Epidemiologic typing of multiply drug-resistant Pseudomonas aeruginosa isolated from an outbreak in an intensive care unit.

From June to August 1991, there was an outbreak of Pseudomonas aeruginosa infections in an intensive care unit in a general hospital in Sao Paulo, Brazil. We obtained 14 isolates from 14 patients, 11 from tracheal aspirate, and 3 from surgical wound exudates. These strains were typed by serotyping, pyocin typing, and pulsed-field electrophoresis (CHEF) of chromosomal DNA (chrDNA), and the different typing methods were analyzed. These three methods demonstrated seven identical strains. We also performed an extensive antibiogram (33 drugs) in all 14 isolates. The incidence of resistance to aminoglycosides, extended-spectrum beta-lactams, and quinolones was very high among the seven identical isolates; however, the antibiogram profile differed significantly among the isolates. Our results suggest that a unique strain caused several cross-transmitted infections during this period of time, and the emergence of antimicrobial resistance has been occurring before and after the establishment of the epidemic strain by selective drug use. The chrDNA fingerprinting proved to be versatile and precise for epidemiologic investigations of P. aeruginosa infections.

Molecular epidemiology and antimicrobial susceptibility testing. Testing of quinolone-resistant Staphylococcus aureus strains isolated in Brazil.

An outbreak of 20 oxacillin-resistant Staphylococcus aureus (ORSA) bloodstream infections (BSIs) was detected in the intensive care unit (ICU) at Hospital Sao Paulo, Brazil. In a surveillance study, 10% of ICU personnel were defined as chronic nasal carriers of ORSA. Thirteen BSIs and five nasal isolates were available for phage typing, restriction endonuclease analysis of plasmid (REAP) and chromosomal DNA hybridized with 32P rRNA gene probe. Susceptibility testing against select antimicrobial agents, including 11 quinolones, six glycopeptides, and five topical agents, was performed by broth microdilution and the disk diffusion tests. Ten of the 13 BSI isolates and four of the five nasal strains were oxacillin and quinolone resistant. The new fluoroquinolones CI-960 and WIN57273, the glycopeptides, and the topical agents ramoplanin, bacitracin, mupirocin, and novobiocin were most active. Fourteen strains, 12 BSI isolates, and three nasal isolates showed the same REAP profile. Moreover, the same REAP and chromosomal profile was detected in at least nine BSI isolates and in two nasal isolates. These strains were nontypable by phage typing. We concluded that nosocomial cross-transmission of a single, multiresistant strain of S. aureus occurred and that the epidemic reservoir was nasal carriage by ICU personnel.

[In vitro susceptibility testing of 446 clinical isolates of gram-positive bacteria to new quinolones, carbapenems and cephalosporins]. / Avaliação da sensibilidade in vitro de 446 amostras clínicas de bactérias gram-positivas testadas para novos antimicrobianos da classe das quinolonas, carbapenens e cefalosporinas.

OBJECTIVE: To assess the in vitro susceptibility of gram-positive bacteria isolated in the São Paulo Hospital against five fluoroquinolones, three carbapenems and three cephalosporins. MATERIALS AND METHOD: Susceptibility was tested in 77 isolates of streptococci, 38 enterococci, 25 S. aureus and 91 S. epidermidis. The strains were isolated in the São Paulo Hospital in June and July of 1992. The susceptibility testing was performed by broth microdilution according to the procedure described by the national committee for Clinical Laboratory Standards (NCCLS). The antimicrobial agents tested were: ciprofloxacin, ofloxacin, levofloxacin, grepafloxacin (formerly OPC 17116), DU-6859, imipenem, meropenem, biapenem, ceftazidime, cefepime and FK-037. RESULTS: The best in vitro activity was demonstrated by the new fluoroquinolones, especially DU 6859. Among the commercially available compounds, the fluoroquinolones ciprofloxacin and ofloxacin (81% susceptibility) and the carbapenem imipenem (74% susceptible) were the most active compounds. The highest resistance rates were shown by enterococci and oxacillin-resistant staphylococci. CONCLUSIONS: The results of the present study showed that the in vitro activities of the new carbapenems are similar to that of imipenem and the fourth generation cephalosporins are more active than ceftazidime against gram-positive bacteria. In addition, the newer fluoroquinolones were four to sixteen-fold more active than that showed by the commercially available compounds of this class, especially against enterococci and oxacillin-resistant staphylococci. These results indicate that these newer fluoroquinolones should be further evaluated in clinical trials.

[Sensitivity pattern of 117 clinical isolates of Staphylococcus aureus from 12 hospitals]. / Padrão de sensibilidade de 117 amostras clínicas de Staphylococcus aureus isoladas em 12 hospitais.

