Antimicrobial susceptibility profiles of Pseudomonas aeruginosa and Staphylococcus aureus isolated in Italy from patients with hospital-acquired infections

Here we report the results of the Sentinel Project 2000 and give the susceptibility to selected antibiotics of 108 Pseudomonas aeruginosa and 108 Staphylococcus aureus strains isolated from patients with hospital-acquired lower respiratory tract infections. In P. aeruginosa, susceptibility to aztreonam and ciprofloxacin was lower than 50%. The resistance rate to beta-lactams was up to 25% and to amikacin 15.7%. Blood isolates showed 80-90% susceptibility to all antibiotics tested except for aztreonam and tobramycin. Overall, oxacillin resistance in S. aureus was 45%, reaching 64.3% among the bronchoalveolar lavage isolates, and 42.9% among the blood isolates. These worrying results confirm the need for continuous monitoring of bacterial resistance trends in the hospitals, mainly in ICUs.     

葡萄球菌耐药性监测及其感染的治疗对策

目的研究葡萄球菌的临床分布和耐药性,指导临床合理应用抗生素.方法应用ATB自动细菌鉴定仪及药敏分析仪对临床标本中分离的327株葡萄球菌进行鉴定和药敏试验,同时进行(ORS检测,并结合临床资料进行分析.结果共分离出葡萄球菌327株,其中金黄色葡萄球菌138株(42.2%)居第一位;表皮葡萄球菌101株(3o.9%)位居第二;其他如溶血葡萄球菌、人葡萄球菌、沃氏葡萄球菌等均占有一定比例.327株葡萄球菌中共检出耐苯唑西林葡萄球菌(ORS)230株,占70.3%,苯唑西林敏感葡萄球菌(OSS)97株.OSS对青霉素和红霉素的耐药率高,分别为80.8%～82.2%和44.4%～51.9%,对其他抗生素均敏感.ORS对万古霉素、替考拉宁、呋喃妥因和利福平等敏感性高,对其余多种抗生素耐药.葡萄球菌主要分离自呼吸道、感染伤口、泌尿道和血液等标本.科室分布依次是ICU、肿瘤科和外科等.结论临床分离菌中的葡萄球菌日益增多,对抗生素的耐药率增高,应重视ORS的检测和药敏试验.同时临床医师应根据药敏结果合理有效地选用抗生素.     

新生儿感染耐甲氧西林葡萄球菌的药敏分析

目的:探索致新生儿感染的耐甲氧西林葡萄球菌(MRS)流行病学及常见10种抗菌药物敏感性。方法:按《全国临床检验操作规程》鉴定细菌,玻片法血浆凝固酶试验,K－B扩散法药敏试验。结果:分离出葡萄球菌323株,其中金黄色葡萄球菌(SA)55株,耐甲氧西林金葡菌(MRSA)14株(25．5%),表皮葡萄球菌 171株,耐甲氧西林表葡菌(MRSE)102株(59,6%),腐生葡萄球菌97株,耐甲氧西林腐生葡菌(MRSS)52株(53．6%),院内感染株中 MRS所占比例明显高于甲氧西林敏感葡萄球菌(MS),x~2=3.978,P＝0.046。对氨苄西林、青霉素及红霉素总耐药率分别为86.8%、84.6%及68.9%,而对万古霉素及头孢唑啉总耐药率分别仅为6.7%(7/140)及11.3%(26/231),万古霉素对全部SA、甲氧西林敏感表葡菌(MSSE)、甲氧西林敏感腐生葡菌(MSSS)均敏感,MRS对青霉素、氨苄西林、头孢哇啉、头孢呋辛、头孢他啶、庆大霉素、阿米卡星、诺氟沙星及万古霉素的耐药率较MSS明显增高(P＜0.01)。结论:新生儿耐甲氧西林葡萄球菌易引起医院感染,其耐药性明显,值得高度重视．     

Activity of eight fluoroquinolones against methicillin-resistant Staphylococcus aureus isolated from cutaneous infections

