Background/Objective: There is a deep concern about the rapid rise in resistance of bacteria to antimicrobial agents. Methicillin-resistant Staphylococcus aureus (MRSA) which pose challenges to the medical community. This study aimed to determine the prevalence and sensitivity pattern of Methicillin-Resistant Staphylococcus Aureus (MRSA) in a tertiary hospital in Cebu City from January 1, 2007 to December 31, 2010. Methods: Charts of patients with MRSA growths were reviewed upon their admission. The sensitivity pattern, demographic profile and risk factors were noted. Results: Out of the 637 isolates of Staphylococcus aureus, MRSA had a prevalence rate of 38.6% (n=246), while Methicillin Sensitive Staphylococcus aureus (MSSA) had 61.4% (n=391). The prevalence rate of health-care associated MRSA was 2% (n=5). The majority of the specimens sent for culture were wound/abscess (70% of pediatric and 76% of adult patients isolates). All MRSA growths were resistant to penicillin G, ampicillin, oxacillin, cefuroxime and amikacin. Local MRSA strains were still susceptible to ciprofloxacin (82.3%), clindamycin (90.6%), erythromycin (91.5%), and sulfamethoxazole-trimethoprim (85.9%). There was no resistance to linezolid and vancomycin. Vancomycin-resistant Staphylococcus aureus was not isolated. The mortality rate on both pediatric and adult population was 2.1% and 4.8%, respectively. Conclusion The prevalence of MRSA is increasing. Clindamycin, erythromycin, sulfamethoxazole- trimethoprim and vancomycin are excellent treatment options treat MRSA.
Methicillin-Resistant Staphylococcus aureus ; Staphylococcus aureus ; Vancomycin

Aims: Staphylococcus aureus is an important opportunistic human pathogen. The emergence of macrolide and vancomycin resistant S. aureus is of great concern for treatment of S. aureus infections. The current study aimed to investigate the pattern of antibiotic resistance in S. aureus clinical isolates recovered from El Boos Students’ hospital in Cairo, Egypt. Methodology and results: Sixty unduplicated S. aureus isolates were recovered from El Boos Students’ hospital in Cairo, Egypt for 11 months period. The antibiotic susceptibility test revealed that all isolates were resistant to eleven antibiotics, but only 49 S. aureus isolates were resistant to cefoxitin. The minimum inhibitory concentrations (MIC) of both erythromycin and vancomycin were determined by broth microdilution method. Two methicillin resistant S. aureus (MRSA) isolates showing tolerance to both erythromycin and vancomycin at high concentration were selected for further characterization. One isolate was recovered from eye infection and had MIC at 256 µg/mL of both erythromycin and vancomycin. While another isolate was recovered from throat infection and had MIC of erythromycin and vancomycin up till 512 µg/mL. The presence of resistance genes (ermA, ermB, ermC, mef, msrA, vanA and vanB) were confirmed by polymerase chain reaction (PCR). Both MRSA isolates carried all tested resistance genes. Conclusion, significance and impact of study This study highlights the concern of presence of multidrug-resistant S. aureus which showed resistance to high concentrations of erythromycin, vancomycin and carried ermA, ermB, ermC, mef, msrA, vanA and vanB genes, therefore imposes risk of failure to treat such infections.
Vancomycin-Resistant Staphylococcus aureus ; Erythromycin

