Apesar das diversas recomendações disponíveis na literatura sobre o diagnóstico laboratorial da resistência à oxacilina em Staphylococcus aureus, a verdade é que ainda não existe consenso absoluto sobre qual ou quais métodos utilizar e quando utilizar cada um deles. Segundo a literatura, a maioria dos métodos disponíveis apresenta um índice não desprezível de erros diagnósticos. Em casos de isolados de processos infecciosos invasivos, ou de infecções persistentes e/ou refratárias aos antimicrobianos, o uso de um método adicional ou confirmatório pode ser importante. Além disso, a contínua reavaliação desses testes é necessária.

Despite guidelines published in the literature, the optimal routine phenotypic method for detecting methicillin resistance in Staphylococcus aureus remains controversial. Most available methods have a considerable rate of errors, according to the literature. When testing invasive isolates or isolates from persistent/refractory infections, using an additional or confirmatory method could be important. In addition, the continual evaluation of these tests is necessary.

Pharmacodynamic analyses were proposed to determine optimal empirical antibiotic therapy against Gram-negative bacteria isolated in a Brazilian ICU. Due to high resistance rates, standard regimens of cefepime, ciprofloxacin, meropenem, and piperacillin/tazobactam were not able to attain significant bactericidal CFR. Prolonged infusion of meropenem achieved 88% CFR, making it a possible empirical regimen in this ICU until susceptibilities become available. Still, even through administration of high dose prolonged infusions, 12.0% of simulated subjects did not achieve bactericidal exposure, suggesting that combination therapy would frequently be required in this setting. In conclusion, we recommend that in the presence of identified resistance problems among Gram-negative bacteria in a unit or hospital, MIC testing of formulary agents should be conducted along with pharmacodynamic simulation to assist in choosing an optimal antibiotic and dosage regimen for empirical use of severe infections until cultures and susceptibilities become available.

OBJECTIVE: We assessed the antimicrobial resistance patterns of pathogens responsible for urinary tract infections (UTI) in outpatients in São Paulo, Brazil, as well as the Escherichia coli antimicrobial resistance trend. MATERIALS AND METHODS: Outpatients urine cultures were collected from January 2000 to December 2003. Statistical analysis considered positive results for one bacterial species with colony count > 100,000 CFU/mL. Stratification was done on age group and gender. Statistical tests used included chi-square and the chi-square test for trend to evaluate differences between susceptibility rates among age groups and ordering in the E. coli resistance rates per year, respectively. RESULTS: There were 37,261 positive results with Enterobacteriaceae isolated in 32,530 (87.3%) and Gram-positive cocci in 2,570 (6.9%) cultures. E. coli had the highest prevalence (71.6%). Susceptibility tests were performed in 31,716 cultures. E. coli had elevated resistance rates (> 30%) to ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. Significant differences between age groups and ordering among years were observed. CONCLUSIONS: The use of trimethoprim-sulfamethoxazole is precluded in the population studied due to elevated resistance rates (> 30%) among most prevalent pathogens. Significant resistance rate differences among age groups and years were observed, particularly for fluoroquinolones. Fluoroquinolones should be used with caution. Nitrofurantoin should be used as empirical therapy for primary, non-complicated urinary tract infections.

O objetivo deste estudo foi verificar a efetividade do tecido de ligamento sarja 2 x 1, usado na confecção de campos duplos de algodão para a embalagem de artigos médico-hospitalares como barreira microbiana eficaz, enquanto novos e após múltiplas lavagens e autoclavações e correlacionar a quebra do poder de barreira microbiana com as alterações das características físicas do tecido. Foram utilizados métodos de testes padronizados tanto para a avaliação das características físicas para a determinação da gramatura, resistência a ruptura, resistência a tração e alongamento quanto para as microbiológicas. Os resultados microbiológicos demonstraram a efetividade da barreira microbiana da embalagem em estudo enquanto novos e, na determinação do número máximo de reprocessamentos, indicaram o número limite de 65. Quanto às alterações das características físicas do tecido reprocessado, a diminuição da gramatura foi o acontecimento que sustentou a quebra da barreira microbiana. O momento da alteração constatada nas medidas físicas de estouro, tração e alongamento no urdume e na trama dos tecidos reprocessados não coincidiu com o da quebra de barreira microbiana. A presente investigação sustenta a segurança do uso do tecido de algodão como embalagem de artigos médico hospitalares na esterilização por calor úmido. O número de reusos deverá ser controlado, não excedendo o de 65 vezes.