The in vitro susceptibility of methicillin-resistant Staphylococcus aureus to eight fluoroquinolones, norfloxacin, ofloxacin, enoxacin, ciprofloxacin, lomefloxacin, sparfloxacin and nadifloxacin, was evaluated. Methicillin-resistant S. aureus strains were isolated from 64 cutaneous infections from 1991 to 1993. Nadifloxacin exhibited the lowest MIC among all of the fluoroquinolones. In addition, there was no resistance to nadifloxacin. The MIC(50) of these drugs has been increasing in the past 3 years.     

Antimicrobial resistance phenotypes and genotypes of methicillin-resistant Staphylococcus aureus CC398 isolates from Spanish hospitals

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of lineage CC398 is an emerging clone causing human infections but is mostly found in pigs. The aim of this study was to characterize the antimicrobial resistance phenotypes/genotypes of a collection of 137 MRSA CC398 isolates obtained in a previous study from 17 Spanish hospitals, using tetracycline resistance as marker for selection. A multidrug-resistant (MDR) phenotype was present in 79% of analysed isolates, with 17% of them resistant to at least six different antimicrobial families. All tetracycline-resistant isolates (n=137) carried the tetM gene and 75% also carried the tetK gene. Almost 50% of MRSA CC398 isolates showed macrolide and/or lincosamide resistance: a) 39% of isolates were ERY^R-CLI^R (all with constitutive phenotype), with 87% of them carrying the ermC gene, followed by msrA (25%), ermB (21%), vgaA (17%), ermA (6%), lsaB (4%), linA (2%), linB (2%), and ermT (2%, this isolate with the new spa-type t18071); and b) 9% of MRSA CC398 isolates showed the dissociated ERY^S-CLI^R phenotype carrying the linA, linB, lsaB and vgaA genes. Other antimicrobial resistance phenotypes in these MRSA CC398 isolates included resistance to ciprofloxacin (67%), aminoglycosides (21%), mupirocin (6%), chloramphenicol (4%) or fusidic acid (2%). The more common resistance genes detected for some of these antimicrobials were: aac(6’)-Ie-aph(2’’)-Ia (16%) and ant(4’)-Ia (12%) for aminoglycosides, and fexA (3%) for chloramphenicol. The high rate of MDR phenotypes with a wide range of antimicrobial resistance genes shown in this study reduce the potential therapeutic options in case of infections.     

Antibiotic resistance of Staphylococcus aureus isolates from community acquired soft tissue infections in Bulawayo

Fifty cases of community acquired strains of Staphylococcus aureus causing superficial abscesses were tested for their sensitivity to commonly used antibiotics. Ninety-two percent of isolates were resistant to benzyl-penicillin and ampicillin. Possible causes for this very high level of resistance and the implications for antibiotic usage are discussed.     

Community-acquired methicillin-resistant Staphylococcus aureus infections

Methicillin-resistant Staphylococcus aureus (MRSA) should no longer be regarded as a strictly nosocomial pathogen. During the past decade, community-acquired MRSA (CA-MRSA) infections among young persons without healthcare-associated (HCA) risk factors have emerged in several areas worldwide. These infections are caused by strains that almost exclusively carry the staphylococcal cassette chromosome mec type IV element and the Panton-Valentine leukocidin genes and, unlike HCA-MRSA strains, are not multiresistant. Although the majority of CA-MRSA infections are mild skin and soft tissue infections, severe life-threatening cases of necrotizing pneumonia, necrotizing fasciitis, myonecrosis and sepsis have been reported. Clindamycin is an effective agent for skin and soft tissue infections, however attention should be paid to the possibility of the emergence of resistance during treatment in strains with the macrolide, lincosamide and group B streptogramin (MLS(B))-inducible resistance phenotype. For patients with invasive infections that may be caused be CA-MRSA, vancomycin, teicoplanin and linezolid represent appropriate empirical therapeutic options.     

