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Minimising antibiotic resistance to Staphylococcus aureus in developing countries.

OBJECTIVE: To assess the role of rational drug use and laboratory service in preventing the emergence of multiple antibiotic resistant Staphylococcus aureus in developing countries. DATA SOURCE: Literature search on compact disk-read only memory (CD-ROM) Medline and Internet using the key words: Staphylococcus and antibiotic resistance. A few articles were manually reviewed. STUDY SELECTION: Relevant studies or articles on antibiotic resistance with special reference to Eastern Africa, region are included in the review. DATA EXTRACTION: From individual studies or articles. DATA SYNTHESIS: Evidence for the spread of S. aureus multiple antibiotic resistance is synchronized under the headings: Introduction, current situation, antibiotic resistance control strategies, are outlined. CONCLUSION: There is need for concerted efforts between different groups to monitor changes in the epidemiology and antibiotic resistance of S. aureus. Strategies aimed at preventing transmission of resistant strains are remarkably effective when strictly enforced. Necessary attention should be given on the subject so that meaningful control measures preventing the expansion of antimicrobial resistance can be formulated, thereby ensuring the future successful treatment of Staphylococcal infections.

Africa, Eastern↗

Evaluation of a selective broth for detection of Staphylococcus aureus using impedance microbiology.

Experiments were conducted to evaluate a selective nutrient broth containing acriflavine and nalidixic acid for detection of Staphylococcus aureus using an impedance microbiological method. Nine species of bacteria, other than S. aureus, were evaluated using the selective broth to determine if these species could be inhibited. A total of 10 ppm of nalidixic acid inhibited the gram-negative species tested, with the exception of Pseudomonas aeruginosa. Similarly, 10 ppm of acriflavine suppressed the Staphylococcus spp. examined; however, S. aureus retained the ability to proliferate. Nutrient broth solution containing 10 ppm of nalidixic acid and 10 ppm of acriflavine (S. aureus impedance broth [SIB]) inhibited multiplication of most of the bacterial species tested and allowed S. aureus to be detected in an average of 16.4 h. Fresh chicken carcass rinses and cooked chicken rinses were inoculated with Escherichia coli and S. aureus and assayed using SIB in conjunction with impedance. Results demonstrated that S. aureus could be detected in less than 11.5 h, although the presence of E. coli decreased detection times. Additionally, impedance assays were conducted using five different poultry products to evaluate the sensitivity of the broth for detecting S. aureus. S. aureus could be detected on poultry products when present at low levels (10(1) CFU/ml) in less than 24 h. These studies demonstrated that SIB may be used in conjunction with impedance for rapid detection of S. aureus. However, without further modification, this method should not be used for enumeration of S. aureus from samples containing mixed microflora.

Acriflavine↗

Real-time quantitative PCR of Staphylococcus aureus and application in restaurant meals.

Staphylococcus aureus is considered the second most common pathogen to cause outbreaks of food poisoning, exceeded only by Campylobacter. Consumption of foods containing this microorganism is often identified as the cause of illness. In this study, a rapid, reliable, and sensitive real-time quantitative PCR was developed and compared with conventional culture methods. Real-time quantitative PCR was carried out by purifying DNA extracts of S. aureus with a Staphylococcus sample preparation kit and quantifying it in the LightCycler system with hybridization probes. The assay was linear from a range of 10 to 10(6) S. aureus cells (r2 > 0.997). The PCR reaction presented an efficiency of >85%. Accuracy of the PCR-based assay, expressed as percent bias, was around 13%, and the precision, expressed as a percentage of the coefficient of variation, was 7 to 10%. Intraday and interday variability were studied at 10(2) CFU/g and was 12 and 14%, respectively. The proposed method was applied to the analysis of 77 samples of restaurant meals in Valencia (Spain). In 11.6% of samples S. aureus was detected by real-time quantitative PCR, as well as by the conventional microbiological method. An excellent correspondence between real-time quantitative PCR and microbiological numbers (CFU/g) was observed with deviations of < 28%.

Colony Count, Microbial↗

Occurrence of methicillin-resistant Staphylococcus aureus in healthy pets in Duhok Province, Kurdistan Region, Iraq.

