Coagulase-negative Isolates Research Articles

Prevalence of resistance phenotypes in Staphylococcus aureus and coagulase-negative isolates of venous ulcers of primary healthcare patients

In venous ulcers, the presence of Staphylococcus aureus and coagulase-negative staphylococcus resistance phenotypes can aggravate and limit the choices for treatment. Staphylococcus isolated from 69 patients (98 ulcers) between October of 2009 and October of 2010 were tested. The macrolide, lincosamide, streptogramin B (MLS B) group resistance phenotype detection was performed using the D-test. Isolates resistant to cefoxitin and/or oxacillin (disk-diffusion) were subjected to the confirmatory test to detect minimum inhibitory concentration (MIC), using oxacillin strips (E-test®). The prevalence of S. aureus was 83%, and 15% of coagulase-negative staphylococcus (CoNS). In addition were detected 28% of methicillin-resistant Staphylococcus aureus (MRSA) and 47% of methicillin-resistant coagulase-negative staphylococcus (MRCoNS). Among the S. aureus, 69.6% were resistant to erythromycin, 69.6% to clindamycin, 69.6% to gentamicin, and 100% to ciprofloxacin. Considering the MRSA, 74% were highly resistant to oxacillin, MIC ≥ 256µg/mL, and the MLS Bc constitutive resistance predominated in 65.2%. Among the 20 isolates sensitive to clindamycin, 12 presented an inducible MLS B phenotype. Of the MRCoNS, 71.4%were resistant to erythromycin, ciprofloxacin and gentamicin. Considering the isolates positive for β-lactamases, the MIC breakpoint was between 0.5 and 2µg/mL. The results point to a high occurrence of multi-drug resistant bacteria in venous ulcers in primary healthcare patients, thus evidencing the need for preventive measures to avoid outbreaks caused by multi-drug resistant pathogens, and the importance of healthcare professionals being able to identifying colonized versus infected venous ulcers as an essential criteria to implementing systemic antibacterial therapy.

Biotypes and Enterotoxigenicity of Staphylococci Isolated from Camel’s Meat in Jordan

A total of 264 camel’s meat and nasal swab samples were collected for isolation and typing of Staphylococci from Irbid Governorate in northern Jordan. About 97 % and 85% of meat and nasal swabs samples showed typical colonies of Staphylococcus aureus on BairdParker agar respectively. Out of 243 presumptively identified isolates, only 74 and 64 were confirmed as S. aureus by Microbact system and PCR technique respectively. About 67% of the isolates were typable by Devriese’s scheme. Fifteen of those isolates (23%) were specifically allocated to human, bovine, ovine or abattoir where, 14% of these host specific isolates belonged to human biovar. The other 44% belonged to non-host specific biovars with majority of them were allocated to NHS1 biovar. When tested for the presence of toxin genes, 71.9% of S. aureus isolates had SE(s) genes with SEA being the most prominent at 91.3%. The study also showed that not only coagulase positive isolates contain toxin genes, coagulase negative isolates also possess toxin genes and thus are considered potential hazards in camel’s meat.

Clinical characterization of Staphylococcus schleiferi infections and identification of risk factors for acquisition of oxacillin-resistant strains in dogs: 225 cases (2003–2009)

To define clinical differences between coagulase-positive and coagulase-negative Staphylococcus schleiferi infections in dogs and to identify risk factors for the isolation of oxacillin-resistant S schleiferi. Retrospective case series. 225 dogs (yielding 225 S schleiferi isolates). Information obtained from affected dogs' medical records included isolate body site source, antimicrobial treatments, and primary disease. For each dog, the S schleiferi isolate was characterized and antimicrobial susceptibility data were recorded. Risk factors for infection based on coagulase status and for S schleiferi oxacillin resistance were investigated. Allergic dermatitis was the most common underlying disease (111/225 dogs). Ears (102 [45%]) and skin (95 [42%]) were sources of most of the 225 isolates. Isolate coagulase status was not significantly associated with any patient-level factors. Of the 225 isolates, 129 (57%) were oxacillin resistant. Coagulase-negative isolates were more likely to be oxacillin resistant than were coagulase-positive isolates (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.1 to 3.0). Administration of penicillin-based or first-generation cephalosporin drugs (OR, 3.0; 95% CI, 1.8 to 5.9) and third-generation cephalosporins (OR, 3.7; 95% CI, 1.1 to 12.3) within 30 days prior to culture were risk factors for oxacillin resistance. Results suggested that coagulase-negative and coagulase-positive S schleiferi are potential pathogens in dogs and are often oxacillin resistant. Recent patient treatments with penicillin or cephalosporin were risk factors for oxacillin resistance. In clinical cases, full speciation of all Staphylococcus isolates should be performed and microbial treatments should be selected on the basis of results of susceptibility testing.