Antimicrobial therapy of Staphylococcus aureus bloodstream infection

Staphylococcus aureus bloodstream infection (BSI) contributes significantly to the morbidity and mortality of in-patients. The optimal therapy for methicillin-susceptible S. aureus BSI consists of penicillins. The efficacy of these drugs is well documented from several published data and supported from a long clinical experience. Methicillin-resistant S. aureus (MRSA) strains are responsible for the majority of nosocomial BSI and are recovered with increasing frequency at hospital admission. Although glycopeptides still represent the drugs of choice, there are several concerns on the treatment of MRSA BSI: reports of clinical failure with vancomycin treatment, regardless of the in vitro susceptibility; increasing reports of MRSA strains with reduced vancomycin susceptibility; difficulty in therapeutic dosage monitoring of teicoplanin; lack of evidence on the efficacy of combination therapy. Recently, new drugs have been introduced in the therapeutic arsenal for MRSA infections, but their clinical use is not yet clearly established for BSI. The review summarises evidence on present therapeutic options for the treatment of S. aureus BSI.     

Antimicrobial therapy of Staphylococcus aureus bloodstream infection

Staphylococcus aureus bloodstream infection (BSI) contributes significantly to the morbidity and mortality of in-patients. The optimal therapy for methicillin-susceptible S. aureus BSI consists of penicillins. The efficacy of these drugs is well documented from several published data and supported from a long clinical experience. Methicillin-resistant S. aureus (MRSA) strains are responsible for the majority of nosocomial BSI and are recovered with increasing frequency at hospital admission. Although glycopeptides still represent the drugs of choice, there are several concerns on the treatment of MRSA BSI: reports of clinical failure with vancomycin treatment, regardless of the in vitro susceptibility; increasing reports of MRSA strains with reduced vancomycin susceptibility; difficulty in therapeutic dosage monitoring of teicoplanin; lack of evidence on the efficacy of combination therapy. Recently, new drugs have been introduced in the therapeutic arsenal for MRSA infections, but their clinical use is not yet clearly established for BSI. The review summarises evidence on present therapeutic options for the treatment of S. aureus BSI.     

Staphylococcus aureus bacteriuria and surgical site infections by methicillin-resistant Staphylococcus aureus

Surgical site infection (SSI) remains an important cause of morbidity among hospitalized patients. We reviewed 421 patients who underwent open urological operations between January 1993 and December 1997 in our institute. Group I consisted of 259 patients who received uncontrolled antimicrobial prophylaxis (AMP) between 1993 and 1995. Group II consisted of 162 patients who received controlled AMP between 1996 and 1997. In group II, penicillins or first to second-generation cephalosporins was used and the duration of use for these agents regulated according to the wound class of each operation. The operations with clean wounds showed the lowest rate of SSI in both groups; the operations with contaminated wounds showed the highest rate of SSI (32.0% in group I and 33.3% in group II). There was no significant difference in the total rates of SSI between the two groups (P=0.216). The most frequently isolated bacterial species was methicillin-resistant Staphylococcus aureus (MRSA), isolated in 73.3% of the cases in group I and in 93.3% in group II. There was no significant difference in the incidence of MRSA isolation between the two groups (P=0.114). The controlled AMP could not lower the incidence of MRSA-induced SSIs. In SSI patients, 22.7% of group I and 35.7% in group II, had MRSA bacteriuria before operation. The prohibition of third-generation cephalosporins and shorter duration of AMP did not reduce the incidence of SSI induced by MRSA because MRSA was not the emerging microorganism but rather a resident in the urological ward. On the other hand, the total incidence of SSI did not increase after regulation of AMP. This finding suggests that older antibacterial agents can prevent infection, except those caused by resistant microorganisms such as MRSA. The effective counter-measure for the prevention of MRSA-induced SSI is needed.     

