Olusegun O. Soge

Characterization of methicillin-resistant Staphylococcus aureus and methicillin-resistant coagulase-negative Staphylococcus spp. isolated from US West Coast public marine beaches

OBJECTIVES The aim of this study was to isolate and characterize methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus spp. (MRCoNS) from marine water and intertidal beach sand from public beaches in Washington State, USA. METHODS Fifty-one staphylococci from Washington State beaches were characterized using antimicrobial susceptibility testing, carriage of acquired tetracycline and/or macrolide resistance genes, staphylococcal cassette chromosome mec (SCCmec) typing, the BBL Crystal Gram-Positive ID System and/or 16S rRNA sequencing, coagulase test and multilocus sequence typing (MLST) for MRSA. RESULTS Five multidrug-resistant MRSA SCCmec type I, of which three were MLST type ST45, one ST59 and one a new MLST type, ST1405, plus one susceptible non-typeable (NT) MRSA ST30 were characterized. Thirty-three MRCoNS isolates, representing 21 strains from 9 Staphylococcus spp., carried a range of SCCmec types [I (2), II (6), III (3), V (2), I/II (1) and NT (7)] and varied in their antibiotic susceptibility to other antibiotic classes and carriage of acquired tetracycline/macrolide resistance gene(s). MRSA and MRCoNS donors co-transferred tet(M) and erm(A) genes to an Enterococcus faecalis recipient at a frequency of 10(-8). CONCLUSIONS This is the first report of MRSA and MRCoNS isolated from marine water and intertidal beach sand. The MLST types and antibiotic carriage of five MRSA isolates were similar to hospital MRSA isolates rather than US community-acquired MRSA isolates. Our results suggest that public marine beaches may be a reservoir for transmission of MRSA to beach visitors as well as an ecosystem for exchange of antibiotic resistance genes among staphylococci and related genera.

Neisseria gonorrhoeae With High-Level Resistance to Azithromycin: Case Report of the First Isolate Identified in the United States

We report on the first Neisseria gonorrhoeae isolate in the United States identified with high-level resistance to azithromycin. This report discusses the epidemiologic case investigation, the molecular studies of resistance-associated mutations and N. gonorrhoeae multiantigen sequence typing, and challenges posed by emerging gonococcal antimicrobial resistance.

Neisseria gonorrhoeae Antimicrobial Resistance Among Men Who Have Sex With Men and Men Who Have Sex Exclusively With Women: The Gonococcal Isolate Surveillance Project, 2005–2010

BACKGROUND Gonorrhea treatment has been complicated by antimicrobial resistance in Neisseria gonorrhoeae. Gonococcal fluoroquinolone resistance emerged more rapidly among men who have sex with men (MSM) than men who have sex exclusively with women (MSW). OBJECTIVE To determine whether N. gonorrhoeae urethral isolates from MSM were more likely than isolates from MSW to exhibit resistance to or elevated minimum inhibitory concentrations (MICs) of antimicrobials used to treat gonorrhea. DESIGN 6 years of surveillance data from the Gonococcal Isolate Surveillance Project. SETTING Publicly funded sexually transmitted disease clinics in 30 U.S. cities. PATIENTS Men with a total of 34 600 episodes of symptomatic urethral gonorrhea. MEASUREMENTS Percentage of isolates exhibiting resistance or elevated MICs and adjusted odds ratios for resistance or elevated MICs among isolates from MSM compared with isolates from MSW. RESULTS In all U.S. regions except the West, isolates from MSM were significantly more likely to exhibit elevated MICs of ceftriaxone and azithromycin than isolates from MSW (P < 0.050). Isolates from MSM had a high prevalence of resistance to ciprofloxacin, penicillin, and tetracycline and were significantly more likely to exhibit antimicrobial resistance than isolates from MSW (P < 0.001). LIMITATIONS Sentinel surveillance may not be representative of all patients with gonorrhea. HIV status, travel history, and antimicrobial use data were missing for some patients. CONCLUSION Men who have sex with men are vulnerable to the emerging threat of antimicrobial-resistant N. gonorrhoeae. Because antimicrobial susceptibility testing is not routinely done in clinical practice, clinicians should monitor for treatment failures among MSM diagnosed with gonorrhea. Strengthened prevention strategies for MSM and new antimicrobial treatment options are needed.

Neisseria gonorrhoeae Antimicrobial Susceptibility Surveillance - The Gonococcal Isolate Surveillance Project, 27 Sites, United States, 2014.

