Detection of methicillin resistance in Staphylococcus aureus isolated from pediatric patients: is the cefoxitin disk diffusion test accurate enough?

We evaluated the performance of several methods for the detection of methicillin resistance in Staphylococcus aureus using 101 clinical S. aureus isolates from pediatric patients in a tertiary hospital in Brazil; 50 isolates were mecA-positive and 51 were mecA-negative. The Etest and oxacillin agar screening plates were 100% sensitive and specific for mecA presence. Oxacillin and cefoxitin disks gave sensitivities of 96 and 92%, respectively, and 98% specificity. Alterations of CLSI cefoxitin breakpoints increased sensitivity to 98%, without decreasing specificity. Our results highlight the importance of a continuing evaluation of the recommended microbiological methods by different laboratories and in different settings. If necessary, laboratories should use a second test before reporting a strain as susceptible, especially when testing strains isolated from invasive or serious infections. With the new (2007) CLSI breakpoints, the cefoxitin-disk test appears to be a good option for the detection of methicillin resistance in S. aureus.

Antibacterial activity of anesthetic solutions and preservatives: an in vitro comparative study.

PURPOSE: To investigate the antibacterial activity of topical anesthetic solutions and their preservatives individually in vitro, to determine involvement with bacterial growth inhibition. MATERIAL AND METHODS: Proparacaine and tetracaine (in concentrations of 0.125%, 0.25%, and 0.50%), edetate disodium (EDTA), benzalkonium chloride, EDTA + benzalkonium chloride, and sterile saline solution were used. Five microliters of each solution were applied to standard filter paper disks and placed in Mueller-Hinton agar previously inoculated with known strains of Pseudomonas aeruginosa and Staphylococcus aureus. Zones of growth inhibition were measured 24 hours later and analyzed. RESULTS: There were no zones of inhibition in the agar inoculated with P. aeruginosa to all tested solutions. Benzalkonium chloride alone and associated with EDTA inhibited growth of S. aureus. All other solutions did not inhibit S. aureus. CONCLUSION: Preservative-free anesthetic solutions seemed not to interfere with bacterial development in culture media. Benzalkonium chloride alone and associated with EDTA inhibited development of gram positive bacteria, S. aureus, but did not inhibit P. aeruginosa.

High frequency of colonization and absence of identifiable risk factors for methicillin-resistant Staphylococcus aureus (MRSA)in intensive care units in Brazil.

Colonization of hospitalized patients with methicillin-resistant Staphylococcus aureus (MRSA) is of increasing concern. To evaluate this problem in Intensive Care Units (ICUs) in Brazil, we studied 100 patients admitted to two ICUs from April to June, 1997. Of the 100 patients, 70 were male, 53 were age 60 years or older, 55 were previously hospitalized, 78 were transferred to the ICU from other hospital units, 49 had received antibiotic therapy, and 66 had undergone recent surgery. Nasal and axillary swab cultures were obtained on admission and every 48 hours thereafter until discharge. MRSA were identified by plating any cultured S. aureus on Mueller-Hinton agar containing 6 microg/ml of oxacillin. At the time of admission, 46 (46%) of the patients were colonized with MRSA. No associated risk factors for acquiring MRSA (age, previous hospitalization, prior surgery) could be identified. Of the 54 patients negative for MRSA on admission, 28 (52%) became colonized while in the ICU. Sixteen (22%) of the 74 colonized patients (colonized either on admission or during ICU stay) had associated respiratory or urinary tract infections due to MRSA, and 9 (56%) died. No correlation with special risk factors (invasive procedures, antibiotic use, age, chronic disease) was identified. MRSA occurred frequently, but there was minimal evidence of associated risk factors. Thus, control of MRSA cannot be accomplished by targeting special factors alone, but requires attention to preventing microbial spread in all areas. Of special concern is the high frequency of acquiring the organism in the ICU (52%). Education concerning the importance of hand washing, environmental surface cleaning, and barrier protection from infected patients is needed.

Oropharynx microbiota among alcoholics and non-alcoholics.

