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PubMedDate not supplied

Occurrence of resistance to antibiotics, metals, and plasmids in clinical strains of Staphylococcus spp.

BACKGROUND: Presence of staphylococci resistant to antibiotics is of concern, as is the possible spread of resistance determinants among Staphylococcus species. During the past several years, a series of staphylococcal isolates that demonstrated reduced susceptibility to vancomycin or other glycopeptides has been reported. However, there are no useful data on species sensitivity of coagulase-negative staphylococci to heavy metals. METHODS: A total of 22 Staphylococcus spp. isolates recovered from clinical sources was studied for antibiotic and heavy metal resistance patterns and plasmid profiles. Isolated strains were biochemically identified by conventional tests followed by use of API Staph system. Isolates were tested for antimicrobial susceptibility by standard methods. Resistance patterns to nickel chloride (NiCl(2)), zinc sulfate (ZnSO(4)), lead acetate Pb(CH(3)COO)(2), cobalt chloride (CoCl(2)), copper sulfate (CuSO(4)), potassium chromate (K(2)Cr(2)O(7)), silver nitrate (AgNO(3)), and mercuric chloride (HgCl(2)) were surveyed by agar-dilution method. Plasmid DNA was prepared according to a previously described modification of alkaline lysis procedure. RESULTS: In this study, isolated strains included eight (36.4%) Staphylococcus xylosus, five (22.7%) Staphylococcus aureus, four (18.2%) nonidentifiable Staphylococcus spp., one (4.5%) Staphylococcus capitis, one (4.5%) Staphylococcus lentus, one (4.5%) Staphylococcus epidermidis, one (4.5%) Staphylococcus sciuri, and one (4.5%) Staphylococcus chromogenes. All strains showed widest resistance profile to both antibiotics and metals. Methicillin resistance of Staphylococcus aureus (MRSA) was 40%. Resistance to oxacillin was 53% in coagulase-negative staphylococci (CNS) strains. No isolate was resistant to vancomycin. All isolates were resistant to K(2)Cr(2)O(7) and Pb(CH(3)COO)(2); on the other hand, all isolates were sensitive to AgNO(3). Highest incidence of metal-antibiotic multiple resistance existed between K(2)Cr(2)O(7), Pb(CH(3)COO)(2), and penicillin-G. Plasmid content and profile studies showed that isolates carried plasmids ranging from 2.224 to 20.650 kb in size. CONCLUSIONS: Fifty percent of studied strains harbored plasmids and association between occurence of plasmids and resistance to antibiotics and heavy metals was observed.

Anti-Bacterial Agents↗

PubMed2003

Staphylococcus nepalensis sp. nov., isolated from goats of the Himalayan region.

Four coagulase-negative, novobiocin-resistant cocci, designated CW1(T), PM34, MM3 and RW78, were isolated from the respiratory tract of goats kept in the Himalayan region. The four isolates were assigned to a single species on the basis of almost identical biochemical and physiological traits, protein profiles obtained after SDS-PAGE and identical genomic fingerprints generated after enterobacterial repetitive intergenic consensus (ERIC)-PCR. Strain CW1(T) showed highest 16S rDNA sequence similarities to Staphylococcus cohnii subsp. urealyticus ATCC 49330(T), Staphylococcus saprophyticus subsp. saprophyticus ATCC 15305(T), S. cohnii subsp. cohnii ATCC 29974(T), Staphylococcus arlettae ATCC 43957(T), Staphylococcus gallinarum ATCC 35539(T), Staphylococcus succinus ATCC 700337(T) and Staphylococcus xylosus ATCC 29971(T) (99.0, 98.8, 98.8, 98.4, 98.2, 98.1 and 98.1 %, respectively), indicating its classification within the genus Staphylococcus. The polar lipid composition, fatty acid profiles, quinone systems and diagnostic cell-wall diamino acid were in agreement with the characteristics of the genus Staphylococcus. DNA-DNA hybridization with closely related Staphylococcus species suggested that strain CW1(T) represents an as-yet unrecognized species. Based on these results, a novel species of the genus Staphylococcus is described, Staphylococcus nepalensis sp. nov. The type strain is CW1(T) (=DSM 15150(T)=CCM 7045(T)) and the most dissimilar strain is PM34 (=DSM 15151=CCM 7046).

