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Introduction: Female sex workers (FSWs) are the second most affected population by HIV in Iran. However, their HIV testing practices are poorly understood. The aim of this study was to investigate testing and its associated factors among HIV negative FSWs. Materials and Methods: Using facility based sampling, 1005 FSWs were recruited in 14 cities of Iran in 2010. Biological and survey data were collected through dried blood spot testing and standardized risk assessment questionnaire, respectively. In this paper, the prevalence of HIV testing and its correlates were explored among 714 HIV-negative FSWs using descriptive statistics and logistic regression models. Results: Overall 65.4% had not tested in the past year. Only 27.5% had tested in the past year and received their results. FSWs who perceived themselves at risk of HIV (Adjusted Odds Ratio (AOR) = 8.35, 95% CI: 1.46, 47.6), had received free condom during past year (AOR = 3.90, 95% CI: 1.67, 9.14), started sex work at an older age (AOR18–24 = 2.83, 95% CI: 1.14, 7.0; AOR >24 = 2.76, 95% CI: 1.11, 6.84), and knew an HIV testing site (AOR = 5.67, 95% CI: 2.60, 12.4) had a significantly higher chance of having a recent HIV test result. Conclusions: Less than one third of FSWs in Iran knew their recent HIV status. Interventions to help FSWs evaluate their potential risk for HIV and integrate HIV testing services in condom distribution programs, could be viable strategies in increasing HIV testing uptake among FSWs. Health policy makers should also try to de-stigmatize HIV testing, identify the barriers to HIV testing, and make HIV testing sites more visible to FSWs. [ABSTRACT FROM AUTHOR]

Objective: Mycobacterium marinum causes a rare cutaneous disease known as fish tank granuloma (FTG). The disease manifestations resemble those associated with Cutaneous Leishmaniasis (CL). The aim of this study was to determine whether FTG was the cause of cutaneous lesions in patients who were referred to the Parasitology laboratory of Imam Reza Hospital in Mashhad to be investigated for CL. Materials/Methods: One hundered patients, clinically diagnosed with CL between April 2014 and March 2015, were included in this study. Ziehl-Neelsen staining was performed to identify acid-fast Mycobacterium in addition to bacterial cultures using Löwenstein-Jensen medium. Skin lesion samples were also collected and kept on DNA banking cards for PCR testing. Results: Twenty-nine of the 100 individuals with skin lesions, and therefore suspected of suffering from CL, tested positive for Mycobacterium marinum by PCR. Of these, 21 (72.4%) were male and 8(27.6%) were female. In 97% of these cases the lesions were located on hands and fingers. These patients had a history of manipulating fish and had been in contact with aquarium water. A sporotrichoid appearance was observed in 58.6% of the patients with mycobacterial lesions; 67% of patients had multiple head appearance. Conclusion: Patients suspected to have CL and who test negative for CL could be affected by FTG. Therefore, after obtaining an accurate case history, molecular diagnosis is recommended for cases that give a negative result by conventional methods. [ABSTRACT FROM AUTHOR]

Three populations of Xiphinema primum n. sp. and two populations of X. pachtaicum were recovered from natural forests and cultural regions of northern Iran. Both species belong to the X. americanum-group and were characterized by their morphological, morphometric and molecular data. The new species, which was recovered in three locations, belongs to the X. brevicolle-complex and is characterized by 2124–2981 μm long females with a widely rounded lip region separated from the rest of the body by a depression, 103–125 μm long odontostyle, two equally developed genital branches with endosymbiont bacteria inside the ovary, which are visible under light microscope (LM), vulva located at 51.8–58.0%, the tail is 26–37 μm long with a bluntly rounded end and four juvenile developmental stages. It was morphologically compared with nine similar species viz. X. brevicolle, X. diffusum, X. incognitum, X. himalayense, X. luci, X. parabrevicolle, X. paramonovi, X. parataylori and X. taylori. The second species, X. pachtaicum, was recovered in two geographically distant points close to city of Amol. Molecular phylogenetic studies of the new species were performed using partial sequences of the D2-D3 expansion segments of the large subunit ribosomal RNA gene (LSU rDNA D2-D3), the internal-transcribed spacer rDNA (ITS = ITS1+5.8S+ITS2), and the mitochondrial cytochrome c oxidase I gene (COI mtDNA) regions. The Iranian population of X. pachtaicum was also phylogenetically studied based upon its LSU rDNA D2-D3 sequences. Both species were also inspected for their putative endosymbiont bacteria. Candidatus Xiphinematobacter sp. was detected from two examined populations of the new species, whereas the second endosymbiont bacterium, detected from three examined isolates of X. pachtaicum, was related to the plant and fungal endosymbionts of the family Burkholderiaceae. The phylogenetic analyses of the two endosymbiont bacteria were performed using partial sequences of 16S rDNA. In cophylogenetic analyses, significant levels of cophylogenetic signal were observed using both LSU rDNA D2-D3 and COI mtDNA markers of the host nematodes and 16S rDNA marker of the endosymbiont bacteria. [ABSTRACT FROM AUTHOR]