CONTEXT: The oropharynx microbiota plays an important role in the origin of infections, especially among alcoholics whose airway defenses are impaired. OBJECTIVE: To compare the normal oropharingeal flora in heavy alcohol drinker and non-alcoholics. PATIENTS: 117 persons, 58 heavy alcohol drinkers and 59 non-alcoholics. SETTING: Santa Casa de São Paulo Emergency Service. DESIGN: A blind prospective study. MAIN OUTCOMES MEASURES: Prevalence of aerobic and anaerobic bacteria, and fungi. RESULTS: The study of the oropharynx microbiota among heavy alcohol drinkers demonstrated the presence of anaerobic microorganisms in 84.5% of them, including: Bacteroides sp, Prevotella melaninogenica, Fusobacterium sp, Veilonella sp, Peptostreptococcus sp, Propionibacterium sp, Bifidobacterium sp and Clostridium sp, versus 30.5% (p < 0.005) of non-alcoholics. Candida sp was present in 34.5% of heavy alcohol drinkers and 5.1% of non-alcoholics (p < 0.005). Enterobacteria predominated among heavy alcohol drinkers (25%) compared with non-alcoholics (5.5%) only in the age group 14 to 34 years (p < 0.05). CONCLUSION: Based upon these results, it was possible to conclude that the knowledge of the oropharynx microbiota among heavy drinkers and non-alcoholics has an important predictive value concerning probable etiologic agents of lower airway infections. Infections caused by anaerobic microorganisms and fungi should be taken into consideration during the choice of empirical therapy for heavy alcohol drinkers.

Aspergillosis of the central nervous system.

The authors report an unusual case involving a 38 year-old man who developed a intracranial abscess caused by Aspergillus of the parietal lobe. Cerebral aspergilloma of an initial pulmonary origin developed in a patient with "Fungus Ball" secondary to tuberculosis sequelae. The diagnosis was made through the isolation of Aspergillus from the secretion of the brain abscesses. The patient was treated with drainage of the abscesses and Amphotericin B. He presented a progressive regression of the radiological images (brain and pulmonary) over a period of 55 days. This report emphasizes the importance of combined anti-fungal therapy and surgical resection as a treatment for cerebral aspergilloma. Furthermore, an early initiation of therapy should improve the prognosis in such cases.

[Bacteremia induced by labor. Is prophylaxis for infective endocarditis necessary?]. / Bacteremia induzida pelo trabalho de parto. Cabe a profilaxia da endocardite infecciosa?

PURPOSE: To characterize the occurrence of bacteremia during delivery and to verify the necessity of prophylaxis against infective endocarditis. METHODS: The authors collected hemoculture of 100 women, 15,30 and 45 minutes after delivery. The data were collected from May 1992 until May 1993. The positive hemocultures were followed by antibiogram. RESULTS: Seven hemocultures were positive: six for Staphylococcus, one for Candida sp, Penicilium sp, Clandosporum sp and Aspergillus sp that were found in association. Four patients had prematures amniorrhexis, longer than 6 hours before delivery (p < 0.05). Six patients had labor longer than 6 hours after admission (p < 0.05). The authors did not observe differences related to vaginal delivery with or without forceps or cesarean section. The samples were all sensible to cefalotin at the antibiogram. CONCLUSION: Labor and delivery is a high risk procedure for bacteremia and so for ineffective endocarditis in susceptible patients. The statistical analysis recognize as risk factors labor longer than 6 hours inside the hospital and premature amniorrhexis. We propose the use of intravenous cefalotin 1g 60 minutes before expulsion and repeated 6 and 12 hours later.

[Study of the susceptibility of Staphylococcus sp. and Enterococcus sp. to teicoplanin and vancomycin]. / Estudo da sensibilidade de Staphylococcus sp. e Enterococcus sp. à teicoplanina e à vancomicina.