BACKGROUND: Worldwide, Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen responsible for various infections in humans and animals. AIM: This study aimed to determine the prevalence and molecular characteristics of MRSA isolates in healthy pets, specifically cats and dogs. METHODS: In this study, swab samples were collected from 135 healthy pets, including 100 cats and 35 dogs. The samples were analyzed using standard microbiology and molecular methods. RESULTS: The results showed the detection of MRSA in nostril isolates at a total rate of 23.2% (13/56) from both cats and dogs through the detection mecA gene. The prevalence rate was different in cats and dogs and it was 22% (9/41) and 27% (4/15), respectively. The same isolates were cefoxitin-positive and oxacillin-resistant. Basic Local Alignment Search Tool analysis of partial mecA sequences revealed 100% similarity with mecA genes from human Staphylococcus aureus isolates. All 13 mecA sequences exhibited identical results. Two partial mecA sequences from this study have been deposited in GenBank under accession numbers PQ881807 and PQ881808. The MRSA isolates only displayed staphylococcal cassette chromosome types I and IV (a and b). The results also showed a high prevalence of certain virulence factors, such as hemolysins, across the isolates and multidrug-resistant MRSA isolates among both cats and dogs. CONCLUSION: This study is the first to confirm the occurrence of MRSA among Duhok pets. The findings suggest the role of healthy animals as reservoirs of multidrug-resistant MRSA and highlight the potential threat of zoonotic transmission of MRSA between pets and humans.

Animals↗

[Studies on recent clinically isolated Staphylococcus aureus--drug susceptibility and incidence of MRSA in clinical isolates].

Susceptibility of various antimicrobial agents against clinically isolated Staphylococcus aureus was evaluated by Kirby Bauer methods. The incidence of MRSA (Methicillin cephem resistant Staphylococcus aureus) was also investigated. When S. aureus was isolated from urine, the clinical background of the case was further studied. The results are listed below; 1) M1N0 showed the highest susceptibility rate (83.1%) against 537 strains of S. aureus tested, followed by CMZ (63.7%) and CET (63.5%). The susceptibility rate of DMPPC was 41.9%. The incidence of MRSA was 31.3%. 2) In effusion, MRSA was most highly isolated (72.2%). 3) S. aureus isolated from blood and sputa was relatively more resistant to beta-lactams. 4) Strains from urine showed relatively high susceptibility rates. No MRSA was isolated from urine. 5) Thirteen out of twenty-four cases, whose urines were proven to be S. aureus positive, were polymicrobial infection patients.

Adolescent↗

Characterization of a bifunctional aminoglycoside-modifying enzyme with novel substrate specificity and its gene from a clinical isolate of methicillin-resistant Staphylococcus aureus with high arbekacin resistance.

A clinical isolate (designated PRC104) of methicillin-resistant Staphylococcus aureus was discovered with a novel aminoglycoside resistance profile, including unusually high resistance (MIC 128 microg/ml) to arbekacin (an effective anti-MRSA drug in Japan). We characterized the activity and gene of its bifunctional aminoglycoside-modifying enzyme, AAC(6')/APH(2"), in comparison with those of a regular one that has been known as the critical resistance basis to both gentamicin and arbekacin in methicillin-resistant Staphylococcus aureus. The aac(6')/aph(2") gene of strain PRC104 contained a single base alteration at a novel site (G1126A) resulting in one amino acid substitution (S376N) in the phosphorylation catalytic motif. The phosphorylation activity of the PRC104 enzyme was enhanced for arbekacin and reduced for gentamicin. Both strain PRC104 and S. aureus RN4220 containing the cloned gene were identical in terms of the substrate specificity of the enzyme as well as the aminoglycoside resistance profile, although both mRNA and aminoglycoside resistance levels were markedly high in strain PRC104. Therefore, the cloned aac(6')/aph(2") gene may represent the molecular basis for the novel aminoglycoside modification capability as well as novel aminoglycoside resistance profile of S. aureus PRC104.

Amino Acid Sequence↗

Mupirocin prophylaxis against nosocomial Staphylococcus aureus infections in nonsurgical patients: a randomized study.