BACKGROUND: Small colony variants (SCVs) of Staphylococcus aureus have emerged to be commonly associated with persistent and relapsing infections. Arbekacin (ABK) is one of a few alternatives to vancomycin in intractable case of methicillin resistant S. aureus (MRSA) infection. However, it has not yet been defined whethter ABK tends to be efficacious to the MRSA SCVs. In this study, we employed an in vitro pharmacodynamic infection model (IVPDIM) to define efficacies of ABK against MRSA SCVs. MATERIALS AND METHODS: Using four strains of clinically isolated MRSA (MRSA122, MRSA160, MRSA18, MRSA123), we adopted IVPDIM comprised of two-compartment in which effective surface-to-volume ratio of 5.34 cm(-1). Human pharmacokinetic regimen simulations of ABK were as follows: 100 mg every 12 h (q12h), 200 mg q24h, 200 mg q12h, and 400 mg q24h. Samples were taken from each model at 0, 1, 2, 4, 6, 12, 24, and 30 h, and the bacterial colony counts were determined. The experiments were repeated twice with ABK-administered groups and control group. RESULTS: MICs of ABK for MRSA122, MRSA160, MRSA18, and MRSA123 were 2, 2, 2, and 1 microgram/mL, respectively. In case of MRSA122, MRSA160, MRSA18, C(max)/MIC were less than 9.0 except for ABK 400 mg q24h regimen. In MRSA123, C(max)/MIC were 8.9 on average at ABK 100 mg q12h regimen. But, other regimen showed C(max)/MIC >9. Four regimens for 4 strains showed statistically different colony counts at 30 h (P=0.000). The more dosage or less frequent dosing interval, the more colonies tended to reduce in all strains. In 100 mg q12h groups, SCVs were observed in all strains within 24 h. With increment of dosage or changing dosing interval from q12h to 24h, SCVs were reduced (P=0.000). Regimen of 400 mg q24h did not let SCVs appear in all strains of MIC 2 microgram/mL during the experiments. CONCLUSION: SCVs were observed when MIC of ABK against MRSA were 1-2 microgram/mL, especially in most cases of C(max)/MIC <9. Those findings were also associated with re-growth of colony during the experiments. Once-daily dosing of ABK could reduce or eliminate the appearance of SCV.
Humans ; Linear Energy Transfer ; Methicillin Resistance* ; Methicillin* ; Methicillin-Resistant Staphylococcus aureus ; Staphylococcus aureus* ; Staphylococcus* ; Vancomycin

BACKGROUND: Small colony variants (SCVs) of Staphylococcus aureus have emerged to be commonly associated with persistent and relapsing infections. Arbekacin (ABK) is one of a few alternatives to vancomycin in intractable case of methicillin resistant S. aureus (MRSA) infection. However, it has not yet been defined whethter ABK tends to be efficacious to the MRSA SCVs. In this study, we employed an in vitro pharmacodynamic infection model (IVPDIM) to define efficacies of ABK against MRSA SCVs. MATERIALS AND METHODS: Using four strains of clinically isolated MRSA (MRSA122, MRSA160, MRSA18, MRSA123), we adopted IVPDIM comprised of two-compartment in which effective surface-to-volume ratio of 5.34 cm(-1). Human pharmacokinetic regimen simulations of ABK were as follows: 100 mg every 12 h (q12h), 200 mg q24h, 200 mg q12h, and 400 mg q24h. Samples were taken from each model at 0, 1, 2, 4, 6, 12, 24, and 30 h, and the bacterial colony counts were determined. The experiments were repeated twice with ABK-administered groups and control group. RESULTS: MICs of ABK for MRSA122, MRSA160, MRSA18, and MRSA123 were 2, 2, 2, and 1 microgram/mL, respectively. In case of MRSA122, MRSA160, MRSA18, C(max)/MIC were less than 9.0 except for ABK 400 mg q24h regimen. In MRSA123, C(max)/MIC were 8.9 on average at ABK 100 mg q12h regimen. But, other regimen showed C(max)/MIC >9. Four regimens for 4 strains showed statistically different colony counts at 30 h (P=0.000). The more dosage or less frequent dosing interval, the more colonies tended to reduce in all strains. In 100 mg q12h groups, SCVs were observed in all strains within 24 h. With increment of dosage or changing dosing interval from q12h to 24h, SCVs were reduced (P=0.000). Regimen of 400 mg q24h did not let SCVs appear in all strains of MIC 2 microgram/mL during the experiments. CONCLUSION: SCVs were observed when MIC of ABK against MRSA were 1-2 microgram/mL, especially in most cases of C(max)/MIC <9. Those findings were also associated with re-growth of colony during the experiments. Once-daily dosing of ABK could reduce or eliminate the appearance of SCV.
Humans ; Linear Energy Transfer ; Methicillin Resistance* ; Methicillin* ; Methicillin-Resistant Staphylococcus aureus ; Staphylococcus aureus* ; Staphylococcus* ; Vancomycin