Genotypic relatedness and phenotypic characterization of Staphylococcus schleiferi subspecies in clinical samples from dogs

To assess the degree of biological similarity (on the basis of genotype determined via pulsed-field gel electrophoresis [PFGE]) between isolates of 2 Staphylococcus schleiferi subspecies (S schleiferi subsp coagulans and S schleiferi subsp schleiferi) in clinical samples obtained from dogs. 161 S schleiferi isolates from 160 canine patients. A commercial microbiology identification system was used to identify each isolate as S schleiferi. Isolates underwent slide and tube coagulase testing and antimicrobial susceptibility testing. A mecA PCR assay and a latex agglutination test for penicillin-binding protein 2a (PBP2a) were also performed on each isolate. Clonal clusters with a similarity cutoff value of 80% were identified via PFGE. Of the 161 isolates, 61 (38%), 79 (49%), and 21 (13%) were obtained from cutaneous sites, ears, and other sites, respectively; 110 (68%) were coagulase negative, and 51 (32%) were coagulase positive. Among the coagulase-negative and coagulase-positive isolates, 65% (71/110) and 39% (20/51) were oxacillin resistant, respectively. All oxacillin-resistant isolates yielded positive results via mecA PCR assay and PBP2a latex agglutination testing. Via PFGE, 15 major clusters and 108 individual pulsed-field profiles were identified. Oxacillin-resistant and oxacillin-susceptible isolates clustered separately. Clonal clusters were heterogeneous and contained representatives of both subspecies. Coagulase-positive and coagulase-negative isolates were not genotypically distinct and may represent a single S schleiferi sp with variable coagulase production, rather than 2 biologically distinct subspecies. Further studies are needed to characterize clinical or epidemiological differences associated with infections with coagulase-positive and coagulase-negative S schleiferi in dogs.

Prevalence and antimicrobial susceptibility of Staphylococci isolated from the vagina of healthy ewes

The aims of this study were identify the species of Staphylococcus sp. from the vagina of healthy ewes and determine their invitro susceptibility to antibiotics. Sterile cotton swabs were used to collect samples from the vagina of 24 ewes. Standardbacteriological procedures were conducted. Coagulase-positive Staphylococcus species (COPS) represented 60% of theisolates and were significantly more resistant to antibiotics than coagulase-negative isolates. Resistance to antibiotics wasfrequently observed, and 66.6% of the isolates showed resistance to at least one tested drug. Ciprofloxacin was the mostactive antimicrobial agent (100%), while Penicillin G was the less effective (40% of resistance). This study confirms thepresence of Staphylococcal isolates in the vagina of ewes, with predominance of CoPS isolates resistant to various antibiotics.This study contributes to a better knowledge about the role of Staphylococcus species in the ewe’s vagina and their antimicrobialsusceptibility, collaborating for a better treatment of the vaginitis determined by these bacteria.