哺乳期乳腺脓肿分离的金黄色葡萄球菌耐药性与毒力基因研究

目的研究哺乳期乳腺脓肿分离的金黄色葡萄球菌耐药性和毒力基因,为临床治疗提供参考依据。方法收集2015年1月至2017年12月我院乳腺科哺乳期妇女发生乳腺脓肿后分离到的金黄色葡萄球菌,包括耐甲氧西林金黄色葡萄球菌(MRSA)60株和甲氧西林敏感金黄色葡萄球菌(MSSA)64株,用聚合酶链反应(PCR)的方法分析mecA、hla、pvl、clfA、nuc、sea、psm-mec基因。结果 MRSA和MSSA菌株对青霉素(≥90.6%)和红霉素(≥59.4%)的耐药率较高,对利福平、磺胺甲噁唑/甲氧苄啶、莫西沙星、替加环素、万古霉素和利奈唑烷的敏感性较高(≥98.3%)。MRSA对克林霉素、四环素的耐药率明显高于MSSA (P<0.05)。60株MRSA经mecA基因检测均为阳性,64株MSSA均为阴性。Hla、clfA、nuc毒力因子在MSSA和MRSA中均具有较高的携带率(≥98.3%),MRSA携带毒力因子pvl明显低于MSSA (P<0.05)。结论 MRSA携带mecA基因,对克林霉素、四环素的耐药率高于MSSA;MRSA毒力因子pvl携带率低于MSSA,临床应针对哺乳期乳腺脓肿进行MRSA防控,同时需监测MSSA携带毒力基因的状况,评估患者的预后。     

血流感染中分离的耐甲氧西林溶血葡萄球菌的药物敏感性、SCCmec基因分型及同源性分析

摘要：目的 调查分析本地区血流感染中分离耐甲氧西林溶血葡萄球菌(MRSH)的药物敏感性、葡萄球菌盒染色体mec(SCCmec)分型及分子流行病学特征。方法 收集2013年1月1日—2014年12月31日湖南省20家三甲医院血流感染患者的MRSH 78株,采用微量肉汤稀释法进行体外药敏试验;PCR扩增mecA基因及SCCmec基因;脉冲场凝胶电泳(PFGE) 检测MRSH的同源性。结果 78株MRSH中,96.1%的菌株存在mecA基因,MRSH对红霉素、左氧氟沙星和克林霉素的耐药率分别为94.9%、80.7%和53.8%,2株对利奈唑胺耐药,1株对替考拉宁耐药,没有菌株对万古霉素耐药。SCCmec可分型为50%(39/78),不可分型为50%(39/78)。39株可分型菌株中,单个SCCmec类型以Ⅰ型为主(18/39,46.1%),混合型SCCmec类型以Ⅰ+Ⅱ型为主(12/39,30.8%)。PFGE带型整体较为分散,但有6组菌株间存在100%同源性。结论 本地区血流感染中MRSH的耐药形势严峻;在SCCmec可分型的菌株中,以Ⅰ型SCCmec为主,SCCmec多样且不同SCCmec型别之间的耐药性存在差异;本地区MRSH以散发为主,但存在院间及院内交叉感染的可能性,应加强对其监测,减少MRSH的进一步传播。     

Antimicrobial therapy of methicillin resistant Staphylococcus aureus infection

Methicillin-resistant Staphylococcus aureus (MRSA) is now one of the commonest causes of nosocomial infection worldwide. The mainstay of treatment until now has been the glycopeptides (vancomycin and teicoplanin). They are not without toxicity and need parenteral administration and monitoring of levels. The increasing frequency of MRSA infections, coupled with the emergence of glycopeptide resistance in S. aureus has made the introduction of new drugs active against Gram-positive organisms essential. New agents active against Gram-positive organisms represent either genuinely novel classes of antimicrobials (e.g., oxazolidinones and lipoproteins) or those derived from existing classes (e.g., tetracyclines, glycopeptides, streptogramins and cephalosporins). Some of these newer antibiotics appear to be effective against multi-resistant organisms including MRSA.     