BACKGROUND: Staphylococcus aureus nasal carriage is a major risk factor for nosocomial S. aureus infection. Studies show that intranasal mupirocin can prevent nosocomial surgical site infections. No data are available on the efficacy of mupirocin in nonsurgical patients. OBJECTIVE: To assess the efficacy of mupirocin prophylaxis in preventing nosocomial S. aureus infections in nonsurgical patients. DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: 3 tertiary care academic hospitals and 1 nonacademic hospital. PATIENTS: 1602 culture-proven S. aureus carriers hospitalized in nonsurgical departments. INTERVENTION: Therapy with mupirocin 2% nasal ointment (n = 793) or placebo ointment (n = 809), twice daily for 5 days, started 1 to 3 days after admission. MEASUREMENTS: Nosocomial S. aureus infections according to defined criteria, in-hospital mortality, duration of hospitalization, and time to nosocomial S. aureus infection. Staphylococcus aureus isolates were genotyped to assess whether infection was caused by endogenous strains. RESULTS: The mupirocin and placebo groups did not statistically differ in the rates of nosocomial S. aureus infections (mupirocin, 2.6%; placebo, 2.8%; risk difference, 0.2 percentage point [95% CI, -1.5 to 1.9 percentage points]), mortality (mupirocin, 3.0%; placebo, 2.8%; risk difference, -0.2 percentage point [CI, -1.9 to 1.5 percentage points]), or duration of hospitalization (median for both, 8 days). However, time to nosocomial S. aureus infection was decreased in the mupirocin group from 12 to 25 days (P > 0.2). A total of 77% of S. aureus nosocomial infections were endogenous. LIMITATIONS: A few infections in both groups may have been missed because investigators assessed a patient for infection only if microbiology culture results were positive for S. aureus. CONCLUSION: Routine culture for S. aureus nasal carriage at admission and subsequent mupirocin application does not provide effective prophylaxis against nosocomial S. aureus infections in nonsurgical patients.

Administration, Intranasal↗

Nosocomial septicemia due to multiply antibiotic-resistant Staphylococcus epidermidis.

Thirteen episodes of Staphylococcus epidermidis sepsis occurred over a 20-month period in 11 patients receiving general surgical and medical care. These episodes were characterized by fever, toxicity, multiple positive blood cultures, and uniformly colonized intravascular catheters. An additional 16 patients had possible sepsis. Four associated deaths occurred; all three patients autopsied had multiple pulmonary abscesses in which gram-positive cocci were profusely present. In individual patients, prolonged episodes of septicemia were confirmed by multiple blood culture isolates of S. epidermidis, identical in antibiotic resistance pattern, phage type, and biotype. A prominent feature of the S. epidermidis isolates was resistance to many commonly used antimicrobial agents. Case-control studies and review of laboratory records indicated a significant association between multiply resistant S. epidermidis blood isolates and prolonged hospitalization and parenteral hyperalimentation. Most of these patients were hospitalized in the intensive care unit; nose and hand cultures taken from the personnel showed frequent carriage of multiply resistant S. epidermidis Staphylococcus epidermidis associated with intravascular devices may produce life-threatening bloodstream infections.

Adult↗

Methicillin resistant Staphylococcus aureus and its implications for nursing practice: a literature review.

The subject of methicillin-resistant Staphylococcus aureus (MRSA) and its implications for nursing practice are reviewed. Resistance of Staphylococcus aureus to antibiotics, and the emergence and incidence of MRSA both in the United Kingdom and abroad, are examined. Modes of transmission of MRSA by transfer of affected patients and, specifically, cross infection by staff are reviewed with methods to prevent cross infection, including screening of staff, handwashing techniques, barrier and cohort nursing, being examined. The costs of an MRSA outbreak, both financially and psychologically, to staff and patients are discussed. Guidelines for the control of epidemic MRSA are explained in the context of the above topics, and all areas are related to improving nursing practice.

Cross Infection↗

Analysis of mec regulator genes in clinical methicillin-resistant Staphylococcus aureus isolates according to the production of coagulase, types of enterotoxin, and toxic shock syndrome toxin-1.