Role of different classes of mammalian cell surface molecules in adherence of coagulase positive and coagulase negative staphylococci

In the present study the role of different mammalian cell receptors in adherence of the coagulase positive pathogen, Staphylococcus aureus and some coagulase negative staphylococci, namely Staphylococcus epidermidis and Staphylococcus saprophyticus was investigated. Upon testing the adherence to Vero and Hep-2 cells, S. aureus isolates showed an adherence to both cell lines while S. epidermidis and S. saprophyticus isolates adhered to Vero cells only. According to the obtained results, both O-linked and N-linked mammalian cell surface glycoproteins are involved in the adherence of S. aureus isolates to Vero and Hep-2 cells, whereas only the O-linked ones serve as receptors for adherence of S. epidermidis and S. saprophyticus isolates to Vero cells. Of the O-linked glycoproteins, GAG-like receptors are involved in adherence of all tested isolates to Vero cells. The coagulase positive staphylococci preferred to adhere to the highly sulphated GAGs (Heparin and chondroitin sulphate B) while the coagulase negative isolates showed higher affinity to the less sulphated ones (Chondroitin sulphate A and C). Mucin like receptors appeared to be important for the adherence of all tested staphylococci. The role exhibited by fibronectin- and fibrinogen-like receptors was detected with S. aureus and S. epidermidis but not with S. saprophyticus isolates. While, collagen and gelatin were found to contribute to the adherence of S. aureus isolates only. Neither carbohydrate moieties of the glycoconjugates nor lipid molecules on the mammalian cell surface played a role in the adherence of the tested staphylococcal isolates. Taken together, the results revealed that both coagulase negative and coagulase positive staphylococcal tested isolates adhere to the same classes of mammalian cell surface receptors such as mucin-like, fibrinogen-like, fibronectin-like and GAG-like receptors. However, the tested isolates exhibited different degrees of affinities to such receptors.

A study of the enterotoxigenicity of coagulase-negative and coagulase-positive staphylococcal isolates from food poisoning outbreaks in Minas Gerais, Brazil

The purpose of this study was to identify enterotoxin genes from isolates of coagulase-negative staphylococci and coagulase-positive staphylococci obtained from dairy products, responsible for 16 outbreaks of food poisoning. From the pool of 152 staphylococcal isolates, 15 coagulase-negative and 15 coagulase-positive representatives were selected for this study. The 15 coagulase-negative isolates were tested for the presence of coa and femA genes, which are known to be characteristic of Staphylococcus aureus. After testing for enterotoxin genes by polymerase chain reaction (PCR), the 30 selected isolates were tested for the presence of toxin by immunoassay. Seven of the coagulase-negative isolates amplified the coa gene and were subsequently reclassified as coagulase-positive. Twenty-one of 30 selected isolates had staphylococcal enterotoxin genes and most of these produced toxin as well. The most frequently encountered enterotoxin genes were sea and seb. Among eight coagulase-negative isolates, five had enterotoxin genes, all of which were found to have detectable toxin by immunoassay. The results from this study demonstrate that coagulase-negative as well as coagulase-positive staphylococci isolated from dairy products are capable of genotypic and phenotypic enterotoxigenicity. Furthermore, these data demonstrate that PCR is a sensitive and specific method for screening outbreak isolates regardless of coagulase expression.

Rhodomyrtone from Rhodomyrtus tomentosa (Aiton) Hassk. as a Natural Antibiotic for Staphylococcal Cutaneous Infections

The ethanol extract of Rhodomyrtus tomentosa (Aiton) Hassk. (R. tomentosa )w as determined for its antibacterial activity on staphylococci isolated from acne lesions. Antibiotic susceptibility patterns of the isolates were performed. Preliminary screening of the antibacterial propert yo f the extrac tu singdisk diffusion method demonstrated pronounced antibacterial activity of the extract on all tested isolates. Th ea verage inhibition zones of 64 coagulase-positive and 85 coagulase-negative isolates were 12 mm and 14 mm, respectively. Minimal inhibitory concentration (MIC) was determined by broth microdilution method. The MIC50 and MIC90 ranged from 64– 512µg/ml. Time-kill curves were assessed at 0.5 MIC, MIC, 2 MIC, and 4 MIC by counting viable bacterial cells after time intervals. At 4 MIC, the level of treated staphylococci declined by at least 3 log fold within 6–8 hr. Rhodomyrtone, a pure compound in acylphloroglucinol class, isolated from this plant species was very effective against Staphylococcus aureus (S. aureus )A TCC25923 with the MIC value at 0.5µg/ml which is very closed to that of vancomycin. This finding challenges the use of rhodomyrtone as an alternative agent for staphylococcal cutaneous infections.