Altitude↗

PubMed1991

Susceptibility of Staphylococcus species and subspecies to teicoplanin.

Twenty-four Staphylococcus species and their subspecies were examined for their susceptibilities to teicoplanin by disk diffusion (30-micrograms disk) and agar dilution for the determination of MICs. Moderately susceptible and resistant clinical strains were further tested for their susceptibilities to oxacillin and vancomycin. Teicoplanin resistance was not observed in the reference strains of the various Staphylococcus species isolated from healthy volunteers or animals. However, the novobiocin-resistant species Staphylococcus saprophyticus, Staphylococcus cohnii, Staphylococcus xylosus, Staphylococcus arlettae, Staphylococcus kloosii, and Staphylococcus gallinarum were less susceptible to teicoplanin (MIC, 2 to 8 micrograms/ml) than most of the novobiocin-susceptible species were (MIC, 0.5 to 4 micrograms/ml). Clinical isolates of coagulase-negative species were generally less susceptible to teicoplanin than were reference strains. Seven percent of the Staphylococcus epidermidis clinical strains were moderately susceptible (MIC, 16 micrograms/ml) to teicoplanin. Of these strains, 70% were oxacillin resistant. For Staphylococcus haemolyticus strains, 11% were resistant (MIC, greater than 16 micrograms/ml) and 21% were moderately susceptible to teicoplanin. Of these strains, 95% were oxacillin resistant, No strains of S. epidermidis or S. haemolyticus were intermediate or resistant to vancomycin. Teicoplanin appears to be less active in vitro against oxacillin-resistant S. haemolyticus. However, teicoplanin is an effective antimicrobial agent against many Staphylococcus species.

Animals↗

PubMed2003

Staphylococcus aureus colonization in a community sample of HIV-infected and HIV-uninfected drug users.

HIV-infected individuals, especially those with a history of injecting drug use, are at high risk of Staphylococcus aureus infection. Moreover, the use of antimicrobial agents for opportunistic infections may increase nasal colonization by antimicrobial-resistant Staphylococcus aureus in this population and, subsequently, levels of infection with multidrug-resistant Staphylococcus aureus in the community. Between February 1999 and March 2000, 500 subjects from a community-based cohort of drug users completed an interview and underwent a physical exam. Risk factors for colonization by Staphylococcus aureus were examined, the antibiotic susceptibility profiles of all strains were determined, and DNA strain analysis was performed. One hundred twenty (24%) subjects had positive Staphylococcus aureus nasal cultures. Only HIV infection and homelessness were associated with Staphylococcus aureus colonization. Ten (8%) isolates were methicillin-resistant Staphylococcus aureus. Methicillin-resistant Staphylococcus aureus isolates were found more frequently among HIV-infected than HIV-uninfected respondents (14% vs. 3%, P=0.04). Among those colonized and HIV infected, the mean number of resistant isolates was higher for those currently reporting antibiotic use (5.0 vs. 2.3, P<0.001) and for those with CD4+ counts <or =200/ microl (3.8 vs. 2.3, P=0.02). The increased use of antimicrobial agents in HIV-infected individuals colonized with Staphylococcus aureus may be an underlying mechanism that contributes to the presence of multidrug-resistant Staphylococcus aureus in the community.

AIDS-Related Opportunistic Infections↗

PubMed2005

Methicillin-resistant Staphylococcus species in a cardiac surgical intensive care unit: a 5-year experience.