The objective of this study was to verify the efficacy of cotton fabric, made of serge bonding 2 x 1, as microbial barrier, when new and after multiple laundering and steam sterilization procedures. The power of the microbial barrier was correlated with physical characteristics of the fabric, using standard test methods for evaluation of weight, traction, stretching tearing resistance and microbiological characteristics. The microbiological results evidenced that the microbial barrier was effective when the wrapping material was new or went through a maximum of new 65 reprocessing procedures. As for the alterations in the physical characteristics of the reprocessed material, the decrease in weight seemed to be the event responsible for microbial barrier breaking. The timing of detected alterations in bursting, traction and stretching in the wrap and the reprocessed fabrics did not coincide with the moment of bacterial barrier breaking. The present investigation corroborates that the use double cotton fabric, for wrapping medical and hospital items for steam sterilization, is safe. Re-use number must be controlled, not exceeding 65 times.

Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2003. Gram-negative bacteria (n = 1,550) causing nosocomial infections were collected at 20 Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by Etest methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). Pseudomonas aeruginosa (30.3%) was the most frequent isolate, followed by E. coli (18.6%), Klebsiella pneumoniae (16.9%), Acitenobacter baumannii (8.8%), and Enterobacter cloacae (7.1%). Pseudomonas aeruginosa (n=470) isolates presented susceptibility rates of 64% to meropenem, 63.8% to piperacillin/tazobactam, 63.4% to amikacin, 58.7% to imipenem. Acitenobacter baumannii presented susceptibility rates to meropenem of 97.1%, and 73% to tobramycin. E. coli and K. pneumoniae were highly susceptible to both carbapenems.Carbapenem resistance among the Enterobacteriaceae is still rare in the region. Acitenobacter baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since they play an important role in nosocomial infections in this environment, the use of empirical combination therapy to treat these pathogens may be justified.

OBJECTIVE: Establish the susceptibility pattern of Gram-negative bacteria causing infections in ICU patients, MYSTIC Program Brazil 2002. MATERIAL AND METHODS: Gram-negative bacteria (n = 503) causing nosocomial infections were collected at seven Brazilian centers. The central laboratory confirmed the identification and performed the susceptibility tests by E-test methodology (AB Biodisk, Solna, Sweden) for meropenem, imipenem, ciprofloxacin, ceftazidime, cefepime, cefotaxime, piperacillin/tazobactam, gentamicin, and tobramycin. Interpretation criteria used were according to National Committee for Clinical Laboratory Standards (NCCLS). RESULTS: Pseudomonas aeruginosa (33%) was the most frequently isolated, followed by A. baumannii (17.1%), K. pneumoniae (12.1%), E. coli (10.5%), and E. cloacae (7.9%). Pseudomonas aeruginosa isolates had susceptibility rates of 67.5% to piperacillin/tazobactam, 59.8% to meropenem, 57.3% to imipenem. A. baumannii presented susceptibility rates to meropenem of 89.5%, 88.4% to imipenem, and 74.4% to tobramycin. E. coli and K. pneumoniae were fully susceptible to both carbapenems. CONCLUSIONS: Carbapenem resistance among Enterobacteriaceae is still rare in this region. A. baumannii and P. aeruginosa presented elevated resistance rates to all antimicrobials. Since these two bacterial species play an important role in nosocomial infections, the use of empirical combination therapy to treat these pathogens may be justified.