Use of the VITEK 2 system for rapid identification of clinical isolates of Staphylococci from bloodstream infections.

Staphylococci are an increasing cause of bloodstream infections. Rapid reliable identification of these organisms is essential for accurate diagnosis and prompt effective treatment. We evaluated the ability of the VITEK 2 system (bioMérieux, Inc, Hazelwood, Mo.) to identify these organisms rapidly and accurately. A total of 405 clinically relevant nonduplicate staphylococcal isolates (Staphylococcus aureus, n = 130; coagulase-negative staphylococci, n = 275) collected from blood cultures were tested. VITEK 2 results were considered correct when they were identical to those furnished by the comparison method based on the ID 32 STAPH system (bioMérieux, Marcy l'Etoile, France) plus supplementary manual testing. When discrepancies occurred, isolate identity was verified by molecular typing. The VITEK 2 correctly identified 387 (95.6%) isolates at the species level: 379 (including all but one [99.2%] of 130 S. aureus isolates and 249 of 275 [90.5%] coagulase-negative isolates) were identified by the automated reading; for the other eight, supplemental tests suggested by the manufacturer had to be used. Only one strain (0.2%) was misidentified (Staphylococcus hominis as Staphylococcus epidermidis), and four (1%), all S. epidermidis, were not identified. For the remaining 13 strains (including 10 S. hominis), the VITEK 2 system was unable to discriminate among two species, and no supplemental tests were suggested for conclusive identification. Over 90% of results were obtained within 4 h. These results suggest that the VITEK 2 system can provide rapid, accurate, and reliable species-level identification of staphylococci responsible for bloodstream infections, although there is room for improvement in the identification of certain coagulase-negative species, especially S. hominis.

The changing clinical aspects of infective endocarditis: descriptive review of 90 episodes in a French teaching hospital and risk factors for death.

We wanted to describe the epidemiological aspects of infective endocarditis (IE) in a French hospital and identify the prognostic factors. We reviewed the clinical, echocardiographic and microbiological features, and the outcome of 89 patients (90 episodes, median age 60 years) with IE over 18 months. Logistic regression analysis was used to identify prognostic factors for death. A native valve was involved in 68 cases (75.5%); in 7 of these the patient was an intravenous drug user. A prosthetic valve was involved in 22 cases (24.5%); 5 of these were of early onset. Diagnosis was definite in 87% of cases. Median time to diagnosis was 3 days. Twenty-five patients (28%) were immunocompromised. A portal of entry, usually cutaneous, was identified in 65% of cases. Sixty-two percent of patients had an underlying heart disorder, usually degenerative. The infection involved the left heart in more than 75% of cases. One or more vegetations were detected in 75% of cases. The median size of vegetation was 15 mm. Isolated agents were mainly staphylococci (n=40 (44%), including 12 coagulase-negative isolates), and streptococci (n=23 (25%), including 7 enterococci). In 11 cases (12%), cultures remained negative. Nineteen episodes were nosocomial and Staphylococcus aureus was implicated in 11 of them. Fifty percent of patients had at least one complication: heart failure (n=42), kidney failure (n=44), embolism (n=35), septic shock (n=19). Surgery was performed in 49 cases (54%) due to heart failure (n=19), cerebral embolism (n=12), and/or severe valve lesions (n=27). Eighteen patients died, 10 of whom were infected with S. aureus. Nosocomial IE (P=0.0008), heart failure (P=0.004) and prosthetic valve (P=0.01), but not S. aureus were independently associated with death. S. aureus was the main microorganism isolated in our patients. However, it was not independently predictive of fatal outcome.