PROBLEM/CONDITION Gonorrhea is the second most commonly reported notifiable disease in the United States; 350,062 gonorrhea cases were reported in 2014. Sexually transmitted infections caused by Neisseria gonorrhoeae are a cause of pelvic inflammatory disease in women, which can lead to serious reproductive complications including tubal infertility, ectopic pregnancy, and chronic pelvic pain. Prevention of sequelae and of transmission to sexual partners relies largely on prompt detection and effective antimicrobial treatment. However, treatment has been compromised by the absence of routine antimicrobial susceptibility testing in clinical care and evolution of antimicrobial resistance to the antibiotics used to treat gonorrhea. PERIOD COVERED 2014. DESCRIPTION OF THE SYSTEM The Gonococcal Isolate Surveillance Project (GISP) was established in 1986 as a sentinel surveillance system to monitor trends in antimicrobial susceptibilities of N. gonorrhoeae strains in the United States. Each month, N. gonorrhoeae isolates are collected from up to the first 25 men with gonococcal urethritis attending each of the participating sexually transmitted disease (STD) clinics at 27 sites. The number of participating sites has varied over time (21-30 per year). Selected demographic and clinical data are abstracted from medical records. Isolates are tested for antimicrobial susceptibility using agar dilution at one of five regional laboratories. RESULTS A total of 5,093 isolates were collected in 2014. Of these, 25.3% were resistant to tetracycline, 19.2% to ciprofloxacin, and 16.2% to penicillin (plasmid-based, chromosomal, or both). Reduced azithromycin susceptibility (Azi-RS) (defined as minimum inhibitory concentration [MIC] ≥2.0 µg/mL) increased from 0.6% in 2013 to 2.5% in 2014. The increase occurred in all geographic regions, but was greatest in the Midwest, and among all categories of sex of sex partners (men who have sex with men [MSM], men who have sex with men and women [MSMW], and men who have sex with women [MSW]). No Azi-RS isolates exhibited reduced cefixime or ceftriaxone susceptibility (Cfx-RS and Cro-RS, respectively). The prevalence of Cfx-RS (MIC ≥0.25 µg/mL) increased from 0.1% in 2006 to 1.4% in both 2010 and 2011, decreased to 0.4% in 2013, and increased to 0.8% in 2014. Cro-RS (MIC ≥0.125 µg/mL) increased following a similar pattern but at lesser percentages (increased from 0.1% in 2008 to 0.4% in 2011 and decreased to 0.1% in 2013 and 2014). The percentage of isolates resistant to tetracycline, ciprofloxacin, penicillin, or all three antimicrobials, was greater in isolates from MSM than from MSW. INTERPRETATION This is the first report to present comprehensive surveillance data from GISP and summarize gonococcal susceptibility over time, as well as underscore the history and public health implications of emerging cephalosporin resistance. Antimicrobial susceptibility patterns vary by geographic region within the United States and by sex of sex partner. Because dual therapy with ceftriaxone plus azithromycin is the only recommended gonorrhea treatment, increases in azithromycin and cephalosporin MICs are cause for concern that resistance to these antimicrobial agents might be emerging. It is unclear whether increases in the percentage of isolates with Azi-RS mark the beginning of a trend. The percentage of isolates with elevated cefixime MICs increased during 2009-2010, then decreased during 2012-2013 after treatment recommendations were changed in 2010 to recommend dual therapy (with a cephalosporin and a second antibiotic) and a higher dosage of ceftriaxone. Subsequently, the treatment recommendations were changed again in 2012 to no longer recommend cefixime as part of first-line therapy (leaving ceftriaxone-based dual therapy as the only recommended therapy). Despite the MIC decrease (i.e., trend of improved cefixime susceptibility) during 2012-2013, the increase in the number of strains with Cfx-RS in 2014 underscores the potential threat of cephalosporin-resistant N. gonorrhoeae. PUBLIC HEALTH ACTION The National Strategy for Combating Antibiotic-Resistant Bacteria identifies prevention, rapid detection, and control of outbreaks of ceftriaxone-resistant N. gonorrhoeae infection as a priority for U.S. PUBLIC HEALTH ACTION Antimicrobial susceptibility surveillance is conducted to guide development of treatment recommendations for effective therapy and prevention of complications from and transmission of gonorrhea. Federal agencies can use GISP data to develop national treatment recommendations and set research and prevention priorities. Local and state health departments can use GISP data to determine allocation of STD prevention services and resources, guide prevention planning, and communicate best treatment practices to health care providers. Continued surveillance, appropriate treatment, development of new antibiotics, and prevention of transmission remain the best strategies to reduce gonorrhea incidence and morbidity.