One of the most important fungal agents of pistachio dieback disease belongs to the ascomycete genus Paecilomyces that has been identified as P. variotii. In 2012–2014, 700 plant samples from pistachio trees and 27 other plant species with dieback symptoms were collected from 10 provinces of Iran. Of the 567 pistachio samples, 277 Paecilomyces strains were obtained and from the 133 samples of other plants (except pistachio and including Pistacia mutica, Punica granatum, Prunus amygdalus, Caesalpinia gilliesii, Nerium oleander, Tamarix aphylla, Tamarix hispida and Haloxylon sp.), 23 fungal isolates were recovered and five isolates were obtained from the air of infected pistachio orchards. Based on morphology, all 305 isolates were identified as P. variotii. Physiological studies revealed that 299 isolates belong to P. formosus. Three isolates were assigned to P. variotii, while three isolates could not be assigned to any of the known species. Of the 305 isolates, 62 were selected for phylogenetic analysis based on DNA variation (ITS, β-tubulin and calmodulin). This analysis showed that all of our isolates form a clade with P. formosus. P. formosus consists of the three former species P. formosa, P. lecythidis and P. maximus. This study shows that our isolates form a strongly supported clade with strains of P. lecythidis. So, the causal agent of dieback disease of pistachio and other examined trees is P. formosus which is closely related to the former species P. lecythidis and has some differences with the former species P. formosa and P. maximus. Based on phylogenetic studies P. formosus thus seems to be a species complex that could be divided into three separate species. [ABSTRACT FROM AUTHOR]

Recent studies have shown that oilfield harbours diverse microbial communities. Water-flooding is believed to be the main contaminating factor of oil reservoirs, however, less attempts have been made to study the effect of natural gas injection on microbial community of oilfields. Molecular methods were used to evaluate the microbial diversity of Haftkel (HK) and Lali (LA) petroleum reservoirs in the south of Iran. The HK oilfield has been injected with natural gas for long duration, but LA oilfield had no enhanced oil recovery (EOR) process. Next generation sequencing (NGS) of 16S rRNA archaeal genes indicated that the genus Methanofollis was observed with high presence in 89.7% and 92.6% frequency in the HK and LA oilfields, respectively. Most abundant phyla in HK oilfield were Synergistes (58.1%), Firmicutes (17%), Proteobacteria (Betaproteobacteria) 12.8% and unclassified bacteria (5.2%), while Thermotogae (78%), Firmicutes (10.8%), Synergistes (4%) and unclassified bacteria (3.8%) were observed in LA oilfield. The comparison of the results indicated that the injection of natural gas could increase bacterial diversity and most probable cause to increase frequency of bacterial genus Anaerobaculum belonging to the Synergistes. [ABSTRACT FROM AUTHOR]

Two strains of true branched heterocytous cyanobacteria, SA33 and SA16, isolated from dried paddy fields of Mazandaran, Iran, were studied using morphological, ecological, and molecular tools. Morphological characterization of the strains indicated them to be commonly showing profuse T-type branching, large irregularly shaped cells of main filament and tapering branches. Strain SA33 showed development of interesting biseriate filaments with unilateral branching, while strain SA16 showed uniseriate filaments with bilateral branching. Ecological examination of the localities consisted of the assessment of the habitat and correlations with the overall environment of the habitats. 16S rRNA gene-based molecular and phylogenetic assessment gave unique positioning to both the strains separated with good bootstrap support from rest of the members of the true branched clade. Full length sequencing of the 16S-23S ITS region and folding of the secondary structures gave interesting secondary structures and comparison with the closely related sequences clearly indicated the secondary structures of both the strains to be unique. All the results indicated the strains to be members of a morphologically cryptic but phylogenetically distinct unknown genus of cyanobacteria. Comprehensive evaluation of all the findings and comparative assessment of previous studies indicate that SA33 and SA16 are indeed two new species of a new genus of true branched cyanobacteria. In accordance with the International Code of Nomenclature for algae, fungi and plants, we propose the name of the new genus as Neowestiellopsis with the names of the species being Neowestiellopsis persica and Neowestiellopsis bilateralis. [ABSTRACT FROM AUTHOR]