Antimicrobial resistance of feline staphylococci in south‐eastern England

Staphylococcus aureus is reported as the predominant feline staphylococcal pathogen. There is concern that cats may transfer resistant staphylococci to humans. In this study, staphylococci were obtained from skin and mucosae of 20 domestic cats, 9 with lesions, and 10 healthy feral cats. Species were identified by DNase and API ID32 Staph tests. Of 187 isolates, 21.4% were coagulase-positive and predominately from lesional cats; 90% of these were Staphylococcus intermedius. Coagulase-negative species were isolated equally in all three groups. All isolates were susceptible to coamoxiclav, cephalexin and bacitracin. Twenty-two, including 18 coagulase-negative isolates, showed some resistance to cotrimoxazole, lincomycin, enrofloxacin or oxytetracycline. Two isolates were resistant to more than one antibiotic. More resistant isolates were obtained from feral cats (P < 0.01). The results suggest that S. intermedius is the principal coagulase-positive species. Antibiotic resistance is generally low amongst feline staphylococci. Higher resistance amongst feral cats suggests exposure to environmental antibiotics.

Incidence risk and aetiology of mammary abnormalities in dry ewes in 10 flocks in Southern Greece

In a field investigation of 10 flocks in Southern Greece, 3367 dairy ewes were examined twice, in order to estimate the incidence risk and the aetiology of mammary abnormalities during the dry-period. Abnormal secretion, lumps, nodules, diffuse hardness, abscesses and cysts were the abnormalities detected. The cumulative incidence of mammary abnormalities during the dry-period was 5.1% (95% confidence interval: 4.4–5.8%); 47% of the cases detected developed during the first three weeks after cessation of lactation. Despite variation in the flock size, there was no between-flock variation in the risk of a ewe developing mammary abnormalities. Staphylococci ( Staphylococcus aureus and coagulase-negative isolates) were the most frequently isolated bacteria from mammary samples; Actinomyces pyogenes, Clostridium perfringens, streptococci and Escherichia coli were also isolated. Resistance was encountered among the staphylococcal isolates.

Branched-DNA assay for detection of the mecA gene in oxacillin-resistant and oxacillin-sensitive staphylococci.

The identification of methicillin-resistant staphylococcus isolates in the clinical laboratory has typically been performed by using methods that detect phenotypic expression of resistance determinants. However, these methods may be difficult to interpret and some isolates do not express resistance until selective pressure is administered. Assays that detect genetic determinants are not subject to these limitations and have been effective in distinguishing isolates that are capable of expressing the resistance phenotype. In this study, a novel branched-DNA (bDNA) hybridization assay was used to test for the mecA gene in 416 clinical staphylococcal isolates. The results were compared with those obtained by a PCR-based assay and oxacillin disk diffusion. For 155 Staphylococcus aureus and 261 coagulase-negative Staphylococcus isolates, the bDNA assay and PCR results were 100% concordant. Among the S. aureus isolates, 20 were MecA+ and 135 were MecA-. For the coagulase-negative staphylococci, 150 were MecA+ and 111 were MecA-. The results from the genotypic detection methods were compared with those obtained by oxacillin disk diffusion. No discrepancies were detected among the S. aureus isolates; however, 10 coagulase-negative isolates were MecA+ but oxacillin sensitive and 1 isolate was MecA- but oxacillin resistant. Oxacillin resistance was induced in 6 of the 10 MecA+ isolates previously classified as oxacillin sensitive. These results suggest that the bDNA method described here is a sensitive and efficient method for detection of methicillin resistance in staphylococci and that genetic detection methods may be useful for detection of potential methicillin resistance in the clinical laboratory.

An inexpensive and reliable method for routine identification of staphylococcal species.

