, but lower in bronchia. The dominant species were Streptococcus viridans and Staphylococcus saprophyticcus, followed by S. epidermidis, Lactobacilli and S. cohnii I which were present on every studied days but at different proportions. This paper is the first part of a research topic investigating the protective effect of the indigenous flora against pathogens using the mice as an experimental model.