Introduction: Unintended pregnancies and abortion may be considered as occupational hazards for female sex workers (FSWs). As our understanding of contraceptive and abortion practices of Iranian FSWs is very limited, this study tries to assess the dynamics of contraception and abortion among this sub-population. Methods: This survey was conducted in 2010, by recruiting 872 FSWs through facility-based sampling from 21 sites in 14 cities in Iran. Data were collected through face-to-face interviews using a pilot-tested standardized risk assessment questionnaire. We applied the logistic regression model to investigate the correlates of induced abortion among FSWs. Results: Of the 863 participants with valid responses to the abortion variable, 35.3% (95% CI: 32.1–38.6) acknowledged ever induced abortion and the annual rate of abortion was estimated at 20.7 per 1000 women. Around 31.2% of FSWs reported no usual contraceptive use, 32.6% barrier method, 23.6% non-barrier modern contraception methods, and 12.5% dual protection. In our multivariable model, older age (Adjusted Odds Ratio (AOR) = 1.74, 95% Confidence Interval (CI): 1.02, 2.96), group sex (AOR = 1.92, 95% CI: 1.10, 3.35), history of travel for sex work (AOR = 1.55, 95% CI: 1.09, 2.20), sexual violence (AOR = 1.77, 95% CI: 1.25, 2.50), STIs in last year (AOR = 1.53, 95% CI: 1.09, 2.14), and accessing family planning services (AOR = 1.76, 95% CI: 1.24, 2.49) were significant predictors of lifetime abortion. Conclusions: The reproductive health needs of Iranian FSWs are unmet and around one-third of FSWs reported induced abortion. Scaling-up comprehensive family planning services and empowering FSWs to have safer sex practices may help them to prevent unintended pregnancies and further risk of HIV transmission. [ABSTRACT FROM AUTHOR]

Introduction: The evidence is mixed on the HIV knowledge, attitude, and practices of youth in Iran. The aim of the current study was to assess knowledge, attitudes, and practices of Iranian youth towards HIV through a national survey. Materials and Methods: Through a cross-sectional study with multistage cluster sampling, we administered a pilot-tested standard questionnaire to assess the levels of HIV knowledge, attitudes and practices of individuals aged 15–29 years old. Participants were recruited from 13 provinces in Iran and consisted of 2456 men and 2412 women. Results: Only 37.3% of the participants had a high knowledge score. Most participants knew the main routes of HIV transmission; however, misconceptions existed about the transmission of HIV through mosquito bites across all age groups (31.7% correct response). Positive levels of attitude wereobserved among 20.7% of the participants. Most participants believed that people living with HIV (PLHIV) should be supported (88.3%) while only 46.3% were ready to share a table with them. Among those aged 19–29 years old, the main source of HIV information was mass media (69.1%), only 13.1% had ever tested for HIV, around 20.8% had ever had extramarital sex (31.7% male vs. 9.6% female),1.8% ever injected drugs (2.9% male vs. and 0.7% female). Among sexually active subjects in this age group, only 21.8% (26.1% male vs. 7.1% female) were consistent condom users. Conclusions: The findings showed that Iranian youth and young adults have relatively insufficient overall knowledge and negative attitudes about HIV and PLHIV. Novel strategies involving schools and youth’s networks could be employed to deliver a culturally sensitive sexual health program. [ABSTRACT FROM AUTHOR]