PURPOSE: The study was performed in order to evaluate the susceptibility of Enterococcus and Staphylococcus to teicoplanin and vancomycin. METHODS: 150 Enterococcus strains and 450 Staphylococcus strains (298 Staphylococcus aureus and 152 negative coagulase strains) isolated in three Brazilian hospitals were studied. The MICs were determined using teicoplanin and vancomycin E Test strips. The range of the antimicrobial concentration in each strip went from 256 mcg/mL to 0.016 mcg/mL. Diffusion tests using disks impregnated with 10 mcg of teicoplanin and 30 mcg of vancomycin were also performed. RESULTS: All the 298 Staphylococcus aureus strains were susceptible to the two antimicrobials. Three of the 152 negative coagulase strains presented intermediate susceptibility to teicoplanin (MICs between 8 and 16 mcg/mL). Four of the 150 Enterococcus strains presented intermediate susceptibility to vancomycin but were totally susceptible to teicoplanin. CONCLUSION: According to these results teicoplanin and vancomycin are good therapeutical options in the treatment of staphylococcal and enterococcal infections.

[The skin flora: a source of the contamination of central venous catheters?]. / Flora cutânea: fonte de contaminação de cateteres venosos centrais?

The authors studied the incidence of catheter related infection in 24 central venous catheter at the Departamento de Cirurgia da Faculdade de Ciências Médicas da Santa Casa de São Paulo. Skin and blood cultures were done in the first and fifth days and when the catheter were discharged. There were correlation between skin and catheter cultures in 33%. The results suggest that the skin flora is an important source of catheter related infection.

Microbiological study of disposable soft contact lenses after photorefractive keratectomy.

PURPOSE: To evaluate the bacterial contamination of bandage disposable soft contact lenses used in patients following photorefractive keratectomy (PRK) and to correlate our findings with clinical data. METHODS: Forty-six patients (81 eyes) underwent PRK. Immediately after each procedure, disposable soft contact lenses were positioned with sterile forceps. After 3 days, the lenses were removed in a sterile manner, placed in sterile Eppendorf pipettes containing 8 mL of enriched brain heart infusion broth, and analyzed for microbial contamination. RESULTS: Seven positive cultures were found: six gram positive cocci (7.4%) and one gram negative bacillus (1.2%). There was no clinical correlation with these findings. CONCLUSION: Isolated microorganisms were similar to those described in the literature as agents of bacterial keratitis and are components of the normal ocular flora. Klebsiela pneumoniae--considered an occasional or transient flora--was the exception. All isolated microorganisms but K. pneumoniae were sensitive to most of the antibiotics tested. Our findings suggest that the risk of infectious keratitis after PRK related to soft contact lens wear for 3 days seems to be low, which may be because lenses were not manipulated by the patient during the wearing period, and the postoperative antibiotic regimen was strictly followed by patients. However, care should be taken to instruct patients in proper lens care practices to reduce the risk of bacterial keratitis in contact lens wear following PRK.

[Persistence of colonization time in patients infected by Salmonella]. / Estudo da persistência de colonização em pacientes infectados por Salmonella.

Salmonella is an important etiological agent of hospital infection in children, reaching endemic levels in some Brazilian states during the seventies and the eighties. We have prospectively studied twenty five children between four and one hundred eighty days old acutely infected with salmonella non typhi to determine the duration of carrier status and its clinical repercussion. After the diagnosis, the children were submitted monthly to clinical examination, and cultures were collected from skin, oropharynx, urine, stools, genitals, nostrils and auditive conduct. During the follow-up, eighteen (72%) children still had positive culture at four weeks after the diagnosis, ten (40%) at sixteen weeks, four (16%) at twenty weeks, and one (4%) at twenty four weeks. In eleven children, we performed biotype and antibiotic susceptibility study of the bacteria recovered at the diagnosis and during the follow-up. In every child the biotype of the bacteria recovered at the diagnosis and during the follow-up was the same. These data indicate that there is a persistent excretion of salmonella that can last for 24 weeks. Such bacterial elimination may be a dissemination source either to hospital or to home contacts. The use of specific antibiotics was effective for the clinical improvement of the patients during the acute disease, but it didn't avoid the carrier state.

Microbial flora of the normal esophagus.

The endogenous flora of the skin and some mucous membranes are well known, however, we were unable to find descriptions about normal esophageal flora in literature. We believe that knowledge about normal esophageal flora is important for therapeutic implications. We compiled data on 30 patients without infection of the oropharynx or esophagus who were admitted for an endoscopy of the upper digestive tract to determine normal esophageal flora. The samples were collected by injecting 10 ml of 0.9% physiological solution into the esophagus and oropharynx and removing it by suction. Esophageal samples from 30 patients and oropharingeal samples from 10 of these patients were collected. We identified mixed flora being Streptococcus viridans the most frequent microorganism found. Where samples from both the esophagus and oropharynx were collected, three occurrences of this same microorganism were found. We concluded that the isolation frequency of germs in the esophagus by the method used was high and the most frequently found germ was S. viridans. There is therefore a possible correlation between the flora from the oropharynx and the esophagus.