Antimicrobial proteins from snake venoms: direct bacterial damage and activation of innate immunity against Staphylococcus aureus skin infection

The innate immune system is the first line of defense against microbial diseases. Antimicrobial proteins produced by snake venoms have recently attracted significant attention due to their relevance to bacterial infection and potential development into new therapeutic agents. Staphylococcus aureus is one of the major human pathogens causing a variety of infections involving pneumonia, toxic shock syndrome, and skin lesions. With the recent emergence of methicillin (MRSA) and vancomycin (VRSA) resistance, S. aureus infection is a serious clinical problem that will have a grave socio-economic impact in the near future. Although S. aureus susceptibility to innate antimicrobial peptides has been reported recently, the protective effect of snake venom phospholipase A? (svPLA?) proteins on the skin from S. aureus infection has been understudied. This review details the protective function of svPLA?s derived from venoms against skin infections caused by S. aureus. We have demonstrated in vivo that local application of svPLA? provides complete clearance of S. aureus within 2 weeks after treatment compared to fusidic acid ointment (FAO). In vitro experiments also demonstrate that svPLA? proteins have inhibitory (bacteriostatic) and killing (bactericidal) effects on S. aureus in a dose-dependant manner. The mechanism of bacterial membrane damage and perturbation was clearly evidenced by electron microscopic studies. In summary, svPLA?s from Viperidae and Elapidae snakes are novel molecules that can activate important mechanisms of innate immunity in animals to endow them with protection against skin infection caused by S. aureus.     

Characterisation of Staphylococcus haemolyticus isolated from urinary tract infections

OBJECTIVE: To determine some virulence factors and antimicrobial susceptibilities of Staphylococcus haemolyticus from urinary tract infections. DESIGN: This was a laboratory based cross sectional study on S. haemolyticus isolates from urinary tract infections. SETTING: College of Health Sciences in Harare, Zimbabwe. SUBJECTS: People of all ages with urinary tract infections presenting at health centres in Harare. MAIN OUTCOMEMEASURES: Prevalence of virulence factors and antimicrobial susceptibilities of S. haemolyticus isolates. RESULTS: Deoxyribonuclease (DNase) was produced by 91.8%, delta-haemolysin by 75.5% and slime by 32.7% of the 49 S. haemolyticus isolates. Less than 10% of the isolates produced lipase, alpha haemolysin and protease. All the S. haemolyticus isolates were sensitive to vancomycin and 79.6% to clindamycin. Over 70% of the isolates were resistant to chloramphenicol, co-trimoxazole, erythromycin, oxacillin, ampicillin and penicillin G. Multi-drug resistance to five or more drugs was observed in 69.4% of the isolates. Twenty nine of the 37 isolates that produced delta-haemolysin showed multi-drug resistance. CONCLUSIONS: The virulence factors produced by many S. haemolyticus were DNase and delta-haemolysin. Most of the isolates were resistant to many antimicrobial drugs.     

耐甲氧西林金黄色葡萄球菌多重耐药研究

目的了解本地区耐甲氧西林金黄色葡萄球菌（MRSA）的多重耐药情况。方法收集经头孢西丁纸片扩散试验和青霉素结合蛋白2a胶乳凝集实验分离出的51株MRSA,用β-内酰胺酶实验、D试验、Kirby-Bauer法检测MRSA产β-内酰胺酶以及对红霉素、克林霉素、4种氟喹诺酮类药物（氧氟沙星、诺氟沙星、左旋氧氟沙星、加替沙星）和万古霉素耐药性。结果51株MRSA头孢西丁纸片抑菌圈直径介于6～20mm,产β-内酰胺酶率为84.3%,对红霉素、克林霉素、氟喹诺酮类、万古霉素耐药率分别为98.0%、86.3%、88.2%、0,红霉素诱导克林霉素耐药率为50.0%（3/6）。结论MRSA呈多重耐药,轻度感染可根据药敏结果选万古霉素与氟喹诺酮类？生素联合用药。