Background:Broad-spectrumβ-lactams are used for empirical therapy of severe infections with non-typhoidSalmonellaserotypes; however, activities of these drugs against the strains producing differentβ-lactamase is not so clear. This study investigated the prevalence ofβ-lactamase genes among isolates ofS. entericaserovars from human faecal samples and determined their diversity in activity against differentβ-lactams. Methods:Antimicrobial resistance of faecal isolates ofS. entericato extended-spectrum cephalosporins was analysed and MIC values were determined for the strains presenting extended-spectrumβ-lactamases (ESBLs) phenotypes. Theβ-lactamase genes were identified by PCR and sequencing.β-lactamase activity of theSalmonellastrains exhibiting ESBL phenotype was detected by biological, iodometric, spectrophotometry and nitrocefin assays. Results:Out of 202S. entericaisolates, ESBLs phenotype was detected among 3.4% (7/202) of the strains.blaTEM-1andblaCTX-M-15were among the frequentβ-lactamase genes. Detection ofblaTEM-169inS. entericaserovar Typhimurium andS. entericaserovar Bredeney andblaPER-1inS. entericaserovar Infantis was a new finding in this experiment. Location ofblaCTX-M-15/blaTEM-169/blaPER-1genes on plasmid was confirmed in a transformation experiment. While crude extracts of the enzymes from each strain showed higher activity against cephalothin and cefotaxime, the lowest activity was detected against ceftazidime. The greatest synergistic activity was seen in a strain ofS. entericathat carriedblaCTX-M-15andblaPER-1genes compared with those presentingblaCTX-M-15/blaTEM-169orblaCTX-M-15/blaTEM-1genotypes. Conclusions:The results show dissemination of ESBLs encoding genes and their combined activity among different serovars ofS. entericathat are a threat for future treatment options. [ABSTRACT FROM PUBLISHER]

Objective: Invasive cervical cancer (ICC) is the fourth most common cancer among women worldwide. Cervical screening programs have reduced the incidence and mortality rates of ICC. We studied the cost-effectiveness of different cervical screening strategies in the Islamic Republic of Iran, a Muslim country with a low incidence rate of ICC. Methods: We constructed an 11-state Markov model, in which the parameters included regression and progression probabilities, test characteristics, costs, and utilities; these were extracted from primary data and the literature. Our strategies included Pap smear screening and human papillomavirus (HPV) DNA testing plus Pap smear triaging with different starting ages and screening intervals. Model outcomes included lifetime costs, life years gained, quality-adjusted life years (QALY), and incremental cost-effectiveness ratios (ICERs). One-way sensitivity analysis was performed to examine the stability of the results. Results: We found that the prevented mortalities for the 11 strategies compared with no screening varied from 26% to 64%. The most cost-effective strategy was HPV screening, starting at age 35 years and repeated every 10 years. The ICER of this strategy was $8,875 per QALY compared with no screening. We found that screening at 5-year intervals was also cost-effective based on GDP per capita in Iran. Conclusion: We recommend organized cervical screening with HPV DNA testing for women in Iran, beginning at age 35 and repeated every 10 or 5 years. The results of this study could be generalized to other countries with low incidence rates of cervical cancer. [ABSTRACT FROM AUTHOR]

Background and aims. The aim of this investigation was to compare clinical and microbiological effectiveness of adjunctive photodynamic therapy (PDT) in the treatment of periodontitis. Materials and methods. Twenty-four subjects (14 women and 10 men) diagnosed with moderate to severe chronic periodontitis underwent scaling and root planing (SRP). One tooth in each quadrant (probing depth >4 mm) was selected for combined PDT and SRP (PDT group) with the contralateral tooth (SRP group), as a control site (SRP-treated site). Clinical assessment was carried out at baseline and 1 and 3 month later. Microbial assessment was carried out by real-time PCR. Periodontal probing depth (PPD) was considered as the primary outcome. Results. Baseline PPDs were 4.86±0.77 and 4.04±0.65 in the SRP and PDT groups, respectively (P>0.05), which decreased to 3.65±0.58 in the SRP and 3.86±0.56 in the PDT groups after one month and to 3.20±0.68 in the SRP and 3.34±0.56 in the PDT groups three months later. Although values decreased significantly in both groups after one (P=0.001 in the SRP and P=0.001 in the PDT groups) and three months (P=0.001 in the SRP and P=0.001 in the PDT groups) the inter-group differences were not significant after one (P=0.25) and three months (P=0.51). Clinical measurements showed significant decreases after one and three months at both sites, without inter-group differences, except for bleeding on probing after one (P=0.004) and three months (P=0.0001). Conclusion. Subgingival application of PDT combined with scaling and root planing could not improve clinical and microbiological results. [ABSTRACT FROM AUTHOR]