In the advanced stages of AIDS, characterized by severe immunodepression, tuberculosis (TB) may present with a clinical picture of septic shock, due to typical bacteremia. Hematogenic dissemination of mycobacteria is frequent in immunodepressed patients with TB or disseminated mycobacteriosis, leading to increased positivity in detection by automated blood culture. The objective of our study was to determine the prevalence of mycobacteremia in patients with AIDS and with prolonged fever seen at the Emilio Ribas Institute of Infectology. Patients with a history of daily fever (37.8ºC), lasting more than 30 days, and with CD4+ helper lymphocyte counts below 200 cells/mL, were selected from February 2001 to March 2002. A 5 mL peripheral blood sample was collected from each patient for mycobacterial blood culture by an automated method, using the BACTEC 9000 MB and MB/BACT techniques. Forty-five patients aged on average 35 years, most of them males, were included in the study. The mean T CD4+ lymphocyte count was 58 cells/mL. Among the samples submitted to blood culture, 30% gave M. tuberculosis growth, with 62% sensitivity. Among the patients with a negative blood culture, nine had received a diagnosis of TB by another method. Automated blood culture proved to be a technique of relevant diagnostic value for M. tuberculosis in patients with prolonged fever in advanced stages of AIDS. The method is simple, and it helps the physician to select the best therapeutic option.

A Klebsiella pneumoniae strain was isolated from the urine of a patient at one of the centers participating in the 2001 edition of the MYSTIC program in Brazil. The initial phenotypic findings of the isolated K. pneumoniae presented an unusual MIC of 8 mug/mL to meropenem, 2 mug/mL to imipenem, elevated MICs to broad spectrum cephalosporins (ceftazidime/cefotaxime/cefepime MIC > 256 mug/mL), aminoglycosides (gentamycin > 256 mug/mL and tobramycin = 48 mug/mL), piperacillin/tazobactam (MIC > 256 mug/mL) and susceptibility to ciprofloxacin (MIC = 0.25 mug/mL). The strain also tested positive for ESBL production with double-disk and E-test methodologies. More detailed investigation revealed that the strain produced a SHV-4 type enzyme and also lacked a 36 kDa outer membrane porin.

Haemophilus influenzae é um dos mais importantes agentes bacterianos de otites e sinusites. Em crianças menores de seis anos de idade não vacinadas contra o H. influenzae do tipo b (Hib), essa bactéria é uma das principais causadoras de meningite, pneumonia e sepse. O objetivo deste estudo foi determinar a prevalência da colonização da orofaringe de crianças previamente saudáveis por H. influenzae e Hib e avaliar o perfil de suscetibilidade desses microorganismos a um grupo seleto de antimicrobianos, que habitualmente são utilizados para tratar as infecções respiratórias agudas. MÉTODO: Foram colhidos swabs da orofaringe de 987 crianças menores de seis anos de idade que freqüentavam 29 creches da cidade de Taubaté (São Paulo, Brasil), entre julho e dezembro de 1998, para realização de culturas de H. influenzae e antibiograma. RESULTADOS: A prevalência de portadores do H. influenzae foi de 17,4% e somente 5,5% das cepas isoladas eram produtoras de beta-lactamase. A prevalência de portadores do Hib foi alta, com média de 7,3% (variando entre 0.0 e 33,3%). CONCLUSÕES: A baixa prevalência da colonização por cepas resistentes às penicilinas indica que não é necessário substituir esses antibióticos para tratar empiricamente as otites e sinusites causadas por H. influenzae em Taubaté.

Haemophilus influenzae is one of the most important bacterial agents of otitis and sinusitis. H. influenzae type b (Hib) is one of the main causes of meningitis, pneumonia, and septicemia in nonvaccinated children under 6 years of age. The aims of this study were to determine the prevalence of H. influenzae and Hib oropharyngeal colonization prior to the onset of the Hib vaccination program in Brazil in previously healthy children and to assess the susceptibility profile of this microorganism to a selected group of antimicrobials that are used to treat acute respiratory infections. METHOD: Cultures of Haemophilus influenzae were made from oropharynx swabs from 987 children under 6 years of age who were enrolled in 29 day-care centers in Taubaté (a city of São Paulo state, Brazil) between July and December 1998. RESULTS: The prevalence of H. influenzae carriers was 17.4%, and only 5.5% of the strains were beta-lactamase producers. The prevalence of Hib carriers was high, 7.3% on average (range, 0.0 - 33.3%). CONCLUSIONS: The low prevalence of colonization by penicillin-resistant strains indicates that it is not necessary to substitute ampicilin or amoxicilin to effectively treat otitis and sinusitis caused by H. influenzae in Taubaté.