OBJECTIVES: Methicillin-resistant Staphylococcus is a growing problem in intensive care units (ICUs). The aim of this study was to describe the epidemiology of methicillin-resistant Staphylococcus isolates in a cardiac surgical ICU over a 5-year period and to determine the risk factors and outcome of this condition. METHODS: During the period from January 1998 to July 2003, the clinical data of all adult patients who underwent cardiac surgery in a university hospital were prospectively recorded in a database; the perioperative clinical variables and microbiologic data were studied by means of univariate and multivariate analysis in order to identify risk factors for the development of methicillin resistance and in-hospital death. RESULTS: Methicillin-resistant Staphylococcus species strains were isolated in 118 of 6,423 patients operated on during the study period (7.6 cases per 1,000 days of ICU stay), with a constant prevalence rate throughout the years. Methicillin-resistant Staphylococcus species have been the most frequently isolated microorganisms in the authors' ICU; 75% of Staphylococcus aureus and 95% of coagulase-negative staphylococci were methicillin resistant. In-hospital mortality in methicillin-resistant Staphylococcus-positive patients was 50.0% (59/118), whereas it was 1.7% (108/6305) in other patients (p < 0.0001). On multivariate analysis, methicillin-resistant Staphylococcus species isolation was the single risk factor with the strongest association with in-hospital death (odds ratio, 8.5; 95% confidence interval 4.9-14.7). In the present series, there were no isolates of vancomycin-resistant species (Enterococcus species or Staphylococcus species). CONCLUSIONS: Staphylococcus species represent the most frequently isolated microorganisms in the authors' ICU. In-hospital mortality in cardiac surgical patients is strongly correlated to the isolation of methicillin-resistant Staphylococcus.

Adult↗

PubMed1999

Biochemical and molecular characterization of erthromycin-resistant avian Staphylococcus spp. isolated from chickens.

The epidemiology of the two common erythromycin-resistant methylase (erm) genes ermC and ermA was analyzed in 12 coagulase-negative Staphylococcus spp. and 34 coagulase-positive Staphylococcus spp. isolated from chicken. Southern hybridization indicated that only 2 of the 12 coagulase-negative Staphylococcus spp. strains contained the ermC gene on the plasmid; 1 strain of Staphylococcus xylosus harbored the ermC gene on a 2.5-kb plasmid, and 1 strain of Staphylococcus cohnii harbored the gene on a 4.0-kb plasmid. Twelve of the 34 strains of Staphylococcus aureus contained the ermC gene. Eleven of these strains had the ermC gene on a 2.5-kb plasmid, and 1 strain had the gene on a 4.0-kb plasmid. Ten of the 12 coagulase-negative Staphylococcus spp. and 22 of the 34 coagulase-positive Staphylococcus spp. harbored the ermA gene exclusively on the chromosome. Two different ermA EcoRI restriction fragment length polymorphisms (RFLP) were identified. A majority of the isolates was found to have two chromosomal inserts (8.0- and 6.2-kb EcoRI fragments) of ermA. One strain of S. aureus had different chromosomal inserts (6.4- and 5.8-kb EcoRI fragments) of ermA. Our results indicate that either the ermC or ermA gene, homologous to those described in human isolates, was present in all avian Staphylococcus spp. and that ermA was the predominant gene in coagulase-negative and coagulase-positive avian Staphylococcus spp. The size and copy numbers of the ermA gene were different from its human counterpart.

Amino Acid Sequence↗

PubMedDate not supplied

Prospective randomized study determining whether a 3-day application of ofloxacin results in the selection of fluoroquinolone-resistant coagulase-negative Staphylococcus.