Introduction: The results of the network scale-up (NSU) method in estimating the size of key populations for HIV might be biased if the recruited subjects are not fully informed of the risky behaviors of people in their networks (low visibility), or key populations have a smaller social network (low popularity). We aimed to measure such biases in the size estimation of people who inject drugs (PWIDs), and female sex workers (FSWs) in Iran. Methods: We interviewed 163 male PWIDs, 76 FSWs (known as egos) and 600 subjects from the general population. We selected twenty first-names (ten males and ten females) and asked the study subjects separately how many people they knew with one of these names (known as alters). Visibility Factor (VF) was defined as the percentage of FSW or PWID alters that were aware of their behavior. In addition, the popularity factor (PF) was calculated by dividing the number of alters reported by FSWs and PWIDs into that of the general population. The 95% uncertainty intervals (UI) were calculated using bootstrap technique. Results: The VF was estimated at 54% (95% UI: 52%–56%) for PWID and 45% (95% UI: 42%– 48%) for FSW. The VF among the peer alters was significantly higher than non-peer ones. The PF for PWID and FSW was 69% (95% UI: 66%–73%) and 77% (95% UI: 72%–83%), respectively. The cross-validation and name splitting analysis showed that our estimates were not influenced by any single name. Conclusions: Both correction factors, particularly VF were far from one, and NSU results without correction, could lead to up to 4 times underestimation of the sizes. Therefore, applying these coefficients is necessary in NSU projects. [ABSTRACT FROM AUTHOR]

The objective of this study was to identify and estimate the prevalence of Escherichia coli O157:H7 in cattle fecal samples in northwest of Iran, using multiplex polymerase chain reaction (PCR). In this study, cattle fecal samples were collected from an abattoir in Tabriz, Iran. After enrichment, isolation was carried out on CT-SMAC culture and afterwards, the identification of E. coli O157 was achieved on colorless sorbitol negative colonies. Then, one of these colonies was analyzed by PCR to identify genes coding for verotoxin 1 and 2 (vt1 and vt2), intimin (eceAO157), and H7 flagella antigen (fliCh7). Of 200 samples, 22 were positive by CT-SMAC culture. Of the 22 sorbitol- negative samples investigated by PCR, two isolates were identified as E. coli O157:H7. Three isolates carried eaeAO157 specific locus (non-VTEC E.coli O157) and one or both the verotoxin genes (vtx1 and vtx2) only (non-O157 VTEC). Low prevalence rates of E. coli O157:H7 in cattle feces as an important animal reservoir of the mentioned bacterium should be added to the variety of factors mentioned for the low prevalence of E. coli O157:H7 in Iran. [ABSTRACT FROM AUTHOR]

Measles virus (MV) causes small and large outbreaks in Iran. Molecular assays allow identifying and the sources of measles imported from neighboring countries. We carried out a phylogenetic analysis of measles virus circulating in Iran over the period 2010–2012. Specimens from suspected cases of measles were collected from different regions of Iran. Virus isolation was performed on urine and throat swabs. Partial nucleoprotein gene segments of MV were amplified by RT-PCR. PCR products of 173 samples were sequenced and analyzed. The median age of confirmed cases was 2 years. Among all confirmed cases, 32% had unknown vaccination status, 20% had been vaccinated, and 48% had not been vaccinated. Genotypes B3 and D8 (for the first time), H1 and D4 were detected mainly in unvaccinated toddlers and young children. Genotype B3 became predominant in 2012 and was closely related to African strains. H1 strains were also found in small and large outbreaks during 2012 but were not identical to Iranian H1-2009 strains. A majority of the Iranian D4 strains during 2010–2012 outbreaks were linked to the D4 strain identified in the Pakistan in 2007. We identified a single case in 2010 belonging to D8 genotype with 99.7% identity to Indian isolates. Although the vaccination program is currently good enough to prevent nationwide epidemics and successfully decreased measles incidence in Iran, the fraction of protected individuals in the population was not high enough to prevent continuous introduction of cases from abroad. Due to increasing number of susceptible individuals in some areas, sustained transmission of the newly introduced viral genotype remains possible. [ABSTRACT FROM AUTHOR]

Background: Alveolar echinococcosis is a zoonotic disease caused by the metacestode of Echinococcus multilocularis. Many species of small mammals, including arvicolid rodents or Ochotona spp., are natural intermediate hosts of the cestode. The main aim of this study was to identify natural intermediate hosts of E. multilocularis in Chenaran County, Razavi Khorasan Province, northeastern Iran, where the prevalence of infected wild and domestic carnivores is high. Methodology/Principal Findings: A program of trapping was carried out in five villages in which this cestode was reported in carnivores. The livers of 85 small mammals were investigated for the presence of E. multilocularis infection using multiplex PCR of mitochondrial genes. Infections were identified in 30 specimens: 23 Microtus transcaspicus, three Ochotona rufescens, two Mus musculus, one Crocidura gmelini, and one Apodemus witherbyi. Conclusions/Significance: A range of small mammals therefore act as natural intermediate hosts for the transmission of E. multilocularis in Chenaran County, and the prevalence suggested that E. multilocularis infection is endemic in this region. The existence of the life cycle of this potentially lethal cestode in the vicinity of human habitats provides a significant risk of human infection. [ABSTRACT FROM AUTHOR]

