Identification and antimicrobial susceptibility of Staphylococcus from home-treated peritoneal dialysis patients

Staphylococcus aureus is the main agent of infections during peritoneal dialysis (PD). The presence of S. aureus in the nasal cavity has been extensively studied and suggested as a risk factor of dialysis-related infections, whereas coagulase-negative Staphylococcus (CNS) species are frequently considered part of the normal human microbiota. The aim of this study was to identify Staphylococcus in the nasal cavity, pericatheter skin and peritoneal effluent from PD patients, as well as to evaluate the antimicrobial activity evolution in vitro. Thirty-two chronic PD patients were observed during 12 months and had nasal and pericatheter skin samples collected for culture. When peritonitis was detected, samples were also collected from the peritoneal effluent for culture. The activity of several antimicrobial drugs (penicillin G, oxacillin, cephalothin, ofloxacin, netilmicin and vancomycin) against different Staphylococcus species was measured by using the agar drug diffusion assay (Kirby-Bauer method). Staphylococcus was separated into S. aureus, S. epidermidis and other CNS species in order to determine the in vitro resistance level. S. epidermidis resistance to oxacillin progressively increased during the study period (p < 0.05). Resistance to ofloxacin was inexpressive, whereas resistance to netilmicin and vancomycin was not detected. Of the oxacillin-resistant species (n = 74), 83 percent were S. epidermidis, 13 percent other CNS and 4 percent S. aureus (p < 0.05). Regarding multi-drug resistant strains (n = 45), 82 percent were S. epidermidis, 13 percent other CNS, and 5 percent S. aureus (p < 0.05). This study shows the relevance of resistance to oxacillin and CNS multi-drug resistance, particularly concerning S. epidermidis, in PD patients.

Risk of peritonitis during peritoneal dialysis in carriers of Staphylococcus aureus and coagulase-negative staphylococci

The presence of Staphylococcus aureus in the nasal cavities and pericatheter skin of peritoneal dialysis patients put them at high risk of developing peritonitis. However, it is not clear whether the presence of coagulase-negative staphylococci (CNS) in the nasal passages and skin of patients is related to subsequent occurrence of peritoneal infection. The aim of the present study was to verify the relationship between endogenous sources of S. aureus and CNS and occurrence of peritonitis in patients undergoing peritoneal dialysis. Thirty-two patients on peritoneal hemodialysis were observed for 18 months. Staphylococcus species present in their nasal passage, pericatheter skin and peritoneal effluent were identified and compared based on drug susceptibility tests and dendrograms, which were drawn to better visualize the similarity among strains from extraperitoneal sites as well as their involvement in the causes of infection. Out of 288 Staphylococcus strains isolated, 155 (53.8 percent) were detected in the nasal cavity, 122 (42.4 percent) on the skin, and 11 (3.8 percent) in the peritoneal effluent of patients who developed peritonitis during the study. The most frequent Staphylococcus species were CNS (78.1 percent), compared with S. aureus (21.9 percent). Among CNS, S. epidermidis was predominant (64.4 percent), followed by S. warneri (15.1 percent), S. haemolyticus (10.7 percent), and other species (9.8 percent). Seven (64 percent) out of 11 cases of peritonitis analyzed presented similar strains. The same strain was isolated from different sites in two (66 percent) out of three S. aureus infection cases. In the six cases of S. epidermidis peritonitis, the species that caused infection was also found in the normal flora. From these, two cases (33 percent) presented highly similar strains and in three cases (50 percent), it was difficult to group strains as to similarity. Patients colonized with multidrug-resistant S. epidermidis...

Predictive factors of outcome following staphylococcal peritonitis in continuous ambulatory peritoneal dialysis.

BACKGROUND AND AIMS: Staphylococcus epidermidis and other coagulase-negative staphylococci (CoNS) are the most common agents of continuous ambulatory peritoneal dialysis (CAPD) peritonitis. Episodes caused by Staphylococcus aureus evolve with a high method failure rate while CoNS peritonitis is generally benign. The purpose of this study was to compare episodes of peritonitis caused by CoNS species and S. aureus to evaluate the microbiological and host factors that affect outcome. MATERIAL AND METHODS: Microbiological and clinical data were retrospectively studied from 86 new episodes of peritonitis caused by staphylococci species between January 1996 and December 2000 in a university dialysis center. The influence of microbiological and host factors (age, sex, diabetes, use of vancomycin, exchange system and treatment time on CAPD) was analyzed by logistic regression model. The clinical outcome was classified into two results (resolution and non-resolution). RESULTS: The odds of peritonitis resolution were not influenced by host factors. Oxacillin susceptibility was present in 30 of 35 S. aureus lineages and 22 of 51 CoNS (p = 0.001). There were 32 of 52 (61.5%) episodes caused by oxacillin-susceptible and 20 of 34 (58.8%) by oxacillin-resistant lineages resolved (p = 0.9713). Of the 35 cases caused by S. aureus, 17 (48.6%) resolved and among 51 CoNS episodes 40 (78.4%) resolved. Resolution odds were 7.1 times higher for S. epidermidis than S. aureus (p = 0.0278), while other CoNS had 7.6 times higher odds resolution than S. epidermidis cases (p = 0.052). Episodes caused by S. haemolyticus had similar resolution odds to S. epidermidis (p = 0.859). CONCLUSIONS: S. aureus etiology is an independent factor associated with peritonitis non-resolution in CAPD, while S. epidermidis and S. haemolyticus have a lower resolution rate than other CoNS. Possibly the aggressive nature of these agents, particularly S. aureus, can be explained by their recognized pathogenic factors, more than antibiotic resistance.