Aztreonam in the treatment of bacterial meningitis.

The monobactam aztreonam was used to treat 22 young patients with meningitis caused by gram-negative bacilli. Haemophilus influenzae was isolated from the CSF of 21 patients and Salmonella heidelberg from the CSF of 1. Dosages ranged from 100 to 200 mg/kg/day in 4 doses at 6-hour intervals. Minimal inhibitory concentrations were determined by the broth dilution method for all isolated strains, and values ranged from 0.05 to 2.0 micrograms/ml. Blood and CSF drug levels were determined by a microbiologic plate diffusion method, and mean values for CSF and blood were 1.4 and 14.9 micrograms/ml, respectively. The outcome was good in 21 patients; 1 patient died. Complications were mild; subdural effusion occurred in 6 cases and was managed clinically; asymptomatic hydrocephalus was seen in 4; seizure during the acute phase occurred in 6 cases; hypoacusis was noted in 2, and motor impairment was detected at the follow-up in 1 case. Aztreonam achieved good blood and CSF penetration and performed well in the treatment of 20 cases of H. influenzae meningitis and in the one case of S. heidelberg meningitis.

Decreased point prevalence of Haemophilus influenzae type b (Hib) oropharyngeal colonization by mass immunization of Brazilian children less than 5 years old with hib polyribosylribitol phosphate polysaccharide-tetanus toxoid conjugate vaccine in combination with diphtheria-tetanus toxoids-pertussis vaccine.

A protective herd effect has been described after susceptible populations of children are vaccinated with conjugate Haemophilus influenzae type b (Hib). Hib carriage was studied in children aged 6-24 months attending day care centers in two cities in southern Brazil (Curitiba and Porto Alegre). In Curitiba, routine immunization with Hib polyribosylribitol phosphate polysaccharide-tetanus toxoid conjugate vaccine (PRP-T) in combination with diphtheria-tetanus toxoids-pertussis vaccine (PRP-T/DTP) has been offered since September 1996; DTP vaccine alone is routinely given in Porto Alegre. Children in Porto Alegre (n=643) were 8 times less likely to have received adequate Hib vaccination and 4 times more likely to be Hib carriers than children in Curitiba (n=647; i.e., point prevalence of oropharyngeal colonization, 4.8% vs. 1.2%). Point prevalence of carriage with non-type b or other nontypeable Hi was similar in children of both cities. There was a vaccination effect on carriage rates in children who received a primary 3-dose series, independent of the booster dose, suggesting that a booster may be unnecessary to induce population protection.

Evaluation of the Antimicrobial Activity of Sparfloxacin, Relative to Other Oral Antibiotics Against 1,125 Bacterial Isolates from 10 Medical Centers in Brazil.

A multicenter study was carried out in order to compare the in vitro activity of sparfloxacin to ciprofloxacin, amoxicillin/clavulanic acid, cephalexin, cefuroxine and azithromycin, against 1,125 microorganisms recently isolated from clinical specimens, most of them representative of respiratory tract infections. Sparfloxacin demonstrated potent action and was more active than the beta-lactam agents and azithromycin against most of the bacterial strains tested. Sparfloxacin was more potent (96% and 95% sensitivity, with MIC(90) of 0.19µg/mL and 0.5µg/mL, respectively)than the other antimicrobial agents tested against the Enterobacteriaceae family (Escherichia coli and Elebsiella pneumoniae). It was found to be equivalent in activity to ciprofloxacin (96% and 91% sensitivity and MIC(90) of 0.25 and 0.75µg/mL, respectively). Sparfloxacin was also found to be very active against the most fastidious microorganisms commonly associated to respiratory tract infections such as the penicillin-susceptible and resistant Streptococcus pneumoniae (MIC(90) 0.5µg/mL and 0.38µg/mL, respectively), ampicillin-susceptible and -resistant Haemophilus influenzae (MIC(90) 0.016µg/mL and 0.38µg/mL, respectively), beta-lactamase producing Moraxella catarrhalis (MIC(90) 0.032µg/mL) and non beta-lactamase producing M.catarrhalis (MIC(90) 0.5µg/mL).