BACKGROUND AND OBJECTIVES: Recently, methicillin resistent Staphylococcus aureus (MRSA) infecton in persistent otorrhea is on the increase. Beside the systemic side effects of vancomycin, systemic vancomycin injection needs admission and higher medical cost. We used vancomycin topically in the treatment of otorrhea by MRSA infection to minimize the disadvantages of systemic vancomycin injection. The objective of this study was to compare the therapeutic effects between topical and systemic use of vancomycin. MATERIALS AND METHODS: Twenty-five patients with persistent otorrhea were performed ordinary culture and sensitivity test. Among them, 18 patients were proved to have MRSA and they were divided into two groups. One group was treated with topical vancomycin packing, the other with systemic injection. RESULTS: MRSA was cultured in 18 cases (72%) among the 25 patients with persistent otorrhea. Therapeutic effects of topical vancomycin on MRSA infection was 77% and the average therapeutic period was 13.5 days. On the other hand, therapeutic effect was 100% and the average period was 5.6 days in systemic vancomycin injection group. CONCLUSION: Topical vancomycin packing in the treament of chronic otitis media with MRSA infection has advantages in view of time and economy, though the average therapeutic period is longer than that of systemic vancomycin injection.
Hand ; Humans ; Methicillin ; Methicillin-Resistant Staphylococcus aureus ; Otitis Media ; Staphylococcus aureus* ; Staphylococcus* ; Vancomycin*

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of health care-associated infections. Vancomycin remains an acceptable treatment option. There has been a welcome increase in the number of agents available for the treatment of MRSA infection. These drugs have certain differentiating attributes and may offer some advantages over vancomycin, but they also have significant limitations. These agents provide some alternative when no other options are available.
Bacteremia* ; Methicillin Resistance* ; Methicillin-Resistant Staphylococcus aureus* ; Vancomycin

BACKGROUND: The aim of the study was to determine prevalence of potential heterogeneous vancomycin-resistant Staphylococcus aureus (h-VRSA) among methicillin-resistant S. aureus (MRSA) isolated in Korea by using Mu-3 agar and to determine the effect of in vitro vancomycin exposure on the resistance. METHODS: MRSAs isolated in 1980-1999 were screened for the presence of VISA or h-VRSA using Mu-3 agar. MIC of vancomycin was tested by NCCLS agar dilution and broth microdilution tests. Suspected h-VRSA were selected by vancomycin-containing media and change of resistance was determined by population analysis. A strain with Mu50 type growth was serially exposed to 8 pg/ml of vancomycin containing media and change of the vancomycin resistance was determined. RESULTS: Among the 455 MRSA isolates, 18 (3.9 %) grew on selective brain heart infusion agar (BHIA), and 354 (77,8%) on Mu-3 agar, 66 (14.5%) with Mu3 type growth and 78 (17.1%) with Mu50 type growth. MIC of vancomycin was 11 pg/ml for some of the isolates when inocula were approximately 10' CFU, but VISA was not present when tested by NCCLS broth microdilution test. Exposure of the isolates to van-cornycin raised the MIC. Serial exposure once to 8 pg/ml of vancomycin resulted in significant decrease of cells susceptible to 8-12 pg/ml of vancomycin. CONCLUSION: VISA was not present among the test isolates, but 34.2% were suspected to be potential h-VRSAs, suggesting possible emergence of VISA if vancomycin was administered prolonged period. It is considered that suitable screening media are vancomycin containing BHIA for VISA and Mu-3 agar for h-VRSA. The isolates showing Mu50 type growth on Mu-3 agar are not always VISA, but rather h-VRSA.
Agar* ; Brain ; Heart ; Korea ; Mass Screening ; Methicillin Resistance ; Methicillin-Resistant Staphylococcus aureus ; Prevalence ; Staphylococcus aureus* ; Staphylococcus* ; Vancomycin Resistance ; Vancomycin*

