Introduction. Pseudomonas aeruginosa is one of the important causes of hospital-acquired infections in Intensive Care Unit (ICU) and considered as a major determinant of morbidity and mortality in patients affected by cystic fibrosis (CF). The aim of this study was to investigate clonal diversity among randomly picked P. aeruginosa isolates of CF and the other hospitalized patients in ICU.
Methods. Cultivation, identification, and antimicrobial suscep- tibility testing of P. aeruginosa isolates were performed using standard techniques. The genetic similarity of the strains was investigated by amplification of the Enterobacterial Repetitive Intergenic Consensus-polymerase chain reaction (ERIC-PCR) sequence. Results and discussion. Among 49 isolates, sixteen were isolated from 11 patients affected by CF and 33 came from an epidemiologi- cal investigation of 25 P. aeruginosa infected patients of ICU. Five clusters were generated for all isolates analyzed through ERIC-PCR genotyping. Two major clusters (B and C) were discovered in P. aer- uginosa isolates of ICU and CF patients during the whole period of this study. Fifteen unique antibiogram patterns obtained from all iso- lates and multi-resistant P. aeruginosa (MRPA) were identified in 23 isolates (47%). MRPA isolates were detected in all clusters (except A) while pan-resistant isolates were recovered only in cluster C. The high prevalence of related or identical isolates in CF and non-CF patients can be due to transmission of particular domi- nant clones in ICU ward. Therefore, enhanced infection-control may become necessary to prevent further spread of clonal strains

Ashtiani Haghi, MT

Hosseinpour Sadeghi, R

Mahmoudi, S

Mamishi, S

Movahedi, Z

Pourakbari, B

Sabouni, F

English

PubMed

Journal of Preventive Medicine and Hygiene (JPMH)