OBJECTIVE: To evaluate the antimicrobial susceptibility pattern of oxacillin susceptible (OSSA) and resistant Staphylococcus aureus (ORSA) isolates to other antimicrobial agents that can be used for the treatment of staphylococcal infections. MATERIAL AND METHOD: We evaluated 117 clinical S. aureus isolates from several São Paulo hospitals. Clinical isolates from Campinas, SP and from João Pessoa, PB, were also included. The in vitro susceptibility testing was performed by broth microdilution as described by the National Committee for Clinical Laboratory Standards (NCCLS). The minimum inhibitory concentration (MIC) was evaluated for 24 antimicrobial agents, including beta-lactams, fluoroquinolones, aminoglycosides, glycopeptides, macrolides, lincosamides and streptogramins. Both commercially available and experimental drugs were included in the study. Cross-resistance among fluoroquinolones was evaluated by susceptibility testing 24 isolates to 10 fluoroquinolones. RESULTS: The antimicrobial agents that showed the highest in vitro activity were the glycopeptides, the streptogramin RP-59.500, and the mupirocin (100% susceptibility). Eighty-seven percent of the OSSA and only 38% of the ORSA isolates were susceptible to ciprofloxacin (MIC50 0.25 microgram/mL and > 4 micrograms/mL, respectively). Cross-resistance among fluoroquinolones were noted even for the experimental drugs. Two fluoroquinolones remained active against ciprofloxacin-resistant isolates, clinafloxacin and WIN-57.273. However, the ciprofloxacin-resistant isolates had MICs eight-to 64-fold higher than the ciprofloxacin-susceptible isolates, suggesting that the MICs may continue to increase when these fluoroquinolones become commercially available. CONCLUSION: Our results showed a high rate of antimicrobial resistance among S. aureus from the Brazilian hospitals. Very few drugs can still be used for the treatment of staphylococcal infections.

[Sensitivity profile of 147 strains of S. aureus isolated from patients in continuous ambulatory peritoneal dialysis]. / Perfil de sensibilidade de 147 cepas de "S. aureus" isoladas de pacientes em diálise peritoneal ambulatorial contínua.

Staphylococcus aureus is reported to be the most common organism to cause peritonitis in continuous ambulatorial peritoneal dialysis (CAPD). Staphylococcal nasal carriage is frequently seen in these patients. The authors studied the sensitivity of S. aureus strains isolated from CAPD patients and some close family contacts. Susceptibility of 147 strains of S. aureus to 23 antimicrobial agents were determined based on 348 samples. All strains tested were susceptible to vancomycin. Penicillin resistance was found in nearly all strains. Resistance to rifampicin was seen in just 5% of the strains. A high rate of resistance to ampicillin, amoxicillin, tetracycline, and also to cotrimoxazole, gentamicin, and tobramycin were observed. Cephalosporins and some aminoglycosides (amicacin and netilmicin) have a good in vitro bactericidal activity anti-S. aureus. Knowledge of the susceptibility profile of bacteria frequently isolated at a given hospital ward will provide the basis for a more effective empirical antibiotic treatment in such ward.

Staphylococcus aureus prophylaxis in hemodialysis patients using central venous catheter: effect of mupirocin ointment.

Central venous catheterization is a common technique to establish rapid and temporary access for hemodialysis. However, it is a known risk factor for Staphylococcus aureus infection and bacteremia. Mupirocin is a topical antibiotic with high in vitro anti-staphylococcal activity. A randomized prospective trial was conducted to assess the effectiveness of mupirocin ointment in the prevention of Staphylococcus aureus skin and catheter colonization, and episodes of bacteremia in 136 end-stage renal disease patients. Of these, 67 received skin disinfection at the venous catheter insertion site with povidone iodine (control group), and 69 received the same treatment followed by application of 2% mupirocin ointment at the cannula site after catheter placement and at the end of each dialysis session. Patients were followed until catheter removal and were monitored for the development of Staphylococcus aureus skin/catheter colonization and episodes of bacteremia. Median duration of catheter use was greater in the mupirocin than in the control group (37 versus 20 d, P < 0.01). Patients in the mupirocin group had a significantly lower rate of Staphylococcus aureus isolation from the pericatheter skin (1.76 per 1000 versus 14.27 per 1000 patient-days, P < 0.001) and from the catheter surface (3.17 per 1000 versus 14.27 per 1000 patient-days, P < 0.001). The proportion of patients with Staphylococcus aureus skin infection at the insertion site was lower in the mupirocin group (4.3% versus 23.9%, P = 0.001). Staphylococcus aureus-associated bacteremia was observed in 17 patients (two in the mupirocin group [0.71 episodes per 1000 patient-days] and 15 in the control group [8.92 per 1000 patient-days], P < 0.001). The hazard ratio of developing Staphylococcus aureus bacteremia was 7.2 (95% confidence interval, 1.6 to 31.6) times greater in patients not receiving mupirocin. Mupirocin applied to the insertion site significantly reduces the risk of Staphylococcus aureus skin and catheter colonization, exit-site infection, and Staphylococcus aureus bacteremia in hemodialysis patients.