PURPOSE: To determine whether a 3-day application of ofloxacin results in the selection of fluoroquinolone-resistant conjunctival coagulase-negative Staphylococcus. DESIGN: Prospective randomized trial. METHODS: Patients scheduled for ocular surgery were randomized to a control (89 eyes) or study group (70 eyes). The study group received topical ofloxacin (0.3%) four times a day for 3 days. Conjunctival cultures were obtained at baseline (T0) and after 3 days of ofloxacin (T1). Cultures were also obtained at T0 and T1 for the control group, but these eyes did not receive an antibiotic. Bacteria isolated were identified and antibiotic susceptibility was determined. RESULTS: At T0, 53 out of 89 patients (60%) in the control and 48 out of 70 patients (69%) in the study group harbored coagulase-negative Staphylococcus. Among these coagulase-negative Staphylococcus, 12 out of 53 in the control and 11 out of 48 in the study group were resistant to ofloxacin (p>0.9999). At T1, significantly fewer coagulase-negative Staphylococcus (p=0.0003) were isolated from the study group (18 coagulase-negative Staphylococcus), compared the control group (48 coagulase-negative Staphylococcus). Of these, 5 out of 17 coagulase-negative Staphylococcus in the study group and 9 out of 48 coagulase-negative Staphylococcus in the control group were resistant to ofloxacin (p=0.5649). There was no significant difference in the number of coagulase-negative Staphylococcus resistant to ciprofloxacin or norfloxacin in the study group compared to the control group at T1. CONCLUSIONS: Ofloxacin given four times a day for 3 days does not select out for conjunctival fluoroquinolone-resistant coagulase-negative Staphylococcus.

Administration, Topical↗

PubMed1984

Identification, clinical distribution, and susceptibility to methicillin and 18 additional antibiotics of clinical Staphylococcus isolates: nationwide investigation in Italy.

A multicentric study of clinical Staphylococcus isolates was performed by seven operative units working in different areas of Italy. Over a 6-month period, a total of 3,226 staphylococci, isolated from in- and outpatients, were identified and tested for antimicrobial susceptibility by a protocol agreed upon by all units. On the basis of their bacteriolytic-activity patterns and other conventional tests, the isolates were identified by lyogroups , which closely correlate with human Staphylococcus species. Lyogroup I (Staphylococcus aureus) and lyogroup III (Staphylococcus capitis) were the most and the least frequently isolated staphylococci, respectively. Significant differences depending on strain origin from in- or outpatients were only observed with lyogroup IV (i.e., novobiocin- resistant staphylococci), whose isolation from outpatients was three times greater than from inpatients. Lyogroup I was predominant among isolates from most clinical sources. Lyogroup IV predominated in strains isolated from the urinary tract; lyogroup V (Staphylococcus epidermidis) predominated in strains from blood, cerebrospinal fluid, and indwelling artificial devices; and lyogroup VI ( Staphylococcus hominis, Staphylococcus haemolyticus, and Staphylococcus warneri ) predominated in strains from bile and the male genital tract. The incidence of methicillin resistance within the different lyogroups varied from unit to unit, suggesting epidemiological differences among different hospitals and different geographical areas. On the whole, methicillin resistance was more frequent in coagulase-negative staphylococci than in S. aureus and ranged from 19% for lyogroups I and III to 30% for lyogroup II (Staphylococcus simulans). Laboratory testing with 18 additional antibiotics suggested the occurrence of some specific differences in susceptibility among the different lyogroups . The rate of organisms resistant to the various antibiotics was greater among methicillin-resistant than among methicillin -susceptible staphylococci; particularly marked differences occurred with cephalosporins, rifampin, gentamicin, and tobramycin. The results suggested an increasing spread in Italy, during the last few years, of staphylococcal resistance to methicillin and to many other antibiotics. Some questions about the actual reliability of laboratory tests for the determination of staphylococcal susceptibility to methicillin and other beta-lactam antibiotics were raised by parallel test performances in which both unsupplemented and 5% NaCl-supplemented Mueller-Hinton agars were used. The presence of NaCl heightened, on the whole, the number of resistant strains detected; however, a few isolates resistant in the unsupplemented medium and susceptible in the salt-supplemented medium were also encountered. This was true not only for methicillin but also for all other beta-lactam antibiotics tested except cefamandole. With cefamandole, the presence of 5% NaCl reduced the number of resistant strains detected.

Anti-Bacterial Agents↗

PubMed1994

Distribution of coagulase-negative staphylococci, including the newly described species Staphylococcus schleiferi, in nosocomial and community acquired urinary tract infections.