The intrinsic resistance of methicillin-resistant Staphylococcus aureus (MRSA) is frequently explained by the production of an additional penicillin-binding protein (PBP), which is encoded by the mecA gene. The mec regulator genes, mecR1 and mecI, was identified in mecA-carrying Staphylococcus aureus N315. Between February and March, 1993, 179 clinical MRSA isolates were collected from institutions in Hiroshima prefecture. According to serological types of coagulase, enterotoxins, and toxic shock syndrome toxin-1 (TSST-1) productions, these strains were classified into 6 groups. In 53 strains chosen from all groups, mec regulatory gene distributions were divided into two groups; one with whole regulatory genes and another with the lacking region, including 3'-partial region of the mecR1 gene and mecI gene. This same deletion was detected across the different groups, suggesting that the deletion occurred at the ancestral strain before branching according to coagulase or enterotoxin productions. The strains with this lacking region showed a high-level of resistance to methicillin, while the strains with whole regulatory genes consisted of low and high levels of resistant strains. The highly resistant strains with whole regulatory genes were found to harbor a point mutation in the mecI gene. The basal levels of mecA gene transcription were elevated in the strains with the lacking region or the mecI point mutations. These data suggest that deletion or mutation of the mecI gene, the repressor on the mecA gene, might play an important role in methicillin resistance in clinical isolates of MRSA.

Bacterial Proteins↗

[7 cases of Staphylococcus lugdunensis infection].

Staphylococci are frequently isolated from human, animal and environmental samples. The genus Staphylococcus comprises 27 species, of which 23 are coagulase-negative. The pathogenic role of the coagulase-negative species remains to be fully established. Staphylococcus lugdunensis is a recently described coagulase-negative species. Its Latin name reflects the city (Lyon, France) where the bacteria was first described. The present study reports 7 cases of human infection caused by S. lugdunensis. Case 1: a 64 y/o diabetic woman in whom S. lugdunensis was isolated in the conjunctival exudate. Case 2: a 51 y/o male diagnosed of a bladder tumor, with S. lugdunensis detected in the purulent exudate of a transurethral resection. Case 3: an 81 y/o woman with cerebrovascular stroke, in whom S. lugdunensis was isolated from urine. Case 4: a 65 y/o male with bacterial endocarditis and S. lugdunensis isolation in blood culture. Case 5: a 79 y/o male with liver cirrhosis and S. lugdunensis in blood culture. Case 6: a 75 y/o female with cerebrovascular stroke, in whom S. lugdunensis was isolated from urine. Case 7: a 77 y/o male diagnosed of femoral osteosarcoma and isolation of S. lugdunensis in the purulent exudate of the wound. The present communication broadens the range of clinical syndromes in which coagulase-negative S. lugdunensis appears as pathogen.

Aged↗

Evaluation in an animal model and in vitro of the combination clavulanic acid and cephalosporins against beta-lactamase producing and nonproducing Staphylococcus aureus strains.

Beta-lactamase enzymes are the most common cause of bacterial resistance to Beta-lactam antibiotics. They hydrolyze the amide bound in the Beta-lactam ring and produce acidic derivatives that have no antibacterial properties. The aim of this study was to evaluate a combination of clavulanic acid with cephalosporins against Beta-lactamase-producing and nonproducing strains of Staphylococcus aureus using in vitro tests and a rat animal model. In vitro tests (MIC) of the drug combination were done using standard methods. In an animal model, rats were submitted to surgical implantation of polyurethane sponges in their backs to induce granulomatous tissue. After seven days, the animals received cephalexin, cephalexin with clavulanic acid, ceftriaxone, ceftriaxone with clavulanic acid or clavulanic acid alone. One hour after the drug administration, granulomatous tissue was removed and placed in Petri dishes previously inoculated with 10(8) cfu of producing or non-producing Beta-lactamase Staphylococcus aureus. After 24h at 37 degrees C, the inhibition zones formed by granulomatous tissue was measured and scored for statistical analysis. Both tests (ex vivo ¿animal model¿ and in vitro) showed that the cephalexin was more active than ceftriaxone against non-producing Beta-lactamase S.aureus (p<0.01). Against Beta-lactamase producing S.aureus, ceftriaxone was more active than cephalexin, which was inactive. Combinations of clavulanic acid with cephalexin or ceftriaxone had similar antimicrobial activity against non-producing Beta-lactamase S.aureus compared to the cephalosporins used alone. When tested using Beta-lactamase producing strains, the combination of clavulanic acid with cephalosporins showed synergism. We conclude that the combination of cephalosporins with clavulanic acid could be useful in staphylococcal infections caused by Beta-lactamase producing strains.