OBJETIVO: o Streptococcus pneumoniae habitualmente coloniza a orofaringe de pessoas sadias. O estado de portador assintomático está relacionado à invasão de estruturas adjacentes e ao surgimento de doença invasiva. Foi realizado estudo transversal, descritivo, objetivando verificar a prevalência de colonização de orofaringe pelo S. pneumoniae em crianças que freqüentam creches no município de Taubaté, SP, verificar a freqüência de sorotipos de Streptococcus pneumoniae nas cepas isoladas e relacionar os sorotipos mais freqüentes com os sorotipos presentes na composição da vacina pneumocócica heptavalente conjugada atualmente em uso. MÉTODOS: foram coletados, de 29 de junho a 15 de dezembro de 1998, 987 swabs de orofaringe de crianças entre 8 e 71 meses de idade, matriculadas nas creches municipais de Taubaté, SP. A identificação do S. pneumoniae foi baseada na observação das colônias que apresentassem hemólise parcial nos meios AS e AS-G, e pela observação da inibição do crescimento ao redor do disco de optoquina. A sorotipagem foi realizada pela reação de Quellung, utilizando anti-soros específicos, e adotado o sistema de nomenclatura dinamarquês. RESULTADOS: o Streptococcus pneumoniae foi isolado em 209 das 987 crianças (taxa de colonização= 21,1%). Vinte e oito sorotipos foram identificados. Os sete sorotipos mais freqüentes foram: 6A/6B (21,5%), 19F (14,8%), 18C (7,4%), 23F (7,4%), 9V (6,7%),14 (5,2%) e 10A (4,4%). Com exceção do sorotipo 10A, todos os outros seis estão incluídos na vacina. O único sorotipo vacinal não encontrado foi o sorotipo 4. CONCLUSÃO: estima-se, então, uma concordância de 63% entre os sorotipos colonizadores de orofaringe e os sorotipos presentes na vacina.

OBJECTIVE: Streptococcus pneumoniae usually colonizes the oropharynx of healthy people. Oropharyngeal carriage is related to the invasion of adjacent structures and to the development of invasive disease. A descriptive cross-sectional study was performed aiming at verifying the prevalence of oropharyngeal colonization by S. pneumoniae in children attending day care centers in the city of Taubaté - SP; verifying the frequency of S. pneumoniae serotypes in isolated strains; and relating the most frequent serotypes to the composition of the conjugated heptavalent pneumococcal vaccine currently in use. METHODS: from June 29 to December 15 1998, samples of oropharyngeal material were collected from 987 children, ranging from 8 to 71 months old, enrolled in day care centers in Taubaté - SP. The identification of S. pneumoniae was based on the observation of the colonies that presented partial hemolysis in agar-blood and agar-blood with gentamycin plates and on the observation of inhibited growth around the optochin disc. Serotyping was performed by the Quellung reaction, using specific antiserum, provided by the Centers for Disease Control and Prevention (Atlanta, GA/USA), and the Danish nomenclature system. RESULTS: as a result, S. pneumoniae was isolated from the oropharynx in 209 out of 987 children (colonization rate of 21.2%). Twenty eight serotypes were identified. The seven most frequent serotypes were: 6A/6B (21.5%), 19F (14.8%), 18C (7.4%), 23F (7.4%), 9V (6.7%), 14 (5.2%), 10A (4.4%). Except for serotype 10A, all the other six are included in the vaccine. The only vaccine serotype which was not found was serotype 4. CONCLUSION: agreement of 63% between the oropharynx colonizer serotypes and the serotypes present in the vaccine was found.