The aim of this study was to develop a simple, reliable, and inexpensive in-house system for routine species identification of staphylococci in clinical practice. The system combines 15 key tests (including carbohydrate fermentation) performed in micro-well strips and antimicrobial disk diffusion susceptibility tests performed on standardised paper disk method antibiotic sensitivity medium agar. Twenty-eight staphylococcal reference strains belonging to 18 different species were correctly identified using this in-house system. A total of 291 clinical staphylococci isolates were evaluated with the in-house system and a conventional identification scheme. The in-house system identified 281 (96.6%) of these 291 isolates. Eleven different species were recognised. The five species most frequently identified were Staphylococcus epidermidis (48.6%), Staphylococcus aureus (27.8%), Staphylococcus haemolyticus (8.2%), Staphylococcus hominis (5.7%), and Staphylococcus warneri (5.3%). There was an agreement of 86.3% between the species identification obtained with the in-house system and the conventional identification scheme. All coagulase-negative isolates initially identified as species other than Staphylococcus epidermidis as well as indistinctly identified isolates were also evaluated with a commercial identification system. The agreement between species identification obtained with the in-house system and the commercial system for 101 identified isolates was 73%. Several isolates that were difficult to distinguish with the conventional scheme and/or the commercial system were identified with the aid of the antimicrobial susceptibility test included in the in-house system. The described test scheme should be of value for identification of clinically significant staphylococci species.

Methicillin-resistant coagulase-negative staphylococcal osteomyelitis and its relationship to broad-spectrum oral antibiosis in a predominantly diabetic population

Awareness of the virulence of coagulase-negative Staphylococci, previously regarded as saprophytes with minimal pathogenicity, has steadily increased. Eighty-seven individual patients diagnosed with acute osteomyelitis, as confirmed by microbiologic and pathologic analysis, were included in this study. Of these patients, 82% (71/87) were known to have diabetes mellitus. The prevalence of coagulase negative Staphylococcus was 40% (35/87) in deep bone cultures, 63% (22/35) of which were methicillin resistant. When the coagulase negative Staphylococcus group was assessed for prior long-term (> 2 week) oral antibiotic treatment with ciprofloxacin, it was found that 54% (12/22) of the methicillin-resistant coagulase-negative Staphylococcal infected patients had received such treatment, compared with 15% (2/13) of patients with methicillin-sensitive coagulase-negative Staphylococcal osteomyelitis (p < 0.034). When the group was analyzed for prior long-term antibiotic treatment with amoxicillin/clavulanate, 23% (5/22) of the methicillin-resistant patients had received oral amoxicillin/clavulanate, compared with 23% (3/13) of patients with methicillin-sensitive coagulase-negative Staphylococcal osteomyelitis (p > 0.05). Prevalence of polymicrobial infections, which constituted 29% (25/87) of all individual patients, was also analyzed. Of those patients with coagulase-negative isolates, 29% (10/35) were polymicrobial (p > 0.05). The results from this study suggest that infections of bone caused by coagulase-negative Staphylococci are associated with a high prevalence of methicillin resistance. This study also raises the question of whether injudicious prolonged use of ciprofloxacin may, in fact, promote proliferation of resistant organism strains.

Use of gas-liquid chromatography for subgrouping coagulase-negative staphylococci during a nosocomial sepsis outbreak.

Gas-liquid chromatographic (GLC) fatty acid profile correlation analysis was applied for the subgrouping of 169 coagulase-negative staphylococci collected during an outbreak of nosocomial sepsis in a hematologic unit. The fatty acid profile similarity index between six ciprofloxacin-resistant Staphylococcus epidermidis septicemia strains was as high as 98.39 +/- 0.68, indicating a high degree of resemblance. This finding corroborated the finding by conventional typing methods that the isolates shared the same strain characteristics and, therefore, could be derived from the same epidemiological origin. Further, the GLC fatty acid profiles were analyzed for coagulase-negative staphylococcal cutaneous isolates recovered from colonization cultures of the patients and personnel in that same unit. The similarity index between 88 ciprofloxacin-resistant Staphylococcus epidermidis skin isolates with similar plasmid profiles was as high as 95.47 +/- 3.78, whereas the correlation coefficient between 45 ciprofloxacin-susceptible Staphylococcus epidermidis skin isolates with different plasmid profiles was only 85.23 +/- 10.82. Cluster analysis grouped the ciprofloxacin-resistant Staphylococcus epidermidis isolates into one distinct cluster, while most of the ciprofloxacin-susceptible Staphylococcus epidermidis isolates were grouped into two separate clusters. When compared with the plasmid profiling, the GLC method congruously grouped 127 (87%) of the 146 Staphylococcus epidermidis isolates, thereby suggesting its potential value in subgrouping coagulase-negative staphylococci during nosocomial outbreaks.