Animals↗

[Staphylococcus aureus purulent pleurisy in children. Experience of the Albert Royer Hospital for Children of the Fann University Hospital Center in Dakar].

The authors report here by a retrospective study 58 cases of Staphylococcus aureus empyema at Albert ROYER child hospital located in the Fann University Teaching Hospital of Fann between January 1st 1992 and December 31, 1995. In this study staphylococcus aureus is the bacterium involved in pleural effusions of the children (54%) a long way ahead Streptococcus pneumoniae (16%). Infant less than 30 month is more affected (86%). The average age of the patients is 16.8 month +/- 16.6. The resistance of the germ to usual antibiotics, the precariousness of the research field and mechanical complications linked to the outpouring explain their seriousness. The treatment lies upon an adapted antibiotic and bactericidal therapy associated to closed chest tube drainage.

Age Distribution↗

Staphylococcus aureus opsonization mediated via the classical and alternative complement pathways. A kinetic study using MgEGTA chelated serum and human sera deficient in IgG and complement factors C1s and C2.

Staphylococcus aureus opsonization was studied kinetically by: (1) determination of the uptake of [3H]-thymidine labelled bacteria by human PMN's; (2) fluorescent anti-C3 and anti-IgG staining of opsonized bacteria; and (3) measuring bacterial complement consumption. Maximum opsonization in normal serum occurred within 5 min of incubation. About 80% of staphylococci were then taken up by PMN's, and IgG and C3b could be detected on the bacterial surface. In the absence of a functional classical complement pathway, as in sera deficient in C1s and C2 and in MgEGTA chelated serum, maximal opsonization was only achieved after 30--60 min incubation. Opsonization in IgG deficient serum occurred at a rate similar to that found in C2 deficient or MgEGTA chelated serum. Opsonization was greatly enhanced when sera were reconstituted. It was concluded that in IgG deficient serum Staphylococcus aureus opsonization is mediated via the alternative complement pathway. Dilution of normal serum primarily affected the classical complement pathway, resulting in a decreased rate of opsonization. In normal serum IgG did not appear to be a rate-limiting factor. S. Aureus opsonization was best studied by the phagocytosis assay and the fluorescent-antibody technique. Measuring haemolytic complement consumption was found to be an insensitive indicator of bacterial complement activation and opsonization.

Complement Activation↗

Staphylococcus sciuri: recommendation for simple identification.

We report the isolation of Staphylococcus sciuri, primarily animal species, from samples taken from hospitalised patients. Considering that Staphylococcus sciuri often remains unrecognised in routine laboratory practice, we propose the criteria for simple identification of this bacterium.

Bacterial Typing Techniques↗

[Empyema caused by Staphylococcus aureus in children: the experience of the Albert Royer Children's Hospital at Fann University Hospital, Dakar].

We report a retrospective study of 58 cases of empyema caused by Staphylococcus aureus at the Albert Royer Children's Hospital at the Fann University Hospital, between January 1st 1992 and December 31st 1995. Staphylococcus aureus is the principal bacterium responsible for pleural effusions in children (54%), way ahead of Streptococcus pneumoniae (19%). Most of the children affected (86%) are less than 30 months old. Theses infections are often serious due to the resistance of the bacterium to the usual antibiotics, the lack of solid research data and mechanical complications associated with the effusion. Treatment is based on the use of an appropriate bactericidal antibiotic treatment and pleural drainage.

Age Factors↗

[Occurrence of Staphylococcus aureus in "frescal" type cheese].

OBJECTIVE: To verify the occurrence of Staphylococcus aureus in a sample of cheese sold in a city of the Southeastern region of Brazil and assess the potential risk for the consumers. METHODS: Eighty samples of homemade cheese sold in a city of the southern region of Brazil were evaluated for the presence and the most probable number of Staphylococcus aureus agents. RESULTS: The study revealed the presence of S. aureus in 40 samples (50.0%, with a mean count of 10(5)/g. CONCLUSION: These results are worrisome because the Health Ministry has established a safety threshold of 10(3)/g, and the values obtained are close to the number of bacteria able to produce enough enterotoxins to cause a foodborne disease outbreak.

Brazil↗