Detection of methicillin resistance in Staphylococcus aureus isolated from pediatric patients: is the cefoxitin disk diffusion test accurate enough?

We evaluated the performance of several methods for the detection of methicillin resistance in Staphylococcus aureus using 101 clinical S. aureus isolates from pediatric patients in a tertiary hospital in Brazil; 50 isolates were mecA-positive and 51 were mecA-negative. The Etest and oxacillin agar screening plates were 100 percent sensitive and specific for mecA presence. Oxacillin and cefoxitin disks gave sensitivities of 96 and 92 percent, respectively, and 98 percent specificity. Alterations of CLSI cefoxitin breakpoints increased sensitivity to 98 percent, without decreasing specificity. Our results highlight the importance of a continuing evaluation of the recommended microbiological methods by different laboratories and in different settings. If necessary, laboratories should use a second test before reporting a strain as susceptible, especially when testing strains isolated from invasive or serious infections. With the new (2007) CLSI breakpoints, the cefoxitin-disk test appears to be a good option for the detection of methicillin resistance in S. aureus.

Aztreonam, atividade in vitro frente a bactérias gram-negativas / Aztreonam in vitro activity front a Gram-negative bacteria

Os autores estudaram a atividade in vitro de Aztreonam frente a 560 cepas de Enterobactérias e 83 cepas de bacilos Gram-negativos näo fundamentadores de glicose, 95,89% das Enterobactérias e 77,11% dos näo fermentadores foram sensíveis a Aztreonam

Estudo da sensibilidade de Staphylococcus sp. e Enterococcus sp. à teicoplanina e à vancomicina / Study of the susceptibility of Staphylococcus sp. and Enterococcus sp. to teicoplanin and vancomycin

Objetivo. Avaliar a sensibilidade de Enterococcus e Staphylococcus à teicoplanina e à vancomicina. Métodos. Foram estudadas 150 cepas de Enterococcus e 450 de Staphylococcus (298 Staphylococcus aureus e 152 de coagulase negativas) isoladas de três hospitais brasileiros. As CIMs foram determinadas utilizando o E Test. A concentraçao de antimicrobiano em cada fita foi de 256mcg/mL a 0,016mcg/mL. Também foi feito o estudo da sensibilidade pelo método de difusao empregando discos impregnados com 10mcg de teicoplanina e 30 mcg de vancomicina, respectivamente. Resultados. Todas as 298 cepas de Staphylococcus aureus foram sensíveis a dois antimicrobianos. Três cepas coagulase negativas apresentaram sensibilidade intermediária à teicoplanina (CIMs entre 8 e 16mcg/mL). Quatro das 150 cepas de Enterococcus apresentaram sensibilidade intermediária à vancomicina, mas foram totalmente sensíveis à teicoplanina. Conclusao. De acordo a estes resultados, teicoplanina e vancomicina sao boas opçoes terapêuticas nas infecçoes provocadas por Enterococcus e Staphylococcus.

Ceftriaxona em meningites na infância: possibilidade de tratamento ambulatorial / Ceftriaxone in miningitis childhood

Devido ao amplo espectro antimicrobiano e seu esquema de dose única diária, a ceftriaxona tem sido largamente usada para o tratamento de infecçöes graves, incluindo meningite bacteriana. Entre os importantes problemas enfrentados por médicos e pacientes em países desenvolvidos, estäo a falta de leitos hospitalares e a alta incidência de hospitalares. Por estas razöes e baseados em nossa experiência prévia com o uso de ceftriaxona, decidimos estudar a possibilidade de um regime terapêutico que permitisse tratamento ambulatorial de pacientes com meningite bacteriana. Vinte crianças com idades variando entre 3 e 75 meses e com diagnóstico de meningite bacteriana causada por N. meningitidis, S. pneumoniae ou H. influenzae, foram tratadas com dose única...