A xylanase producer Bacillus mojavensis strain, called AG137, isolated from cotton farm (Kashan-Iran). The optimal xylanase activity reached at 55°C & pH 9.0. Enzyme yield was studied using a medium with different agricultural wastes as inducers. Xylanase production of about 249.308 IU/mL was achieved at pH 8 and 37°C, within 48 h submerged fermentation in enzyme production medium supplemented with 2% (w/v) oat bran as an optimum carbon source. A mixture of 1% (w/v) yeast extract and 1%(w/v) tryptone as optimum nitrogen sources, agitation speed 200 rpm, and inoculumsize 2%(v/v) were the optimums for maximum production. Accordingly, xylanase yield from 194.68 IU/mL under non-optimized fermentation condition enhanced to 302.466 IU/mL in optimized condition. Screened xylanase is thermostable, presenting 70% stability at 60?C during 30 min. Further enzyme incubation in higher temperature caused a decrease in the residual enzyme activity, yet it retained 68%-50% of its activity after 1 hour from 45?C to 55°C. Besides, it is stable in pH 9 and 10, maintaining over 70% of its activity for 2 h. The enzyme also could preserve 71% and 63% of its initial activity after 3 hours of pre-incubation in the same alkaline condition. Produced xylanase therefore was introduced as an alkaline-active and stable one, displaying suitable thermostability feature, confirmed by HPLC analysis. Hence, all xylanase properties highlight its promising uses in industrial scale. [ABSTRACT FROM AUTHOR]

In this research, antimicrobial activity of Salvia leriifolia leaf extract was investigated on Staphylococcus aureus growth with different concentrations (5,000, 10,000, 15,000 and 20,000 mg/L) in hamburger. Purified S. aureus was inoculated to hamburger and then stored at -12C. Samples were subjected to microbiological analyses (total viable count and numbers of S. aureus) at different time intervals (15, 30 and 45 days). Results showed that total viable count and the number of S. aureus in all samples with different concentrations of extract declined during storage. This effect was significant at day 15 and 30 for S. aureus and total viable count, respectively. The highest concentration of S. leriifolia extract caused maximum reduction in S. aureus population and total viable count. These data indicated that S. leriifolia extract can exhibit antimicrobial activity against S. aureus, so it can be considered as an alternative natural preservative in such food products. [ABSTRACT FROM AUTHOR]

Purpose: To examine the microbiology and antibiogram of specimens from patients with dacryocystitis. Methods: A total of 66 samples from lacrimal sac contents of 61 consecutive patients with acute and chronic dacryocystitis were obtained. These specimens were cultured for bacteria with a routine microbiological technique. Antibiograms were acquired from positive cultures. Results: A total of 61 patients (12 patients with acute and 49 patients with chronic dacryocystitis) were included in this investigation with the average age of 40 (12-85) years (female = 74% and male = 26%). Five patients were culture-negative and five patients had mixed gram-positive cultures (a total of 66 samples were obtained). The total prevalence of gram-positive, gram-negative, and culture-negative samples were 71.2%, 21.2%, and 7.6%, respectively. The prevalence of gram-positive, gram-negative, and culture-negative samples were 77.4%, 18.9%, and 3.8% in the chronic and 46.2%, 30.8%, and 23.1% in the acute groups, respectively. The most prevalent pathogen in both groups was Staphylococcus epidermis. In 38% of patients the culture results were similar to those of the contralateral conjunctival flora. Gram-negative bacteria had a high sensitivity to ciprofloxacin and cephalexin while the gram-positive ones were highly sensitive to ceftriaxone and ampicillin. Conclusion: The responsible pathogens in acute and chronic dacryocystitis are significantly different. Because of the high prevalence of gram-negative bacteria and also culture-negative samples and considering the necessity of treatment in acute dacryocystitis, selecting an appropriate antibiotic with a good coverage of gram-negative and gram-positive bacteria seems essential. [ABSTRACT FROM AUTHOR]