Padräo de sensibilidade de 117 amostras clínicas de Staphylococcus aureus isoladas em 12 hospitais / Sensitivity pattern of 117 clinical isolates of Staphylococcus aureus from 12 hospitals

OBJETIVO. Avaliar o padräo de sensibilidade in vitro de amostras clínicas de Staphylococcus aureus sensíveis (ossa) e resistentes à oxacilina (ORSA) a outros antimicrobianos que podem ser utilizados no tratamento de infecçöes estafilocócicas. MATERIAL E MÉTODO. Foram analisadas 117 amostras clínicas de S. aureus isoladas em vários hospitais de Säo Paulo. Também foram incluídas amostras isoladas em Campinas, SP, e Joäo Pessoa, PB. A avaliaçäo da sensibilidade in vitro aos antimicrobianos foi realizada pela técnica de microdiluiçäo em caldo, utilizando os procedimentos preconizados pelo National Committee for Clinical Laboratory Standards (NCCLS). Foi avaliada a concentraçäo inibitória mínima (MIC) para 24 antimicrobianos da classe dos beta-lactâmicos, fluoroquinolonas, aminoglicosídeos, glicopeptídeos, macrolídeos, lincosaminas e estreptograminas. Foram avaliadas tanto drogas disponíveis comercialmente quanto as que ainda se encontram em fase de pesquisa. A resistência cruzada entre dez fluoroquinolonas foi avaliada em 24 amostras. RESULTADOS. Os glicopeptídeos, o RP-59500 e a mupirocina foram os antimicrobianos que apresentaram maior atividade in vitro contra amostras de ORSA (100 por cento sensibilidade). Oitenta e sete por centro das amostras de OSSA foram sensíveis à ciprofloxacina (MIC50, 0,25 mug/mL), enquanto que, para os ORSA, a sensibilidade foi de apenas 38 por cento (MIC50 > 4mug/mL). A resistência cruzada pra as fluoroquinolonas foi observada mesmo para drogas nÒo disponíveis comercialmente. As fluoroquinolonas que permaneceram ativas contra amostras resistentes à ciprofloxacina (clinafloxacina e WIN-57.273) apresentaram MICs 8 a 64 vezes mais elevados que as amostras sensíveis à ciprofloxacina, sugerindo que, quando lançadas na prática clínica, esses MICs possam se elevar ainda mais, inviabilizando o uso clínico desses compostos. CONCLUSÃO. Os resultados do presente estudo mostraram uma alta taxa de resistência a antimicrobianos das amostras de S. aureus nos hospitais do Brasil, restando poucas opçöes para o tratamento de infecçöes causadas por ORSA.

Avaliaçäo da sensibilidade in vitro de 446 amostras clínicas de bactérias gram-positivas testadas para novos antimicrobianos da classe das quinolonas, carbapenens e cefalosporinas / In vitro susceptibility testing of 446 clinical isolates of gram-positive bacteria against new quinolones, carbapenems and cephalosporins

Objetivo. Avaliar a sensibilidade in vitro de amostras clínicas de bactérias gram-positivas, hospitalares contra cinco fluoroquinolonas, três carbapenens e três cefalosporinas. Material e Método. Foram analisadas 67 amostras de estreptococos, 38 de enterococos, 250 de S. aureus e 91 de S. epidermidis. As amostras foram isoladas no Hospital Sao Paulo durante os meses de junho e julho de 1992. Os valores de concentraçao inibitória mínima (MIC) foram determinados por microdiluiçao em caldo seguindo a padronizaçao do National Commitee for Clinical Laboratory Standards (NCCLS). Os antimicrobianos testados foram: ciprofloxacina, ofloxacina, levofloxacina, grepafloxacina, DU-6859, imipenem, meropenem, biapenem, ceftazidima, cefepime e FK-037. Resultados. As novas fluoroquinolonas, especialmente o DU-6859, foram os antimicrobianos que demonstraram maior atividade contra as bactérias testadas. Entre as drogas disponíveis comercialmente, as fluoroquinolonas ciprofloxacina e ofloxacina (81 por cento de sensibilidade) e o carbapenem imipenem (74 por cento de sensibilidade) foram as mais ativas. Os enterococos e os estafilococos resistentes à oxacilina foram as bactérias que demonstraram maior resistência antimicrobiana. Conclusao. Os resultados do presente estudo mostraram que os novos carbapenens apresentam potência semelhante àquela apresentada pelo imipenem, enquanto que as cefalosporina de quarta geraçao apresentam atividade superior àquela mostrada pela ceftazidima. Por outro lado, as novas fluoroquinolonas demonstraram espectro e potência superiores às fluoroquinolonas disponíveis comercialmente, especialmente contra enterococos e estafilococos resistentes à oxacilina e à ciprofloxacina, indicando que essas novas drogas merecem ser avaliadas em ensaios clínicos.