Coagulase deficiency in clinical isolates of Staphylococcus aureus involves both transcriptional and post-transcriptional defects

The molecular basis of the non-expression of coagulase was investigated for 14 coagulase-negative isolates of Staphylococcus aureus obtained from different clinical samples. These isolates had typical S. aureus characteristics such as production of clumping factor, DNAase and protein A, but, with one exception, failed to produce detectable amounts of alpha-haemolysin. All 14 strains had DNA homologous to the coagulase gene (coa), but a coa-specific transcript was found in only seven of them. alpha-Haemolysin mRNA was detected in only eight strains without direct correlation to coa-mRNA expression. Thus, coagulase and alpha-haemolysin deficiencies in S. aureus may involve either transcriptional or post-transcriptional alterations although additional regulatory factors may influence the expression of both genes.

Antimicrobial activity of MDL 62,873, a semisynthetic derivative of teicoplanin, in vitro and in experimental infections.

MDL 62,873 is an amide derivative of teicoplanin A2-2. Like those of natural glycopeptides, its antibacterial activity is mediated by inhibition of cell wall peptidoglycan synthesis. Against streptococci and enterococci, the in vitro activity of MDL 62,873 was similar to that of teicoplanin and greater than that of vancomycin. Against staphylococci, it has activity similar to that of vancomycin, and it was significantly more active than teicoplanin against coagulase-negative isolates. Like teicoplanin and vancomycin, MDL 62,873 had slow but significant bactericidal activity (99 to 99.9% killing in 24 h) against staphylococci at concentrations near the MIC. In murine septicemia studies with Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae, the 50% effective doses were lower than those of vancomycin. In staphylococcal endocarditis in rats, MDL 62,873 at 20 mg/kg of body weight and vancomycin at 40 mg/kg, both doses given intravenously twice daily, had similar efficacies in reducing the heart bacterial load. These results probably reflect the longer half-life of MDL 62,873, which has a pharmacokinetic profile in rats similar to that of teicoplanin.

Reactivity of coagulase-negative staphylococci isolated from cow and goat milk with monoclonal antibodies to Staphylococcus aureus capsular polysaccharide types 5 and 8

Monoclonal antibodies to Staphylococcus aureus capsular polysaccharide types 5 and 8 were used in an enzyme-linked immunosorbent assay to serotype 74 and 42 coagulase-negative isolates from cow and goat milk, respectively. Eighteen (15.5%) isolates were typable: 13 Staphylococcus haemolyticus, 1 S. hyicus, 1 S. simulans, and 1 S. warneri from bovine origin and 2 S. lentus from caprine origin. Type 5 was predominant, accounting for about 89% of typable isolates. Reactivity with monoclonal antibodies varied considerably according to isolates. The significance and the potential importance of these findings are discussed.

In-vitro activity of PD 117 596, a new quinolone, against bacterial isolates from cancer patients

The in-vitro activity of PD117 596, a new 4-quinolone antimicrobial agent was compared with that of ciprofloxacin against 798 Gram-positive and Gram-negative distinct isolates from cancer patients. PD117 596 was found to have a broad antimicrobial spectrum with excellent activity against the Enterobacteriaceae (MIC90 0.03 mg/l) Acinetobacter spp. (MIC90 0.25 mg/l), Aeromonas spp. (MIC100 0.06 mg/l) and Pseudomonas spp. including Ps. aeruginosa (MIC90 0.5 mg/l). It was also extremely active against Gram-positive micro-organisms particularly Staphylococcus spp. (including methicillin-resistant and coagulase-negative isolates) Bacillus spp. and streptococci. PD117 596 had lower minimal inhibitory concentrations against most isolates tested than ciprofloxacin, the most active currently available 4-quinolone.