Four hundred and four coagulase-negative staphylococci were isolated from 4905 urine specimens obtained from 4192 inpatients and outpatients. The distribution of the strains was as follows: 193 Staphylococcus epidermidis (47.8%), 171 Staphylococcus saprophyticus (42.3%), 29 Staphylococcus haemolyticus (7.2%), 5 Staphylococcus warneri (1.2%), 3 Staphylococcus schleiferi (0.7%), 2 Staphylococcus hominis (0.5%) and 1 Staphylococcus simulans (0.2%). All three Staphylococcus schleiferi strains were isolated from inpatients: a 64-year-old female, a 68-year-old male and a 3-month-old male with colony counts of 468,000 cfu/ml, 324,000 cfu/ml and 764,000 cfu/ml respectively. These findings show that among coagulase-negative staphylococci, Staphylococcus schleiferi, a newly described species of coagulase-negative staphylococci not previously reported as a uropathogen, may also cause hospital acquired urinary tract infection.

Aged↗

PubMed1998

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.

Adolescent↗

PubMed1992

Association between Staphylococcus aureus nasopharyngeal colonization and septicemia in patients infected with the human immunodeficiency virus.

In an attempt to identify risk factors for Staphylococcus aureus septicemia, 136 consecutive HIV-infected patients were investigated for the presence of nasopharyngeal colonization with Staphylococcus aureus and subsequent Staphylococcus aureus infection. Sixty of 136 (44.1%) HIV-infected patients had staphylococci which were detected in the nasopharynx on initial culture compared to 12 of 39 (30.8%) patients with chronic diseases and 11 of 47 (23.4%) healthy hospital staff. Another 12 HIV-infected subjects proved to be Staphylococcus aureus carriers on follow-up cultures. Patients with full-blown AIDS had a higher carriage rate compared to subjects who were only HIV-positive (p < 0.05), indicating that Staphylococcus aureus colonized patients were more severely ill. Eight patients with Staphylococcus aureus septicemia were observed, all of whom were carriers; no septicemia occurred in the non-colonized patients (p < 0.01). Colonized patients with neutropenia (< 1000/microliters) were significantly more likely to develop septicemia (p < 0.01). Nasopharyngeal colonization with Staphylococcus aureus and the presence of an indwelling catheter were established to be factors that help identify patients at risk of acquiring subsequent Staphylococcus aureus infection.

Adult↗

PubMed1988

The role of coagulase-negative Staphylococcus in neonatal necrotizing enterocolitis.

Coagulase-negative Staphylococcus has emerged as a prominent pathogen in the neonatal intensive care unit and a recent report has implicated this organism in necrotizing enterocolitis (NEC). This same study suggests that Staphylococcus epidermidis is most commonly associated with a "mild form of enterocolitis." This prompted a review of the role of coagulase-negative Staphylococcus in the surgical complications of NEC. Between 1982 and 1986, 86 newborns underwent operation for perforation or intestinal necrosis secondary to NEC. Blood cultures, obtained within 72 hours of surgery, were positive in nine of 71 infants (13%). One third of these grew coagulase-negative Staphylococcus. Peritoneal cultures obtained at the time of operation were positive in 71 neonates. The incidence of Staphylococcus epidermidis was 30%. In a third of these cases, coagulase-negative Staphylococcus was the only organism covered. Overall mortality within the group was 33%. Coagulase-negative Staphylococcus was the single most frequent organism recovered from those infants who expired (35%). This data clearly indicates that Staphylococcus epidermidis must be considered as a significant pathogen in NEC. It is associated with both morbidity and mortality and, therefore, warrants appropriate aggressive therapy when recovered from the neonate with enterocolitis.

Enterocolitis, Pseudomembranous↗

PubMed1997

Staphylococcus aureus in dairy products in the Bologna area.

A study was carried out to evaluate the extent of contamination by Staphylococcus spp. and in particular by Staphylococcus aureus in dairy products on sale in the Bologna area. Staphylococcus aureus was found in 16.30% of the 135 cheese samples examined: 8.3% in soft cheese, 17.60% in blue cheese, 18.9% in semi-soft cheese and 25.0% in mozzarella-type cheese. The mean concentration was 2699 CFU/g in the 22 positive samples. The most commonly found species were Staphylococcus epidermidis (14.8%), Staphylococcus hominis (19.5%), Staphylococcus xylosus 2 (19.2%) and Staphylococcus cohnii (16.3%). Staphylococcus aureus was found mostly during the hot months while the other common species were found mostly in the period October-March.