24IntroductionPseudomonas aeruginosa is one of the important caus-es of hospital-acquired infections in intensive care unit (ICU) and considered as a major determinant of morbid-ity and mortality in patients affected by cystic fibrosis (CF) [1-3]. Surveillance of nosocomial P. aeruginosa infections has revealed trends of increasing antimicrobial resist-ance [4]. The emergence of transmissible P. aeruginosa strains at hospital and its spread to other P. aeruginosa-negative patients raise concerns especially in ICU set-tings, where the number of antibiotic agents with good activity is limited [5, 6]. Several studies describe the pa-tient-to-patient transmission of this bacteria from cent-ers related with CF patients [7, 8]. At our hospital, CF patients are cared in gastroenterol-ogy ward and P. aeruginosa-positive and P. aerugino-sa-negative patients are not separated from each other in this ward. In addition, these patients move to other wards especially ICU during their hospitalization. The aim of this study was to investigate epidemiology of an-timicrobial resistance and clonal diversity among ran-domly picked P. aeruginosa isolates of CF and the other hospitalized patients in ICU.Material and methods Between January and December 2010, randomly picked P. aeruginosa isolates of infected patient in ICU and pa-tients affected by CF were collected from the tertiary referral Children Medical Hospital in Tehran, Iran. The patients investigated in this study were all prone to P. aeruginosa infection. An infected patient was defined as a patient with clinical symptoms of infection, and from whom a clinical culture yielded a dominant growth of P.aeruginosa. Clinical information on P. aeruginosa pa-tient isolates was collected from medical records. Infor-mation included age, sex, length of hospital stay, history of transfer from another wards, clinical outcome and mi-crobiological data. A number of CF patients had more than one isolates and some of them were isolated while they were transferred to the ICU. In addition several cultures were obtained oRiginal aRticlePseudomonas aeruginosa infection among cystic fibrosis and ICU patients in the referral Children  Medical Hospital in Tehran, IranZ. MOVAHEDI, B. POURAKBARI*, S. MAHMOUDI*, F. SABOUNI**, M.T. HAGHI ASHTIANI***,  R. HOSSEINPOUR SADEGHI*, S. MAMISHI* **Department of Pediatric Infectious Diseases, School of Medicine, Qom University of Medical Sciences, Qom, Iran; * Pediatric Infectious Diseases Research Center, Tehran University of Medical Sciences, Tehran, Iran; ** Department of Pediatric Infectious Disease, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; *** Department of Pathology, School of Medicine, Tehran University of Medical Sciences, Tehran, IranKey wordsPseudomonas aeruginosa	•	Cystic	fibrosis	•	Cross-infectionSummaryIntroduction. Pseudomonas aeruginosa is one of the important causes of hospital-acquired infections in Intensive Care Unit (ICU) and considered as a major determinant of morbidity and mortality in patients affected by cystic fibrosis (CF). The aim of this study was to investigate clonal diversity among randomly picked P. aeruginosa isolates of CF and the other hospitalized patients in ICU.Methods. Cultivation, identification, and antimicrobial suscep-tibility testing of P. aeruginosa isolates were performed using standard techniques. The genetic similarity of the strains was investigated by amplification of the Enterobacterial Repetitive Intergenic Consensus-polymerase chain reaction (ERIC-PCR) sequence. Results and discussion. Among 49 isolates, sixteen were isolated from 11 patients affected by CF and 33 came from an epidemiologi-cal investigation of 25 P. aeruginosa infected patients of ICU. Five clusters were generated for all isolates analyzed through ERIC-PCR genotyping. Two major clusters (B and C) were discovered in P. aer-uginosa isolates of ICU and CF patients during the whole period of this study. Fifteen unique antibiogram patterns obtained from all iso-lates and multi-resistant P. aeruginosa (MRPA) were identified in 23 isolates (47%). MRPA isolates were detected in all clusters (except A) while pan-resistant isolates were recovered only in cluster C.The high prevalence of related or identical isolates in CF and non-CF patients can be due to transmission of particular domi-nant clones in ICU ward. Therefore, enhanced infection-control may become necessary to prevent further spread of clonal strains.J prev med hyg 2013; 54: 24-28Pseudomonas aeruginosa infection among cystic fibrosis Patients25Tab. I. patient details, origin and date of isolation, outcome and microbiological data of all the p. aeruginosa isolates.Patient* isolates age (month)gender ward type of specimenlentgh of hospital stay(Day) time of isolation after hospitalization(Day)outcome ERIC-PCR patternantibiogram pattern1 a 11 m pICU Trachea tube 21 4 death d 122 a 12 m pICU Wound 30 6 discharge B 33 a 12 F pICU ear secretion 58 5 discharge C 154 a 7 m pICU Trachea tube 34 20 discharge e 115 a 2.5 F pICU Urine 29 2 discharge