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.

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.

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.

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.

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.

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.

[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.

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.