Animals↗

PubMed2001

[Study of methicillin-resistant Staphylococcus aureus colonization among intermediate-care facility patients].

PURPOSE: Prevalence of methicillin-resistant Staphylococcus aureus is high in the Poitiers teaching hospital, particularly in the intermediate care facilities. We performed a survey of methicillin-resistant Staphylococcus aureus colonization in the intermediate care facilities and 265 patients were included. METHODS: Nasal, cutaneous and wound swab cultures were done at the time of admission and at the time of the patients' departure. A decolonization procedure of methicillin-resistant Staphylococcus aureus carriers was performed using nasal application of fusidic acid and different soaps for the skin. At entry, 17.7% of patients were methicillin-resistant Staphylococcus aureus carriers (of at least one location). At departure, 30.4% were methicillin-resistant Staphylococcus aureus carriers. Among methicillin-resistant Staphylococcus aureus non-carriers at entry, 24.3% became methicillin-resistant Staphylococcus aureus carriers. RESULTS: The principal risk factor of carriage was the initial presence of a wound (RR = 3.6). The incidence rate of methicillin-resistant Staphylococcus aureus infection among the 265 patients included was 3%. CONCLUSION: The systematic screening of patients at the time of admission is expensive and isolation technically hard to manage in the intermediate care facilities. The risk factor we found in this study allow us to propose a 'light' screening limited to patients with wounds.

Aged↗

PubMed1991

Susceptibility of Staphylococcus species and subspecies to fleroxacin.

Twenty-four Staphylococcus species or subspecies were examined for their susceptibilities to the fluoroquinolone fleroxacin (Ro 23-6240) by disk diffusion (5-micrograms disk) and by agar dilution for the determination of MICs. Resistant strains were further tested for their susceptibilities to oxacillin and the fluoroquinolone ciprofloxacin. Reference strains of the novobiocin-resistant species (Staphylococcus saprophyticus, Staphylococcus cohnii, Staphylococcus xylosus, Staphylococcus arlettae, and Staphylococcus gallinarum) had an intrinsic intermediate susceptibility (MIC, 4 micrograms/ml) to fleroxacin. Fleroxacin resistance was not observed in the reference strains of the novobiocin-susceptible species (MIC, 0.5 to 2.0 micrograms/ml). Clinical isolates of coagulase-negative species were generally less susceptible to fleroxacin than were reference strains. Seven percent of the Staphylococcus epidermidis clinical strains were resistant (MIC, greater than or equal to 8 micrograms/ml) to fleroxacin. Of these strains, 77% were resistant to oxacillin and 50% were resistant to ciprofloxacin. Thirty-four percent of the Staphylococcus haemolyticus clinical strains were resistant to fleroxacin, and 9% had intermediate susceptibility. Of the resistant strains, 95% were resistant to oxacillin and 77% were resistant to ciprofloxacin, while 23% had intermediate susceptibility to ciprofloxacin. Fleroxacin is an effective antimicrobial agent against most staphylococci.

Animals↗

PubMed1995

Four-year prospective study of STAPH-IDENT system and conventional method for reference identification of Staphylococcus, Stomatococcus, and Micrococcus spp..