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia with a vancomycin minimum inhibitory concentration (MIC) of 2 microg/mL presents a high rate of therapeutic failure in response to vancomycin. In addition, polymorphism in accessory gene regulator (agr) is associated with vancomycin therapeutic effects. The association between agr polymorphism and vancomycin MICs was investigated in MRSA isolates. METHODS: Agr group-specific PCR was conducted on 118 MRSA bloodstream isolates. Vancomycin susceptibility tests were conducted, while E-test GRD (bioMerieux SA, France) was used to detect heterogeneous vancomycin-intermediate S. aureus (hVISA). RESULTS: Of the 118 MRSA isolates, 59 (50.0%), 43 (36.4%), and 10 (8.5%) isolates belonged to agr group I, II, and III, respectively. Six isolates could not be classified. Twenty-six, 73, and 19 isolates presented a vancomycin MIC of 2, 1, and 0.5 microg/mL, respectively. Nine (34.6%), 14 (53.8%), and 2 (7.7%) isolates with MICs of 2 microg/mL belonged to agr group I, II, and III, respectively. Thirty-seven (50.6%), 26 (35.6%), and 6 (8.2%) isolates with MICs of 1 microg/mL belonged to agr group I, II, and III, respectively. Thirteen (68.4%), 3 (15.8%), and 2 (10.5%) isolates with MICs of 0.5 microg/mL belonged to agr group I, II, and III, respectively. The agr group II presented more isolates with MIC of 2 microg/mL (32.6%) than the agr non-group II (16%). Four isolates tested positive for hVISA. Three of them belonged to agr group II. CONCLUSIONS: MRSA isolates with vancomycin MIC of 2 microg/mL were more common in agr group II than in agr non-group II.
Bacteremia ; Methicillin-Resistant Staphylococcus aureus* ; Microbial Sensitivity Tests* ; Polymerase Chain Reaction ; Staphylococcus aureus ; Vancomycin*

BACKGROUND: The transition from manual processing of patient samples to automated workflows in medical microbiology is challenging. Although automation enables microbiologists to evaluate all samples following the same incubation period, the essential incubation times have yet to be determined. We defined essential incubation times for detecting methicillin-resistant Staphylococcus aureus (MRSA), multi-drug resistant gram-negative bacteria (MDRGN), and vancomycin-resistant enterococci (VRE). METHODS: We monitored the growth kinetics of MRSA, MDRGN, and VRE between two and 48 hours on chromogenic media to establish the time points of first growth, single colony appearance, and typical morphology for 102, 104, 106, and 108 colony forming units/mL. Subsequently, we imaged plates inoculated with 778 patient samples after 20, 24, and 36 hours. RESULTS: The first growth, single colony appearance, and typical morphology time points were inoculum-dependent. First growth appeared after 6–18 hours, 4–18 hours, and 8–48 hours for MRSA, MDRGN, and VRE, respectively, and single colonies appeared at 12–18 hours, 6–20 hours, and 12–48 hours, respectively. Typical morphology was visible at 14–22 hours and 12–48 hours for MRSA and VRE, but was not determined for MDRGN. By examining patient samples, ≥98% of MRSA and MDRGN were visible 20 hours after the start of incubation. Following 24 hours of incubation, only 79.5% of VRE were clearly visible on the respective plates. CONCLUSIONS: An incubation time of 20 hours is sufficient for detecting MRSA and MDRGN. VRE growth is much slower and requires additional imaging after 36 hours.
Automation ; Automation, Laboratory* ; Bacteria* ; Gram-Negative Bacteria ; Humans ; Kinetics* ; Methicillin-Resistant Staphylococcus aureus ; Vancomycin-Resistant Enterococci

An antimicrobial compound has been isolated from the leaves of Glochidion superbum. The compound was determined as methyl 3, 4, 5-trihydroxybenzoate (methyl gallate), based on ultraviolet (UV), infrared (IR), nuclear magnetic resonance (NMR) and mass spectroscopy (MS) analysis. The isolated compound exhibited potent antimicrobial activity against three clinical isolates of methicillin resistant Staphylococcus aureus (MRSA) by qualitative agar disc diffusion method and quantitative broth dilution method. Agar disc diffusion was done in a dose-dependent manner for each bacterial isolate at disc potencies of 25, 50, 100, and 150 µg/disc. The zones of inhibition were on average equal to 12.27, 14.20, 15.43, and 24.17 mm respectively. The inhibition zones were compared with that of vancomycin disc at 30 µg as a reference standard. The MIC and MBC values were 50 µg/mL and 100 µg/mL respectively. The results of anti MRSA activity were analyzed using one-way ANOVA with Turkey's HSD and Duncan test. In conclusion, methyl gallate which was isolated from G. superbum showed the inhibition activity against methicillin resistant S. aureus.
Agar ; Diffusion ; Magnetic Resonance Spectroscopy ; Mass Spectrometry ; Methicillin Resistance* ; Methicillin* ; Methicillin-Resistant Staphylococcus aureus ; Methods ; Staphylococcus aureus* ; Staphylococcus* ; Vancomycin