Há alguns anos tem-se verificado um aumento progressivo da resistência de alguns cocos gram-positivos a determinados antimicrobianos. Este aumento da resistência tem sido observado principalmente no ambiente hospitalar, e as bactérias mais comumente envolvidas são os Staphylococcus spp. e os Enterococcus spp. Devido a este fato, novos antimicrobianos são avaliados para o tratamento de infecções causadas por estas cepas multirresistentes. A associação quinupristina/dalfopristina (Q/D), também conhecida como Synercid®, é um antibacteriano da classe das estreptograminas, de uso endovenoso, composto por dois derivados semi-sintéticos da pristinamicina. A combinação das estreptograminas B e A na razão de 30:70 tem atividade antimicrobiana voltada para cocos gram--positivos, como Staphylococcus spp., Streptococcus spp., incluindo S. pneumoniae e Enterococcus faecium, sendo o E. faecalis habitualmente resistente. Neste estudo foi avaliada a atividade in vitro de Q/D e outros oito antimicrobianos frente a 631 amostras de cocos gram-positivos isoladas de cinco centros brasileiros, complementadas com outras 20 cepas de E. faecium resistentes à vancomicina, provenientes dos Estados Unidos. Para a avaliação da sensibilidade aos antimicrobianos foi determinada a concentração inibitória mínima (MIC) pelo método do Etest (AB Biodisk, Solna, Suécia) e as cepas testadas foram: Staphylococcus aureus (n = 267), Staphylococcus coagulase negativo (n = 131), Streptococcus pneumoniae (n = 130), Streptococcus beta-hemolíticos (n = 28), Enterococcus faecalis (n = 44) e E. faecium (n = 51). A Q/D demonstrou excelente atividade contra Staphylococcus spp., independente de serem sensíveis ou resistentes à oxacilina. Para S. pneumoniae, a Q/D apresentou igualmente uma ótima atividade, inclusive para as cepas com resistência intermediária ou total para penicilina. Entre as cepas de E. faecium sensíveis à vancomicina, o MIC90 de Q/D obtido foi de 3µg/ml, sendo que 45% das cepas testadas foram sensíveis e 55% apresentaram sensibilidade intermediária à associação. Desta forma, pode-se afirmar que a associação Q/D representa uma nova opção para o tratamento endovenoso de infecções causadas por cocos gram-positivos, principalmente para as cepas multirresistentes, sendo também uma alternativa ao uso de glicopeptídeos.

A progressive increase of resistance among Gram-positive cocci (GPC) towards some antimicrobial agents has been observed for the past few years. This rise of resistance, most often seen in Staphylococcus spp., and Enterococcus spp., has mainly been noticed in hospital environments. Due to these recent patterns of resistance, newly developed antimicrobial agents need to be evaluated for the treatment of infections caused by these multi-resistant microorganisms. Quinupristin/dalfopristin (Q/D), also known as Synercid®, is an antimicrobial agent of intravenous administration, composed of two semi-synthetic derivatives of pristinomycin belonging to the group of streptogramins. The combination of streptogramins B and A at 3:7 ratio has an antimicrobial activity against gram-positive cocci. This combination has potent activity against gram-positive cocci such as Staphylococcus spp., Streptococcus spp. including Streptococcus pneumoniae, and Enterococcus faecium. However, strains of E. faecalis are usually resistant to this compound. The aim of this study was to evaluate the in vitro activity of Q/D and other eight antibiotics against 631 strains of GPC isolated from five Brazilian centers. Additionally, 20 vancomycin-resistant strains of E. faecium provided by a reference center from the United States were also included in this study. Minimal Inhibitory Concentrations (MICs) were determined by E-test methodology (AB Biodisk, Solna, Sweden), using standardized and controlled procedures. The evaluated strains were as follows: Staphylococcus aureus (267), coagulase negative Staphylococcus (131), Streptococcus pneumoniae (130), b-hemolytic Streptococcus (28), Enterococcus faecalis (44), and E. faecium (51). Quinuprintin/dalfopristin presented an excellent activity against Staphylococcus spp., regardless if these were susceptible or not to oxacillin. Against S. pneumoniae, Q/D also presented excellent activitiy regardless of their susceptibility to penicillin. Among vancomycin susceptible E. faecium studied, the MIC90 was 3mg/ml where 45% of the strains were susceptible, and 55% revealed intermediate resistance to quinupristin/dalfopristin. Overall, Q/D showed good activity against Staphylococcus spp., Streptococcus spp. including S. pneumoniae, and Enterococcus faecium representing a new option for the treatment of infections caused by multi-resistant gram-positive cocci, as well as an alternative for the use of glycopeptides.