Prevalence and in vitro antifungal susceptibility of Candida spp isolated from clinical specimens in São Paulo, Brazil.

We examined the prevalence and the in vitro susceptibility to antifungal drugs of Candida spp isolated from clinical specimens at our university hospital in São Paulo, Brazil. Among 6,417 samples studied, positive cultures, were obtained from 222 (3.5%) most of them (68%) from the pediatric unit and nursery. Candida albicans and Candida parapsilosis were the most frequent species and the susceptibility patterns of a panel of 130 isolates to amphotericin B, ketoconazole and fluconazole, showed that the order of antifungal efficacy was amphotericin B > ketoconazole > fluconazole.

Evaluation of the in vitro activity of cefepime compared to other broad-spectrum cephalosporins against clinical isolates from eighteen Brazilian hospitals by using the Etest.

The in vitro activity of cefepime was compared to that of ceftazidime, ceftriaxone, and cefotaxime in a multicenter study involving 10 clinical microbiology laboratories and clinical isolates from 18 Brazilian hospitals from 7 cities (4 states). A total of 982 isolates consecutively collected between December 1995 and March 1996 were susceptibility tested by using Etest and following the NCCLS procedures for agar diffusion tests. The cefepime spectrum was broader than that of the other broad-spectrum cephalosporins against both Gram-negative rods and Gram-positive cocci. Cefepime was particularly more active against Enterobacter sp. (MIC90, 2 micrograms/ml), Serratia sp. (MIC90, 2 micrograms/ml) and oxacillin-susceptible Staphylococcus aureus (MIC90, 3 micrograms/ml). Against Pseudomonas aeruginosa, cefepime (MIC90, 16 micrograms/ml) was slightly more active than ceftazidime (MIC90, 32 micrograms/ml) and 8- to 16-fold more active than ceftriaxone of cefotaxime (MIC90, > 256 micrograms/ml). Our results show that nosocomial bacteria, especially Gram-negative rods, have a high rate of cephalosporin resistance in Brazil. However, part of these resistant bacteria remains susceptible to cefepime. The Etest was shown to be an excellent method for multicenter studies of the in vitro evaluation of new antimicrobial agents.

The diagnostic value of Gram stain for initial identification of the etiologic agent of peritonitis in CAPD patients.

OBJECTIVE: To evaluate the effectiveness of the Gram stain in the initial diagnosis of the etiologic agent of peritonitis in continuous ambulatory peritoneal dialysis (CAPD). DESIGN: Retrospective study analyzing the sensitivity (S), specificity (SS), positive predictive value (+PV), and negative predictive value (-PV) of the Gram stain relating to the results of cultures in 149 episodes of peritonitis in CAPD. The data were analyzed in two studies. In the first, only the cases with detection of a single agent by Gram stain were taken (Study 1). In the second, only the cases with two agents in Gram stain were evaluated (Study 2). SETTING: Dialysis Unit and Laboratory of Microbiology of a tertiary medical center. PATIENTS: Sixty-three patients on regular CAPD who presented one or more episodes of peritonitis from May 1992 to May 1995. RESULTS: The positivity of Gram stain was 93.2% and the sensitivity was 95.7%. The values of S, SS, +PV, and -PV were respectively: 94.9%, 53.5%, 68.3%, and 90.9% for gram-positive cocci and 83.3%, 98.8%, 95.2%, and 95.6% for gram-negative bacilli. The association of gram-positive cocci plus gram-negative bacilli were predictive of growth of both in 6.8%, growth of gram-positive cocci in 13.7%, and growth of gram-negative bacilli in 72.5%. CONCLUSIONS: The Gram stain is a method of great value in the initial diagnosis of the etiologic agent of peritonitis in CAPD, especially for gram-negative bacilli.

Lomefloxacin activity against 2,813 clinical isolates: a collaborative study at three medical centers in Brazil.

The in vitro activity of lomefloxacin was compared to norfloxacin and two parenteral drugs against 2,813 clinical isolates at three medical centers in Brazil. Considering MICs less than or equal to 4 micrograms/ml as the criterion, lomefloxacin inhibited 97.9% of all enterobacteriaceae, 100% of staphylococci, 100% of Neisseria gonorrhoeae, 100% of Campylobacter pylori, 81% of Pseudomonas aeruginosa, and 79% of Streptococcus spp. Norfloxacin was generally comparable in potency and spectrum, but cefotaxime and gentamicin were less effective because of high-resistance prevalence in some species. The highest rates of fluoro-quinolone resistance among the Enterobacteriaceae were in the Proteus-Providencia group of species.

Uso de associacao enzimatica e ampicilina no tratamento de infeccao urinaria da mulher. / Use of an enzymatic association with ampicillin in the treatment of women urinary infection

Estudamos 20 pacientes do sexo feminino com episodio agudo de infeccao urinaria, caracterizada clinica e laboratorialmente antes de iniciada a terapeutica com a associacao do complexo alfquimotripsina-tripsina, lisozima e ampicilina. Houve 14 pacientes curados (70%) e seis com infeccao recorrente (30%), todas estas referindo antecedentes de infeccao previa do trato urinario. Efeitos colaterais registrados em seis casos nao impediram a execucao do esquema de tratamento planejado