Methicillin-resistant Staphylococcus aureus from dental school clinic surfaces and students

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) isolated from frequently touched dental school clinic surfaces were compared with MRSA isolated nasal cultures of dental students. METHOD Sixty-one dental students and 95 environmental surfaces from 7 clinics were sampled using SANICULT (Starplex Scientific Inc, Etobicoke, Ontario, Canada) swabs. Antimicrobial susceptibility testing was performed, and pulsed-field gel electrophoresis analysis, the mecA gene, multilocus sequence type, and SCCmec type were determined by polymerase chain reaction and sequencing. RESULTS Thirteen (21%) dental students and 8 (8.4%) surfaces were MRSA positive. Three MRSA strains were SCCmec type IV, whereas 3 were nontypeable isolates and Panton-Valentine leukocidin positive (PVL+), and none were USA300. One surface and 1 student isolate shared the same multilocus sequence type ST 8 and were 75% related. Two groups of students carried the same MRSA strains. CONCLUSION The MRSA-positive samples were from 4 of 7 dental clinics. In addition, 21% of the dental students carried MRSA, which is > 10 times higher than the general public and twice as frequent as in other university students. This is the first study to characterize MRSA from dental clinic surfaces and dental students and suggests that both may be reservoirs for MRSA. Further studies are needed to verify this premise.

Vancomycin-resistant Enterococcus spp. in marine environments from the West Coast of the USA.

Aims:  The aim of the study was to determine if vancomycin‐resistant Enterococcus spp. [VRE] carrying vanA and/or vanB genes were present in public marine beaches and a fishing pier [2001–2003, 2008] from Washington and California [2008].

Characterization of Methicillin‐resistant Staphylococcus aureus isolated from public surfaces on a University Campus, Student Homes and Local Community

Aim:  Isolation and characterization of methicillin‐resistant Staphylococcus aureus (MRSA) from frequently touched nonhospital environmental surfaces at a large university, student homes and community sites.

A conjugative macrolide resistance gene, mef(A), in environmental Clostridium perfringens carrying multiple macrolide and/or tetracycline resistance genes

Aims:  To determine if environmental Clostridium perfringens carry antibiotic resistance genes and if the genes are mobile.

Characterization of macrolide resistance genes in Haemophilus influenzae isolated from children with cystic fibrosis

OBJECTIVES to determine the mechanism(s) of macrolide resistance in Haemophilus influenzae isolated from cystic fibrosis (CF) patients participating in a randomized placebo-controlled trial of azithromycin. METHODS macrolide susceptibility, mutations and carriage of the macrolide resistance genes erm(A), erm(B), erm(C), erm(F) and mef(A) were determined using PCR assays and sequencing or hybridization of the PCR products. H. influenzae isolates were used as donors in conjugation studies with H. influenzae and Enterococcus faecalis recipients. Transconjugant susceptibility and the macrolide resistance genes carried were determined. RESULTS of the 106 H. influenzae isolates, 27 were resistant and 78 intermediate resistant to azithromycin and/or erythromycin. All isolates carried one or more macrolide resistance gene(s), with the mef(A), erm(B) and erm(F) genes found in 74%, 31% and 29% of the isolates, respectively. None of the selected isolates had L4 or L22 mutations. Twenty-five donors, with various macrolide MICs, transferred macrolide resistance genes to H. influenzae Rd (3.5 × 10(-7)-1 × 10(-10)) and/or E. faecalis (1 × 10(-7)-1 × 10(-8)) recipients. The H. influenzae transconjugants were phenotypically resistant or intermediate to both macrolides while E. faecalis transconjugants were erythromycin resistant. CONCLUSIONS this is the first identification of erm(A), erm(C) and erm(F) genes in H. influenzae or bacteria from CF patients and the first characterization of macrolide gene transfer from H. influenzae donors. The high level of H. influenzae macrolide gene carriage suggests that the use of azithromycin in the CF population may ultimately reduce the effectiveness of continued or repeated macrolide therapy.

In vitro synergy testing of novel antimicrobial combination therapies against Neisseria gonorrhoeae

BACKGROUND Antimicrobial-resistant Neisseria gonorrhoeae is a major public health threat. Current CDC treatment guidelines for uncomplicated gonorrhoea recommend only ceftriaxone plus either azithromycin or doxycycline. Additional treatment options are needed. METHODS We used antibiotic gradient synergy testing (the Etest) to evaluate antimicrobial combinations that included a third-generation cephalosporin (cefixime or ceftriaxone) plus azithromycin, doxycycline, gentamicin, rifampicin or fosfomycin. We tested each combination against 28 clinical N. gonorrhoeae isolates and four control strains of varying susceptibility profiles, and compared the results with those obtained using combination antimicrobial testing using agar dilution. We calculated the fractional inhibitory concentration index (FICI) for each combination to determine synergy, the results being interpreted as follows: FICI ≤ 0.5 = synergy; FICI > 4.0 = antagonism; and FICI > 0.5-4 = indifference. RESULTS The combinations of a third-generation cephalosporin plus azithromycin, doxycycline, rifampicin, gentamicin or fosfomycin produced FICIs of indifference. The Etest and agar dilution methods produced comparable results. CONCLUSIONS Combinations of ceftriaxone plus rifampicin, gentamicin or fosfomycin may warrant further clinical investigation as treatments for gonorrhoea. Using the Etest for synergy testing is a viable method that has practical advantages over agar dilution.