A tuberculose é uma doença de importância mundial e há alguns anos, em muitos países, foi quase erradicada, mas, com o advento da Aids, novos casos da doença começaram a ocorrer, com o agravante do surgimento de cepas resistentes a diversos antimicrobianos. Concomitantemente a este aumento na incidência de tuberculose, as metodologias diagnósticas apresentaram avanços consideráveis, e atualmente existem diversas metodologias manuais ou automatizadas para um diagnóstico mais rápido das infecções por micobactérias. Um dos sistemas semi-automatizados, o Bactec 460 (Becton Dickinson Diagnostic Systems, Sparks, MD), é utilizado para detectar a presença de micobactérias em espécimes clínicos, realizar testes de sensibilidade aos antimicrobianos e fazer a diferenciação entre micobactérias do complexo tuberculosis e as não-pertencentes a este complexo, diminuindo o tempo do processo em vários dias. O intuito deste trabalho foi verificar o impacto ocasionado com a introdução de um sistema semi-automatizado na rotina do laboratório. No período de janeiro a junho de 1995, foram processadas, pelo método tradicional de cultura em meio de Lowenstein-Jensen (LJ), 326 amostras, das quais 39 (12%) foram positivas, sendo 77% destas identificadas como Mycobacterium tuberculosis. Do total de amostras positivas para M. tuberculosis, 29 (74,3%) apresentaram um prazo de detecção superior a 30 dias. No mesmo período, no ano de 1997, com a introdução do sistema semi-automatizado, foram processadas 340 amostras, das quais 50 (14,7%) foram positivas, sendo 46% destas identificadas como Mycobacterium tuberculosis. O tempo médio para detecção do crescimento das amostras positivas para M. tuberculosis foi de 12 dias. A implantação do sistema automatizado para culturas de micobactérias proporcionou um aumento no número de isolamento de diferentes espécies, em diversos materiais clínicos, com diminuição no tempo de detecção, além de oferecer maior segurança para os técnicos durante a realização destes procedimentos.

Tuberculosis is a disease of worldwide importance and several years ago in many countries the disease was almost eradicated. With the advent of Aids infection, new cases of the disease started to emerge with the appearance of multiple drug resistant strains. Together with the increase in tuberculosis cases, diagnostic methodologies showed an advance and nowadays there are several manual and automated methodologies for the diagnosis of these infections. The Bactec 460 (Becton Dickinson Diagnostic Systems, Sparks, MD) system is used for the direct detection of mycobacteria in clinical specimens, for susceptibility testing against tuberculostatic drugs and differentiation of Mycobacterium tuberculosis complex from other species not of the complex, shortening the process in several days. In this study we evaluated the impact of the introduction of an automated system. In the period of January to June 1995, 326 specimens were processed using the traditional methodology of culture in Lowenstein-Jensen (LJ). Thirty-nine (12%) were positive being 77% of these identified as M. tuberculosis. Of the total of 39 positive cultures for M. tuberculosis, 29 (74.3%) showed a time for detection greater than 30 days. In the same period in the year of 1997 with the introduction of the semiautomated system, 340 specimens were processed of which 50 (14.7%) were positive being 46% of these M. tuberculosis. The mean time for detection of positive cultures for M. tuberculosis was 12 days. The use of the automated system for culture of mycobacteria showed an increase in the number of different species isolated from different specimens, decreasing the time for detection and allowing a better and safe condition for technicians while executing theses procedures.

The in vitro antimicrobial susceptibility of the respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis to commonly tested and prescribed agents was investigated during 1999-2000 and compared with results obtained during a previous 1997-1998 study. Of 448 isolates of S. pneumoniae collected and tested in 1999-2000, 77.2% were susceptible, 19.9% were intermediate, and 2.9% were resistant to penicillin, demonstrating that there were no major changes in susceptibility to penicillin from 1997-1998 (77.1% susceptible, 18.7% intermediate, 4.2% resistant). All S. pneumoniae isolates from 1999-2000 were susceptible to levofloxacin and vancomycin, and >90% were susceptible to the beta-lactams (amoxicillin-clavulanate, ceftriaxone, and cefuroxime) and macrolides (azithromycin and clarithromycin), showing that susceptibility to these agents also remained unchanged since 1997-1998. The most notable increase in resistance between the two studies was demonstrated by trimethoprim-sulfamethoxazole, which increased from 23.4% to 38.6%. Penicillin resistance correlated with resistance to beta-lactams, macrolides, and trimethoprim-sulfamethoxazole in both studies. In H. influenzae, the prevalence of beta-lactamase-producing isolates remained unchanged (10.6% in 1999-2000; 11.0% in 1997-1998). All H. influenzae isolates were susceptible to levofloxacin, ceftriaxone, cefuroxime, and azithromycin, and showed no change between the two studies. Trimethoprim-sulfamethoxazole resistance was present in 40.1% of isolates in 1999-2000, and in 45.2% in 1997-1998. In M. catarrhalis, the prevalence of beta-lactamase-producing isolates was unchanged (97.9% in 1999-2000; 98.0% in 1997-1998). The most active agents against M. catarrhalis were azithromycin (MIC90, <0.03 mug/ml) and levofloxacin (MIC90, 0.03 mug/ml). Overall, these results suggest that, in Brazil, between 1999-2000 and 1997-1998, there have been no significant changes in the susceptibility of respiratory pathogens to any of the commonly tested and prescribed agents with the exception of trimethoprim-sulfamethoxazole for S. pneumoniae.