C 156 a 10 F pICU Urine 30 21 death C 157 a 6 F pICU Wound 11 10 death A 68 a 3 m pICU Urine 21 5 death B 79 a 11 F pICU Trachea tube 5 2 discharge B 810a3 F pICU Wound 22 12 deathB 7b eye 22 B 411 a 7 F pICU Trachea tube 15 5 discharge B 412 a 120 m pICU Urine 13 2 discharge B 313 a 2 m pICU Trachea tube 5 3 death B 1114a 9 m pICU Trachea tube 39 4 dischargeB 4b   Wound 17 B 315 a 108 F pICU Trachea tube 54 2 discharge B 216 a 24 m pICU Trachea tube 4 3 discharge A 717a4 F pICUBlood284dischargee 10b Alveolar aspirate 14 A 3c Sputum 8 A 3d Alveolar aspirate 8 C 1218a8 m pICU Trachea tube 18 2 dischargeC 2b Urine 14 C 119a36FpICU Wound 403dischargeB 7b F 5 C 14c F 20 C 1220 a 4 m pICU Urine 25 1 discharge C 1521 a 31 F pICU Urine 26 5 discharge B 322 a 36 m pICU Blood 58 1 dischrge C 1523 a 120 m pICU Trachea tube 19 4 discharge B 324 a 24 m pICU pharynx 15 6 discharge C 1425 a 3 F pICU Wound 51 3 death C 1526 a 12 F pICU Wound 14 14 death C 1527a192 Fgastroenterology Alveolar aspirate564deathB 6b gastroenterology Sputum 40 B 7c gastroenterology Sputum 46 B 628a72 mpICU Trachea tube122deathB 5b pICU Tracheal aspirate 7 B 13c pICU Trachea tube 11 B 1129 a 5 F pICU Sputum 10 1 dischage C 1530 a 45 m gastroenterology Sputum 14 2 dischage B 831 a 120 m gastroenterology Sputum 12 2 death B 732 a 10 m pICU Wound 10 9 death C 1533 a 5 F gastroenterology Urine 11 1 dischage B 934 a 7 m gastroenterology Urine 36 2 death C 1535 a 72 m pICU Trachea tube 7 2 deathB 3b gastroenterology Sputum 7 C 1536 a 48 F gastroenterology Sputum 7 1 dischage B 10*Isolates number of 26 to 36 isolated from CF patients. pICU: pediatric Intensive Care UnitZ. Movahedi et al.26from some patients as long as they stayed in the ICU. Cultivation, identification, and antimicrobial suscepti-bility testing of P. aeruginosa isolates were performed using standard techniques [9].Multi-resistant P. aeruginosa (MRPA) was defined as strains resistant to ≥ 3 of the following classes of antibi-otics: antipseudomonal penicillins, antipseudomonal ox-yimino-b-lactams, fluoroquinolones, aminoglycosides, and carbapenems [10].The genetic similarity of the strains was investigated by amplification of the Enterobacterial Repetitive Intergen-ic Consensus-polymerase chain reaction (ERIC-PCR).sequence  [11]. Comparison of banding patterns was performed using Gelcompar II, version 6.5 (Applied Maths, Sint-Matens-latem, Belgium). Cluster analy-sis was accomplished with the unweighted pair group method using average linkages (UPGMA). ERIC-PCR was performed for P. aeruginosa isolates and related-ness among genetic clones was defined as 80% similar-ity as belonging to one clone.ResultsDuring one year, 36 patients aged 3.5 to 192 month (av-erage 33.4) were entered to this study. Table I illustrated the patient details, origin and date of isolation, outcome, ERIC-PCR and antibiogram pattern of all isolates. Among 49 isolates, sixteen were isolated from 11 pa-tients affected by CF and 33 came from an epidemio-logical investigation of 25 P. aeruginosa strains isolated from infected patients of ICU. P. aeruginosa isolates were recovered from trachea tube (26%), urine (18%), wound (16%), sputum (18%), al-veolar aspirate (8%), blood (4%), tracheal aspirate (2%), ear secretion (2%), and eye (2%).Average length of hospital stay in all patients was 24 days. Of the 36 patients, 14 died during the study (case fatality rate, 39%); whereas half of them were from CF patients (case fatality rate, 64%). MRPA were identified in 23 isolates (47%) and consistently detected during the study period. Among all isolates, 11 considered as pan-resistant isolates that 5 of them belonged to CF patients.Five clusters were generated for all isolates analyzed through ERIC-PCR genotyping, which were designated alphabetically from A to D (Fig.  1). Cluster B and C comprised both ICU and CF isolates while cluster A, D and E had only isolates of ICU ward. Elev-en isolates of cluster B were identical whereas cluster C comprised of only 3 identical isolates. MRPA isolates were detected in all clusters (except A) while pan-resist-ant isolates were recovered only in cluster C.Cluster B and C was seen during the study period (4 seasons) (Fig. 2). Clus-ter A was introduced during summer and remained present during the rest Fig. 1. dendrogram of genotype analysis derived from 49 p. aer-uginosa isolates. The scale at the top represents the genetic dis-tance between the isolates..Fig. 2. distribution of different clusters during 2010.Pseudomonas aeruginosa infection among cystic fibrosis Patients27of the study. During the autumn, one patient appeared in cluster D and E. However, cluster D emerged in the third season, detection of this cluster during the winter did not occur. In our study, 15 unique antibiogram patterns obtained from all isolates (Tab. II). Most of the isolates were re-sistant to antipseudomonal oxyimino-b-lactams. The highest percentage of susceptibility was seen in amino-glycosides (71%) followed by piperacillin-tazobactam (67%), imipenem (63%), ciprofloxacin (59%), and meropenem (55%). Different antibiogram patterns were displayed in a number of isolates even with ≥ 95% simi-larity.DiscussionOur hospital is a tertiary referral center in which the ICU setting includes mixed patients such as CF patients and transmission of P. aeruginosa strains between CF and the other hospitalized patients in ICU is probable,Therefore genotyping of P. aeruginosa isolates seems to be essential to clarify our hospital epidemiology. The spread of infec-tion from patients with CF is a definite risk in children’s wards especially in ICU [12, 13]. In this study, molecular typing suggests cross-transmission between CF and non-CF patients. According to our results, infections were predominantly caused by strains with cluster B and C. presence of these patterns during the whole period of this study suggesting that these clones are adapted to our hos-pital. Cluster B was identified in 25 strains (51% of all typed isolates) and highly appeared in the first 3 months of 2010 and circulated until end of the study.Our analysis demonstrated that CF isolates are genotypi-cally closely related to non-CF isolates. The two major clusters (B and C) in our study were discovered in both patient populations that suggest probable occurrence of cross-infection between these patients. Studies about P. aeruginosa cross-infection demonstrat-ed controversy evidence of clonal spread in CF centers. Some studies have revealed convincing evidence of clonal spread at CF holiday camps or centers  [14-18]. Another study at the Vancouver CF Centre did not rep-resent any evidence of significant cross-infection with P. aeruginosa [19]. Emergence of MDR expect to become more preva-lent in many hospitals [20, 21]. There is no doubt that cross-transmission plays an important epidemiological role in MRPA isolates  [22, 23], so prevention of the acquisition of these isolates are essential due to lim-ited therapeutic options and increased mortality  [24]. On the other hand, prevalence of strains with resistance to all antimicrobial agents is a major risk for hospital-ized patients especially in CF patients because of rare P. aeruginosa eradication and subsequently occurrence of chronic infection [25, 26]. P. aeruginosa has capacity to develop resistance to es-sentially antimicrobial agents  [27] and may require treatment with less commonly used antibacterial agents such as colistin [4]. Our results support other studies  [28] that mentioned aminoglycosides are clinically effective against P. aer-uginosa isolates when administrated intravenously or by nebulization.Finally, in our study the high prevalence of related or identical isolates in CF and non–CF patients can be due to transmission of particular dominant clones in ICU ward. This suggests cross-infection can occur between CF and non-CF patients. Therefore, enhanced infection-control including strict segregation policies, basic hygiene meas-ures and continued microbiological surveillance may be-come necessary to prevent further spread of clonal strains.Tab. II. Antibiogram patterns of 49 p. aeruginosa isolates.Pattern numberIsolates* CF FEP CP MEM CAZ PTZ IMP GM AM1 18b S S S S S S S S S2 15,18a S S S S r S S S S3 2a,12,14b,17b,17c,21,23,35a r S S S S S S S S4 10b,11,14a r S S S r S S S S5 28a S S S r S S S r S6 7,27a,27c r r S S S S S S S7 8,10a,16,19a,27b,31 r r S S r S S S S8 9,30 r r S r r S S S S9 33 r r r r r S S S S10 17a,36 r r S r r r S S S11 2c,10b,28c r r r S r S r S S12 1,17d,19c r r r r r r S S S13 28b r r S S r S r r r14 19b,24 r r r r r S r r r15 2b,5,6,20,22,25,26,29,32,34,35b r r r r r r r r rCF, Cephalothin; Fep, Cefepime; Cp, Ciprofloxacin; mem, meropenem; CAZ, Ceftazidime; pTZ, piperacillin-tazobactam; Imp, Imipenem; gm, gentamycin; Am, Amikacin * Isolate number of 26 to 36 belongs to CF patientsZ. Movahedi et al.28Reference [1] Emerson J, Rosenfeld M, McNamara S, et al. Pseudomonas aeruginosa and other predictors of mortality and morbid-ity in young children with cystic fibrosis. 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The role of mutators in the emergence of antibiotic-resistant bacteria. Drug Resist Updat 2003;6:137-45.[28] Ratjen F, Brockhaus F, Angyalosi G. Aminoglycoside therapy against Pseudomonas aeruginosa in cystic fibrosis: a review. J Cyst Fibros 2009;8:361-9.n	 Received on April 28, 2012. Accepted on November 21, 2012.n	 Correspondence: Dr. Setareh Mamishi, Department of Pediatric Infectious Diseases, Children Medical Center Hospital School of Medicine, Tehran University of Medical Sciences, No.62, Gharib St., Keshavarz Blvd., Tehran, Iran – Tel. +98- 21- 6642- 8996 - Fax: +98- 21- 6642- 8996 - E-mail: smamishi@sina.tums.ac.ir

Pseudomonas aeruginosa infection among cystic fibrosis and ICU patients in the referral Children Medical Hospital in Tehran, Iran

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Pseudomonas aeruginosa infection among cystic fibrosis and ICU patients in the referral Children Medical Hospital in Tehran, Iran

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