A 4-year prospective study compared the accuracy of the STAPH-IDENT system (bioMérieux Vitek, Inc., Hazelwood, Mo.) with that of the reference procedure of the Centers for Disease Control and Prevention for the identification of Staphylococcus species, Stomatococcus mucilaginosus, and Micrococcus species. The study compared the results from 1,106 cultures (500 eye cultures, 217 strains submitted for reference identification, and 389 known stock strains) representing 21 species of the family Micrococcaceae. The overall agreement of genus and species identifications was 81.1%. The percent agreement for the five most common clinical isolates was as follows: Staphylococcus epidermidis, 97.1% (517 isolates); Staphylococcus hominis, 82.5% (57 isolates); Staphylococcus aureus, 77.2% (162 isolates); Staphylococcus haemolyticus, 75.8% (61 isolates); and Staphylococcus warneri, 64.1% (39 isolates). The lowest percent agreement was with Staphylococcus cohnii (11.1%; (9 isolates). Of the 217 isolates sent to the Centers for Disease Control and Prevention for identification, 60.4% (131) were correctly identified by the STAPH-IDENT system. Of these, S. epidermidis accounted for 23.9%, S. aureus accounted for 15.6%, S. warneri accounted for 6.9%, Staphylococcus lugdunensis accounted for 6.5%, S. haemolyticus accounted for 5.5%, and S. hominis accounted for 4.1%. The STAPH-IDENT system did not perform adequately when dealing with commonly encountered organisms and is unsuitable for identifying uncommon isolates.

Bacterial Typing Techniques↗

PubMed2002

rpoB gene sequence-based identification of Staphylococcus species.

The complete sequence of rpoB, the gene encoding the beta subunit of RNA polymerase was determined for Staphylococcus saccharolyticus, Staphylococcus lugdunensis, S taphylococcus caprae, and Staphylococcus intermedius and partial sequences were obtained for an additional 27 Staphylococcus species. The complete rpoB sequences varied in length from 3,452 to 3,845 bp and had a 36.8 to 39.2% GC content. The partial sequences had 71.6 to 93.6% interspecies homology and exhibited a 0.08 to 0.8% intraspecific divergence. With a few exceptions, the phylogenetic relationships inferred from the partial rpoB sequences were in agreement with those previously derived from DNA-DNA hybridization studies and analyses of 16S ribosomal DNA gene sequences and partial HSP60 gene sequences. The staphylococcal rpoB sequence database we established enabled us to develop a molecular method for identifying Staphylococcus isolates by PCR followed by direct sequencing of the 751-bp amplicon. In blind tests, this method correctly identified 10 Staphylococcus isolates, and no positive results were obtained with 10 non-Staphylococcus gram-positive and gram-negative bacterial isolates. We propose partial sequencing of the rpoB gene as a new tool for the accurate identification of Staphylococcus isolates.

Bacterial Typing Techniques↗

PubMed1998

New strategies to prevent Staphylococcus aureus infections in peritoneal dialysis patients.

The importance of Staphylococcus aureus as etiological agent for catheter-related infections and peritonitis in peritoneal dialysis patients is well established. To evaluate groups at risk of developing Staphylococcus aureus infections, nasal and exit-site cultures were performed in 76 peritoneal dialysis patients monthly over a period of 3 yr. The risk of Staphylococcus aureus catheter infection was significantly higher in diabetic (group 1) and immunosuppressed (group 2) patients compared with nondiabetic and nonimmunosuppressed (group 3) patients. In diabetic patients, Staphylococcus aureus-positive nasal cultures were more frequent than positive cultures taken from the bland exit-site (73.3% versus 60.0%). On the other hand, both positive and negative exit-site cultures had a better prognostic value for Staphylococcus aureus catheter infection compared with nasal cultures. In immunosuppressed patients, both nasal and exit-site carriages were associated with a very high risk of Staphylococcus aureus catheter infection, but nasal swabs were far more often positive than swabs from the bland exit-site (72.7% versus 25.0%). However, the risk of infection was also high for non-nasal and non-exit-site carriers in this group. In nondiabetic and nonimmunosuppressed patients, the risk of Staphylococcus aureus catheter infection was increased only if two or more positive nasal cultures were detected. It is concluded that in diabetic patients, antibiotic prophylaxis should be performed in all Staphylococcus aureus exit-site carriers. All immunosuppressed patients should be treated prophylactically. In contrast, in nondiabetic and nonimmunosuppressed patients, prophylactic treatment should be considered only in nasal carriers with two or more positive cultures. The overall low peritonitis rate does not influence this prevention strategy.

Adult↗