This study was conducted to evaluate the activity of azithromycin in comparison to 12 other antibacterial agents against recent isolates obtained consecutively from patients with respiratory tract or skin infections, from January to July, 2000. A total of 717 Gram-positive cocci were analyzed in this study and the following species were studied: Staphylococcus aureus (n=576), beta-hemolytic streptococci ( n=115), and Streptococcus pneumoniae (n=26). Susceptibility testing was carried out by the disk diffusion method and interpreted according to NCCLS breakpoints. The activity of azithromycin was compared to erythromycin, clindamycin, chloramphenicol, ciprofloxacin, ofloxacin, oxacillin, penicillin, ceftriaxone, tetracycline, trimethoprim/sulfamethoxazole, teicoplanin, and vancomycin. Of the 26 S. pneumoniae isolates recovered from the respiratory tract, 5 (19.2%) were intermediate resistant to penicillin. All of these strains were susceptible to chloramphenicol, ofloxacin, and vancomycin, and 24 (92%) were also susceptible to azithromycin, clindamycin, and erythromycin. Among the 67 beta-hemolytic streptococci strains isolated from the respiratory tract, 66 (99%) were susceptible to azithromycin, erythromycin, clindamycin, and ofloxacin. All 48 beta-hemolytic streptococci strains isolated from skin were susceptible to azithromycin and clindamycin, 47 (98%) were susceptible to erythromycin, and 46 (96%) were susceptible to ofloxacin. Of the 576 strains of S. aureus, 253 (43.9%) were isolated from the respiratory tract and 323 (56.1%) from skin. Among S. aureus isolates from the respiratory tract and skin, 46 (18%) and 78 (24%), respectively were resistant to oxacillin. Isolates from the respiratory tract and skin showed the same percentage of resistance (36%) to azithromycin. These in vitro results suggest that azithromycin can be a therapeutic option for treatment of infections caused by these bacteria since the newer macrolides have several distinct advantages over erytromycin including improved oral bioavailability, longer half-life allowing once or twice daily administration, higher tissue concentrations and less gastrointestinal adverse effects.

This study was done to determine the occurrence of mycobacteria in the bloodstreams of patients with fever and advanced AIDS in a Brazilian hospital. We also verified the capability of an automated method for recovering these bacteria. During a period of 19 months, 254 patients with AIDS were evaluated. Blood cultures were generally submitted in pairs and drawn separately. Blood cultures were processed by the BACTEC 460TB System (Becton Dickinson Microbiology Systems, Sparks, MD), using the Bactec 13A media (Becton Dickinson Microbiology Systems, Sparks, MD). Of the 530 vials submitted, 77 (14.5%) from 41 (16%) patients were positive. Mycobacterium avium complex was recovered from 45 (58.4%) of the 77 positive vials, corresponding to 22 (53.6%) patients with positive blood cultures. The average time to detect Mycobacterium avium complex was 15 days. Mycobacterium tuberculosis was recovered from 26 (33.8%) of the 77 positive vials, corresponding to 15 (36.6%) patients with positive blood cultures, with an average detection time of 24 days. Other species of mycobacteria were recovered from 6 (7.8%) of the 77 vials, corresponding to 4 (9.8%) patients. M.avium complex was fairly prevalent (8.7%) in severely ill patients with AIDS in our hospital. M. tuberculosis was also an important (6.0%) agent of systemic bacterial infections in these patients. The rapid diagnosis of mycobacteremia was possible with the implementation of this automated technology.